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Barber BE, Webster R, Potter AJ, Llewellyn S, Sahai N, Leelasena I, Mathison S, Kuritz K, Flynn J, Chalon S, Marrast AC, Gobeau N, Moehrle JJ. Characterising the blood-stage antimalarial activity of pyronaridine in healthy volunteers experimentally infected with Plasmodium falciparum. Int J Antimicrob Agents 2024; 64:107196. [PMID: 38734217 DOI: 10.1016/j.ijantimicag.2024.107196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2023] [Revised: 04/23/2024] [Accepted: 05/03/2024] [Indexed: 05/13/2024]
Abstract
With the spread of artemisinin resistance throughout Southeast Asia and now in Africa, the antimalarial drug pyronaridine is likely to become an increasingly important component of new antimalarial drug regimens. However, the antimalarial activity of pyronaridine in humans has not been completely characterised. This volunteer infection study aimed to determine the pharmacokinetic/pharmacodynamic (PK/PD) relationship of pyronaridine in malaria naïve adults. Volunteers were inoculated with Plasmodium falciparum-infected erythrocytes on day 0 and administered different single oral doses of pyronaridine on day 8. Parasitaemia and concentrations of pyronaridine were measured and standard safety assessments performed. Curative artemether-lumefantrine therapy was administered if parasite regrowth occurred, or on day 47 ± 2. Outcomes were parasite clearance kinetics, PK and PK/PD parameters from modelling. Ten participants were inoculated and administered 360 mg (n = 4), 540 mg (n = 4) or 720 mg (n = 1) pyronaridine. One participant was withdrawn without receiving pyronaridine. The time to maximum pyronaridine concentration was 1-2 h, the elimination half-life was 8-9 d, and the parasite clearance half-life was approximately 5 h. Parasite regrowth occurred with 360 mg (4/4 participants) and 540 mg (2/4 participants). Key efficacy parameters including the minimum inhibitory concentration (5.5 ng/mL) and minimum parasiticidal concentration leading to 90% of maximum effect (MPC90: 8 ng/mL) were derived from the PK/PD model. Adverse events considered related to pyronaridine were predominantly mild to moderate gastrointestinal symptoms. There were no serious adverse events. Data obtained in this study will support the use of pyronaridine in new antimalarial combination therapies by informing partner drug selection and dosing considerations.
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Affiliation(s)
- Bridget E Barber
- QIMR Berghofer Medical Research Institute, Herston, QLD, Australia; University of the Sunshine Coast Clinical Trials, Morayfield, QLD, Australia; Royal Brisbane and Women's Hospital, Herston, QLD, Australia
| | - Rebecca Webster
- QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Adam J Potter
- QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Stacey Llewellyn
- QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Nischal Sahai
- University of the Sunshine Coast Clinical Trials, Morayfield, QLD, Australia
| | - Indika Leelasena
- University of the Sunshine Coast Clinical Trials, Morayfield, QLD, Australia
| | - Susan Mathison
- University of the Sunshine Coast Clinical Trials, Morayfield, QLD, Australia
| | | | - Julia Flynn
- Medicines for Malaria Venture, Geneva, Switzerland
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Achan J, Barry A, Leroy D, Kamara G, Duparc S, Kaszubska W, Gandhi P, Buffet B, Tshilab P, Ogutu B, Taylor T, Krishna S, Richardson N, Ramachandruni H, Rietveld H. Defining the next generation of severe malaria treatment: a target product profile. Malar J 2024; 23:174. [PMID: 38835069 DOI: 10.1186/s12936-024-04986-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Accepted: 05/14/2024] [Indexed: 06/06/2024] Open
Abstract
BACKGROUND Severe malaria is a life-threatening infection, particularly affecting children under the age of 5 years in Africa. Current treatment with parenteral artemisinin derivatives is highly efficacious. However, artemisinin partial resistance is widespread in Southeast Asia, resulting in delayed parasite clearance after therapy, and has emerged independently in South America, Oceania, and Africa. Hence, new treatments for severe malaria are needed, and it is prudent to define their characteristics now. This manuscript focuses on the target product profile (TPP) for new treatments for severe malaria. It also highlights preparedness when considering ways of protecting the utility of artemisinin-based therapies. TARGET PRODUCT PROFILE Severe malaria treatments must be highly potent, with rapid onset of antiparasitic activity to clear the infection as quickly as possible to prevent complications. They should also have a low potential for drug resistance selection, given the high parasite burden in patients with severe malaria. Combination therapies are needed to deter resistance selection and dissemination. Partner drugs which are approved for uncomplicated malaria treatment would provide the most rapid development pathway for combinations, though new candidate molecules should be considered. Artemisinin combination approaches to severe malaria would extend the lifespan of current therapy, but ideally, completely novel, non-artemisinin-based combination therapies for severe malaria should be developed. These should be advanced to at least phase 2 clinical trials, enabling rapid progression to patient use should current treatment fail clinically. New drug combinations for severe malaria should be available as injectable formulations for rapid and effective treatment, or as rectal formulations for pre-referral intervention in resource-limited settings. CONCLUSION Defining the TPP is a key step to align responses across the community to proactively address the potential for clinical failure of artesunate in severe malaria. In the shorter term, artemisinin-based combination therapies should be developed using approved or novel drugs. In the longer term, novel combination treatments should be pursued. Thus, this TPP aims to direct efforts to preserve the efficacy of existing treatments while improving care and outcomes for individuals affected by this life-threatening disease.
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Affiliation(s)
| | - Aïssata Barry
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Didier Leroy
- Medicines for Malaria Venture, Route de Pré-Bois 20, Post Box 1826, CH-1215, Geneva 15, Switzerland
| | - George Kamara
- Médecins Sans Frontières, Magburaka District Hospital, Freetown, Sierra Leone
| | - Stephan Duparc
- Medicines for Malaria Venture, Route de Pré-Bois 20, Post Box 1826, CH-1215, Geneva 15, Switzerland
| | - Wiweka Kaszubska
- Medicines for Malaria Venture, Route de Pré-Bois 20, Post Box 1826, CH-1215, Geneva 15, Switzerland
| | | | - Bénédicte Buffet
- Medicines for Malaria Venture, Route de Pré-Bois 20, Post Box 1826, CH-1215, Geneva 15, Switzerland
| | | | - Bernhards Ogutu
- Centre for Clinical Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Terrie Taylor
- Queen Elizabeth Central Hospital and Blantyre Malaria Project, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Sanjeev Krishna
- Institut Für Tropenmedizin, Eberhard Karls Universität Tübingen, and German Center for Infection Research (Dzif), Tübingen, Germany
- Centre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon
- Clinical Academic Group, Institute for Infection and Immunity, St. George's University of London, London, UK
- St George's University Hospitals NHS Foundation Trust, London, UK
| | | | - Hanu Ramachandruni
- Medicines for Malaria Venture, Route de Pré-Bois 20, Post Box 1826, CH-1215, Geneva 15, Switzerland.
| | - Hans Rietveld
- Medicines for Malaria Venture, Route de Pré-Bois 20, Post Box 1826, CH-1215, Geneva 15, Switzerland.
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Webster R, Mitchell H, Peters JM, Heunis J, O'Neill B, Gower J, Lynch S, Jennings H, Amante FH, Llewellyn S, Marquart L, Potter AJ, Birrell GW, Edstein MD, Shanks GD, McCarthy JS, Barber BE. Transmission Blocking Activity of Low-dose Tafenoquine in Healthy Volunteers Experimentally Infected With Plasmodium falciparum. Clin Infect Dis 2023; 76:506-512. [PMID: 35731843 DOI: 10.1093/cid/ciac503] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 06/13/2022] [Accepted: 06/16/2022] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Blocking the transmission of parasites from humans to mosquitoes is a key component of malaria control. Tafenoquine exhibits activity against all stages of the malaria parasite and may have utility as a transmission blocking agent. We aimed to characterize the transmission blocking activity of low-dose tafenoquine. METHODS Healthy adults were inoculated with Plasmodium falciparum 3D7-infected erythrocytes on day 0. Piperaquine was administered on days 9 and 11 to clear asexual parasitemia while allowing gametocyte development. A single 50-mg oral dose of tafenoquine was administered on day 25. Transmission was determined by enriched membrane feeding assays predose and at 1, 4, and 7 days postdose. Artemether-lumefantrine was administered following the final assay. Outcomes were the reduction in mosquito infection and gametocytemia after tafenoquine and safety parameters. RESULTS Six participants were enrolled, and all were infective to mosquitoes before tafenoquine, with a median 86% (range, 22-98) of mosquitoes positive for oocysts and 57% (range, 4-92) positive for sporozoites. By day 4 after tafenoquine, the oocyst and sporozoite positivity rate had reduced by a median 35% (interquartile range [IQR]: 16-46) and 52% (IQR: 40-62), respectively, and by day 7, 81% (IQR 36-92) and 77% (IQR 52-98), respectively. The decline in gametocyte density after tafenoquine was not significant. No significant participant safety concerns were identified. CONCLUSIONS Low-dose tafenoquine (50 mg) reduces P. falciparum transmission to mosquitoes, with a delay in effect.
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Affiliation(s)
- Rebecca Webster
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Hayley Mitchell
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Jenny M Peters
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Juanita Heunis
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Brighid O'Neill
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Jeremy Gower
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Sean Lynch
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Helen Jennings
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Fiona H Amante
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | | | | | - Adam J Potter
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Geoffrey W Birrell
- Australian Defence Force Malaria and Infectious Disease Institute, Brisbane, Australia
| | - Michael D Edstein
- Australian Defence Force Malaria and Infectious Disease Institute, Brisbane, Australia
| | - G Dennis Shanks
- Australian Defence Force Malaria and Infectious Disease Institute, Brisbane, Australia
| | - James S McCarthy
- QIMR Berghofer Medical Research Institute, Brisbane, Australia.,The Peter Doherty Institute for Infection and Immunity, Melbourne, Australia
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Assefa A, Mohammed H, Anand A, Abera A, Sime H, Minta AA, Tadesse M, Tadesse Y, Girma S, Bekele W, Etana K, Alemayehu BH, Teka H, Dilu D, Haile M, Solomon H, Moriarty LF, Zhou Z, Svigel SS, Ezema B, Tasew G, Woyessa A, Hwang J, Murphy M. Therapeutic efficacies of artemether-lumefantrine and dihydroartemisinin-piperaquine for the treatment of uncomplicated Plasmodium falciparum and chloroquine and dihydroartemisinin-piperaquine for uncomplicated Plasmodium vivax infection in Ethiopia. Malar J 2022; 21:359. [PMID: 36451216 PMCID: PMC9714156 DOI: 10.1186/s12936-022-04350-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 10/27/2022] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Routine monitoring of anti-malarial drugs is recommended for early detection of drug resistance and to inform national malaria treatment guidelines. In Ethiopia, the national treatment guidelines employ a species-specific approach. Artemether-lumefantrine (AL) and chloroquine (CQ) are the first-line schizonticidal treatments for Plasmodium falciparum and Plasmodium vivax, respectively. The National Malaria Control and Elimination Programme in Ethiopia is considering dihydroartemisinin-piperaquine (DHA/PPQ) as an alternative regimen for P. falciparum and P. vivax. METHODS The study assessed the clinical and parasitological efficacy of AL, CQ, and DHA/PPQ in four arms. Patients over 6 months and less than 18 years of age with uncomplicated malaria mono-infection were recruited and allocated to AL against P. falciparum and CQ against P. vivax. Patients 18 years or older with uncomplicated malaria mono-infection were recruited and randomized to AL or dihydroartemisinin-piperaquine (DHA/PPQ) against P. falciparum and CQ or DHA/PPQ for P. vivax. Patients were followed up for 28 (for CQ and AL) or 42 days (for DHA/PPQ) according to the WHO recommendations. Polymerase chain reaction (PCR)-corrected and uncorrected estimates were analysed by Kaplan Meier survival analysis and per protocol methods. RESULTS A total of 379 patients were enroled in four arms (n = 106, AL-P. falciparum; n = 75, DHA/PPQ- P. falciparum; n = 142, CQ-P. vivax; n = 56, DHA/PPQ-P. vivax). High PCR-corrected adequate clinical and parasitological response (ACPR) rates were observed at the primary end points of 28 days for AL and CQ and 42 days for DHA/PPQ. ACPR rates were 100% in AL-Pf (95% CI: 96-100), 98% in CQ-P. vivax (95% CI: 95-100) at 28 days, and 100% in the DHA/PPQ arms for both P. falciparum and P. vivax at 42 days. For secondary endpoints, by day three 99% of AL-P. falciparum patients (n = 101) cleared parasites and 100% were afebrile. For all other arms, 100% of patients cleared parasites and were afebrile by day three. No serious adverse events were reported. CONCLUSION This study demonstrated high therapeutic efficacy for the anti-malarial drugs currently used by the malaria control programme in Ethiopia and provides information on the efficacy of DHA/PPQ for the treatment of P. falciparum and P. vivax as an alternative option.
