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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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Greyling N, van der Watt M, Gwarinda H, van Heerden A, Greenhouse B, Leroy D, Niemand J, Birkholtz LM. Genetic complexity alters drug susceptibility of asexual and gametocyte stages of Plasmodium falciparum to antimalarial candidates. Antimicrob Agents Chemother 2024; 68:e0129123. [PMID: 38259087 PMCID: PMC10916389 DOI: 10.1128/aac.01291-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 12/06/2023] [Indexed: 01/24/2024] Open
Abstract
Malaria elimination requires interventions able to target both the asexual blood stage (ABS) parasites and transmissible gametocyte stages of Plasmodium falciparum. Lead antimalarial candidates are evaluated against clinical isolates to address key concerns regarding efficacy and to confirm that the current, circulating parasites from endemic regions lack resistance against these candidates. While this has largely been performed on ABS parasites, limited data are available on the transmission-blocking efficacy of compounds with multistage activity. Here, we evaluated the efficacy of lead antimalarial candidates against both ABS parasites and late-stage gametocytes side-by-side, against clinical P. falciparum isolates from southern Africa. We additionally correlated drug efficacy to the genetic diversity of the clinical isolates as determined with a panel of well-characterized, genome-spanning microsatellite markers. Our data indicate varying sensitivities of the isolates to key antimalarial candidates, both for ABS parasites and gametocyte stages. While ABS parasites were efficiently killed, irrespective of genetic complexity, antimalarial candidates lost some gametocytocidal efficacy when the gametocytes originated from genetically complex, multiple-clone infections. This suggests a fitness benefit to multiclone isolates to sustain transmission and reduce drug susceptibility. In conclusion, this is the first study to investigate the efficacy of antimalarial candidates on both ABS parasites and gametocytes from P. falciparum clinical isolates where the influence of parasite genetic complexity is highlighted, ultimately aiding the malaria elimination agenda.
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Affiliation(s)
- Nicola Greyling
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
- Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, South Africa
| | - Mariëtte van der Watt
- Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, South Africa
| | - Hazel Gwarinda
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
- Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, South Africa
| | - Ashleigh van Heerden
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
- Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, South Africa
| | - Bryan Greenhouse
- Department of Medicine, University of California-San Francisco, San Francisco, California, USA
| | - Didier Leroy
- Medicines for Malaria Venture, Geneva, Switzerland
| | - Jandeli Niemand
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
- Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, South Africa
| | - Lyn-Marié Birkholtz
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Pretoria, South Africa
- Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, South Africa
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Courlet P, Wilkins JJ, Oeuvray C, Gao W, Khandelwal A. Semi-mechanistic population pharmacokinetic/pharmacodynamic modeling of a Plasmodium elongation factor 2 inhibitor cabamiquine for prevention and cure of malaria. Antimicrob Agents Chemother 2023; 67:e0089123. [PMID: 37966273 PMCID: PMC10720512 DOI: 10.1128/aac.00891-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 09/23/2023] [Indexed: 11/16/2023] Open
Abstract
Cabamiquine is a novel antimalarial agent that demonstrates the potential for chemoprevention and treatment of malaria. In this article, the dose-exposure-response relationship of cabamiquine was characterized using a population pharmacokinetic (PK)/pharmacodynamic (PD) model, incorporating the effects of cabamiquine on parasite dynamics at the liver and blood stages of malaria infection. Modeling was performed sequentially. First, a three-compartmental population PK model was developed, comprising linear elimination, a transit absorption model in combination with first-order absorption, and a recirculation model. Second, this model was expanded into a PK/PD model using parasitemia data from an induced blood stage malaria (IBSM) human challenge model. To describe the parasite growth and killing in the blood, a turnover model was used. Finally, the liver stage parasite dynamics were characterized using data from a sporozoite challenge model (SpzCh), and system parameters were fixed based on biological plausibility. Cabamiquine concentration in the central compartment was used to drive parasite killing at the blood and liver stages. Blood stage minimum inhibitory concentrations (MICb) were estimated at 7.12 ng/mL [95% confidence interval (CI95%): 6.26-7.88 ng/mL] and 1.28 ng/mL (CI95%: 1.12-1.43 ng/mL) for IBSM and SpzCh populations, respectively, while liver stage MICl was lower (0.61 ng/mL; CI95%: 0.24-0.96 ng/mL). In conclusion, a population PK/PD model was developed by incorporating parasite dynamics and drug activity at the blood and liver stages based on clinical data and biological knowledge. This model can potentially facilitate antimalarial agent development by supporting the efficient selection of the optimal dosing regimen.
