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Jajosky RP, Wu SC, Jajosky PG, Stowell SR. Plasmodium knowlesi ( Pk) Malaria: A Review & Proposal of Therapeutically Rational Exchange (T-REX) of Pk-Resistant Red Blood Cells. Trop Med Infect Dis 2023; 8:478. [PMID: 37888606 PMCID: PMC10610852 DOI: 10.3390/tropicalmed8100478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 10/09/2023] [Accepted: 10/12/2023] [Indexed: 10/28/2023] Open
Abstract
Plasmodium knowlesi (Pk) causes zoonotic malaria and is known as the "fifth human malaria parasite". Pk malaria is an emerging threat because infections are increasing and can be fatal. While most infections are in Southeast Asia (SEA), especially Malaysia, travelers frequently visit this region and can present with Pk malaria around the world. So, clinicians need to know (1) patients who present with fever after recent travel to SEA might be infected with Pk and (2) Pk is often misdiagnosed as P. malariae (which typically causes less severe malaria). Here we review the history, pathophysiology, clinical features, diagnosis, and treatment of Pk malaria. Severe disease is most common in adults. Signs and symptoms can include fever, abdominal pain, jaundice, acute kidney injury, acute respiratory distress syndrome, hyponatremia, hyperparasitemia, and thrombocytopenia. Dengue is one of the diseases to be considered in the differential. Regarding pathophysiologic mechanisms, when Pk parasites invade mature red blood cells (RBCs, i.e., normocytes) and reticulocytes, changes in the red blood cell (RBC) surface can result in life-threatening cytoadherence, sequestration, and reduced RBC deformability. Since molecular mechanisms involving the erythrocytic stage are responsible for onset of severe disease and lethal outcomes, it is biologically plausible that manual exchange transfusion (ET) or automated RBC exchange (RBCX) could be highly beneficial by replacing "sticky" parasitized RBCs with uninfected, deformable, healthy donor RBCs. Here we suggest use of special Pk-resistant donor RBCs to optimize adjunctive manual ET/RBCX for malaria. "Therapeutically-rational exchange transfusion" (T-REX) is proposed in which Pk-resistant RBCs are transfused (instead of disease-promoting RBCs). Because expression of the Duffy antigen on the surface of human RBCs is essential for parasite invasion, T-REX of Duffy-negative RBCs-also known as Fy(a-b-) RBCs-could replace the majority of the patient's circulating normocytes with Pk invasion-resistant RBCs (in a single procedure lasting about 2 h). When sequestered or non-sequestered iRBCs rupture-in a 24 h Pk asexual life cycle-the released merozoites cannot invade Fy(a-b-) RBCs. When Fy(a-b-) RBC units are scarce (e.g., in Malaysia), clinicians can consider the risks and benefits of transfusing plausibly Pk-resistant RBCs, such as glucose-6-phosphate dehydrogenase deficient (G6PDd) RBCs and Southeast Asian ovalocytes (SAO). Patients typically require a very short recovery time (<1 h) after the procedure. Fy(a-b-) RBCs should have a normal lifespan, while SAO and G6PDd RBCs may have mildly reduced half-lives. Because SAO and G6PDd RBCs come from screened blood donors who are healthy and not anemic, these RBCs have a low-risk for hemolysis and do not need to be removed after the patient recovers from malaria. T-REX could be especially useful if (1) antimalarial medications are not readily available, (2) patients are likely to progress to severe disease, or (3) drug-resistant strains emerge. In conclusion, T-REX is a proposed optimization of manual ET/RBCX that has not yet been utilized but can be considered by physicians to treat Pk malaria patients.
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Affiliation(s)
- Ryan Philip Jajosky
- Joint Program in Transfusion Medicine, Brigham and Women’s Hospital, Harvard Medical School, 630E New Research Building, 77 Avenue Louis Pasteur, Boston, MA 02115, USA; (S.-C.W.)
- Biconcavity Inc., Lilburn, GA 30047, USA
| | - Shang-Chuen Wu
- Joint Program in Transfusion Medicine, Brigham and Women’s Hospital, Harvard Medical School, 630E New Research Building, 77 Avenue Louis Pasteur, Boston, MA 02115, USA; (S.-C.W.)
| | | | - Sean R. Stowell
- Joint Program in Transfusion Medicine, Brigham and Women’s Hospital, Harvard Medical School, 630E New Research Building, 77 Avenue Louis Pasteur, Boston, MA 02115, USA; (S.-C.W.)