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Affiliation(s)
- Ashenafi Assefa
- Ethiopian Public Health Institute, Addis Ababa, Ethiopia. .,Institute for Global Health and Infectious Diseases, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
| | - Hussein Mohammed
- grid.452387.f0000 0001 0508 7211Ethiopian Public Health Institute, Addis Ababa, Ethiopia
| | - Anjoli Anand
- grid.416738.f0000 0001 2163 0069Epidemic Intelligence Service, U.S. Centers for Disease Control and Prevention, Atlanta, GA USA ,grid.416738.f0000 0001 2163 0069Malaria Branch, U.S. Centers for Disease Control and Prevention, Atlanta, GA USA
| | - Adugna Abera
- grid.452387.f0000 0001 0508 7211Ethiopian Public Health Institute, Addis Ababa, Ethiopia
| | - Heven Sime
- grid.452387.f0000 0001 0508 7211Ethiopian Public Health Institute, Addis Ababa, Ethiopia
| | - Anna A. Minta
- grid.416738.f0000 0001 2163 0069Epidemic Intelligence Service, U.S. Centers for Disease Control and Prevention, Atlanta, GA USA ,grid.416738.f0000 0001 2163 0069Malaria Branch, U.S. Centers for Disease Control and Prevention, Atlanta, GA USA
| | | | | | - Samuel Girma
- ICAP at Columbia University, Addis Ababa, Ethiopia ,U.S. President’s Malaria Initiative, USA Agency for International Development, Addis Ababa, Ethiopia
| | - Worku Bekele
- World Health Organization, Addis Ababa, Ethiopia
| | - Kebede Etana
- grid.414835.f0000 0004 0439 6364Ethiopian Federal Ministry of Health, Addis Ababa, Ethiopia
| | | | - Hiwot Teka
- U.S. President’s Malaria Initiative, USA Agency for International Development, Addis Ababa, Ethiopia
| | - Dereje Dilu
- grid.414835.f0000 0004 0439 6364Ethiopian Federal Ministry of Health, Addis Ababa, Ethiopia
| | - Mebrahtom Haile
- grid.414835.f0000 0004 0439 6364Ethiopian Federal Ministry of Health, Addis Ababa, Ethiopia
| | - Hiwot Solomon
- grid.414835.f0000 0004 0439 6364Ethiopian Federal Ministry of Health, Addis Ababa, Ethiopia
| | - Leah F. Moriarty
- grid.416738.f0000 0001 2163 0069U.S. President’s Malaria Initiative, Malaria Branch, US Centers for Disease Control and Prevention, Atlanta, GA USA
| | - Zhiyong Zhou
- grid.416738.f0000 0001 2163 0069Malaria Branch, U.S. Centers for Disease Control and Prevention, Atlanta, GA USA
| | - Samaly Souza Svigel
- grid.416738.f0000 0001 2163 0069Malaria Branch, U.S. Centers for Disease Control and Prevention, Atlanta, GA USA
| | - Bryan Ezema
- grid.416738.f0000 0001 2163 0069Malaria Branch, U.S. Centers for Disease Control and Prevention, Atlanta, GA USA
| | - Geremew Tasew
- grid.452387.f0000 0001 0508 7211Ethiopian Public Health Institute, Addis Ababa, Ethiopia
| | - Adugna Woyessa
- grid.452387.f0000 0001 0508 7211Ethiopian Public Health Institute, Addis Ababa, Ethiopia
| | - Jimee Hwang
- grid.416738.f0000 0001 2163 0069U.S. President’s Malaria Initiative, Malaria Branch, US Centers for Disease Control and Prevention, Atlanta, GA USA
| | - Matthew Murphy
- grid.416738.f0000 0001 2163 0069U.S. President’s Malaria Initiative, Malaria Branch, US Centers for Disease Control and Prevention, Atlanta, GA USA
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Woolley SD, Marquart L, Woodford J, Chalon S, Moehrle JJ, McCarthy JS, Barber BE. Haematological response in experimental human Plasmodium falciparum and Plasmodium vivax malaria. Malar J 2021; 20:470. [PMID: 34930260 PMCID: PMC8685492 DOI: 10.1186/s12936-021-04003-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Accepted: 12/01/2021] [Indexed: 11/25/2022] Open
Abstract
Background Malaria-associated anaemia, arising from symptomatic, asymptomatic and submicroscopic infections, is a significant cause of morbidity worldwide. Induced blood stage malaria volunteer infection studies (IBSM-VIS) provide a unique opportunity to evaluate the haematological response to early Plasmodium falciparum and Plasmodium vivax infection. Methods This study was an analysis of the haemoglobin, red cell counts, and parasitaemia data from 315 participants enrolled in IBSM-VIS between 2012 and 2019, including 269 participants inoculated with the 3D7 strain of P. falciparum (Pf3D7), 15 with an artemisinin-resistant P. falciparum strain (PfK13) and 46 with P. vivax. Factors associated with the fractional fall in haemoglobin (Hb-FF) were evaluated, and the malaria-attributable erythrocyte loss after accounting for phlebotomy-related losses was estimated. The relative contribution of parasitized erythrocytes to the malaria-attributable erythrocyte loss was also estimated. Results The median peak parasitaemia prior to treatment was 10,277 parasites/ml (IQR 3566–27,815), 71,427 parasites/ml [IQR 33,236–180,213], and 34,840 parasites/ml (IQR 13,302–77,064) in participants inoculated with Pf3D7, PfK13, and P. vivax, respectively. The median Hb-FF was 10.3% (IQR 7.8–13.3), 14.8% (IQR 11.8–15.9) and 11.7% (IQR 8.9–14.5) in those inoculated with Pf3D7, PfK13 and P. vivax, respectively, with the haemoglobin nadir occurring a median 12 (IQR 5–21), 15 (IQR 7–22), and 8 (IQR 7–15) days following inoculation. In participants inoculated with P. falciparum, recrudescence was associated with a greater Hb-FF, while in those with P. vivax, the Hb-FF was associated with a higher pre-treatment parasitaemia and later day of anti-malarial treatment. After accounting for phlebotomy-related blood losses, the estimated Hb-FF was 4.1% (IQR 3.1–5.3), 7.2% (IQR 5.8–7.8), and 4.9% (IQR 3.7–6.1) in participants inoculated with Pf3D7, PfK13, and P. vivax, respectively. Parasitized erythrocytes were estimated to account for 0.015% (IQR 0.006–0.06), 0.128% (IQR 0.068–0.616) and 0.022% (IQR 0.008–0.082) of the malaria-attributable erythrocyte loss in participants inoculated with Pf3D7, PfK13, and P. vivax, respectively. Conclusion Early experimental P. falciparum and P. vivax infection resulted in a small but significant fall in haemoglobin despite parasitaemia only just at the level of microscopic detection. Loss of parasitized erythrocytes accounted for < 0.2% of the total malaria-attributable haemoglobin loss. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-04003-7.
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Gadalla AAH, Siciliano G, Farid R, Alano P, Ranford-Cartwright L, McCarthy JS, Thompson J, Babiker HA. Real-time PCR assays for detection and quantification of early P. falciparum gametocyte stages. Sci Rep 2021; 11:19118. [PMID: 34580326 PMCID: PMC8476600 DOI: 10.1038/s41598-021-97456-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 08/25/2021] [Indexed: 11/11/2022] Open
Abstract
The use of quantitative qRT-PCR assays for detection and quantification of late gametocyte stages has revealed the high transmission capacity of the human malaria parasite, Plasmodium falciparum. To understand how the parasite adjusts its transmission in response to in-host environmental conditions including antimalarials requires simultaneous quantification of early and late gametocytes. Here, we describe qRT-PCR assays that specifically detect and quantify early-stage P. falciparum gametocytes. The assays are based on expression of known early and late gametocyte genes and were developed using purified stage II and stage V gametocytes and tested in natural and controlled human infections. Genes pfpeg4 and pfg27 are specifically expressed at significant levels in early gametocytes with a limit of quantification of 190 and 390 gametocytes/mL, respectively. In infected volunteers, transcripts of pfpeg4 and pfg27 were detected shortly after the onset of blood stage infection. In natural infections, both early (pfpeg4/pfg27) and late gametocyte transcripts (pfs25) were detected in 71.2% of individuals, only early gametocyte transcripts in 12.6%, and only late gametocyte transcripts in 15.2%. The pfpeg4/pfg27 qRT-PCR assays are sensitive and specific for quantification of circulating sexually committed ring stages/early gametocytes and can be used to increase our understanding of epidemiological processes that modulate P. falciparum transmission.
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Affiliation(s)
- Amal A H Gadalla
- College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Oman.,Division of Population Medicine, School of Medicine, College of Biomedical Sciences, Cardiff University, Cardiff, UK
| | - Giulia Siciliano
- Dipartimento di Malattie Infettive, Istituto Superiore di Sanità, Rome, Italy
| | - Ryan Farid
- QIMR Berghofer Medical Research Institute and University of Queensland, Brisbane, Australia
| | - Pietro Alano
- Dipartimento di Malattie Infettive, Istituto Superiore di Sanità, Rome, Italy
| | - Lisa Ranford-Cartwright
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - James S McCarthy
- QIMR Berghofer Medical Research Institute and University of Queensland, Brisbane, Australia
| | - Joanne Thompson
- Institute of Immunology and Infection Research, School of Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, UK
| | - Hamza A Babiker
- College of Medicine and Health Sciences, Sultan Qaboos University, Muscat, Oman.
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7
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Memvanga PB, Nkanga CI. Liposomes for malaria management: the evolution from 1980 to 2020. Malar J 2021; 20:327. [PMID: 34315484 PMCID: PMC8313885 DOI: 10.1186/s12936-021-03858-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Accepted: 07/16/2021] [Indexed: 12/31/2022] Open
Abstract
Malaria is one of the most prevalent parasitic diseases and the foremost cause of morbidity in the tropical regions of the world. Strategies for the efficient management of this parasitic infection include adequate treatment with anti-malarial therapeutics and vaccination. However, the emergence and spread of resistant strains of malaria parasites to the majority of presently used anti-malarial medications, on the other hand, complicates malaria treatment. Other shortcomings of anti-malarial drugs include poor aqueous solubility, low permeability, poor bioavailability, and non-specific targeting of intracellular parasites, resulting in high dose requirements and toxic side effects. To address these limitations, liposome-based nanotechnology has been extensively explored as a new solution in malaria management. Liposome technology improves anti-malarial drug encapsulation, bioavailability, target delivery, and controlled release, resulting in increased effectiveness, reduced resistance progression, and fewer adverse effects. Furthermore, liposomes are exploited as immunological adjuvants and antigen carriers to boost the preventive effectiveness of malaria vaccine candidates. The present review discusses the findings from studies conducted over the last 40 years (1980-2020) using in vitro and in vivo settings to assess the prophylactic and curative anti-malarial potential of liposomes containing anti-malarial agents or antigens. This paper and the discussion herein provide a useful resource for further complementary investigations and may pave the way for the research and development of several available and affordable anti-malarial-based liposomes and liposomal malaria vaccines by allowing a thorough evaluation of liposomes developed to date for the management of malaria.
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Affiliation(s)
- Patrick B Memvanga
- Faculty of Pharmaceutical Sciences, Laboratory of Pharmaceutics and Phytopharmaceutical Drug Development, University of Kinshasa, B.P. 212, Kinshasa XI, Democratic Republic of the Congo.
| | - Christian I Nkanga
- Faculty of Pharmaceutical Sciences, Laboratory of Pharmaceutics and Phytopharmaceutical Drug Development, University of Kinshasa, B.P. 212, Kinshasa XI, Democratic Republic of the Congo
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Persistent Submicroscopic Plasmodium falciparum Parasitemia 72 Hours after Treatment with Artemether-Lumefantrine Predicts 42-Day Treatment Failure in Mali and Burkina Faso. Antimicrob Agents Chemother 2021; 65:e0087321. [PMID: 34060901 PMCID: PMC8284475 DOI: 10.1128/aac.00873-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A recent randomized controlled trial, the WANECAM (West African Network for Clinical Trials of Antimalarial Drugs) trial, conducted at seven centers in West Africa, found that artemether-lumefantrine, artesunate-amodiaquine, pyronaridine-artesunate, and dihydroartemisinin-piperaquine all displayed good efficacy. However, artemether-lumefantrine was associated with a shorter interval between clinical episodes than the other regimens. In a further comparison of these therapies, we identified cases of persisting submicroscopic parasitemia by quantitative PCR (qPCR) at 72 h posttreatment among WANECAM participants from 5 sites in Mali and Burkina Faso, and we compared treatment outcomes for this group to those with complete parasite clearance by 72 h. Among 552 evaluable patients, 17.7% had qPCR-detectable parasitemia at 72 h during their first treatment episode. This proportion varied among sites, reflecting differences in malaria transmission intensity, but did not differ among pooled drug treatment groups. However, patients who received artemether-lumefantrine and were qPCR positive at 72 h were significantly more likely to have microscopically detectable recurrent Plasmodium falciparum parasitemia by day 42 than those receiving other regimens and experienced, on average, a shorter interval before the next clinical episode. Haplotypes of pfcrt and pfmdr1 were also evaluated in persisting parasites. These data identify a possible threat to the parasitological efficacy of artemether-lumefantrine in West Africa, over a decade since it was first introduced on a large scale.
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McCarthy JS, Donini C, Chalon S, Woodford J, Marquart L, Collins KA, Rozenberg FD, Fidock DA, Cherkaoui-Rbati MH, Gobeau N, Möhrle JJ. A Phase 1, Placebo-controlled, Randomized, Single Ascending Dose Study and a Volunteer Infection Study to Characterize the Safety, Pharmacokinetics, and Antimalarial Activity of the Plasmodium Phosphatidylinositol 4-Kinase Inhibitor MMV390048. Clin Infect Dis 2021; 71:e657-e664. [PMID: 32239164 PMCID: PMC7744986 DOI: 10.1093/cid/ciaa368] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 04/01/2020] [Indexed: 02/01/2023] Open
Abstract
Background MMV390048 is the first Plasmodium phosphatidylinositol 4-kinase inhibitor to reach clinical development as a new antimalarial. We aimed to characterize the safety, pharmacokinetics, and antimalarial activity of a tablet formulation of MMV390048. Methods A 2-part, phase 1 trial was conducted in healthy adults. Part 1 was a double-blind, randomized, placebo-controlled, single ascending dose study consisting of 3 cohorts (40, 80, 120 mg MMV390048). Part 2 was an open-label volunteer infection study using the Plasmodium falciparum induced blood-stage malaria model consisting of 2 cohorts (40 mg and 80 mg MMV390048). Results Twenty four subjects were enrolled in part 1 (n = 8 per cohort, randomized 3:1 MMV390048:placebo) and 15 subjects were enrolled in part 2 (40 mg [n = 7] and 80 mg [n = 8] cohorts). One subject was withdrawn from part 2 (80 mg cohort) before dosing and was not included in analyses. No serious or severe adverse events were attributed to MMV390048. The rate of parasite clearance was greater in subjects administered 80 mg compared to those administered 40 mg (clearance half-life 5.5 hours [95% confidence interval {CI}, 5.2–6.0 hours] vs 6.4 hours [95% CI, 6.0–6.9 hours]; P = .005). Pharmacokinetic/pharmacodynamic modeling estimated a minimum inhibitory concentration of 83 ng/mL and a minimal parasiticidal concentration that would achieve 90% of the maximum effect of 238 ng/mL, and predicted that a single 120-mg dose would achieve an adequate clinical and parasitological response with 92% certainty. Conclusions The safety, pharmacokinetics, and pharmacodynamics of MMV390048 support its further development as a partner drug of a single-dose combination therapy for malaria. Clinical Trials Registration NCT02783820 (part 1); NCT02783833 (part 2).