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Affiliation(s)
- Perrine Courlet
- Merck Institute for Pharmacometrics, Ares Trading S.A., (an affiliate of Merck KGaA, Darmstadt, Germany), Lausanne, Switzerland
| | | | - Claude Oeuvray
- The Global Health Institute of Merck (an affiliate of Merck KGaA, Darmstadt, Germany), Eysins, Switzerland
| | - Wei Gao
- EMD Serono Research and Development Institute, Inc., Billerica, Massachusetts, USA
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van der Plas JL, Kuiper VP, Bagchus WM, Bödding M, Yalkinoglu Ö, Tappert A, Seitzinger A, Spangenberg T, Bezuidenhout D, Wilkins J, Oeuvray C, Dhingra SK, Thathy V, Fidock DA, Smidt LCA, Roozen GVT, Koopman JPR, Lamers OAC, Sijtsma J, van Schuijlenburg R, Wessels E, Meij P, Kamerling IMC, Roestenberg M, Khandelwal A. Causal chemoprophylactic activity of cabamiquine against Plasmodium falciparum in a controlled human malaria infection: a randomised, double-blind, placebo-controlled study in the Netherlands. THE LANCET. INFECTIOUS DISEASES 2023; 23:1164-1174. [PMID: 37414066 DOI: 10.1016/s1473-3099(23)00212-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 03/05/2023] [Accepted: 03/24/2023] [Indexed: 07/08/2023]
Abstract
BACKGROUND Cabamiquine is a novel antimalarial that inhibits Plasmodium falciparum translation elongation factor 2. We investigated the causal chemoprophylactic activity and dose-exposure-response relationship of single oral doses of cabamiquine following the direct venous inoculation (DVI) of P falciparum sporozoites in malaria-naive, healthy volunteers. METHODS This was a phase 1b, randomised, double-blind, placebo-controlled, adaptive, dose-finding, single-centre study performed in Leiden, Netherlands. Malaria-naive, healthy adults aged 18-45 years were divided into five cohorts and randomly assigned (3:1) to receive cabamiquine or placebo. Randomisation was done by an independent statistician using codes in a permuted block schedule with a block size of four. Participants, investigators, and study personnel were masked to treatment allocation. A single, oral dose regimen of cabamiquine (200, 100, 80, 60, or 30 mg) or matching placebo was administered either at 2 h (early liver-stage) or 96 h (late liver-stage) after DVI. The primary endpoints based on a per-protocol analysis set were the number of participants who developed parasitaemia within 28 days of DVI, time to parasitaemia, number of participants with documented parasite blood-stage growth, clinical symptoms of malaria, and exposure-efficacy modelling. The impact of cabamiquine on liver stages was evaluated indirectly by the appearance of parasitaemia in the blood. The Clopper-Pearson CI (nominal 95%) was used to express the protection rate. The secondary outcomes were safety and tolerability, assessed in those who had received DVI and were administered one dose of the study intervention. The trial was prospectively registered on ClinicalTrials.gov (NCT04250363). FINDINGS Between Feb 17, 2020 and April 29, 2021, 39 healthy participants were enrolled (early liver-stage: 30 mg [n=3], 60 mg [n=6], 80 mg [n=6], 100 mg [n=3], 200 mg [n=3], pooled placebo [n=6]; late liver-stage: 60 mg [n=3], 100 mg [n=3], 200 mg [n=3], pooled placebo [n=3]). A dose-dependent causal chemoprophylactic effect was observed, with four (67%) of six participants in the 60 mg, five (83%) of six participants in the 80 mg, and all three participants in the 100 and 200 mg cabamiquine dose groups protected from parasitaemia up to study day 28, whereas all participants in the pooled placebo and 30 mg cabamiquine dose group developed parasitaemia. A single, oral dose of 100 mg cabamiquine or higher provided 100% protection against parasitaemia when administered during early or late liver-stage malaria. The median time to parasitaemia in those with early liver-stage malaria was prolonged to 15, 22, and 24 days for the 30, 60, and 80 mg dose of cabamiquine, respectively, compared with 10 days for the pooled placebo. All participants with positive parasitaemia showed documented blood-stage parasite growth, apart from one participant in the pooled placebo group and one participant in the 30 mg cabamiquine group. Most participants did not exhibit any malaria symptoms in both the early and late liver-stage groups, and those