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Saralamba S, Simpson JA, Choosri N, White L, Pan-Ngum W, Dondorp AM, White NJ. An artesunate pharmacometric model to explain therapeutic responses in falciparum malaria. J Antimicrob Chemother 2023; 78:2192-2202. [PMID: 37473441 PMCID: PMC10477127 DOI: 10.1093/jac/dkad219] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Accepted: 06/29/2023] [Indexed: 07/22/2023] Open
Abstract
BACKGROUND The artemisinins are potent and widely used antimalarial drugs that are eliminated rapidly. A simple concentration-effect pharmacometric model does not explain why dosing more frequently than once daily fails to augment parasite clearance and improve therapeutic responses in vivo. Artemisinins can induce a temporary non-replicative or 'dormant' drug refractory state in Plasmodium falciparum malaria parasites which may explain recrudescences observed in clinical trials despite full drug susceptibility, but whether it explains the dosing-response relationship is uncertain. OBJECTIVES To propose a revised model of antimalarial pharmacodynamics that incorporates reversible asexual parasite injury and temporary drug refractoriness in order to explain the failure of frequent dosing to augment therapeutic efficacy in falciparum malaria. METHODS The model was fitted using a Bayesian Markov Chain Monte Carlo approach with the parasite clearance data from 39 patients with uncomplicated falciparum malaria treated with artesunate from western Cambodia and 40 patients from northwestern Thailand reported previously. RESULTS The revised model captured the dynamics of parasite clearance data. Its predictions are consistent with observed therapeutic responses. CONCLUSIONS A within-host pharmacometric model is proposed in which it is hypothesized that some malaria parasites enter a temporary drug refractory state after exposure to artemisinin antimalarials, which is followed by delayed parasite death or reactivation. The model fitted the observed sequential parasite density data from patients with acute P. falciparum malaria, and it supported reduced ring stage activity in artemisinin-resistant infections.
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Affiliation(s)
- Sompob Saralamba
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Julie A Simpson
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
| | - Noppon Choosri
- Center of Data Analytics and Knowledge Synthesis for Healthcare, Chiang Mai University, Chiang Mai, Thailand
| | - Lisa White
- Department of Biology, University of Oxford, Oxford, UK
| | - Wirichada Pan-Ngum
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Department of Tropical Hygiene, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Arjen M Dondorp
- 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, UK
| | - Nicholas J White
- 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, UK
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de Carvalho LP, Niepoth E, Mavraj-Husejni A, Kreidenweiss A, Herrmann J, Müller R, Knaab T, Burckhardt BB, Kurz T, Held J. Quantification of Plasmodium falciparum HRP-2 as an alternative method to [ 3H]hypoxanthine incorporation to measure the parasite reduction ratio in vitro. Int J Antimicrob Agents 2023; 62:106894. [PMID: 37348620 DOI: 10.1016/j.ijantimicag.2023.106894] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 06/06/2023] [Accepted: 06/10/2023] [Indexed: 06/24/2023]
Abstract
In the absence of a highly efficacious vaccine, chemotherapy remains the cornerstone to control malaria morbidity and mortality. The threat of the emergence of parasites resistant to artemisinin-based combination therapies highlights the need for new antimalarial drugs ideally with superior properties. The killing rate reflects the speed of action of antimalarial drugs, which can be measured in vitro through the parasite reduction ratio (PRR) assay to shortlist interesting candidates. As a standard, the in vitro PRR assay is performed by measuring [3H]hypoxanthine incorporation of Plasmodium falciparum. This methodology is restricted to specialised laboratories owing to the handling of radioactive material. In this work, we describe a sandwich enzyme-linked immunosorbent assay to detect P. falciparum histidine-rich protein 2 (HRP-2) as an alternative methodology to assess the PRR. We first validated the methodology with established antimalarial drugs (artesunate, chloroquine, pyrimethamine and atovaquone) by comparing our results with previous results of the [3H]hypoxanthine incorporation readout provided by an expert laboratory, and subsequently assessed the speed of action of four new antimalarial candidates (compound 22, chlorotonil A, boromycin and ivermectin). The HRP-2 PRR assay achieved comparable results to the [3H]hypoxanthine incorporation readout in terms of parasite growth rate over time, lag phase and parasite clearance time. In addition, parasite growth following drug exposure was quantified after 7, 14, 21 and 28 days of recovery time. In conclusion, the PRR assay based on HRP-2 is similar to [3H]hypoxanthine in determining a drug's parasite killing rate and can be widely used in all research laboratories.
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Affiliation(s)
| | - Elena Niepoth
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany
| | | | - Andrea Kreidenweiss
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany; Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon; German Center for Infection Research (DZIF), Braunschweig, Germany
| | - Jennifer Herrmann
- German Center for Infection Research (DZIF), Braunschweig, Germany; Helmholtz Institute for Pharmaceutical Research Saarland, Saarbrücken, Germany
| | - Rolf Müller
- German Center for Infection Research (DZIF), Braunschweig, Germany; Helmholtz Institute for Pharmaceutical Research Saarland, Saarbrücken, Germany
| | - Tanja Knaab
- Institute of Pharmaceutics and Biopharmaceutics, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Bjoern B Burckhardt
- Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, Münster, Germany
| | - Thomas Kurz
- Institute of Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Jana Held
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany; Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon; German Center for Infection Research (DZIF), Braunschweig, Germany.