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Affiliation(s)
- James S McCarthy
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | | | | | - John Woodford
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Louise Marquart
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | | | - Felix D Rozenberg
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, New York, USA
| | - David A Fidock
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, New York, USA.,Division of Infectious Diseases, Department of Medicine, Columbia University Irving Medical Center, New York, New York, USA
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10
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Ahmad A, Prom A, Bradley J, Ndiath M, Etoketim B, Bah M, Van Geertruyden JP, Drakeley C, Bousema T, Achan J, D'Alessandro U. Gametocyte carriage after seasonal malaria chemoprevention in Plasmodium falciparum infected asymptomatic children. Malar J 2021; 20:169. [PMID: 33771166 PMCID: PMC7995796 DOI: 10.1186/s12936-021-03706-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Accepted: 03/16/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Treatment of clinical Plasmodium falciparum malaria with sulfadoxine-pyrimethamine (SP) and amodiaquine (AQ) is associated with increased post-treatment gametocyte carriage. The effect of seasonal malaria chemoprevention (SMC) with SP and AQ on gametocyte carriage was assessed in asymptomatic P. falciparum infected children. METHODS The study was carried out in eastern Gambia. Asymptomatic P. falciparum malaria infected children aged 24-59 months old who were eligible to receive SMC (SMC group) and children 5-8 years that were not eligible to receive SMC (comparison group) were recruited. Gametocytaemia was determined by molecular methods before and after SMC administration. Gametocyte carriage between the groups was compared using the chi-squared test and within-person using conditional logistic regression. RESULTS During the 2017 and 2018 malaria transmission seasons, 65 and 75 children were recruited in the SMC and comparison groups, respectively. Before SMC administration, gametocyte prevalence was 10.7% (7/65) in the SMC group and 13.3% (10/75) in the comparison group (p = 0.64). At day 13 (IQR 12, 13) after SMC administration, this was 9.4% (5/53) in children who received at least the first dose of SMC treatment and 12.7% (9/71) for those in the comparison group (p = 0.57). Similarly, there was no difference in prevalence of gametocytes between children that adhered to all 3-day doses of SMC treatment 15.6% (5/32) and those in the comparison group (p = 0.68). In the SMC group, within-group gametocyte carriage was similar before and after SMC administration in children that received at least the first dose of SMC treatment (OR 0.6, 95% CI 0.14-2.51; p = 0.48) and in those that adhered to all 3-day doses of SMC treatment (OR 1.0, 95% CI 0.20-4.95; p = 1.0). CONCLUSION In this study with relative low gametocyte prevalence prior to SMC treatment, no evidence was observed that SMC treatment increased gametocyte carriage in asymptomatic P. falciparum malaria infected children.
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Affiliation(s)
- Abdullahi Ahmad
- Disease Control and Elimination Theme, Medical Research Council Unit The Gambia At London, School of Hygiene and Tropical Medicine, P.O Box 273, Banjul, The Gambia.
- Global Health Institute, University of Antwerp, Gouverneur Kinsbergencentrum, Campus Drie Eiken, Doornstraat 331, 2610, Wilrijk, Belgium.
| | - Aurelia Prom
- Disease Control and Elimination Theme, Medical Research Council Unit The Gambia At London, School of Hygiene and Tropical Medicine, P.O Box 273, Banjul, The Gambia
| | - John Bradley
- MRC Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Mamadou Ndiath
- Disease Control and Elimination Theme, Medical Research Council Unit The Gambia At London, School of Hygiene and Tropical Medicine, P.O Box 273, Banjul, The Gambia
| | - Blessed Etoketim
- Disease Control and Elimination Theme, Medical Research Council Unit The Gambia At London, School of Hygiene and Tropical Medicine, P.O Box 273, Banjul, The Gambia
| | - Mamadou Bah
- Disease Control and Elimination Theme, Medical Research Council Unit The Gambia At London, School of Hygiene and Tropical Medicine, P.O Box 273, Banjul, The Gambia
| | - Jean-Pierre Van Geertruyden
- Global Health Institute, University of Antwerp, Gouverneur Kinsbergencentrum, Campus Drie Eiken, Doornstraat 331, 2610, Wilrijk, Belgium
| | - Chris Drakeley
- Department of Immunology and Infection, School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Center, Geert Grooteplein 28, Microbiology 268, 6500 HB, Nijmegen, The Netherlands
| | - Jane Achan
- Disease Control and Elimination Theme, Medical Research Council Unit The Gambia At London, School of Hygiene and Tropical Medicine, P.O Box 273, Banjul, The Gambia
| | - Umberto D'Alessandro
- Disease Control and Elimination Theme, Medical Research Council Unit The Gambia At London, School of Hygiene and Tropical Medicine, P.O Box 273, Banjul, The Gambia
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11
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Semimechanistic Pharmacokinetic and Pharmacodynamic Modeling of Piperaquine in a Volunteer Infection Study with Plasmodium falciparum Blood-Stage Malaria. Antimicrob Agents Chemother 2021; 65:AAC.01583-20. [PMID: 33468477 PMCID: PMC8097471 DOI: 10.1128/aac.01583-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Accepted: 01/10/2021] [Indexed: 11/20/2022] Open
Abstract
Dihydroartemisinin-piperaquine is a recommended first-line artemisinin combination therapy for Plasmodium falciparum malaria. Piperaquine is also under consideration for other antimalarial combination therapies. The aim of this study was to develop a pharmacokinetic-pharmacodynamic model that might be useful when optimizing the use of piperaquine in new antimalarial combination therapies. The pharmacokinetic-pharmacodynamic model was developed using data from a previously reported dose-ranging study where 24 healthy volunteers were inoculated with 1,800 blood-stage Plasmodium falciparum parasites. All volunteers received a single oral dose of piperaquine (960 mg, 640 mg, or 480 mg) on day 7 or day 8 after parasite inoculation in separate cohorts. Parasite densities were measured by quantitative PCR (qPCR), and piperaquine levels were measured in plasma samples. We used nonlinear mixed-effect modeling to characterize the pharmacokinetic properties of piperaquine and the parasite dynamics associated with piperaquine exposure. The pharmacokinetics of piperaquine was described by a three-compartment disposition model. A semimechanistic parasite dynamics model was developed to explain the maturation of parasites, sequestration of mature parasites, synchronicity of infections, and multiplication of parasites, as seen in natural clinical infections with P. falciparum malaria. Piperaquine-associated parasite killing was estimated using a maximum effect (E max) function. Treatment simulations (i.e., 3-day oral dosing of dihydroartemisinin-piperaquine) indicated that to be able to combat multidrug-resistant infections, an ideal additional drug in a new antimalarial triple-combination therapy should have a parasite reduction ratio of ≥102 per life cycle (38.8 h) with a duration of action of ≥2 weeks. The semimechanistic pharmacokinetic-pharmacodynamic model described here offers the potential to be a valuable tool for assessing and optimizing current and new antimalarial drug combination therapies containing piperaquine and the impact of these therapies on killing multidrug-resistant infections. (This study has been registered in the Australian and New Zealand Clinical Trials Registry under no. ANZCTRN12613000565741.).
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12
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Abstract
Plasmodium vivax bench research greatly lags behind Plasmodium falciparum because of an inability to culture in vitro. A century ago, intentionally inducing a malaria infection was a strategy commonly used to cure late-stage syphilis. These controlled human malaria infections were used with expertise and persisted to the end of World War II. While controlled malaria liver-stage infection has been achieved for both P. vivax and P. falciparum, controlled human transmission to mosquitoes falls short for both species. In this issue of the JCI, Collins et al. present groundbreaking work that establishes a system to transmit P. vivax gametocytes from humans to mosquitoes. The authors injected a unique human isolate of P. vivax that reached high gametocyte density within weeks. This study provides a technical advance that will facilitate the study and eradication of the human parasite P. vivax.
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13
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Defining the Antimalarial Activity of Cipargamin in Healthy Volunteers Experimentally Infected with Blood-Stage Plasmodium falciparum. Antimicrob Agents Chemother 2021; 65:AAC.01423-20. [PMID: 33199389 PMCID: PMC7849011 DOI: 10.1128/aac.01423-20] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Accepted: 11/08/2020] [Indexed: 12/11/2022] Open
Abstract
The spiroindolone cipargamin, a new antimalarial compound that inhibits Plasmodium ATP4, is currently in clinical development. This study aimed to characterize the antimalarial activity of cipargamin in healthy volunteers experimentally infected with blood-stage Plasmodium falciparum. The spiroindolone cipargamin, a new antimalarial compound that inhibits Plasmodium ATP4, is currently in clinical development. This study aimed to characterize the antimalarial activity of cipargamin in healthy volunteers experimentally infected with blood-stage Plasmodium falciparum. Eight subjects were intravenously inoculated with parasite-infected erythrocytes and received a single oral dose of 10 mg cipargamin 7 days later. Blood samples were collected to monitor the development and clearance of parasitemia and plasma cipargamin concentrations. Parasite regrowth was treated with piperaquine monotherapy to clear asexual parasites, while allowing gametocyte transmissibility to mosquitoes to be investigated. An initial rapid decrease in parasitemia occurred in all participants following cipargamin dosing, with a parasite clearance half-life of 3.99 h. As anticipated from the dose selected, parasite regrowth occurred in all 8 subjects 3 to 8 days after dosing and allowed the pharmacokinetic/pharmacodynamic relationship to be determined. Based on the limited data from the single subtherapeutic dose cohort, a MIC of 11.6 ng/ml and minimum parasiticidal concentration that achieves 90% of maximum effect of 23.5 ng/ml were estimated, and a single 95-mg dose (95% confidence interval [CI], 50 to 270) was predicted to clear 109 parasites/ml. Low gametocyte densities were detected in all subjects following piperaquine treatment, which did not transmit to mosquitoes. Serious adverse liver function changes were observed in three subjects, which led to premature study termination. The antimalarial activity characterized in this study supports the further clinical development of cipargamin as a new treatment for P. falciparum malaria, although the hepatic safety profile of the compound warrants further evaluation. (This study has been registered at ClinicalTrials.gov under identifier NCT02543086.)
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14
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Safety and feasibility of apheresis to harvest and concentrate parasites from subjects with induced blood stage Plasmodium vivax infection. Malar J 2021; 20:43. [PMID: 33446191 PMCID: PMC7807416 DOI: 10.1186/s12936-021-03581-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 01/04/2021] [Indexed: 11/27/2022] Open
Abstract
Background In the absence of a method to culture Plasmodium vivax, the only way to source parasites is ex vivo. This hampers many aspects of P. vivax research. This study aimed to assess the safety of apheresis, a method for selective removal of specific components of blood as a means of extracting and concentrating P. vivax parasites. Methods An iterative approach was employed across four non-immune healthy human subjects in single subject cohorts. All four subjects were inoculated with ~ 564 blood stage P. vivax (HMP013-Pv) and subjected to apheresis 10 to 11 days later. Blood samples collected during apheresis (haematocrit layers 0.5% to 11%) were tested for the presence and concentration of P. vivax by microscopy, flow cytometry, 18S rDNA qPCR for total parasites, and pvs25 qRT-PCR for female gametocyte transcripts. Safety was determined by monitoring adverse events. Malaria transmission to mosquitoes was assessed by membrane feeding assays. Results There were no serious adverse events and no significant safety concerns. Apheresis concentrated asexual parasites by up to 4.9-fold (range: 0.9–4.9-fold) and gametocytes by up to 1.45-fold (range: 0.38–1.45-fold) compared to pre-apheresis densities. No single haematocrit layer contained > 40% of all the recovered P. vivax asexual parasites. Ex vivo concentration of parasites by Percoll gradient centrifugation of whole blood achieved greater concentration of gametocytes than apheresis. Mosquito transmission was enhanced by up to fivefold in a single apheresis sample compared to pre-apheresis. Conclusion The modest level of parasite concentration suggests that the use of apheresis may not be an ideal method for harvesting P. vivax. Trial Registration Australia New Zealand Clinical Trials Registry (ANZCTR) Trial ID: ACTRN12617001502325 registered on 19th October 2017. https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=373812.
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15
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Andrews KA, Owen JS, McCarthy J, Wesche D, Gobeau N, Grasela TH, Möhrle JJ. Retrospective Analysis Using Pharmacokinetic/Pharmacodynamic Modeling and Simulation Offers Improvements in Efficiency of the Design of Volunteer Infection Studies for Antimalarial Drug Development. Clin Transl Sci 2020; 14:712-719. [PMID: 33326705 PMCID: PMC7993277 DOI: 10.1111/cts.12934] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 10/13/2020] [Indexed: 01/23/2023] Open
Abstract
Volunteer infection studies using the induced blood stage malaria (IBSM) model have been shown to facilitate antimalarial drug development. Such studies have traditionally been undertaken in single-dose cohorts, as many as necessary to obtain the dose-response relationship. To enhance ethical and logistic aspects of such studies, and to reduce the number of cohorts needed to establish the dose-response relationship, we undertook a retrospective in silico analysis of previously accrued data to improve study design. A pharmacokinetic (PK)/pharmacodynamic (PD) model was developed from initial fictive-cohort data for OZ439 (mixing the data of the three single-dose cohorts as: n = 2 on 100 mg, 2 on 200 mg, and 4 on 500 mg). A three-compartment model described OZ439 PKs. Net growth of parasites was modeled using a Gompertz function and drug-induced parasite death using a Hill function. Parameter estimates for the PK and PD models were comparable for the multidose single-cohort vs. the pooled analysis of all cohorts. Simulations based on the multidose single-cohort design described the complete data from the original IBSM study. The novel design allows for the ascertainment of the PK/PD relationship early in the study, providing a basis for rational dose selection for subsequent cohorts and studies.
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Affiliation(s)
- Kayla Ann Andrews
- Cognigen Corporation, a SimulationsPlus Company, Buffalo, New York, USA.,Department of Pharmaceutical Sciences, State University of New York at Buffalo, Buffalo, New York, USA
| | - Joel S Owen
- Cognigen Corporation, a SimulationsPlus Company, Buffalo, New York, USA
| | - James McCarthy
- The Royal Melbourne Hospital, The University of Melbourne at the Doherty Institute, Melbourne, Australia
| | - David Wesche
- Certara Strategic Consulting, Princeton, New Jersey, USA
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16
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Wockner LF, Hoffmann I, Webb L, Mordmüller B, Murphy SC, Kublin JG, O'Rourke P, McCarthy JS, Marquart L. Growth Rate of Plasmodium falciparum: Analysis of Parasite Growth Data From Malaria Volunteer Infection Studies. J Infect Dis 2020; 221:963-972. [PMID: 31679015 PMCID: PMC7198127 DOI: 10.1093/infdis/jiz557] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 10/29/2019] [Indexed: 12/16/2022] Open
Abstract
Background Growth rate of malaria parasites in the blood of infected subjects is an important
measure of efficacy of drugs and vaccines. Methods We used log-linear and sine-wave models to estimate the parasite growth rate of the 3D7
strain of Plasmodium falciparum using data from 177 subjects from 14
induced blood stage malaria (IBSM) studies conducted at QIMR Berghofer. We estimated
parasite multiplication rate per 48 hour (PMR48), PMR per life-cycle
(PMRLC), and parasite life-cycle duration. We compared these parameters to
those from studies conducted elsewhere with infections induced by IBSM (n=66),
sporozoites via mosquito bite (n=336) or injection (n=51). Results The parasite growth rate of 3D7 in QIMR Berghofer studies was 0.75/day (95% CI:
0.73–0.77/day), PMR48 was 31.9 (95% CI: 28.7–35.4),
PMRLC was 16.4 (95% CI: 15.1–17.8) and parasite life-cycle was 38.8
hour (95% CI: 38.3–39.2 hour). These parameters were similar to estimates from
IBSM studies elsewhere (0.71/day, 95% CI: 0.67–0.75/day; PMR48 26.6,
95% CI: 22.2–31.8), but significantly higher (P < 0.001)
than in sporozoite studies (0.47/day, 95% CI: 0.43–0.50/day; PMR48
8.6, 95% CI: 7.3–10.1). Conclusions Parasite growth rates were similar across different IBSM studies and higher than
infections induced by sporozoite.