reported were mild in severity. A positive dose-exposure-efficacy relationship was established across exposure metrics. The median maximum concentration time was 1-6 h, with a secondary peak observed between 6 h and 12 h in all cabamiquine dose groups (early liver-stage). All cabamiquine doses were safe and well tolerated. Overall, 26 (96%) of 27 participants in the early liver-stage group and ten (83·3%) of 12 participants in the late liver-stage group reported at least one treatment-emergent adverse event (TEAE) with cabamiquine or placebo. Most TEAEs were of mild severity, transient, and resolved without sequelae. The most frequently reported cabamiquine-related TEAE was headache. No dose-related trends were observed in the incidence, severity, or causality of TEAEs. INTERPRETATION The results from this study show that cabamiquine has a dose-dependent causal chemoprophylactic activity. Together with previously demonstrated activity against the blood stages combined with a half-life of more than 150 h, these results indicate that cabamiquine could be developed as a single-dose monthly regimen for malaria prevention. FUNDING The healthcare business of Merck KGaA, Darmstadt, Germany.
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Affiliation(s)
- Johan L van der Plas
- Centre for Human Drug Research, Leiden, Netherlands; Department of Infectious Diseases and Parasitology, Leiden University Center for Infectious Diseases, Leiden University Medical Center, Leiden, Netherlands
| | - Vincent P Kuiper
- Department of Infectious Diseases and Parasitology, Leiden University Center for Infectious Diseases, Leiden University Medical Center, Leiden, Netherlands
| | - Wilhelmina M Bagchus
- Merck Institute for Pharmacometrics, Merck Serono (an affiliate of Merck KGaA, Darmstadt, Germany), Lausanne, Switzerland
| | | | | | - Aliona Tappert
- The healthcare business of Merck KGaA, Darmstadt, Germany
| | | | - Thomas Spangenberg
- Global Health Institute of Merck, Ares Trading (a subsidiary of Merck KGaA, Darmstadt, Germany), Eysins, Switzerland
| | - Deon Bezuidenhout
- Merck (Pty) (an affiliate of Merck KGaA, Darmstadt, Germany), Modderfontein, South Africa
| | | | - Claude Oeuvray
- Global Health Institute of Merck, Ares Trading (a subsidiary of Merck KGaA, Darmstadt, Germany), Eysins, Switzerland
| | | | - Vandana Thathy
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY, USA
| | - David A Fidock
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY, USA; Center for Malaria Therapeutics and Antimicrobial Resistance, Division of Infectious Diseases, Department of Medicine, Columbia University Irving Medical Center, New York, NY, USA
| | | | - Geert V T Roozen
- Department of Infectious Diseases and Parasitology, Leiden University Center for Infectious Diseases, Leiden University Medical Center, Leiden, Netherlands
| | - Jan Pieter R Koopman
- Department of Infectious Diseases and Parasitology, Leiden University Center for Infectious Diseases, Leiden University Medical Center, Leiden, Netherlands
| | - Olivia A C Lamers
- Department of Infectious Diseases and Parasitology, Leiden University Center for Infectious Diseases, Leiden University Medical Center, Leiden, Netherlands
| | - Jeroen Sijtsma
- Department of Infectious Diseases and Parasitology, Leiden University Center for Infectious Diseases, Leiden University Medical Center, Leiden, Netherlands
| | - Roos van Schuijlenburg
- Department of Infectious Diseases and Parasitology, Leiden University Center for Infectious Diseases, Leiden University Medical Center, Leiden, Netherlands
| | - Els Wessels
- Department of Medical Microbiology, Leiden University Center for Infectious Diseases, Leiden University Medical Center, Leiden, Netherlands
| | - Pauline Meij
- Center for Cell and Gene Therapy, Leiden University Center for Infectious Diseases, Leiden University Medical Center, Leiden, Netherlands
| | - Ingrid M C Kamerling
- Centre for Human Drug Research, Leiden, Netherlands; Department of Infectious Diseases and Parasitology, Leiden University Center for Infectious Diseases, Leiden University Medical Center, Leiden, Netherlands
| | - Meta Roestenberg
- Department of Infectious Diseases and Parasitology, Leiden University Center for Infectious Diseases, Leiden University Medical Center, Leiden, Netherlands.