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Wynberg E, Commons RJ, Humphreys G, Ashurst H, Burrow R, Adjei GO, Adjuik M, Anstey NM, Anvikar A, Baird KJ, Barber BE, Barennes H, Baudin E, Bell DJ, Bethell D, Binh TQ, Borghini-Fuhrer I, Chu CS, Daher A, D’Alessandro U, Das D, Davis TME, de Vries PJ, Djimde AA, Dondorp AM, Dorsey G, Faucher JFF, Fogg C, Gaye O, Grigg M, Hatz C, Kager PA, Lacerda M, Laman M, Mårtensson A, Menan HIE, Monteiro WM, Moore BR, Nosten F, Ogutu B, Osorio L, Penali LK, Pereira DB, Rahim AG, Ramharter M, Sagara I, Schramm B, Seidlein L, Siqueira AM, Sirima SB, Starzengruber P, Sutanto I, Taylor WR, Toure OA, Utzinger J, Valea I, Valentini G, White NJ, William T, Woodrow CJ, Richmond CL, Guerin PJ, Price RN, Stepniewska K. Variability in white blood cell count during uncomplicated malaria and implications for parasite density estimation: a WorldWide Antimalarial Resistance Network individual patient data meta-analysis. Malar J 2023; 22:174. [PMID: 37280686 DOI: 10.1186/s12936-023-04583-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 05/07/2023] [Indexed: 06/08/2023] Open
Abstract
BACKGROUND The World Health Organization (WHO) recommends that when peripheral malarial parasitaemia is quantified by thick film microscopy, an actual white blood cell (WBC) count from a concurrently collected blood sample is used in calculations. However, in resource-limited settings an assumed WBC count is often used instead. The aim of this study was to describe the variability in WBC count during acute uncomplicated malaria, and estimate the impact of using an assumed value of WBC on estimates of parasite density and clearance. METHODS Uncomplicated malaria drug efficacy studies that measured WBC count were selected from the WorldWide Antimalarial Resistance Network data repository for an individual patient data meta-analysis of WBC counts. Regression models with random intercepts for study-site were used to assess WBC count variability at presentation and during follow-up. Inflation factors for parasitaemia density, and clearance estimates were calculated for methods using assumed WBC counts (8000 cells/µL and age-stratified values) using estimates derived from the measured WBC value as reference. RESULTS Eighty-four studies enrolling 27,656 patients with clinically uncomplicated malaria were included. Geometric mean WBC counts (× 1000 cells/µL) in age groups < 1, 1-4, 5-14 and ≥ 15 years were 10.5, 8.3, 7.1, 5.7 and 7.5, 7.0, 6.5, 6.0 for individuals with falciparum (n = 24,978) and vivax (n = 2678) malaria, respectively. At presentation, higher WBC counts were seen among patients with higher parasitaemia, severe anaemia and, for individuals with vivax malaria, in regions with shorter regional relapse periodicity. Among falciparum malaria patients, using an assumed WBC count of 8000 cells/µL resulted in parasite density underestimation by a median (IQR) of 26% (4-41%) in infants < 1 year old but an overestimation by 50% (16-91%) in adults aged ≥ 15 years. Use of age-stratified assumed WBC values removed systematic bias but did not improve precision of parasitaemia estimation. Imprecision of parasite clearance estimates was only affected by the within-patient WBC variability over time, and remained < 10% for 79% of patients. CONCLUSIONS Using an assumed WBC value for parasite density estimation from a thick smear may lead to underdiagnosis of hyperparasitaemia and could adversely affect clinical management; but does not result in clinically consequential inaccuracies in the estimation of the prevalence of prolonged parasite clearance and artemisinin resistance.
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T. Thurai Rathnam J, Grigg MJ, Dini S, William T, Sakam SS, Cooper DJ, Rajahram GS, Barber BE, Anstey NM, Haghiri A, Rajasekhar M, Simpson JA. Quantification of parasite clearance in Plasmodium knowlesi infections. Malar J 2023; 22:54. [PMID: 36782162 PMCID: PMC9926767 DOI: 10.1186/s12936-023-04483-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 02/04/2023] [Indexed: 02/15/2023] Open
Abstract
BACKGROUND The incidence of zoonotic Plasmodium knowlesi infections in humans is rising in Southeast Asia, leading to clinical studies to monitor the efficacy of anti-malarial treatments for knowlesi malaria. One of the key outcomes of anti-malarial drug efficacy is parasite clearance. For Plasmodium falciparum, parasite clearance is typically estimated using a two-stage method, that involves estimating parasite clearance for individual patients followed by pooling of individual estimates to derive population estimates. An alternative approach is Bayesian hierarchical modelling which simultaneously analyses all parasite-time patient profiles to determine parasite clearance. This study compared these methods for estimating parasite clearance in P. knowlesi treatment efficacy studies, with typically fewer parasite measurements per patient due to high susceptibility to anti-malarials. METHODS Using parasite clearance data from 714 patients with knowlesi malaria and enrolled in three trials, the Worldwide Antimalarial Resistance Network (WWARN) Parasite Clearance Estimator (PCE) standard two-stage approach and Bayesian hierarchical modelling were compared. Both methods estimate the parasite clearance rate from a model that incorporates a lag phase, slope, and tail phase for the parasitaemia profiles. RESULTS The standard two-stage approach successfully estimated the parasite clearance rate for 678 patients, with 36 (5%) patients excluded due to an insufficient number of available parasitaemia measurements. The Bayesian hierarchical estimation method was applied to the parasitaemia data of all 714 patients. Overall, the Bayesian method estimated a faster population mean parasite clearance (0.36/h, 95% credible interval [0.18, 0.65]) compared to the standard two-stage method (0.26/h, 95% confidence interval [0.11, 0.46]), with better model fits (compared visually). Artemisinin-based combination therapy (ACT) is more effective in treating P. knowlesi than chloroquine, as confirmed by both methods, with a mean estimated parasite clearance half-life of 2.5 and 3.6 h, respectively using the standard two-stage method, and 1.8 and 2.9 h using the Bayesian method. CONCLUSION For clinical studies of P. knowlesi with frequent parasite measurements, the standard two-stage approach (WWARN's PCE) is recommended as this method is straightforward to implement. For studies with fewer parasite measurements per patient, the Bayesian approach should be considered. Regardless of method used, ACT is more efficacious than chloroquine, confirming the findings of the original trials.