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Affiliation(s)
- Leesa F Wockner
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Isabell Hoffmann
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Lachlan Webb
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | | | - Sean C Murphy
- Departments of Laboratory Medicine and Microbiology, University of Washington, Seattle, Washington, USA
| | - James G Kublin
- Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Peter O'Rourke
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - James S McCarthy
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.,School of Medicine, The University of Queensland, Brisbane, Queensland, Australia
| | - Louise Marquart
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
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17
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Peatey C, Chen N, Gresty K, Anderson K, Pickering P, Watts R, Gatton ML, McCarthy J, Cheng Q. Dormant Plasmodium falciparum Parasites in Human Infections Following Artesunate Therapy. J Infect Dis 2020; 223:1631-1638. [PMID: 32901248 DOI: 10.1093/infdis/jiaa562] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 09/02/2020] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Artemisinin monotherapy of Plasmodium falciparum infection is frequently ineffective due to recrudescence. Artemisinin-induced dormancy, shown in vitro and in animal models, provides a plausible explanation. To date, direct evidence of artemisinin-induced dormancy in humans is lacking. METHODS Blood samples were collected from Plasmodium falciparum 3D7- or K13-infected participants before and 48-72 hours after single-dose artesunate (AS) treatment. Parasite morphology, molecular signature of dormancy, capability and dynamics of seeding in vitro cultures, and genetic mutations in the K13 gene were investigated. RESULTS Dormant parasites were observed in post-AS blood samples of 3D7- and K13-infected participants. The molecular signature of dormancy, an up-regulation of acetyl CoA carboxylase, was detected in 3D7 and K13 samples post-AS, but not in pre-AS samples. Posttreatment samples successfully seeded in vitro cultures, with a significant delay in time to reach 2% parasitemia compared to pretreatment samples. CONCLUSIONS This study provides strong evidence for the presence of artemisinin-induced dormant parasites in P. falciparum infections. These parasites are a likely reservoir for recrudescent infection following artemisinin monotherapy and artemisinin combination therapy (ACT). Combination regimens that target dormant parasites or remain at therapeutic levels for a sufficient time to kill recovering parasites will likely improve efficacy of ACTs.
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Affiliation(s)
- Christopher Peatey
- Drug Resistance and Diagnostics, Australian Defence Force Malaria and Infectious Disease Institute, Brisbane, Queensland, Australia
| | - Nanhua Chen
- Drug Resistance and Diagnostics, Australian Defence Force Malaria and Infectious Disease Institute, Brisbane, Queensland, Australia
| | - Karryn Gresty
- Drug Resistance and Diagnostics, Australian Defence Force Malaria and Infectious Disease Institute, Brisbane, Queensland, Australia.,ADFMIDI laboratory, QIMR-Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Karen Anderson
- Drug Resistance and Diagnostics, Australian Defence Force Malaria and Infectious Disease Institute, Brisbane, Queensland, Australia.,ADFMIDI laboratory, QIMR-Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Paul Pickering
- Drug Resistance and Diagnostics, Australian Defence Force Malaria and Infectious Disease Institute, Brisbane, Queensland, Australia
| | - Rebecca Watts
- Clinical Tropical Medicine, QIMR-Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Michelle L Gatton
- School of Public Health and Social Work, Queensland University of Technology, Brisbane, Queensland, Australia
| | - James McCarthy
- Clinical Tropical Medicine, QIMR-Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Qin Cheng
- Drug Resistance and Diagnostics, Australian Defence Force Malaria and Infectious Disease Institute, Brisbane, Queensland, Australia.,ADFMIDI laboratory, QIMR-Berghofer Medical Research Institute, Brisbane, Queensland, Australia
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Wang CYT, Ballard E, Llewellyn S, Marquart L, Bousema T, McCarthy JS, Collins KA. Assays for quantification of male and female gametocytes in human blood by qRT-PCR in the absence of pure sex-specific gametocyte standards. Malar J 2020; 19:218. [PMID: 32576184 PMCID: PMC7310411 DOI: 10.1186/s12936-020-03291-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 06/17/2020] [Indexed: 12/25/2022] Open
Abstract
Background Malaria transmission from humans to Anopheles mosquitoes requires the presence of gametocytes in human peripheral circulation, and the dynamics of transmission are determined largely by the density and sex ratio of the gametocytes. Molecular methods are thus employed to measure gametocyte densities, particularly when assessing transmission epidemiology and the efficacy of transmission-blocking interventions. However, accurate quantification of male and female gametocytes with molecular methods requires pure male and female gametocytes as reference standards, which are not widely available. Methods qRT-PCR assays were used to quantify levels of sex-specific mRNA transcripts in Plasmodium falciparum female and male gametocytes (pfs25 and pfMGET, respectively) using synthetic complimentary RNA standards and in vitro cultured gametocytes. Assays were validated and assay performance was investigated in blood samples of clinical trial participants using these standards and compared to absolute quantification by droplet digital PCR (ddPCR). Results The number of transcript copies per gametocyte were determined to be 279.3 (95% CI 253.5–307.6) for the female-specific transcript pfs25, and 12.5 (95% CI 10.6–14.9) for the male-specific transcript pfMGET. These numbers can be used to convert from transcript copies/mL to gametocyte/mL. The reportable range was determined to be 5.71 × 106 to 5.71 female gametocytes/mL for pfs25, and 1.73 × 107 to 1.73 × 101 male gametocytes/mL for pfMGET. The limit of detection was 3.9 (95% CI 2.5–8.2) female gametocytes/mL for pfs25, and 26.9 (95% CI 19.3–51.7) male gametocytes/mL for PfMGET. Both assays showed minimal intra-assay and inter-assay variability with coefficient of variation < 3%. No cross-reactivity was observed in both assays in uninfected human blood samples. Comparison of results from ddPCR to qRT-PCR assays on clinical blood samples indicated a high-level agreement (ICC = 0.998 for pfs25 and 0.995 for pfMGET). Conclusions This study reports the validation of qRT-PCR assays that are able to accurately quantify female and male P. falciparum gametocytes at sub-microscopic densities. The assays showed excellent reproducibility, sensitivity, precision, specificity, and accuracy. The methodology will enable the estimation of gametocyte density in the absence of pure female and male gametocyte standards, and will facilitate clinical trials and epidemiological studies.
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Affiliation(s)
- Claire Y T Wang
- QPID Laboratory, Centre for Children's Health Research, Brisbane, QLD, Australia
| | - Emma Ballard
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Stacey Llewellyn
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Louise Marquart
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Teun Bousema
- Radboud Institute for Health Science, Radboud University Medical Center, Nijmegen, The Netherlands
| | - James S McCarthy
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Katharine A Collins
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia. .,Radboud Institute for Health Science, Radboud University Medical Center, Nijmegen, The Netherlands.
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Bouwman SA, Zoleko-Manego R, Renner KC, Schmitt EK, Mombo-Ngoma G, Grobusch MP. The early preclinical and clinical development of cipargamin (KAE609), a novel antimalarial compound. Travel Med Infect Dis 2020; 36:101765. [PMID: 32561392 DOI: 10.1016/j.tmaid.2020.101765] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 05/29/2020] [Accepted: 05/30/2020] [Indexed: 11/16/2022]
Abstract
BACKGROUND Cipargamin (KAE609) is a novel spiroindolone class drug for the treatment of malaria, currently undergoing phase 2 clinical development. This review provides an overview and interpretation of the pre-clinical and clinical data of this possible next-generation antimalarial drug published to date. METHODS We systematically searched the literature for studies on the preclinical and clinical development of cipargamin. PubMed and Google Scholar databases were searched using the terms 'cipargamin', 'KAE609' or 'NITD609' in the English language; one additional article was identified during revision. Nineteen of these in total 43 papers identified reported original studies; 13 of those articles were on pre-clinical studies and 6 reported clinical trials. RESULTS A total of 20 studies addressing its preclinical and clinical development have been published on this compound at the time of writing. Cipargamin acts on the PfATP4, which is a P-type Na + ATPase disrupting the Na + homeostasis in the parasite. Cipargamin is a very fast-acting antimalarial, it is active against all intra-erythrocytic stages of the malaria parasite and exerts gametocytocidal activity, with transmission-blocking potential. It is currently undergoing phase 2 clinical trial to assess safety and efficacy, with a special focus on hepatic safety. CONCLUSION In the search for novel antimalarial drugs, cipargamin exhibits promising properties, exerting activity against multiple intra-erythrocytic stages of plasmodia, including gametocytes. It exhibits a favourable pharmacokinetic profile, possibly allowing for single-dose treatment with a suitable combination partner. According to the clinical results of the first studies in Asian malaria patients, a possible safety concern is hepatotoxicity.
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Affiliation(s)
- Suzan Am Bouwman
- Center for Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Division of Internal Medicine, Amsterdam University Medical Centers, Location AMC, Amsterdam Infection & Immunity, Amsterdam Public Health, University of Amsterdam, Meibergdreef 9, 1100 DD, Amsterdam, the Netherlands; Centre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon
| | - Rella Zoleko-Manego
- Centre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon; Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany; Department of Tropical Medicine, Bernhard Nocht Institute for Tropical Medicine & I. Department of Medicine University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | | | - Esther K Schmitt
- Novartis Pharma AG, Global Health Development Unit, Basel, Switzerland
| | - Ghyslain Mombo-Ngoma
- Centre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon; Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany; Department of Tropical Medicine, Bernhard Nocht Institute for Tropical Medicine & I. Department of Medicine University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Martin P Grobusch
- Center for Tropical Medicine and Travel Medicine, Department of Infectious Diseases, Division of Internal Medicine, Amsterdam University Medical Centers, Location AMC, Amsterdam Infection & Immunity, Amsterdam Public Health, University of Amsterdam, Meibergdreef 9, 1100 DD, Amsterdam, the Netherlands; Centre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon; Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.
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20
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Gaur AH, McCarthy JS, Panetta JC, Dallas RH, Woodford J, Tang L, Smith AM, Stewart TB, Branum KC, Freeman BB, Patel ND, John E, Chalon S, Ost S, Heine RN, Richardson JL, Christensen R, Flynn PM, Van Gessel Y, Mitasev B, Möhrle JJ, Gusovsky F, Bebrevska L, Guy RK. Safety, tolerability, pharmacokinetics, and antimalarial efficacy of a novel Plasmodium falciparum ATP4 inhibitor SJ733: a first-in-human and induced blood-stage malaria phase 1a/b trial. THE LANCET. INFECTIOUS DISEASES 2020; 20:964-975. [PMID: 32275867 DOI: 10.1016/s1473-3099(19)30611-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 09/11/2019] [Accepted: 10/10/2019] [Indexed: 12/30/2022]
Abstract
BACKGROUND (+)-SJ000557733 (SJ733) is a novel, orally bioavailable inhibitor of Plasmodium falciparum ATP4. In this first-in-human and induced blood-stage malaria phase 1a/b trial, we investigated the safety, tolerability, pharmacokinetics, and antimalarial activity of SJ733 in humans. METHODS The phase 1a was a single-centre, dose-escalation, first-in-human study of SJ733 allowing modifications to dose increments and dose-cohort size on the basis of safety and pharmacokinetic results. The phase 1a took place at St Jude Children's Research Hospital and at the University of Tennessee Clinical Research Center (Memphis, TN, USA). Enrolment in more than one non-consecutive dose cohort was allowed with at least 14 days required between doses. Participants were fasted in seven dose cohorts and fed in one 600 mg dose cohort. Single ascending doses of SJ733 (75, 150, 300, 600, 900, or 1200 mg) were administered to participants, who were followed up for 14 days after SJ733 dosing. Phase 1a primary endpoints were safety, tolerability, and pharmacokinetics of SJ733, and identification of an SJ733 dose to test in the induced blood-stage malaria model. The phase 1b was a single-centre, open-label, volunteer infection study using the induced blood-stage malaria model in which fasted participants were intravenously infected with blood-stage P falciparum and subsequently treated with a single dose of SJ733. Phase 1b took place at Q-Pharm (Herston, QLD, Australia) and was initiated only after phase 1a showed that exposure exceeding the threshold minimum exposure could be safely achieved in humans. Participants were inoculated on day 0 with P falciparum-infected human erythrocytes (around 2800 parasites in the 150 mg dose cohort and around 2300 parasites in the 600 mg dose cohort), and parasitaemia was monitored before malaria inoculation, after inoculation, immediately before SJ733 dosing, and then post-dose. Participants were treated with SJ733 within 24 h of reaching 5000 parasites per mL or at a clinical score higher than 6. Phase 1b primary endpoints were calculation of a parasite reduction ratio (PRR48) and parasite clearance half-life, and safety and tolerability of SJ733 (incidence, severity, and drug-relatedness of adverse events). In both phases of the trial, SJ733 hydrochloride salt was formulated as a powder blend in capsules containing 75 mg or 300 mg for oral administration. Healthy men and women (of non-childbearing potential) aged 18-55 years were eligible for both studies. Both studies are registered with ClinicalTrials.gov (NCT02661373 for the phase 1a and NCT02867059 for the phase 1b). FINDINGS In the phase 1a, 23 healthy participants were enrolled and received one to three non-consecutive doses of SJ733 between March 14 and Dec 7, 2016. SJ733 was safe and well tolerated at all doses and in fasted and fed conditions. 119 adverse events were recorded: 54 (45%) were unrelated, 63 (53%) unlikely to be related, and two (2%) possibly related to SJ733. In the phase 1b, 17 malaria-naive, healthy participants were enrolled. Seven participants in the 150 mg dose cohort were inoculated and dosed with SJ733. Eight participants in the 600 mg dose cohort were inoculated, but two participants could not be dosed with SJ733. Two additional participants were subsequently inoculated and dosed with SJ733. SJ733 exposure increased proportional to the dose through to the 600 mg dose, then was saturable at higher doses. Fasted participants receiving 600 mg exceeded the target area under the concentration curve extrapolated to infinity (AUC0-∞) of 13 000 μg × h/L (median AUC0-∞ 24 283 [IQR 16 135-31 311] μg × h/L, median terminal half-life 17·4 h [IQR 16·1-24·0], and median timepoint at which peak plasma concentration is reached 1·0 h [0·6-1·3]), and this dose was tested in the phase 1b. All 15 participants dosed with SJ733 had at least one adverse event. Of the 172 adverse events recorded, 128 (74%) were mild. The only adverse event attributed to SJ733 was mild bilateral foot paraesthesia that lasted 3·75 h and resolved spontaneously. The most common adverse events were related to malaria. Based on parasite clearance half-life, the derived log10PRR48 and corresponding parasite clearance half-lives were 2·2 (95% CI 2·0-2·5) and 6·47 h (95% CI 5·88-7·18) for 150 mg, and 4·1 (3·7-4·4) and 3·56 h (3·29-3·88) for 600 mg. INTERPRETATION The favourable pharmacokinetic, tolerability, and safety profile of SJ733, and rapid antiparasitic effect support its development as a fast-acting component of combination antimalarial therapy. FUNDING Global Health Innovative Technology Fund, Medicines for Malaria Venture, and the American Lebanese Syrian Associated Charities.
