scholarly journals Defining the antimalarial activity of cipargamin in healthy volunteers experimentally infected with blood stage Plasmodium falciparum

2020 ◽  
Author(s):  
James S. McCarthy ◽  
Azrin N. Abd-Rahman ◽  
Katharine A. Collins ◽  
Louise Marquart ◽  
Paul Griffin ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Healthy Volunteers ◽  
Antimalarial Activity ◽  
Parasite Clearance ◽  
Clinical Development ◽  
Blood Stage ◽  
Maximum Effect ◽  
Limited Data ◽  
Dose Cohort ◽  
New Treatment

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 3-8 days after dosing, and allowed the pharmacokinetic/pharmacodynamic relationship to be determined. Based on the limited data from the single sub-therapeutic dose cohort, a minimum inhibitory concentration of 11.6 ng/mL and minimum parasiticidal concentration that achieves 90% of maximum effect of 23.5 ng/mL was estimated, and a single 95 mg dose (95% CI: 50-270) 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.

scholarly journals Antimalarial Activity of Artefenomel Against Asexual Parasites and Transmissible Gametocytes During Experimental Blood-Stage Plasmodium vivax Infection

2020 ◽  
Author(s):  
Katharine A Collins ◽  
Azrin N Abd-Rahman ◽  
Louise Marquart ◽  
Emma Ballard ◽  
Nathalie Gobeau ◽  
...  
Keyword(s):  
Plasmodium Vivax ◽  
Inhibitory Concentration ◽  
Antimalarial Activity ◽  
Parasite Clearance ◽  
Clinical Development ◽  
Blood Stage ◽  
Drug Candidate ◽  
Maximum Effect ◽  
Infection Study

Abstract Background Interventions that effectively target Plasmodium vivax are critical for the future control and elimination of malaria. We conducted a P. vivax volunteer infection study to characterize the antimalarial activity of artefenomel, a new drug candidate. Methods Eight healthy, malaria-naive participants were intravenously inoculated with blood-stage P. vivax and subsequently received a single oral 200-mg dose of artefenomel. Blood samples were collected to monitor the development and clearance of parasitemia, and plasma artefenomel concentration. Mosquito feeding assays were conducted before artefenomel dosing to investigate parasite transmissibility. Results Initial parasite clearance occurred in all participants after artefenomel administration (log10 parasite reduction ratio over 48 hours, 1.67; parasite clearance half-life, 8.67 hours). Recrudescence occurred in 7 participants 11–14 days after dosing. A minimum inhibitory concentration of 0.62 ng/mL and minimum parasiticidal concentration that achieves 90% of maximum effect of 0.83 ng/mL were estimated, and a single 300-mg dose was predicted to clear 109 parasites per milliliter with 95% certainty. Gametocytemia developed in all participants and was cleared 4–8 days after dosing. At peak gametocytemia, 75% of participants were infectious to mosquitoes. Conclusions The in vivo antimalarial activity of artefenomel supports its further clinical development as a treatment for P. vivax malaria. Clinical Trials Registration NCT02573857.

scholarly journals A Single-Dose Combination Study with the Experimental Antimalarials Artefenomel and DSM265 To Determine Safety and Antimalarial Activity against Blood-Stage Plasmodium falciparum in Healthy Volunteers

2019 ◽  
Vol 64 (1) ◽  
Author(s):  
James S. McCarthy ◽  
Thomas Rückle ◽  
Suzanne L. Elliott ◽  
Emma Ballard ◽  
Katharine A. Collins ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Antimalarial Activity ◽  
Plasma Concentrations ◽  
Parasite Clearance ◽  
Blood Stage ◽  
Content Type ◽  
Dose Combination ◽  
Combination Study ◽  
Study Support ◽  
New Compounds