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Affiliation(s)
- Jeyamalar T. Thurai Rathnam
- grid.1008.90000 0001 2179 088XCentre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Australia
| | - Matthew J. Grigg
- grid.1043.60000 0001 2157 559XMenzies School of Health Research and Charles Darwin University, Darwin, NT Australia ,Infectious Diseases Society Sabah-Menzies School of Health Research Clinical Research Unit, Kota Kinabalu, Sabah, Malaysia
| | - Saber Dini
- grid.1008.90000 0001 2179 088XCentre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Australia
| | - Timothy William
- Infectious Diseases Society Sabah-Menzies School of Health Research Clinical Research Unit, Kota Kinabalu, Sabah, Malaysia
| | - Sitti Saimah Sakam
- Infectious Diseases Society Sabah-Menzies School of Health Research Clinical Research Unit, Kota Kinabalu, Sabah, Malaysia
| | - Daniel J. Cooper
- grid.1043.60000 0001 2157 559XMenzies School of Health Research and Charles Darwin University, Darwin, NT Australia ,Infectious Diseases Society Sabah-Menzies School of Health Research Clinical Research Unit, Kota Kinabalu, Sabah, Malaysia ,grid.5335.00000000121885934Department of Medicine, School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | - Giri S. Rajahram
- Infectious Diseases Society Sabah-Menzies School of Health Research Clinical Research Unit, Kota Kinabalu, Sabah, Malaysia ,grid.415759.b0000 0001 0690 5255Clinical Research Centre, Queen Elizabeth II Hospital, Ministry of Health, Kota Kinabalu, Sabah, Malaysia
| | - Bridget E. Barber
- grid.1043.60000 0001 2157 559XMenzies School of Health Research and Charles Darwin University, Darwin, NT Australia ,Infectious Diseases Society Sabah-Menzies School of Health Research Clinical Research Unit, Kota Kinabalu, Sabah, Malaysia ,grid.1049.c0000 0001 2294 1395QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Nicholas M. Anstey
- grid.1043.60000 0001 2157 559XMenzies School of Health Research and Charles Darwin University, Darwin, NT Australia ,Infectious Diseases Society Sabah-Menzies School of Health Research Clinical Research Unit, Kota Kinabalu, Sabah, Malaysia
| | - Ali Haghiri
- grid.1008.90000 0001 2179 088XCentre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Australia
| | - Megha Rajasekhar
- grid.1008.90000 0001 2179 088XCentre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Australia
| | - Julie A. Simpson
- grid.1008.90000 0001 2179 088XCentre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Australia
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New In Vitro Interaction-Parasite Reduction Ratio Assay for Early Derisk in Clinical Development of Antimalarial Combinations. Antimicrob Agents Chemother 2022; 66:e0055622. [PMID: 36197116 PMCID: PMC9664866 DOI: 10.1128/aac.00556-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The development and spread of drug-resistant phenotypes substantially threaten malaria control efforts. Combination therapies have the potential to minimize the risk of resistance development but require intensive preclinical studies to determine optimal combination and dosing regimens. To support the selection of new combinations, we developed a novel in vitro-in silico combination approach to help identify the pharmacodynamic interactions of the two antimalarial drugs in a combination which can be plugged into a pharmacokinetic/pharmacodynamic model built with human monotherapy parasitological data to predict the parasitological endpoints of the combination. This makes it possible to optimally select drug combinations and doses for the clinical development of antimalarials. With this assay, we successfully predicted the endpoints of two phase 2 clinical trials in patients with the artefenomel-piperaquine and artefenomel-ferroquine drug combinations. In addition, the predictive performance of our novel in vitro model was equivalent to that of the humanized mouse model outcome. Last, our more informative in vitro combination assay provided additional insights into the pharmacodynamic drug interactions compared to the in vivo systems, e.g., a concentration-dependent change in the maximum killing effect (Emax) and the concentration producing 50% of the killing maximum effect (EC50) of piperaquine or artefenomel or a directional reduction of the EC50 of ferroquine by artefenomel and a directional reduction of Emax of ferroquine by artefenomel. Overall, this novel in vitro-in silico-based technology will significantly improve and streamline the economic development of new drug combinations for malaria and potentially also in other therapeutic areas.