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Affiliation(s)
- Aditya H Gaur
- Department of Infectious Diseases, St Jude Children's Research Hospital, Memphis, TN, USA.
| | - James S McCarthy
- Department of Clinical Tropical Medicine, QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - John C Panetta
- Department of Pharmaceutical Sciences, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Ronald H Dallas
- Department of Infectious Diseases, St Jude Children's Research Hospital, Memphis, TN, USA
| | - John Woodford
- Department of Clinical Tropical Medicine, QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Li Tang
- Department of Biostatistics, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Amber M Smith
- University of Tennessee Health Science Center, University of Tennessee, Memphis, TN, USA
| | - Tracy B Stewart
- Department of Infectious Diseases, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Kristen C Branum
- Department of Infectious Diseases, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Burgess B Freeman
- Department of Pharmaceutical Sciences, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Nehali D Patel
- Department of Infectious Diseases, St Jude Children's Research Hospital, Memphis, TN, USA
| | | | | | - Shelley Ost
- University of Tennessee Health Science Center, University of Tennessee, Memphis, TN, USA
| | - Ryan N Heine
- Department of Infectious Diseases, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Julie L Richardson
- Department of Pharmaceutical Sciences, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Robbin Christensen
- Department of Pharmaceutical Sciences, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Patricia M Flynn
- Department of Infectious Diseases, St Jude Children's Research Hospital, Memphis, TN, USA
| | | | | | | | | | | | - R Kiplin Guy
- University of Kentucky College of Pharmacy, University of Kentucky, Lexington, KY, USA
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21
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Atmar RL, Keitel WA. Searching for Improved Flu Vaccines-The Time Is Now. J Infect Dis 2020; 221:1-4. [PMID: 31665360 DOI: 10.1093/infdis/jiz545] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Accepted: 10/14/2019] [Indexed: 12/21/2022] Open
Affiliation(s)
- Robert L Atmar
- Departments of Medicine and Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
| | - Wendy A Keitel
- Departments of Medicine and Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
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Cao P, Collins KA, Zaloumis S, Wattanakul T, Tarning J, Simpson JA, McCarthy J, McCaw JM. Modeling the dynamics of Plasmodium falciparum gametocytes in humans during malaria infection. eLife 2019; 8:49058. [PMID: 31658944 PMCID: PMC6819085 DOI: 10.7554/elife.49058] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 10/15/2019] [Indexed: 12/25/2022] Open
Abstract
Renewed efforts to eliminate malaria have highlighted the potential to interrupt human-to-mosquito transmission — a process mediated by gametocyte kinetics in human hosts. Here we study the in vivo dynamics of Plasmodium falciparum gametocytes by establishing a framework which incorporates improved measurements of parasitemia, a novel gametocyte dynamics model and model fitting using Bayesian hierarchical inference. We found that the model provides an excellent fit to the clinical data from 17 volunteers infected with P. falciparum (3D7 strain) and reliably predicts observed gametocytemia. We estimated the sexual commitment rate and gametocyte sequestration time to be 0.54% (95% credible interval: 0.30–1.00%) per asexual replication cycle and 8.39 (6.54–10.59) days respectively. We used the data-calibrated model to investigate human-to-mosquito transmissibility, providing a method to link within-human host infection kinetics to epidemiological-scale infection and transmission patterns.
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Affiliation(s)
- Pengxing Cao
- School of Mathematics and Statistics, University of Melbourne, Melbourne, Australia
| | - Katharine A Collins
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Sophie Zaloumis
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Australia
| | - Thanaporn Wattanakul
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Joel Tarning
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Julie A Simpson
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Australia
| | - James McCarthy
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - James M McCaw
- School of Mathematics and Statistics, University of Melbourne, Melbourne, Australia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Australia
- Epidemiology, Peter Doherty Institute for Infection and Immunity, Parkville, Australia
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23
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Ballard E, Wang CYT, Hien TT, Tong NT, Marquart L, Pava Z, Tarning J, O'Rourke P, McCarthy JS. A validation study of microscopy versus quantitative PCR for measuring Plasmodium falciparum parasitemia. Trop Med Health 2019; 47:49. [PMID: 31485189 PMCID: PMC6712708 DOI: 10.1186/s41182-019-0176-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Accepted: 08/12/2019] [Indexed: 12/02/2022] Open
Abstract
Microscopy and 18S qPCR are the most common and field-friendly methods for quantifying malaria parasite density, and it is important that these methods can be interpreted as giving equivalent results. We compared results of quantitative measurement of Plasmodium falciparum parasitemia by microscopy and by 18S qPCR in a phase 2a study. Microscopy positive samples (n = 355; median 810 parasites/μL [IQR 40–10,471]) showed close agreement with 18S qPCR in mean log10/mL transformed parasitemia values by paired t test (difference 0.04, 95%CI − 0.01–0.10, p = 0.088). Excellent intraclass correlation (0.97) and no evidence of systematic or proportional differences by Passing–Bablok regression were observed. 18S qPCR appears to give equivalent parasitemia values to microscopy, which indicates 18S qPCR is an appropriate alternative method to quantify parasitemia in clinical trials.
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Affiliation(s)
- Emma Ballard
- 1QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Claire Y T Wang
- Queensland Paediatric Infectious Diseases Laboratory, Centre for Children's Health Research, Brisbane, Australia
| | - Tran Tinh Hien
- 3Oxford University Clinical Research Unit-Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam
| | - Nguyen Thanh Tong
- 3Oxford University Clinical Research Unit-Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam
| | - Louise Marquart
- 1QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Zuleima Pava
- 1QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Joel Tarning
- 4Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,5Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Oxford University, Oxford, UK
| | - Peter O'Rourke
- 1QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - James S McCarthy
- 1QIMR Berghofer Medical Research Institute, Brisbane, Australia.,6The University of Queensland, Brisbane, Australia
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24
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Ozonide Antimalarial Activity in the Context of Artemisinin-Resistant Malaria. Trends Parasitol 2019; 35:529-543. [PMID: 31176584 DOI: 10.1016/j.pt.2019.05.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 04/02/2019] [Accepted: 05/01/2019] [Indexed: 12/18/2022]
Abstract
The ozonides are one of the most advanced drug classes in the antimalarial development pipeline and were designed to improve on limitations associated with current front-line artemisinin-based therapies. Like the artemisinins, the pharmacophoric peroxide bond of ozonides is essential for activity, and it appears that these antimalarials share a similar mode of action, raising the possibility of cross-resistance. Resistance to artemisinins is associated with Plasmodium falciparum mutations that allow resistant parasites to escape short-term artemisinin-mediated damage (elimination half-life ~1 h). Importantly, some ozonides (e.g., OZ439) have a sustained in vivo drug exposure profile, providing a major pharmacokinetic advantage over the artemisinin derivatives. Here, we describe recent progress made towards understanding ozonide antimalarial activity and discuss ozonide utility within the context of artemisinin resistance.
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25
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Cooper MM, Loiseau C, McCarthy JS, Doolan DL. Human challenge models: tools to accelerate the development of malaria vaccines. Expert Rev Vaccines 2019; 18:241-251. [PMID: 30732492 DOI: 10.1080/14760584.2019.1580577] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
INTRODUCTION Malaria challenge models, where healthy human volunteers are intentionally infected with Plasmodium species parasites under controlled conditions, can be undertaken in several well-defined ways. These challenge models enable evaluation of the kinetics of parasite growth and clearance, host-pathogen interactions and the host immune response. They can facilitate discovery of candidate diagnostic biomarkers and novel vaccine targets. As translational tools they can facilitate testing of candidate vaccines and drugs and evaluation of diagnostic tests. AREAS COVERED Until recently, malaria human challenge models have been limited to only a few Plasmodium falciparum strains and used exclusively in malaria-naïve volunteers in non-endemic regions. Several recent advances include the use of alternate P. falciparum strains and other species of Plasmodia, as well as strains attenuated by chemical, radiation or genetic modification, and the conduct of studies in pre-exposed individuals. Herein, we discuss how this diversification is enabling more thorough vaccine efficacy testing and informing rational vaccine development. EXPERT OPINION The ability to comprehensively evaluate vaccine efficacy in controlled settings will continue to accelerate the translation of candidate malaria vaccines to the clinic, and inform the development and optimisation of potential vaccines that would be effective against multiple strains in geographically and demographically diverse settings.
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Affiliation(s)
- Martha M Cooper
- a Centre for Molecular Therapeutics, Australian Institute of Tropical Health and Medicine , James Cook University , Cairns , Australia
| | - Claire Loiseau
- a Centre for Molecular Therapeutics, Australian Institute of Tropical Health and Medicine , James Cook University , Cairns , Australia
| | - James S McCarthy
- b Infectious Diseases Programme , QIMR Berghofer Medical Research Institute , Brisbane , Australia
| | - Denise L Doolan
- a Centre for Molecular Therapeutics, Australian Institute of Tropical Health and Medicine , James Cook University , Cairns , Australia
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26
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Critical examination of approaches exploited to assess the effectiveness of transmission-blocking drugs for malaria. Future Med Chem 2018; 10:2619-2639. [PMID: 30499742 DOI: 10.4155/fmc-2018-0169] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
In the absence of clinically proven vaccines and emerging resistance to common antimalarials and insecticides, the onus of interrupting the life cycle of Plasmodium falciparum, is upon the transmission-blocking drugs. Current transmission-blocking drug primaquine finds its use restricted because of associated hemolytic toxicity issues in Glucose-6-Phosphate-Dehydrogenase deficient individuals. This article provides an extensive review of the assays used by the investigators to evaluate the transmission-blocking activity of drugs. Furthermore, limitations in existing transmission-blocking assessment approaches/studies are also covered in detail. This review is expected to help in the identification of lacunae in current understanding of transmission-blocking strategies, which are hindering our efforts to develop sustainable and effective transmission-blocking interventions.
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27
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Metabolism of Piperaquine to Its Antiplasmodial Metabolites and Their Pharmacokinetic Profiles in Healthy Volunteers. Antimicrob Agents Chemother 2018; 62:AAC.00260-18. [PMID: 29784841 DOI: 10.1128/aac.00260-18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 05/18/2018] [Indexed: 12/19/2022] Open
Abstract
As a partner antimalarial for artemisinin drug-based combination therapy (ACT), piperaquine (PQ) can be metabolized into two major metabolites, including piperaquine N-oxide (M1) and piperaquine N,N-dioxide (M2). To better understand the antimalarial potency of PQ, the antimalarial activity of the PQ metabolites (M1 and M2) was studied in vitro (in Plasmodium falciparum strains Pf3D7 and PfDd2) and in vivo (in the murine species Plasmodium yoelii) in this study. The recrudescence and survival time of infected mice were also recorded after drug treatment. The pharmacokinetic profiles of PQ and its two metabolites (M1 and M2) were investigated in healthy subjects after oral doses of two widely used ACT regimens, i.e., dihydroartemisinin plus piperaquine phosphate (Duo-Cotecxin) and artemisinin plus piperaquine (Artequick). Remarkable antiplasmodial activity was found for PQ (50% growth-inhibitory concentration [IC50], 4.5 nM against Pf3D7 and 6.9 nM against PfDd2; 90% effective dose [ED90], 1.3 mg/kg of body weight), M1 (IC50, 25.5 nM against Pf3D7 and 38.7 nM against PfDd2; ED90, 1.3 mg/kg), and M2 (IC50, 31.2 nM against Pf3D7 and 33.8 nM against PfDd2; ED90, 2.9 mg/kg). Compared with PQ, M1 showed comparable efficacy in terms of recrudescence and survival time and M2 had relatively weaker antimalarial potency. PQ and its two metabolites displayed a long elimination half-life (∼11 days for PQ, ∼9 days for M1, and ∼4 days for M2), and they accumulated after repeated administrations. The contribution of the two PQ metabolites to the efficacy of piperaquine as a partner drug of ACT for the treatment of malaria should be considered for PQ dose optimization.
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28
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Assessing Plasmodium falciparum transmission in mosquito-feeding assays using quantitative PCR. Malar J 2018; 17:249. [PMID: 29976199 PMCID: PMC6034226 DOI: 10.1186/s12936-018-2382-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Accepted: 06/09/2018] [Indexed: 12/29/2022] Open
Abstract
Background Evaluating the efficacy of transmission-blocking interventions relies on mosquito-feeding assays, with transmission typically assessed by microscopic identification of oocysts in mosquito midguts; however, microscopy has limited throughput, sensitivity and specificity. Where low prevalence and intensity mosquito infections occur, as observed during controlled human malaria infection studies or natural transmission, a reliable method for detection and quantification of low-level midgut infection is required. Here, a semi-automated, Taqman quantitative PCR (qPCR) assay sufficiently sensitive to detect a single-oocyst midgut infection is described. Results Extraction of genomic DNA from Anopheles stephensi midguts using a semi-automated extraction process was shown to have equivalent extraction efficiency to manual DNA extraction. An 18S Plasmodium falciparum qPCR assay was adapted for quantitative detection of P. falciparum midgut oocyst infection using synthetic DNA standards. The assay was validated for sensitivity and specificity, and the limit of detection was 0.7 genomes/µL (95% CI 0.4–1.6 genomes/µL). All microscopy-confirmed oocyst infected midgut samples were detected by qPCR, including all single-oocyst positive midguts. The genome number per oocyst was assessed 8–9 days after feeding assay using both qPCR and droplet digital PCR and was 3722 (IQR: 2951–5453) and 3490 (IQR: 2720–4182), respectively. Conclusions This semi-automated qPCR method enables accurate detection of low-level P. falciparum oocyst infections in mosquito midguts, and may improve the sensitivity, specificity and throughput of assays used to evaluate candidate transmission-blocking interventions. Electronic supplementary material The online version of this article (10.1186/s12936-018-2382-6) contains supplementary material, which is available to authorized users.