ABSTRACT Artefenomel and DSM265 are two new compounds that have been shown to be well tolerated and effective when administered as monotherapy malaria treatment. This study aimed to determine the safety, pharmacokinetics, and pharmacodynamics of artefenomel and DSM265 administered in combination to healthy subjects in a volunteer infection study using the Plasmodium falciparum-induced blood-stage malaria model. Thirteen subjects were inoculated with parasite-infected erythrocytes on day 0 and received a single oral dose of artefenomel and DSM265 on day 7. Cohort 1 (n = 8) received 200 mg artefenomel plus 100 mg DSM265, and cohort 2 (n = 5) received 200 mg artefenomel plus 50 mg DSM265. Blood samples were collected to measure parasitemia, gametocytemia, and artefenomel-DSM265 plasma concentrations. There were no treatment-related adverse events. The pharmacokinetic profiles of artefenomel and DSM265 were similar to those of the compounds when administered as monotherapy, suggesting no pharmacokinetic interactions. A reduction in parasitemia occurred in all subjects following treatment (log10 parasite reduction ratios over 48 h [PRR48] of 2.80 for cohort 1 and 2.71 for cohort 2; parasite clearance half-lives of 5.17 h for cohort 1 and 5.33 h for cohort 2). Recrudescence occurred in 5/8 subjects in cohort 1 between days 19 and 28 and in 5/5 subjects in cohort 2 between days 15 and 22. Low-level gametocytemia (1 to 330 female gametocytes/ml) was detected in all subjects from day 14. The results of this single-dosing combination study support the further clinical development of the use of artefenomel and DSM265 in combination as a treatment for falciparum malaria. (This study has been registered at ClinicalTrials.gov under identifier NCT02389348.)

scholarly journals A Pilot Randomised Trial of Induced Blood-Stage Plasmodium falciparum Infections in Healthy Volunteers for Testing Efficacy of New Antimalarial Drugs

PLoS ONE ◽  
2011 ◽  
Vol 6 (8) ◽  
pp. e21914 ◽  
Author(s):  
James S. McCarthy ◽  
Silvana Sekuloski ◽  
Paul M. Griffin ◽  
Suzanne Elliott ◽  
Nanette Douglas ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Healthy Volunteers ◽  
Randomised Trial ◽  
Antimalarial Drugs ◽  
Blood Stage

scholarly journals Pre-erythrocytic antibody profiles induced by controlled human malaria infections in healthy volunteers under chloroquine prophylaxis

2013 ◽  
Vol 3 (1) ◽  
Author(s):  
Philip L. Felgner ◽  
Meta Roestenberg ◽  
Li Liang ◽  
Christopher Hung ◽  
Aarti Jain ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Life Cycle ◽  
Healthy Volunteers ◽  
Protective Immunity ◽  
Circumsporozoite Protein ◽  
Blood Stage ◽  
Asexual Blood Stage ◽  
Liver Stage ◽  
Human Malaria ◽  
Life Cycle Stages

Abstract Complete sterile protection to Plasmodium falciparum (Pf) infection mediated by pre-erythrocytic immunity can be experimentally induced under chloroquine prophylaxis, through immunization with sporozoites from infected mosquitoes' bites (CPS protocol). To characterize the profile of CPS induced antibody (Ab) responses, we developed a proteome microarray containing 809 Pf antigens showing a distinct Ab profile with recognition of antigens expressed in pre-erythrocytic life-cycle stages. In contrast, plasma from naturally exposed semi-immune individuals from Kenya was skewed toward antibody reactivity against asexual blood stage antigens. CPS-immunized and semi-immune individuals generated antibodies against 192 and 202 Pf antigens, respectively, but only 60 antigens overlapped between the two groups. Although the number of reactive antigens varied between the CPS-immunized individuals, all volunteers reacted strongly against the pre-erythrocytic antigens circumsporozoite protein (CSP) and liver stage antigen 1 (LSA1). Well classified merozoite and erythrocytic antigens were strongly reactive in semi-immune individuals but lacking in the CPS immunized group. These data show that the antibody profile of CPS-immunized and semi-immune groups have quite distinct profiles reflecting their protective immunity; antibodies from CPS immunized individuals react strongly against pre-erythrocytic while semi-immune individuals mainly react against erythrocytic antigens.

scholarly journals Development and evaluation of a new Plasmodium falciparum 3D7 blood stage malaria cell bank for use in malaria volunteer infection studies

2021 ◽  
Author(s):  
Stephen Derek Woolley ◽  
Melissa Fernandez ◽  
Maria Rebelo ◽  
Stacey Llewellyn ◽  
Louise Marquart ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Parasite Clearance ◽  
Blood Stage ◽  
Multiplication Rate ◽  
Weighted Mean ◽  
Cell Bank ◽  
Parasite Multiplication ◽  
Clinical Trials Registry ◽  
Blood Stage Malaria