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Parasite Viability as a Measure of In Vivo Drug Activity in Preclinical and Early Clinical Antimalarial Drug Assessment. Antimicrob Agents Chemother 2022; 66:e0011422. [PMID: 35727057 PMCID: PMC9295577 DOI: 10.1128/aac.00114-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The rate at which parasitemia declines in a host after treatment with an antimalarial drug is a major metric for assessment of antimalarial drug activity in preclinical models and in early clinical trials. However, this metric does not distinguish between viable and nonviable parasites. Thus, enumeration of parasites may result in underestimation of drug activity for some compounds, potentially confounding its use as a metric for assessing antimalarial activity in vivo. Here, we report a study of the effect of artesunate on Plasmodium falciparum viability in humans and in mice. We first measured the drug effect in mice by estimating the decrease in parasite viability after treatment using two independent approaches to estimate viability. We demonstrate that, as previously reported in humans, parasite viability declines much faster after artesunate treatment than does the decline in parasitemia (termed parasite clearance). We also observed that artesunate kills parasites faster at higher concentrations, which is not discernible from the traditional parasite clearance curve and that each subsequent dose of artesunate maintains its killing effect. Furthermore, based on measures of parasite viability, we could accurately predict the in vivo recrudescence of infection. Finally, using pharmacometrics modeling, we show that the apparent differences in the antimalarial activity of artesunate in mice and humans are partly explained by differences in host removal of dead parasites in the two hosts. However, these differences, along with different pharmacokinetic profiles, do not fully account for the differences in activity. (This study has been registered with the Australian New Zealand Clinical Trials Registry under identifier ACTRN12617001394336.)
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Radohery GFR, Gower J, Barber BE, Kansagra K, Möhrle JJ, Davenport MP, McCarthy JS, Khoury DS, Rebelo M. Effect of novel antimalarial ZY-19489 on Plasmodium falciparum viability in a volunteer infection study. THE LANCET. INFECTIOUS DISEASES 2022; 22:760-761. [PMID: 35643094 DOI: 10.1016/s1473-3099(22)00294-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 04/12/2022] [Indexed: 06/15/2023]
Affiliation(s)
| | - Jeremy Gower
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Bridget E Barber
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | | | | | - Miles P Davenport
- Kirby Institute, University of New South Wales, Sydney, NSW, Australia
| | - James S McCarthy
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia; The Peter Doherty Institute for Infection and Immunity, The University of Melbourne and the Royal Melbourne Hospital, Melbourne, VIC, Australia
| | - David S Khoury
- Kirby Institute, University of New South Wales, Sydney, NSW, Australia
| | - Maria Rebelo
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia; Instituto de Medicina Molecular Joao Lobo Antunes, Lisbon 1649-028, Portugal.
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SheelaNair A, Romanczuk AS, Aogo RA, Haldar RN, Lansink LIM, Cromer D, Salinas YG, Guy RK, McCarthy JS, Davenport MP, Haque A, Khoury DS. Similarly efficacious anti-malarial drugs SJ733 and pyronaridine differ in their ability to remove circulating parasites in mice. Malar J 2022; 21:49. [PMID: 35172826 PMCID: PMC8848794 DOI: 10.1186/s12936-022-04075-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 02/06/2022] [Indexed: 11/13/2022] Open
Abstract
Background Artemisinin-based combination therapy (ACT) has been a mainstay for malaria prevention and treatment. However, emergence of drug resistance has incentivised development of new drugs. Defining the kinetics with which circulating parasitized red blood cells (pRBC) are lost after drug treatment, referred to as the “parasite clearance curve”, has been critical for assessing drug efficacy; yet underlying mechanisms remain partly unresolved. The clearance curve may be shaped both by the rate at which drugs kill parasites, and the rate at which drug-affected parasites are removed from circulation. Methods In this context, two anti-malarials, SJ733, and an ACT partner drug, pyronaridine were compared against sodium artesunate in mice infected with Plasmodium berghei (strain ANKA). To measure each compound’s capacity for pRBC removal in vivo, flow cytometric monitoring of a single cohort of fluorescently-labelled pRBC was employed, and combined with ex vivo parasite culture to assess parasite maturation and replication. Results These three compounds were found to be similarly efficacious in controlling established infection by reducing overall parasitaemia. While sodium artesunate acted relatively consistently across the life-stages, single-dose SJ733 elicited a biphasic effect, triggering rapid, partly phagocyte-dependent removal of trophozoites and schizonts, followed by arrest of residual ring-stages. In contrast, pyronaridine abrogated maturation of younger parasites, with less pronounced effects on mature parasites, while modestly increasing pRBC removal. Conclusions Anti-malarials SJ733 and pyronaridine, though similarly efficacious in reducing overall parasitaemia in mice, differed markedly in their capacity to arrest replication and remove pRBC from circulation. Thus, similar parasite clearance curves can result for anti-malarials with distinct capacities to inhibit, kill and clear parasites.