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Kreutzfeld O, Tumwebaze PK, Okitwi M, Orena S, Byaruhanga O, Katairo T, Conrad MD, Rasmussen SA, Legac J, Aydemir O, Giesbrecht D, Forte B, Campbell P, Smith A, Kano H, Nsobya SL, Blasco B, Duffey M, Bailey JA, Cooper RA, Rosenthal PJ. Susceptibility of Ugandan Plasmodium falciparum Isolates to the Antimalarial Drug Pipeline. Microbiol Spectr 2023; 11:e0523622. [PMID: 37158739 PMCID: PMC10269555 DOI: 10.1128/spectrum.05236-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 04/10/2023] [Indexed: 05/10/2023] Open
Abstract
Malaria, especially Plasmodium falciparum infection, remains an enormous problem, and its treatment and control are seriously challenged by drug resistance. New antimalarial drugs are needed. To characterize the Medicines for Malaria Venture pipeline of antimalarials under development, we assessed the ex vivo drug susceptibilities to 19 compounds targeting or potentially impacted by mutations in P. falciparum ABC transporter I family member 1, acetyl-CoA synthetase, cytochrome b, dihydroorotate dehydrogenase, elongation factor 2, lysyl-tRNA synthetase, phenylalanyl-tRNA synthetase, plasmepsin X, prodrug activation and resistance esterase, and V-type H+ ATPase of 998 fresh P. falciparum clinical isolates collected in eastern Uganda from 2015 to 2022. Drug susceptibilities were assessed by 72-h growth inhibition (half-maximum inhibitory concentration [IC50]) assays using SYBR green. Field isolates were highly susceptible to lead antimalarials, with low- to midnanomolar median IC50s, near values previously reported for laboratory strains, for all tested compounds. However, outliers with decreased susceptibilities were identified. Positive correlations between IC50 results were seen for compounds with shared targets. We sequenced genes encoding presumed targets to characterize sequence diversity, search for polymorphisms previously selected with in vitro drug pressure, and determine genotype-phenotype associations. We identified many polymorphisms in target genes, generally in <10% of isolates, but none were those previously selected in vitro with drug pressure, and none were associated with significantly decreased ex vivo drug susceptibility. Overall, Ugandan P. falciparum isolates were highly susceptible to 19 compounds under development as next-generation antimalarials, consistent with a lack of preexisting or novel resistance-conferring mutations in circulating Ugandan parasites. IMPORTANCE Drug resistance necessitates the development of new antimalarial drugs. It is important to assess the activities of compounds under development against parasites now causing disease in Africa, where most malaria cases occur, and to determine if mutations in these parasites may limit the efficacies of new agents. We found that African isolates were generally highly susceptible to the 19 studied lead antimalarials. Sequencing of the presumed drug targets identified multiple mutations in these genes, but these mutations were generally not associated with decreased antimalarial activity. These results offer confidence that the activities of the tested antimalarial compounds now under development will not be limited by preexisting resistance-mediating mutations in African malaria parasites.
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Affiliation(s)
- Oriana Kreutzfeld
- University of California, San Francisco, San Francisco, California, USA
| | | | - Martin Okitwi
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Stephen Orena
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | | | - Thomas Katairo
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Melissa D. Conrad
- University of California, San Francisco, San Francisco, California, USA
| | | | - Jennifer Legac
- University of California, San Francisco, San Francisco, California, USA
| | - Ozkan Aydemir
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | | | - Barbara Forte
- Wellcome Centre for Anti-Infectives Research, Division of Biological Chemistry and Drug Discovery, University of Dundee, Dundee, United Kingdom
| | - Peter Campbell
- Wellcome Centre for Anti-Infectives Research, Division of Biological Chemistry and Drug Discovery, University of Dundee, Dundee, United Kingdom
| | - Alasdair Smith
- Wellcome Centre for Anti-Infectives Research, Division of Biological Chemistry and Drug Discovery, University of Dundee, Dundee, United Kingdom
| | - Hiroki Kano
- Mitsubishi Tanabe Pharma Corporation, Yokohama, Japan
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