Abstract Background New anti-malarial therapeutics are required to counter the threat of increasing drug resistance. Malaria volunteer infection studies (VIS), particularly the induced blood stage malaria (IBSM) model, play a key role in accelerating anti-malarial drug development. Supply of the reference 3D7-V2 Plasmodium falciparum malaria cell bank (MCB) is limited. This study aimed to develop a new MCB, and compare the safety and infectivity of this MCB with the existing 3D7-V2 MCB, in a VIS. A second bank (3D7-V1) developed in 1995 was also evaluated.Methods The 3D7-V2 MCB was expanded in vitro using a bioreactor to produce a new MCB designated 3D7-MBE-008. This bank and 3D7-V1 were then evaluated using the IBSM model, where healthy participants were intravenously inoculated with blood-stage parasites. Participants were treated with artemether-lumefantrine when parasitaemia or clinical thresholds were reached. Safety, infectivity and parasite growth and clearance were evaluated. Results The in vitro expansion of 3D7-V2 produced 200 vials of the 3D7-MBE-008 MCB, with a parasitaemia of 4.3%. This compares to 0.1% in the existing 3D7-V2 MCB, and <0.01% in the 3D7-V1 MCB. All four participants (two per MCB) developed detectable P. falciparum infection after inoculation with approximately 2800 parasites. For the 3D7-MBE-008 MCB, the parasite multiplication rate of 48 hours (PMR48) using non-linear mixed effects modelling was 34.6 (95% CI: 18.5 – 64.6), similar to the parental 3D7-V2 line; parasitaemia in both participants exceeded 10,000/mL by day 8. Growth of the 3D7-V1 was slower (PMR48 of 11.5 [95% CI: 8.5 – 15.6]), with parasitaemia exceeding 10,000 parasites/mL on days 10 and 8.5. Rapid parasite clearance followed artemether-lumefantrine treatment in all four participants, with clearance half-lives of 4.01 and 4.06 (weighted mean 4.04 [95% CI: 3.61 – 4.57]) hours for 3D7-MBE-008 and 4.11 and 4.52 (weighted mean 4.31 [95% CI: 4.16 – 4.47]) hours for 3D7-V1. A total of 59 adverse events occurred; most were of mild severity with three being severe in the 3D7-MBE-008 study. Conclusion The safety, growth and clearance profiles of the expanded 3D7-MBE-008 MCB closely resemble that of its parent, indicating its suitability for future studies. Trial Registration Australian New Zealand Clinical Trials registry numbers:P3487 (3D7-V1): ACTRN12619001085167P3491 (3D7-MBE-008): ACTRN12619001079134

scholarly journals Semi-mechanistic pharmacokinetic and pharmacodynamic modelling of piperaquine in a volunteer infection study with Plasmodium falciparum blood-stage malaria

2021 ◽  
Author(s):  
Thanaporn Wattanakul ◽  
Mark Baker ◽  
Joerg Mohrle ◽  
Brett McWhinney ◽  
Richard M. Hoglund ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Combination Therapy ◽  
Multidrug Resistant ◽  
Pharmacodynamic Model ◽  
Blood Stage ◽  
Maximum Effect ◽  
Combination Therapies ◽  
Triple Combination Therapy ◽  
The Impact ◽  
Parasite Dynamics

Dihydroartemisinin-piperaquine is a recommended first-line artemisinin combination therapy for 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 could be used to optimize 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 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 qPCR, and piperaquine levels were measured in plasma samples. We used nonlinear mixed-effect modelling to characterize the pharmacokinetic properties of piperaquine and the parasite dynamics associated with piperaquine exposure. Pharmacokinetics of piperaquine was described by a three-compartment disposition model. A semi-mechanistic parasite dynamics model was developed to explain maturation of parasites, sequestration of mature parasites, synchronicity of infections, and multiplication of parasites, as seen in natural clinical infections with falciparum malaria. Piperaquine-associated parasite killing was estimated using a maximum effect (Emax) 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 semi-mechanistic pharmacokinetic-pharmacodynamic model described here offers the potential to be a valuable tool to assess and optimize current and new antimalarial drug combinations therapies containing piperaquine, and the impact of these therapies on killing multidrug resistant infections.

scholarly journals Assessment in vitro of the antimalarial and transmission blocking activities of Cipargamin and Ganaplacide in artemisinin resistant Plasmodium falciparum

2022 ◽  
Author(s):  
Achaporn Yipsirimetee ◽  
Pornpawee Chiewpoo ◽  
Rupam Tripura ◽  
Dysoley Lek ◽  
Nicholas P. J. Day ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Antimalarial Activity ◽  
Artemisinin Resistance ◽  
Blood Stage ◽  
Mature Stage ◽  
Asexual Blood Stage ◽  
Male And Female ◽  
Transmission Blocking ◽  
Combination Treatments