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29
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Roestenberg M, Hoogerwerf MA, Ferreira DM, Mordmüller B, Yazdanbakhsh M. Experimental infection of human volunteers. THE LANCET. INFECTIOUS DISEASES 2018; 18:e312-e322. [PMID: 29891332 DOI: 10.1016/s1473-3099(18)30177-4] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2017] [Revised: 02/08/2018] [Accepted: 03/01/2018] [Indexed: 12/13/2022]
Abstract
Controlled human infection (CHI) trials, in which healthy volunteers are experimentally infected, can accelerate the development of novel drugs and vaccines for infectious diseases of global importance. The use of CHI models is expanding from around 60 studies in the 1970s to more than 120 publications in this decade, primarily for influenza, rhinovirus, and malaria. CHI trials have provided landmark data for several registered drugs and vaccines, and have generated unprecedented scientific insights. Because of their invasive nature, CHI studies demand critical ethical review according to established frameworks. CHI-associated serious adverse events are rarely reported. Novel CHI models need standardised safety data from comparable CHI models to facilitate evidence-based risk assessments, as well as funds to produce challenge inoculum according to regulatory requirements. Advances such as the principle of controlled colonisation, the expansion of models to endemic areas, and the use of genetically attenuated strains will further broaden the scope of CHI trials.
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Affiliation(s)
| | | | | | - Benjamin Mordmüller
- Institute of Tropical Medicine and German Center for Infection Research, partner site Tübingen, University of Tübingen, Tübingen, Germany; Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon
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30
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Koepfli C, Yan G. Plasmodium Gametocytes in Field Studies: Do We Measure Commitment to Transmission or Detectability? Trends Parasitol 2018; 34:378-387. [PMID: 29544966 DOI: 10.1016/j.pt.2018.02.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 02/07/2018] [Accepted: 02/21/2018] [Indexed: 01/05/2023]
Abstract
The proportion of Plasmodium spp. infections carrying gametocytes, and gametocyte densities, are often reported as surrogate markers for transmission potential. It remains unclear whether parasites under natural conditions adjust commitment to transmission depending on external factors. Population-based surveys comprising mostly asymptomatic low-density infections are always impacted by the sensitivity of the assays used to diagnose infections and detect gametocytes. Asexual parasite density is an important predictor for the probability of detecting gametocytes, and in many cases it can explain patterns in gametocyte carriage without the need for an adjustment of the gametocyte conversion rate. When reporting gametocyte data, quantification of blood-stage parasitemia and its inclusion as a confounder in multivariable analyses is essential.
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Affiliation(s)
- Cristian Koepfli
- Program in Public Health, University of California, Irvine, CA, 92697, USA.
| | - Guiyun Yan
- Program in Public Health, University of California, Irvine, CA, 92697, USA
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31
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Miura K, Crompton PD. What goes around comes around: modeling malaria transmission from humans back to mosquitos. J Clin Invest 2018. [PMID: 29528336 DOI: 10.1172/jci120260] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Malaria, caused by mosquito-transmitted Plasmodium parasites, continues to take a major toll on global health. The development of drugs and vaccines that reduce malaria transmission from humans back to mosquitos could contribute to the control and eventual eradication of malaria, but research models for the early clinical evaluation of candidate interventions are lacking. In this issue of the JCI, Collins and colleagues report the successful transmission of Plasmodium falciparum parasites from humans to mosquitoes during controlled human malaria infection, thus providing a potential tool to accelerate the development of much needed transmission-blocking drugs and vaccines.
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Affiliation(s)
- Kazutoyo Miura
- Malaria Immunology Section, Laboratory of Malaria and Vector Research, and
| | - Peter D Crompton
- Malaria Infection Biology and Immunity Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, NIH, Rockville, Maryland, USA
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Collins KA, Wang CY, Adams M, Mitchell H, Rampton M, Elliott S, Reuling IJ, Bousema T, Sauerwein R, Chalon S, Möhrle JJ, McCarthy JS. A controlled human malaria infection model enabling evaluation of transmission-blocking interventions. J Clin Invest 2018; 128:1551-1562. [PMID: 29389671 PMCID: PMC5873858 DOI: 10.1172/jci98012] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 01/30/2018] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND. Drugs and vaccines that can interrupt the transmission of Plasmodium falciparum will be important for malaria control and elimination. However, models for early clinical evaluation of candidate transmission-blocking interventions are currently unavailable. Here, we describe a new model for evaluating malaria transmission from humans to Anopheles mosquitoes using controlled human malaria infection (CHMI). METHODS. Seventeen healthy malaria-naive volunteers underwent CHMI by intravenous inoculation of P. falciparum–infected erythrocytes to initiate blood-stage infection. Seven to eight days after inoculation, participants received piperaquine (480 mg) to attenuate asexual parasite replication while allowing gametocytes to develop and mature. Primary end points were development of gametocytemia, the transmissibility of gametocytes from humans to mosquitoes, and the safety and tolerability of the CHMI transmission model. To investigate in vivo gametocytocidal drug activity in this model, participants were either given an experimental antimalarial, artefenomel (500 mg), or a known gametocytocidal drug, primaquine (15 mg), or remained untreated during the period of gametocyte carriage. RESULTS. Male and female gametocytes were detected in all participants, and transmission to mosquitoes was achieved from 8 of 11 (73%) participants evaluated. Compared with results in untreated controls (n = 7), primaquine (15 mg, n = 5) significantly reduced gametocyte burden (P = 0.01), while artefenomel (500 mg, n = 4) had no effect. Adverse events (AEs) were mostly mild or moderate. Three AEs were assessed as severe — fatigue, elevated alanine aminotransferase, and elevated aspartate aminotransferase — and were attributed to malaria infection. Transaminase elevations were transient, asymptomatic, and resolved without intervention. CONCLUSION. We report the safe and reproducible induction of P. falciparum gametocytes in healthy malaria-naive volunteers at densities infectious to mosquitoes, thereby demonstrating the potential for evaluating transmission-blocking interventions in this model. TRIAL REGISTRATION. ClinicalTrials.gov NCT02431637 and NCT02431650. FUNDING. Bill & Melinda Gates Foundation.
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Affiliation(s)
| | - Claire Yt Wang
- Queensland Paediatric Infectious Diseases (QPID) Laboratory, Centre for Children's Health Research, Brisbane, Queensland, Australia
| | - Matthew Adams
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Hayley Mitchell
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Melanie Rampton
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | | | - Isaie J Reuling
- Radboud Institute for Health Science, Radboud University Medical Center, Nijmegen, Netherlands
| | - Teun Bousema
- Radboud Institute for Health Science, Radboud University Medical Center, Nijmegen, Netherlands
| | - Robert Sauerwein
- Radboud Institute for Health Science, Radboud University Medical Center, Nijmegen, Netherlands
| | | | | | - James S McCarthy
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
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Reuling IJ, van de Schans LA, Coffeng LE, Lanke K, Meerstein-Kessel L, Graumans W, van Gemert GJ, Teelen K, Siebelink-Stoter R, van de Vegte-Bolmer M, de Mast Q, van der Ven AJ, Ivinson K, Hermsen CC, de Vlas S, Bradley J, Collins KA, Ockenhouse CF, McCarthy J, Sauerwein RW, Bousema T. A randomized feasibility trial comparing four antimalarial drug regimens to induce Plasmodium falciparum gametocytemia in the controlled human malaria infection model. eLife 2018; 7:31549. [PMID: 29482720 PMCID: PMC5828662 DOI: 10.7554/elife.31549] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 01/14/2018] [Indexed: 12/16/2022] Open
Abstract
Background Malaria elimination strategies require a thorough understanding of parasite transmission from human to mosquito. A clinical model to induce gametocytes to understand their dynamics and evaluate transmission-blocking interventions (TBI) is currently unavailable. Here, we explore the use of the well-established Controlled Human Malaria Infection model (CHMI) to induce gametocyte carriage with different antimalarial drug regimens. Methods In a single centre, open-label randomised trial, healthy malaria-naive participants (aged 18–35 years) were infected with Plasmodium falciparum by bites of infected Anopheles mosquitoes. Participants were randomly allocated to four different treatment arms (n = 4 per arm) comprising low-dose (LD) piperaquine (PIP) or sulfadoxine-pyrimethamine (SP), followed by a curative regimen upon recrudescence. Male and female gametocyte densities were determined by molecular assays. Results Mature gametocytes were observed in all participants (16/16, 100%). Gametocytes appeared 8.5–12 days after the first detection of asexual parasites. Peak gametocyte densities and gametocyte burden was highest in the LD-PIP/SP arm, and associated with the preceding asexual parasite biomass (p=0.026). Male gametocytes had a mean estimated circulation time of 2.7 days (95% CI 1.5–3.9) compared to 5.1 days (95% CI 4.1–6.1) for female gametocytes. Exploratory mosquito feeding assays showed successful sporadic mosquito infections. There were no serious adverse events or significant differences in the occurrence and severity of adverse events between study arms (p=0.49 and p=0.28). Conclusions The early appearance of gametocytes indicates gametocyte commitment during the first wave of asexual parasites emerging from the liver. Treatment by LD-PIP followed by a curative SP regimen, results in the highest gametocyte densities and the largest number of gametocyte-positive days. This model can be used to evaluate the effect of drugs and vaccines on gametocyte dynamics, and lays the foundation for fulfilling the critical unmet need to evaluate transmission-blocking interventions against falciparum malaria for downstream selection and clinical development. Funding Funded by PATH Malaria Vaccine Initiative (MVI). Clinical trial number NCT02836002.
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Affiliation(s)
- Isaie J Reuling
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Lisanne A van de Schans
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Luc E Coffeng
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Kjerstin Lanke
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | | | - Wouter Graumans
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Geert-Jan van Gemert
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Karina Teelen
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Rianne Siebelink-Stoter
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | | | - Quirijn de Mast
- Department of Internal Medicine, Radboud University Medical Center, Nijmegen, Netherlands
| | - André J van der Ven
- Department of Internal Medicine, Radboud University Medical Center, Nijmegen, Netherlands
| | - Karen Ivinson
- PATH Malaria Vaccine Initiative, Washington, United States
| | - Cornelus C Hermsen
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Sake de Vlas
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - John Bradley
- MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | | | - James McCarthy
- Clinical Tropical Medicine Laboratory, QIMR Berghofer, Brisbane, Australia
| | - Robert W Sauerwein
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Teun Bousema
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
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Abstract
Controlled human malaria infection (CHMI) entails deliberate infection with malaria parasites either by mosquito bite or by direct injection of sporozoites or parasitized erythrocytes. When required, the resulting blood-stage infection is curtailed by the administration of antimalarial drugs. Inducing a malaria infection via inoculation with infected blood was first used as a treatment (malariotherapy) for neurosyphilis in Europe and the United States in the early 1900s. More recently, CHMI has been applied to the fields of malaria vaccine and drug development, where it is used to evaluate products in well-controlled early-phase proof-of-concept clinical studies, thus facilitating progression of only the most promising candidates for further evaluation in areas where malaria is endemic. Controlled infections have also been used to immunize against malaria infection. Historically, CHMI studies have been restricted by the need for access to insectaries housing infected mosquitoes or suitable malaria-infected individuals. Evaluation of vaccine and drug candidates has been constrained in these studies by the availability of a limited number of Plasmodium falciparum isolates. Recent advances have included cryopreservation of sporozoites, the manufacture of well-characterized and genetically distinct cultured malaria cell banks for blood-stage infection, and the availability of Plasmodium vivax-specific reagents. These advances will help to accelerate malaria vaccine and drug development by making the reagents for CHMI more widely accessible and also enabling a more rigorous evaluation with multiple parasite strains and species. Here we discuss the different applications of CHMI, recent advances in the use of CHMI, and ongoing challenges for consideration.
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Dechering KJ, Duerr HP, Koolen KMJ, Gemert GJV, Bousema T, Burrows J, Leroy D, Sauerwein RW. Modelling mosquito infection at natural parasite densities identifies drugs targeting EF2, PI4K or ATP4 as key candidates for interrupting malaria transmission. Sci Rep 2017; 7:17680. [PMID: 29247222 PMCID: PMC5732164 DOI: 10.1038/s41598-017-16671-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 11/16/2017] [Indexed: 11/25/2022] Open
Abstract
Eradication of malaria requires a novel type of drug that blocks transmission from the human to the mosquito host, but selection of such a drug is hampered by a lack of translational models. Experimental mosquito infections yield infection intensities that are substantially higher than observed in natural infections and, as a consequence, underestimate the drug effect on the proportion of mosquitoes that become infected. Here we introduce a novel experimental and computational method to adequately describe drug efficacy at natural parasite densities. Parameters of a beta-binomial infection model were established and validated using a large number of experimental mosquito infections at different parasite densities. Analyses of 15 experimental and marketed drugs revealed a class-specific ability to block parasite transmission. Our results highlight the parasite's elongation factor EF2, PI4 kinase and the ATP4 sodium channel as key targets for interruption of transmission, and compounds DDD107498 and KAE609 as most advanced drug candidates.
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Affiliation(s)
- Koen J Dechering
- TropIQ Health Sciences, Transistorweg 5-C02, 6534AT, Nijmegen, The Netherlands.
| | | | - Karin M J Koolen
- TropIQ Health Sciences, Transistorweg 5-C02, 6534AT, Nijmegen, The Netherlands
| | - Geert-Jan van Gemert
- Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Teun Bousema
- Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Jeremy Burrows
- Medicines for Malaria Venture, Route de Pré-Bois 20, 1215, Geneva, 15, Switzerland
| | - Didier Leroy
- Medicines for Malaria Venture, Route de Pré-Bois 20, 1215, Geneva, 15, Switzerland
| | - Robert W Sauerwein
- TropIQ Health Sciences, Transistorweg 5-C02, 6534AT, Nijmegen, The Netherlands
- Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
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Roestenberg M, Mordmüller B, Ockenhouse C, Mo A, Yazdanbakhsh M, Kremsner PG. The frontline of controlled human malaria infections: A report from the controlled human infection models Workshop in Leiden University Medical Centre 5 May 2016. Vaccine 2017; 35:7065-7069. [PMID: 29153778 DOI: 10.1016/j.vaccine.2017.10.093] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 10/30/2017] [Accepted: 10/31/2017] [Indexed: 12/22/2022]
Abstract
Controlled Human Malaria Infection (CHMI) is the most practiced controlled human infection model nowadays and there is an exponential increase in implementation of the model worldwide. During the Controlled Human Infection Models Workshop in Leiden, one day was dedicated to the discussion of the advances made and gaps in Controlled Human Malaria Infection (CHMI) trials. Factors contributing to this impressive expansion in the number of CHMI trials have been related to the ability to perform CHMI using injectable cryopreserved sporozoites (a product from Sanaria Inc. - PfSPZ Challenge), the development of a transmission blocking CHMI model and the need to test more vaccine candidates particularly in the field of whole-sporozoite vaccine development. However, with an increasing number of CHMI trials being undertaken, in an ever-growing number of trial sites, heterogeneity in trial design may compromise universal interpretation of results and require an ongoing dialogue on the need and feasibility of standardization. At the workshop, CHMI investigators convened to share their experiences in CHMI trials and discuss the possibilities for future trials.