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Affiliation(s)
- Arya SheelaNair
- QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, Brisbane, QLD, 4006, Australia
| | - Aleksandra S Romanczuk
- QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, Brisbane, QLD, 4006, Australia
| | - Rosemary A Aogo
- Infection Analytics Program, Kirby Institute for Infection and Immunity, UNSW Sydney, Sydney, 2052, Australia
| | - Rohit Nemai Haldar
- QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, Brisbane, QLD, 4006, Australia
| | - Lianne I M Lansink
- QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, Brisbane, QLD, 4006, Australia.,Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, 792 Elizabeth Street, Parkville, VIC, 3000, Australia
| | - Deborah Cromer
- Infection Analytics Program, Kirby Institute for Infection and Immunity, UNSW Sydney, Sydney, 2052, Australia
| | | | - R Kiplin Guy
- College of Pharmacy, University of Kentucky, Lexington, KY, USA
| | - James S McCarthy
- QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, Brisbane, QLD, 4006, Australia.,Department of Infectious Diseases, Peter Doherty Institute for Infection and Immunity, University of Melbourne, 792 Elizabeth Street, Parkville, VIC, 3000, Australia.,Victorian Infectious Diseases Service, Royal Melbourne Hospital, Parkville, VIC, 3000, Australia
| | - Miles P Davenport
- Infection Analytics Program, Kirby Institute for Infection and Immunity, UNSW Sydney, Sydney, 2052, Australia
| | - Ashraful Haque
- QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, Brisbane, QLD, 4006, Australia. .,Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, 792 Elizabeth Street, Parkville, VIC, 3000, Australia.
| | - David S Khoury
- Infection Analytics Program, Kirby Institute for Infection and Immunity, UNSW Sydney, Sydney, 2052, Australia.
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10
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Artemisinin and Derivatives-Based Hybrid Compounds: Promising Therapeutics for the Treatment of Cancer and Malaria. Molecules 2021; 26:molecules26247521. [PMID: 34946603 PMCID: PMC8707619 DOI: 10.3390/molecules26247521] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 08/18/2021] [Accepted: 08/24/2021] [Indexed: 01/12/2023] Open
Abstract
Cancer and malaria are major health conditions around the world despite many strategies and therapeutics available for their treatment. The most used strategy for the treatment of these diseases is the administration of therapeutic drugs, which suffer from several shortcomings. Some of the pharmacological limitations associated with these drugs are multi-drug resistance, drug toxicity, poor biocompatibility and bioavailability, and poor water solubility. The currently ongoing preclinical studies have demonstrated that combination therapy is a potent approach that can overcome some of the aforementioned limitations. Artemisinin and its derivatives have been reported to exhibit potent efficacy as anticancer and antimalarial agents. This review reports hybrid compounds containing artemisinin scaffolds and their derivatives with promising therapeutic effects for the treatment of cancer and malaria.
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11
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Noreen N, Ullah A, Salman SM, Mabkhot Y, Alsayari A, Badshah SL. New insights into the spread of resistance to artemisinin and its analogues. J Glob Antimicrob Resist 2021; 27:142-149. [PMID: 34517141 DOI: 10.1016/j.jgar.2021.09.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 08/19/2021] [Accepted: 09/02/2021] [Indexed: 12/22/2022] Open
Abstract
Plasmodium falciparum, the causative agent of malaria, has been developing resistance to several drugs worldwide for more than five decades. Initially, resistance was against drugs such as chloroquine, pyrimethamine, sulfadoxine, mefloquine and quinine. Research studies are now reporting parasites with resistance to the most effective and novel drug used against malaria infection worldwide, namely artemisinin. For this reason, the first-line treatment strategy of artemisinin-based combination therapy is becoming unsuccessful in areas where drug resistance is highly prevalent. The increase in artemisinin-resistant P. falciparum strains has threatened international efforts to eliminate malarial infections and to reduce the disease burden. Detection of several phenotypes that display artemisinin resistance, specification of basic genetic factors, the discovery of molecular pathways, and evaluation of its clinical outcome are possible by the current series of research on genomics and transcriptomic levels in Asia and Africa. In artemisinin resistance, slow parasite clearance among malaria-infected patients and enhanced in vitro survival of parasites occurs at the early ring stage. This resistance is due to single nucleotide polymorphisms within the Kelch 13 gene of the parasite and is related to significantly upregulated resistance signalling pathways; thus, the pro-oxidant action of artemisinins can be antagonised. New strategies are required to halt the spread of artemisinin-resistant malarial parasites.