Artemisinin resistance in Plasmodium falciparum has emerged and spread widely in the Greater Mekong Subregion threatening current first line artemisinin combination treatments. New antimalarial drugs are needed urgently. Cipargamin (KAE609) and ganaplacide (KAF156) are promising novel antimalarial compounds in advanced stages of development. Both compounds have potent asexual blood stage activities, inhibit P. falciparum gametocytogenesis and reduce oocyst development in anopheline mosquitoes. In this study, we compared the asexual and sexual stage activities of cipargamin, ganaplacide and artesunate in artemisinin resistant P. falciparum isolates (N=7, K13 mutation; C580Y, G449A and R539T) from Thailand and Cambodia. Asexual blood stage antimalarial activity was evaluated in a SYBR-green I based 72h in vitro assay, and the effects on male and female mature stage V gametocytes were assessed in the P. falciparum dual gamete formation assay. Ganaplacide had higher activities when compared to cipargamin and artesunate, with a mean (SD) IC50 against asexual stages of 5.5 (1.1) nM, 7.8 (3.9) nM for male gametocytes and 57.9 (59.6) nM for female gametocytes. Cipargamin had a similar potency against male and female gametocytes, with a mean (SD) IC50 of 123.1 (80.2) nM for male gametocytes, 88.5 (52.7) nM for female gametocytes and 2.4 (0.6) nM for asexual stages. Both cipargamin and ganaplacide showed significant transmission-blocking activities against artemisinin resistant P. falciparum in vitro .

scholarly journals Development and evaluation of a new Plasmodium falciparum 3D7 blood stage malaria cell bank for use in malaria volunteer infection studies

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Stephen D. Woolley ◽  
Melissa Fernandez ◽  
Maria Rebelo ◽  
Stacey A. Llewellyn ◽  
Louise Marquart ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Parasite Clearance ◽  
Blood Stage ◽  
Multiplication Rate ◽  
Weighted Mean ◽  
Cell Bank ◽  
In Vitro Expansion ◽  
Clinical Trials Registry ◽  
Blood Stage Malaria

Abstract Background New anti-malarial therapeutics are required to counter the threat of increasing drug resistance. Malaria volunteer infection studies (VIS), particularly the induced blood stage malaria (IBSM) model, play a key role in accelerating anti-malarial drug development. Supply of the reference 3D7-V2 Plasmodium falciparum malaria cell bank (MCB) is limited. This study aimed to develop a new MCB, and compare the safety and infectivity of this MCB with the existing 3D7-V2 MCB, in a VIS. A second bank (3D7-V1) developed in 1995 was also evaluated. Methods The 3D7-V2 MCB was expanded in vitro using a bioreactor to produce a new MCB designated 3D7-MBE-008. This bank and 3D7-V1 were then evaluated using the IBSM model, where healthy participants were intravenously inoculated with blood-stage parasites. Participants were treated with artemether-lumefantrine when parasitaemia or clinical thresholds were reached. Safety, infectivity and parasite growth and clearance were evaluated. Results The in vitro expansion of 3D7-V2 produced 200 vials of the 3D7-MBE-008 MCB, with a parasitaemia of 4.3%. This compares to 0.1% in the existing 3D7-V2 MCB, and < 0.01% in the 3D7-V1 MCB. All four participants (two per MCB) developed detectable P. falciparum infection after inoculation with approximately 2800 parasites. For the 3D7-MBE-008 MCB, the parasite multiplication rate of 48 h (PMR48) using non-linear mixed effects modelling was 34.6 (95% CI 18.5–64.6), similar to the parental 3D7-V2 line; parasitaemia in both participants exceeded 10,000/mL by day 8. Growth of the 3D7-V1 was slower (PMR48 of 11.5 [95% CI 8.5–15.6]), with parasitaemia exceeding 10,000 parasites/mL on days 10 and 8.5. Rapid parasite clearance followed artemether-lumefantrine treatment in all four participants, with clearance half-lives of 4.01 and 4.06 (weighted mean 4.04 [95% CI 3.61–4.57]) hours for 3D7-MBE-008 and 4.11 and 4.52 (weighted mean 4.31 [95% CI 4.16–4.47]) hours for 3D7-V1. A total of 59 adverse events occurred; most were of mild severity with three being severe in the 3D7-MBE-008 study. Conclusion The safety, growth and clearance profiles of the expanded 3D7-MBE-008 MCB closely resemble that of its parent, indicating its suitability for future studies. Trial Registration: Australian New Zealand Clinical Trials registry numbers: P3487 (3D7-V1): ACTRN12619001085167. P3491 (3D7-MBE-008): ACTRN12619001079134

Sign in / Sign up

Export Citation Format

Share Document