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Affiliation(s)
| | - Benjamin Mordmüller
- Universitätsklinikum Tübingen, Germany and Centre de Recherches Médicales de Lambaréné, Gabon
| | | | - Annie Mo
- Division of Microbiology and Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, USA
| | | | - Peter G Kremsner
- Universitätsklinikum Tübingen, Germany and Centre de Recherches Médicales de Lambaréné, Gabon
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Shanks GD, Möhrle JJ. Treating malaria: new drugs for a new era. THE LANCET. INFECTIOUS DISEASES 2017; 17:1223-1224. [PMID: 28916444 DOI: 10.1016/s1473-3099(17)30475-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Accepted: 07/26/2017] [Indexed: 01/08/2023]
Affiliation(s)
- G Dennis Shanks
- Australian Army Malaria Institute, Brisbane, QLD 4051, Australia.
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Concentration of Plasmodium falciparum gametocytes in whole blood samples by magnetic cell sorting enhances parasite infection rates in mosquito feeding assays. Malar J 2017; 16:315. [PMID: 28779750 PMCID: PMC5545093 DOI: 10.1186/s12936-017-1959-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 07/28/2017] [Indexed: 01/07/2023] Open
Abstract
Background Mosquito-feeding assays are important tools to guide the development and support the evaluation of transmission-blocking interventions. These functional bioassays measure the sporogonic development of gametocytes in blood-fed mosquitoes. Measuring the infectivity of low gametocyte densities has become increasingly important in malaria elimination scenarios. This will pose challenges to the sensitivity and throughput of existing mosquito-feeding assay protocols. Here, different gametocyte concentration methods of blood samples were explored to optimize conditions for detection of positive mosquito infections. Methods Mature gametocytes of Plasmodium falciparum were diluted into whole blood samples of malaria-naïve volunteers. Standard centrifugation, Percoll gradient, magnetic cell sorting (MACS) enrichment were compared using starting blood volumes larger than the control (direct) feed. Results MACS gametocyte enrichment resulted in the highest infection intensity with statistically significant increases in mean oocyst density in 2 of 3 experiments (p = 0.0003; p ≤ 0.0001; p = 0.2348). The Percoll gradient and standard centrifugation procedures resulted in variable infectivity. A significant increase in the proportion of infected mosquitoes and oocyst density was found when larger volumes of gametocyte-infected blood were used with the MACS procedure. Conclusions The current study demonstrates that concentration methods of P. falciparum gametocyte-infected whole blood samples can enhance transmission in mosquito-feeding assays. Gametocyte purification by MACS was the most efficient method, allowing the assessment of gametocyte infectivity in low-density gametocyte infections, as can be expected in natural or experimental conditions. Electronic supplementary material The online version of this article (doi:10.1186/s12936-017-1959-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Robert E. Sinden
- Department of Life Sciences, Imperial College London, London, United Kingdom
- * E-mail:
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40
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McCarthy JS, Lotharius J, Rückle T, Chalon S, Phillips MA, Elliott S, Sekuloski S, Griffin P, Ng CL, Fidock DA, Marquart L, Williams NS, Gobeau N, Bebrevska L, Rosario M, Marsh K, Möhrle JJ. Safety, tolerability, pharmacokinetics, and activity of the novel long-acting antimalarial DSM265: a two-part first-in-human phase 1a/1b randomised study. THE LANCET. INFECTIOUS DISEASES 2017; 17:626-635. [PMID: 28363636 PMCID: PMC5446412 DOI: 10.1016/s1473-3099(17)30171-8] [Citation(s) in RCA: 92] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 02/10/2017] [Accepted: 02/16/2017] [Indexed: 01/13/2023]
Abstract
BACKGROUND DSM265 is a novel antimalarial that inhibits plasmodial dihydroorotate dehydrogenase, an enzyme essential for pyrimidine biosynthesis. We investigated the safety, tolerability, and pharmacokinetics of DSM265, and tested its antimalarial activity. METHODS Healthy participants aged 18-55 years were enrolled in a two-part study: part 1, a single ascending dose (25-1200 mg), double-blind, randomised, placebo-controlled study, and part 2, an open-label, randomised, active-comparator controlled study, in which participants were inoculated with Plasmodium falciparum induced blood-stage malaria (IBSM) and treated with DSM265 (150 mg) or mefloquine (10 mg/kg). Primary endpoints were DSM265 safety, tolerability, and pharmacokinetics. Randomisation lists were created using a validated, automated system. Both parts were registered with the Australian New Zealand Clinical Trials Registry, number ACTRN12613000522718 (part 1) and number ACTRN12613000527763 (part 2). FINDINGS In part 1, 73 participants were enrolled between April 12, 2013, and July 14, 2015 (DSM265, n=55; placebo, n=18). In part 2, nine participants were enrolled between Sept 30 and Nov 25, 2013 (150 mg DSM265, n=7; 10 mg/kg mefloquine, n=2). In part 1, 117 adverse events were reported; no drug-related serious or severe events were reported. The most common drug-related adverse event was headache. The mean DSM265 peak plasma concentration (Cmax) ranged between 1310 ng/mL and 34 800 ng/mL and was reached in a median time (tmax) between 1·5 h and 4 h, with a mean elimination half-life between 86 h and 118 h. In part 2, the log10 parasite reduction ratio at 48 h in the DSM265 (150 mg) group was 1·55 (95% CI 1·42-1·67) and in the mefloquine (10 mg/kg) group was 2·34 (2·17-2·52), corresponding to a parasite clearance half-life of 9·4 h (8·7-10·2) and 6·2 h (5·7-6·7), respectively. The median minimum inhibitory concentration of DSM265 in blood was estimated as 1040 ng/mL (range 552-1500), resulting in a predicted single efficacious dose of 340 mg. Parasite clearance was significantly faster in participants who received mefloquine than in participants who received DSM265 (p<0·0001). INTERPRETATION The good safety profile, long elimination half-life, and antimalarial effect of DSM265 supports its development as a partner drug in a single-dose antimalarial combination treatment. FUNDING Wellcome Trust, UK Department for International Development, Global Health Innovative Technology Fund, Bill & Melinda Gates Foundation.
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Affiliation(s)
- James S McCarthy
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia; Q-Pharm Pty Ltd, Herston, QLD, Australia.
| | | | | | | | | | | | | | | | | | | | - Louise Marquart
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | | | | | | | - Maria Rosario
- Takeda Development Center Americas, Inc, Cambridge, MA, USA
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Hanron AE, Billman ZP, Seilie AM, Olsen TM, Fishbaugher M, Chang M, Rueckle T, Andenmatten N, Greenhouse B, Arinaitwe E, Rek J, Das S, Domingo GJ, Shipman K, Kappe SH, Kublin JG, Murphy SC. Multiplex, DNase-free one-step reverse transcription PCR for Plasmodium 18S rRNA and spliced gametocyte-specific mRNAs. Malar J 2017; 16:208. [PMID: 28526032 PMCID: PMC5438523 DOI: 10.1186/s12936-017-1863-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 05/13/2017] [Indexed: 01/01/2023] Open
Abstract
Background Plasmodium gametocytes are sexual stages transmitted to female Anopheles mosquitoes. While Plasmodium parasites can be differentiated microscopically on Giemsa-stained blood smears, molecular methods are increasingly used because of their increased sensitivity. Molecular detection of gametocytes requires methods that discriminate between asexual and sexual stage parasites. Commonly tested gametocyte-specific mRNAs are pfs25 and pfs230 detected by reverse transcription polymerase chain reaction (RT-PCR). However, detection of these unspliced mRNA targets requires preceding DNase treatment of nucleic acids to eliminate co-purified genomic DNA. If gametocyte-specific, spliced mRNAs could be identified, DNase treatment could be eliminated and one-step multiplexed molecular methods utilized. Results Expression data was used to identify highly-expressed mRNAs in mature gametocytes that were also low in antisense RNA expression in non-gametocyte stages. After testing numerous candidate mRNAs, the spliced female Pf3D7_0630000 mRNA was selected as a Plasmodium falciparum gametocyte-specific biomarker compatible with Plasmodium 18S rRNA RT-PCR. This mRNA was only detected in samples containing mature gametocytes and was absent in those containing only asexual stage parasites or uninfected human blood. PF3D7_0630000 RT-PCR detected gametocytes across a wide range of parasite densities in both spiked and clinical samples and agreed with pfs25 RT-PCR, the gold standard for RT-PCR-based gametocyte detection. PF3D7_0630000 multiplexed with Plasmodium 18S rRNA RT-PCR was more sensitive than other spliced mRNA targets for one-step RT-PCR gametocyte detection. Conclusions Because the spliced target does not require DNase treatment, the PF3D7_0630000 assay can be multiplexed with Plasmodium 18S rRNA for direct one-step detection of gametocytes from whole human blood. Electronic supplementary material The online version of this article (doi:10.1186/s12936-017-1863-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Amelia E Hanron
- Department of Laboratory Medicine, University of Washington, 750 Republican St., E630, Seattle, WA, 98109, USA
| | - Zachary P Billman
- Department of Laboratory Medicine, University of Washington, 750 Republican St., E630, Seattle, WA, 98109, USA.,Center for Emerging and Re-emerging Infectious Diseases, University of Washington, 750 Republican St., Seattle, WA, 98109, USA
| | - Annette M Seilie
- Department of Laboratory Medicine, University of Washington, 750 Republican St., E630, Seattle, WA, 98109, USA
| | - Tayla M Olsen
- Department of Laboratory Medicine, University of Washington, 750 Republican St., E630, Seattle, WA, 98109, USA
| | - Matthew Fishbaugher
- Center for Infectious Disease Research, 307 Westlake Ave. N, #500, Seattle, WA, 98109, USA
| | - Ming Chang
- Department of Laboratory Medicine, University of Washington, 750 Republican St., E630, Seattle, WA, 98109, USA
| | - Thomas Rueckle
- Medicines for Malaria Venture, PO Box 1826, 20, Route de Pré-Bois, 1215, Geneva, Switzerland
| | - Nicole Andenmatten
- Medicines for Malaria Venture, PO Box 1826, 20, Route de Pré-Bois, 1215, Geneva, Switzerland
| | - Bryan Greenhouse
- Division of HIV, Infectious Diseases and Global Medicine, Department of Medicine, University of California San Francisco, San Francisco, USA
| | - Emmanuel Arinaitwe
- Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, PO Box 7475, Kampala, Uganda.,London School of Hygiene & Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - John Rek
- Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, PO Box 7475, Kampala, Uganda
| | - Smita Das
- PATH, 2201 Westlake Ave #200, Seattle, WA, 98121, USA
| | | | - Kelly Shipman
- Seattle Malaria Clinical Trials Center, Fred Hutch Cancer Research Center, 1100 Fairview Ave. N., #E3-300, Seattle, WA, 98109, USA
| | - Stefan H Kappe
- Center for Infectious Disease Research, 307 Westlake Ave. N, #500, Seattle, WA, 98109, USA
| | - James G Kublin
- Seattle Malaria Clinical Trials Center, Fred Hutch Cancer Research Center, 1100 Fairview Ave. N., #E3-300, Seattle, WA, 98109, USA
| | - Sean C Murphy
- Department of Laboratory Medicine, University of Washington, 750 Republican St., E630, Seattle, WA, 98109, USA. .,Department of Microbiology, University of Washington, 1959 NE Pacific St., Seattle, WA, 98195, USA. .,Center for Emerging and Re-emerging Infectious Diseases, University of Washington, 750 Republican St., Seattle, WA, 98109, USA. .,Center for Infectious Disease Research, 307 Westlake Ave. N, #500, Seattle, WA, 98109, USA.
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Farid R, Dixon MW, Tilley L, McCarthy JS. Initiation of gametocytogenesis at very low parasite density in Plasmodium falciparum infection. J Infect Dis 2017; 215:1167-1174. [PMID: 28498997 PMCID: PMC5426372 DOI: 10.1093/infdis/jix035] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 05/05/2017] [Indexed: 11/28/2022] Open
Abstract
The recent focus on the elimination of malaria has led to an increased interest in the role of sexual stages in its transmission. We introduce Plasmodium falciparum gametocyte exported protein-5 (PfGEXP5) transcript analysis as an important tool for evaluating the earliest (ring) stage sexual gametocytes in the blood of infected individuals. We show that gametocyte rings are detected in the peripheral blood immediately following establishment of asexual infections—without the need for triggers such as high-density asexual parasitemia or drug treatment. Committed gametocytes are refractory to the commonly used drug piperaquine, and mature gametocytes reappear in the bloodstream 10 days after the initial appearance of gametocyte rings. A further wave of commitment is observed following recrudescent asexual parasitemia, and these gametocytes are again refractory to piperaquine treatment. This work has implications for monitoring gametocyte and transmission dynamics and responses to drug treatment.
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Affiliation(s)
- Ryan Farid
- QIMR Berghofer Medical Research Institute and University of Queensland, Brisbane, Australia; and
| | - Matthew W. Dixon
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria, Australia
| | - Leann Tilley
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria, Australia
| | - James S McCarthy
- QIMR Berghofer Medical Research Institute and University of Queensland, Brisbane, Australia; and
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Payne RO, Griffin PM, McCarthy JS, Draper SJ. Plasmodium vivax Controlled Human Malaria Infection - Progress and Prospects. Trends Parasitol 2017; 33:141-150. [PMID: 27956060 PMCID: PMC5270241 DOI: 10.1016/j.pt.2016.11.001] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 11/01/2016] [Accepted: 11/04/2016] [Indexed: 02/06/2023]
Abstract
Modern controlled human malaria infection (CHMI) clinical trials have almost entirely focussed on Plasmodium falciparum, providing a highly informative means to investigate host-pathogen interactions as well as assess potential new prophylactic and therapeutic interventions. However, in recent years, there has been renewed interest in Plasmodium vivax, with CHMI models developed by groups in Colombia, the USA, and Australia. This review summarizes the published experiences, and examines the advantages and disadvantages of the different models that initiate infection either by mosquito bite or using a blood-stage inoculum. As for P. falciparum, CHMI studies with P. vivax will provide a platform for early proof-of-concept testing of drugs and vaccines, accelerating the development of novel interventions.
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Affiliation(s)
- Ruth O Payne
- The Jenner Institute Laboratories, Old Road Campus Research Building, University of Oxford, Oxford, OX3 7DQ, UK; The Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Oxford, OX3 7LE, UK.
| | - Paul M Griffin
- QIMR Berghofer Medical Research Institute, 300 Herston Rd, Herston, Queensland 4006, Australia; Q-Pharm Pty Ltd, Brisbane, Australia; Department of Medicine and Infectious Diseases, Mater Hospital and Mater Medical Research Institute, Brisbane, Australia; The University of Queensland, Brisbane, Australia
| | - James S McCarthy
- QIMR Berghofer Medical Research Institute, 300 Herston Rd, Herston, Queensland 4006, Australia; The University of Queensland, Brisbane, Australia
| | - Simon J Draper
- The Jenner Institute Laboratories, Old Road Campus Research Building, University of Oxford, Oxford, OX3 7DQ, UK.