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Affiliation(s)
- Noreen Noreen
- Department of Chemistry, Islamia College University, Peshawar 25120, Pakistan
| | - Asad Ullah
- Department of Chemistry, Islamia College University, Peshawar 25120, Pakistan
| | | | - Yahia Mabkhot
- Department of Pharmaceutical Chemistry, College of Pharmacy, King Khalid University, P.O. Box 960, Abha 61421, Saudi Arabia.
| | - Abdulrhman Alsayari
- Department of Pharmacognosy, College of Pharmacy, King Khalid University, Abha, Saudi Arabia
| | - Syed Lal Badshah
- Department of Chemistry, Islamia College University, Peshawar 25120, Pakistan.
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12
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Ippolito MM, Moser KA, Kabuya JBB, Cunningham C, Juliano JJ. Antimalarial Drug Resistance and Implications for the WHO Global Technical Strategy. CURR EPIDEMIOL REP 2021; 8:46-62. [PMID: 33747712 PMCID: PMC7955901 DOI: 10.1007/s40471-021-00266-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/01/2021] [Indexed: 12/28/2022]
Abstract
PURPOSE OF REVIEW Five years have passed since the World Health Organization released its Global Technical Strategy for Malaria (GTS). In that time, progress against malaria has plateaued. This review focuses on the implications of antimalarial drug resistance for the GTS and how interim progress in parasite genomics and antimalarial pharmacology offer a bulwark against it. RECENT FINDINGS For the first time, drug resistance-conferring genes have been identified and validated before their global expansion in malaria parasite populations. More efficient methods for their detection and elaboration have been developed, although low-density infections and polyclonality remain a nuisance to be solved. Clinical trials of alternative regimens for multidrug-resistant malaria have delivered promising results. New agents continue down the development pipeline, while a nascent infrastructure in sub-Saharan Africa for conducting phase I trials and trials of transmission-blocking agents has come to fruition after years of preparation. SUMMARY These and other developments can help inform the GTS as the world looks ahead to the next two decades of its implementation. To remain ahead of the threat that drug resistance poses, wider application of genomic-based surveillance and optimization of existing and forthcoming antimalarial drugs are essential.
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Affiliation(s)
- Matthew M. Ippolito
- Divisions of Clinical Pharmacology and Infectious Diseases, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD USA
- The Johns Hopkins Malaria Research Institute, Johns Hopkins University School of Public Health, Baltimore, MD USA
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD USA
| | - Kara A. Moser
- Institute for Global Health and Infectious Diseases, University of North Carolina, Chapel Hill, NC USA
| | | | - Clark Cunningham
- School of Medicine, University of North Carolina, Chapel Hill, NC USA
| | - Jonathan J. Juliano
- Division of Infectious Diseases, Department of Medicine, School of Medicine, University of North Carolina, CB#7030, 130 Mason Farm Rd, Chapel Hill, NC 27599 USA
- Curriculum in Genetics and Molecular Biology, School of Medicine, University of North Carolina, Chapel Hill, NC USA
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC USA
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13
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Rebelo M, Pawliw R, Gower J, Webb L, Mitchell H, Pava Z, Watts RE, Davenport MP, McCarthy JS, Khoury DS. Parasite Viability as a Superior Measure of Antimalarial Drug Activity in Humans. J Infect Dis 2020; 223:2154-2163. [PMID: 33119072 DOI: 10.1093/infdis/jiaa678] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 10/22/2020] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Artemisinin derivatives are the leading class of antimalarial drugs due to their rapid onset of action and rapid clearance of circulating parasites. The parasite clearance half-life measures the rate of loss of parasites from blood after treatment, and this is currently used to assess antimalarial activity of novel agents and to monitor resistance. However, a number of recent studies have challenged the use of parasite clearance to measure drug activity, arguing that many circulating parasites may be nonviable. METHODS Plasmodium falciparum-infected subjects (n = 10) in a malaria volunteer infection study were administered a single dose of artesunate (2 mg/kg). Circulating parasite concentration was assessed by means of quantitative polymerase chain reaction (qPCR). Parasite viability after artesunate administration was estimated by mathematical modeling of the ex vivo growth of parasites collected from subjects. RESULTS We showed that in artemisinin-sensitive infection, viable parasites declined to <0.1% of baseline within 8 hours after artesunate administration, while the total number of circulating parasites measured with quantitative polymerase chain reaction remained unchanged. In artemisinin-resistant infections over the same interval, viable parasites declined to 51.4% (standard error of the mean, 4.6%) of baseline. CONCLUSIONS These results demonstrate that in vivo drug activity of artesunate is faster than is indicated by the parasite clearance half-life.
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Affiliation(s)
- Maria Rebelo
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Rebecca Pawliw
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Jeremy Gower
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Lachlan Webb
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Hayley Mitchell
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Zuleima Pava
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Rebecca E Watts
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - Miles P Davenport
- Kirby Institute, University of New South Wales (Sydney), Sydney, New South Wales, Australia
| | - James S McCarthy
- QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
| | - David S Khoury
- Kirby Institute, University of New South Wales (Sydney), Sydney, New South Wales, Australia
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14
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Ippolito MM, Pringle JC, Siame M, Katowa B, Aydemir O, Oluoch PO, Huang L, Aweeka FT, Bailey JA, Juliano JJ, Meshnick SR, Shapiro TA, Moss WJ, Thuma PE. Therapeutic Efficacy of Artemether-Lumefantrine for Uncomplicated Falciparum Malaria in Northern Zambia. Am J Trop Med Hyg 2020; 103:2224-2232. [PMID: 33078701 DOI: 10.4269/ajtmh.20-0852] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Artemether-lumefantrine (AL) is a first-line agent for uncomplicated malaria caused by Plasmodium falciparum. The WHO recommends periodic therapeutic efficacy studies of antimalarial drugs for the detection of malaria parasite drug resistance and to inform national malaria treatment policies. We conducted a therapeutic efficacy study of AL in a high malaria transmission region of northern Zambia from December 2014 to July 2015. One hundred children of ages 6 to 59 months presenting to a rural health clinic with uncomplicated falciparum malaria were admitted for treatment with AL (standard 6-dose regimen) and followed weekly for 5 weeks. Parasite counts were taken every 6 hours during treatment to assess parasite clearance. Recurrent episodes during follow-up (n = 14) were genotyped to distinguish recrudescence from reinfection and to identify drug resistance single nucleotide polymorphisms (SNPs) and multidrug resistance protein 1 (mdr1) copy number variation. Day 7 lumefantrine concentrations were measured for correspondence with posttreatment reinfection. All children who completed the parasite clearance portion of the study (n = 94) were microscopy-negative by 72 hours. The median parasite elimination half-life was 2.7 hours (interquartile range: 2.1-3.3). Genotype-corrected therapeutic efficacy was 98.8% (95% CI: 97.6-100). Purported artemisinin and lumefantrine drug resistance SNPs in atp6, 3D7_1451200, and mdr1 were detected but did not correlate with parasite recurrence, nor did day 7 lumefantrine concentrations. In summary, AL was highly effective for the treatment of uncomplicated falciparum malaria in northern Zambia during the study period. The high incidence of recurrent parasitemia was consistent with reinfection due to high, perennial malaria transmission.
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Affiliation(s)
- Matthew M Ippolito
- The Johns Hopkins Malaria Research Institute, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland.,Division of Clinical Pharmacology, Johns Hopkins University School of Medicine, Baltimore, Maryland.,Division of Infectious Diseases, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Julia C Pringle
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland
| | - Mwiche Siame
- Ministry of Health, Government of the Republic of Zambia, Lusaka, Zambia
| | | | - Ozkan Aydemir
- Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island
| | - Peter O Oluoch
- Center for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya.,Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island
| | - Liusheng Huang
- Department of Clinical Pharmacology, University of California San Francisco School of Pharmacy, San Francisco, California
| | - Francesca T Aweeka
- Department of Clinical Pharmacology, University of California San Francisco School of Pharmacy, San Francisco, California
| | - Jeffrey A Bailey
- Department of Pathology and Laboratory Medicine, Brown University, Providence, Rhode Island
| | - Jonathan J Juliano
- Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - Steven R Meshnick
- Department of Epidemiology, University of North Carolina Gillings School of Global Public Health, Chapel Hill, North Carolina
| | - Theresa A Shapiro
- The Johns Hopkins Malaria Research Institute, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland.,Division of Clinical Pharmacology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - William J Moss
- Department of Epidemiology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland.,The Johns Hopkins Malaria Research Institute, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland.,W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland
| | - Philip E Thuma
- Macha Research Trust, Macha, Zambia.,The Johns Hopkins Malaria Research Institute, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland
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15
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Wellems TE, Sá JM, Su XZ, Connelly SV, Ellis AC. 'Artemisinin Resistance': Something New or Old? Something of a Misnomer? Trends Parasitol 2020; 36:735-744. [PMID: 32586776 DOI: 10.1016/j.pt.2020.05.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 05/22/2020] [Accepted: 05/25/2020] [Indexed: 01/02/2023]
Abstract
Artemisinin and its derivatives (ART) are crucial first-line antimalarial drugs that rapidly clear parasitemia, but recrudescences of the infection frequently follow ART monotherapy. For this reason, ART must be used in combination with one or more partner drugs that ensure complete cure. The ability of malaria parasites to survive ART monotherapy may relate to an innate growth bistability phenomenon whereby a fraction of the drug-exposed population enters into metabolic quiescence (dormancy) as persister forms. Characterization of the events that underlie entry and waking from persistence may lead to lasting breakthroughs in malaria chemotherapy that can prevent recrudescences and protect the future of ART-based combination therapies.
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Affiliation(s)
- Thomas E Wellems
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Juliana M Sá
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Xin-Zhuan Su
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sean V Connelly
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Angela C Ellis
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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