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Estimation of the In Vivo MIC of Cipargamin in Uncomplicated Plasmodium falciparum Malaria. Antimicrob Agents Chemother 2017; 61:AAC.01940-16. [PMID: 27872070 PMCID: PMC5278730 DOI: 10.1128/aac.01940-16] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 11/10/2016] [Indexed: 01/29/2023] Open
Abstract
The MIC of an antimalarial drug for a particular infection is the drug level associated with a net parasite multiplication rate of one per asexual cycle. To ensure the cure of malaria, the MIC must be exceeded until all parasites have been eliminated. The development of highly sensitive and accurate PCR quantitation of low-density malaria parasitemia enables the prospective pharmacokinetic-pharmacodynamic (PK-PD) characterization of antimalarial drug effects and now allows identification of the in vivo MIC. An adaptive design and a PK-PD modeling approach were used to determine prospectively the MIC of the new antimalarial cipargamin (KAE609) in adults with uncomplicated Plasmodium falciparum malaria in an open-label, dose-ranging phase 2a study. Vietnamese adults with acute P. falciparum malaria were allocated sequentially to treatment with a single 30-mg (n = 6), 20-mg (n = 5), 10-mg (n = 7), or 15-mg (n = 7) dose of cipargamin. Artemisinin-based combination therapy was given after parasite densities had fallen and then risen as cipargamin levels declined below the MIC but before a return of signs or symptoms. The rates of parasite clearance were dose dependent, with near saturation of the effect being seen at an adult dose of 30 mg. The developed PK-PD model accurately predicted the therapeutic responses in 23/25 patients. The predicted median in vivo MIC was 0.126 ng/ml (range, 0.038 to 0.803 ng/ml). Pharmacometric characterization of the relationship between antimalarial drug concentrations and parasite clearance rates following graded subtherapeutic antimalarial drug dosing is safe and provides a rational framework for dose finding in antimalarial drug development. (This study has been registered at ClinicalTrials.gov under identifier NCT01836458.)
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Burrows JN, Duparc S, Gutteridge WE, Hooft van Huijsduijnen R, Kaszubska W, Macintyre F, Mazzuri S, Möhrle JJ, Wells TNC. New developments in anti-malarial target candidate and product profiles. Malar J 2017; 16:26. [PMID: 28086874 PMCID: PMC5237200 DOI: 10.1186/s12936-016-1675-x] [Citation(s) in RCA: 309] [Impact Index Per Article: 44.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 12/30/2016] [Indexed: 11/10/2022] Open
Abstract
A decade of discovery and development of new anti-malarial medicines has led to a renewed focus on malaria elimination and eradication. Changes in the way new anti-malarial drugs are discovered and developed have led to a dramatic increase in the number and diversity of new molecules presently in pre-clinical and early clinical development. The twin challenges faced can be summarized by multi-drug resistant malaria from the Greater Mekong Sub-region, and the need to provide simplified medicines. This review lists changes in anti-malarial target candidate and target product profiles over the last 4 years. As well as new medicines to treat disease and prevent transmission, there has been increased focus on the longer term goal of finding new medicines for chemoprotection, potentially with long-acting molecules, or parenteral formulations. Other gaps in the malaria armamentarium, such as drugs to treat severe malaria and endectocides (that kill mosquitoes which feed on people who have taken the drug), are defined here. Ultimately the elimination of malaria requires medicines that are safe and well-tolerated to be used in vulnerable populations: in pregnancy, especially the first trimester, and in those suffering from malnutrition or co-infection with other pathogens. These updates reflect the maturing of an understanding of the key challenges in producing the next generation of medicines to control, eliminate and ultimately eradicate malaria.
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Affiliation(s)
- Jeremy N Burrows
- Medicines for Malaria Venture, Route de Pré Bois 20, 1215, Geneva 15, Switzerland
| | - Stephan Duparc
- Medicines for Malaria Venture, Route de Pré Bois 20, 1215, Geneva 15, Switzerland
| | | | | | - Wiweka Kaszubska
- Medicines for Malaria Venture, Route de Pré Bois 20, 1215, Geneva 15, Switzerland
| | - Fiona Macintyre
- Medicines for Malaria Venture, Route de Pré Bois 20, 1215, Geneva 15, Switzerland
| | | | - Jörg J Möhrle
- Medicines for Malaria Venture, Route de Pré Bois 20, 1215, Geneva 15, Switzerland
| | - Timothy N C Wells
- Medicines for Malaria Venture, Route de Pré Bois 20, 1215, Geneva 15, Switzerland.
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Coalson JE, Walldorf JA, Cohee LM, Ismail MD, Mathanga D, Cordy RJ, Marti M, Taylor TE, Seydel KB, Laufer MK, Wilson ML. High prevalence of Plasmodium falciparum gametocyte infections in school-age children using molecular detection: patterns and predictors of risk from a cross-sectional study in southern Malawi. Malar J 2016; 15:527. [PMID: 27809907 PMCID: PMC5096312 DOI: 10.1186/s12936-016-1587-9] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 10/28/2016] [Indexed: 01/11/2023] Open
Abstract
Background In endemic areas, many people experience asymptomatic Plasmodium infections, particularly older children and adults, but their transmission contribution is unknown. Though not the exclusive determinant of infectiousness, transmission from humans to mosquitoes requires blood meals containing gametocytes. Gametocytes often occur at submicroscopic densities, challenging measurement in human populations. More sensitive molecular techniques allow better characterization of gametocyte epidemiologic patterns. Methods Approximately 30 households were selected from each of eight sites in southern Malawi during two cross-sectional surveys. Blood was sampled from 623 people during the dry season and 896 the following rainy season. Among people PCR-positive for Plasmodium falciparum, mature gametocytes were detected by qRT-PCR. Regression models evaluated predictors of gametocyte carriage and density in the total population and among those with PCR-positive infections. Results The prevalence of gametocyte carriage by molecular testing was 3.5% during the dry season and 8.6% during the rainy season, and by microscopy 0.8 and 3.3%, respectively. Nearly half of PCR-positive infections carried gametocytes, regardless of recent symptom status. Among P. falciparum-infected people, only living in unfinished houses and age were significantly associated with gametocyte presence. Infected people in unfinished houses had higher odds of carrying gametocytes (OR 2.24, 95% CI 1.16–4.31), and 31% (95% CI 3–65%) higher gametocyte density than those in finished houses. School-age children (5–15 years), had higher odds than adults (≥16 years) of having gametocytes when infected (OR 2.77, 95% CI 1.47–5.19), but 31% (95% CI 11–47%) lower gametocyte density. Children <5 years did not have significantly higher odds of gametocyte carriage or density when infected than adults. Conclusions School-age children frequently carry gametocytes in communities of southern Malawi and represent an under-recognized reservoir of infection. Malaria elimination strategies should address these frequently asymptomatic reservoirs, especially in highly endemic areas. Improved household construction may also reduce the infectious reservoir. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1587-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jenna E Coalson
- Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, MI, USA.
| | - Jenny A Walldorf
- Division of Malaria Research, Institute for Global Health, University of Maryland, Baltimore, MD, USA
| | - Lauren M Cohee
- Division of Malaria Research, Institute for Global Health, University of Maryland, Baltimore, MD, USA
| | - Miriam D Ismail
- Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, MI, USA
| | - Don Mathanga
- Malaria Alert Centre, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Regina Joice Cordy
- Department of Immunology and Infectious Disease, The Harvard School of Public Health, Boston, MA, USA
| | - Matthias Marti
- Department of Immunology and Infectious Disease, The Harvard School of Public Health, Boston, MA, USA
| | - Terrie E Taylor
- Department of Osteopathic Medical Specialties, College of Osteopathic Medicine, Michigan State University, East Lansing, MI, USA
| | - Karl B Seydel
- Department of Osteopathic Medical Specialties, College of Osteopathic Medicine, Michigan State University, East Lansing, MI, USA
| | - Miriam K Laufer
- Division of Malaria Research, Institute for Global Health, University of Maryland, Baltimore, MD, USA
| | - Mark L Wilson
- Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, MI, USA
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McCarthy JS, Rückle T, Djeriou E, Cantalloube C, Ter-Minassian D, Baker M, O'Rourke P, Griffin P, Marquart L, Hooft van Huijsduijnen R, Möhrle JJ. A Phase II pilot trial to evaluate safety and efficacy of ferroquine against early Plasmodium falciparum in an induced blood-stage malaria infection study. Malar J 2016; 15:469. [PMID: 27624471 PMCID: PMC5022189 DOI: 10.1186/s12936-016-1511-3] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 08/31/2016] [Indexed: 01/13/2023] Open
Abstract
Background Ferroquine (SSR97193) is a candidate anti-malarial currently undergoing clinical trials for malaria. To better understand its pharmacokinetic (PK) and pharmacodynamic (PD) parameters the compound was tested in the experimentally induced blood stage malaria infection model in volunteers. Methods Male and non-pregnant female aged 18–50 years were screened for this phase II, controlled, single-centre clinical trial. Subjects were inoculated with ~1800 viable Plasmodium falciparum 3D7A-infected human erythrocytes, and treated with a single-dose of 800 mg ferroquine. Blood samples were taken at defined time-points to measure PK and PD parameters. The blood concentration of ferroquine and its active metabolite, SSR97213, were measured on dry blood spot samples by ultra-performance liquid chromatography with tandem mass spectrometry (LC-MS/MS). Parasitaemia and emergence of gametocytes were monitored by quantitative PCR. Safety was determined by recording adverse events and monitoring clinical laboratory assessments during the course of the study. Results Eight subjects were enrolled into the study, inoculated with infected erythrocytes and treated with 800 mg ferroquine. Ferroquine was rapidly absorbed with maximal exposure after 4–8 and 4–12 h exposure for SSR97213. Non-compartmental PK analysis resulted in estimates for half-lives of 10.9 and 23.8 days for ferroquine and SSR97213, respectively. Parasite clearance as reported by parasite reduction ratio was 162.9 (95 % CI 141–188) corresponding to a parasite clearance half-life of 6.5 h (95 % CI: 6.4–6.7 h). PK/PD modelling resulted in a predicted minimal parasiticidal concentration of 20 ng/mL, and the single dosing tested in this study was predicted to maintain an exposure above this threshold for 454 h (37.8 days). Although ferroquine was overall well tolerated, transient elevated transaminase levels were observed in three subjects. Paracetamol was the only concomitant treatment among the two out of these three subjects that may have played a role in the elevated transaminases levels. No clinically significant ECG abnormalities were observed. Conclusions The parameters and PK/PD model derived from this study pave the way to the further rational development of ferroquine as an anti-malarial partner drug. The safety of ferroquine has to be further explored in controlled human trials. Trial registration anzctr.org.au (registration number: ACTRN12613001040752), registered 18/09/2013 Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1511-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- James S McCarthy
- QIMR Berghofer Medical Research Institute, Brisbane, Australia.,University of Queensland, Brisbane, Australia
| | - Thomas Rückle
- Medicines for Malaria Venture, Route de Pré-Bois 20, 1215, Meyrin, Geneva, Switzerland
| | - Elhadj Djeriou
- Sanofi Aventis Recherche Développement, Chilly-Mazarin, France
| | | | | | - Mark Baker
- Medicines for Malaria Venture, Route de Pré-Bois 20, 1215, Meyrin, Geneva, Switzerland.,Novartis Consumer Health SA, 2 route de l'Etraz, Case Postale 1279, 1260, Nyon, Switzerland
| | - Peter O'Rourke
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Paul Griffin
- QIMR Berghofer Medical Research Institute, Brisbane, Australia.,University of Queensland, Brisbane, Australia.,Mater Health Services, Brisbane, Australia.,Q-Pharm Pty Ltd, Brisbane, Australia
| | - Louise Marquart
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | | | - Jörg J Möhrle
- Medicines for Malaria Venture, Route de Pré-Bois 20, 1215, Meyrin, Geneva, Switzerland.
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Krause A, Dingemanse J, Mathis A, Marquart L, Möhrle JJ, McCarthy JS. Pharmacokinetic/pharmacodynamic modelling of the antimalarial effect of Actelion-451840 in an induced blood stage malaria study in healthy subjects. Br J Clin Pharmacol 2016; 82:412-21. [PMID: 27062080 PMCID: PMC4972157 DOI: 10.1111/bcp.12962] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Revised: 03/10/2016] [Accepted: 03/30/2016] [Indexed: 01/22/2023] Open
Abstract
Aims The aim of this study was to use data from an experimental induced blood stage malaria clinical trial to characterize the antimalarial activity of the new compound Actelion‐451840 using pharmacokinetic/pharmacodynamic (PK/PD) modelling. Then, using simulations from the model, the dose and dosing regimen necessary to achieve cure of infection were derived. Methods Eight healthy male subjects were infected with blood stage P. falciparum. After 7 days, a single dose of 500 mg of Actelion‐451840 was administered under fed conditions. Parasite and drug concentrations were sampled frequently. Parasite growth and the relation to drug exposure were estimated using PK/PD modelling. Simulations were then undertaken to derive estimates of the likelihood of achieving cure in different scenarios. Results Actelion‐451840 was safe and well tolerated. Single dose treatment markedly reduced the level of P. falciparum parasitaemia, with a weighted average parasite reduction rate of 73.6 (95% CI 56.1, 96.5) and parasite clearance half‐life of 7.7 h (95% CI 7.3, 8.3). A two compartment PK/PD model with a steep concentration−kill effect predicted maximum effect with a sustained concentration of 10–15 ng ml−1 and cure achieved in 90% of subjects with six once daily doses of 300 mg once daily. Conclusions Actelion‐451840 shows clinical efficacy against P. falciparum infections. The PK/PD model developed from a single proof‐of‐concept study with eight healthy subjects enabled prediction of therapeutic effects, with cure rates with seven daily doses predicted to be equivalent to artesunate monotherapy. Larger doses or more frequent dosing are not predicted to achieve more rapid cure.
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Affiliation(s)
- Andreas Krause
- Department of Clinical Pharmacology, Actelion Pharmaceuticals Ltd, Allschwil, Switzerland
| | - Jasper Dingemanse
- Department of Clinical Pharmacology, Actelion Pharmaceuticals Ltd, Allschwil, Switzerland
| | - Alexandre Mathis
- Department of Clinical Pharmacology, Actelion Pharmaceuticals Ltd, Allschwil, Switzerland
| | - Louise Marquart
- QIMR Berghofer Medical Research Institute, Brisbane, Australia
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