Therapeutic development to accelerate malaria control through intentional intervention layering.

The clinical development of novel vaccines, injectable therapeutics, and oral chemoprevention drugs has the potential to deliver significant advancements in the prevention of Plasmodium falciparum malaria. These innovations could support regions in accelerating malaria control, transforming existing intervention packages by supplementing interventions with imperfect effectiveness or offering an entirely new tool. However, to layer new medical tools as part of an existing programme, malaria researchers must come to an agreement on the gaps that currently limit the effectiveness of medical interventions for moderate to low transmission settings.

Characterising the blood-stage antimalarial activity of pyronaridine in healthy volunteers experimentally infected with Plasmodium falciparum.

With the spread of artemisinin resistance throughout Southeast Asia and now in Africa, the antimalarial drug pyronaridine is likely to become an increasingly important component of new antimalarial drug regimens. However, the antimalarial activity of pyronaridine in humans has not been completely characterised. This volunteer infection study aimed to determine the pharmacokinetic/pharmacodynamic (PK/PD) relationship of pyronaridine in malaria naïve adults.

Predicting Optimal Antimalarial Drug Combinations from a Standardized Plasmodium falciparum Humanized Mouse Model.

The development of new combinations of antimalarial drugs is urgently needed to prevent the spread of parasites resistant to drugs in clinical use and contribute to the control and eradication of malaria. In this work, we evaluated a standardized humanized mouse model of erythrocyte asexual stages of Plasmodium falciparum (PfalcHuMouse) for the selection of optimal drug combinations. First, we showed that the replication of P.

Characterizing the Blood-Stage Antimalarial Activity of Tafenoquine in Healthy Volunteers Experimentally Infected With Plasmodium falciparum.

Background: The long-acting 8-aminoquinoline tafenoquine may be a good candidate for mass drug administration if it exhibits sufficient blood-stage antimalarial activity at doses low enough to be tolerated by glucose 6-phosphate dehydrogenase (G6PD)-deficient individuals.

Methods: Healthy adults with normal levels of G6PD were inoculated with Plasmodium falciparum 3D7-infected erythrocytes on day 0. Different single oral doses of tafenoquine were administered on day 8.

Development of New Strategies for Malaria Chemoprophylaxis: From Monoclonal Antibodies to Long-Acting Injectable Drugs.

Drug discovery for malaria has traditionally focused on orally available drugs that kill the abundant, parasitic blood stage. Recently, there has also been an interest in injectable medicines, in the form of monoclonal antibodies (mAbs) with long-lasting plasma half-lives or long-lasting depot formulations of small molecules. These could act as prophylactic drugs, targeting the sporozoites and other earlier parasitic stages in the liver, when the parasites are less numerous, or as another intervention strategy targeting the formation of infectious gametocytes.

Haematological response in experimental human Plasmodium falciparum and Plasmodium vivax malaria.

Background: Malaria-associated anaemia, arising from symptomatic, asymptomatic and submicroscopic infections, is a significant cause of morbidity worldwide. Induced blood stage malaria volunteer infection studies (IBSM-VIS) provide a unique opportunity to evaluate the haematological response to early Plasmodium falciparum and Plasmodium vivax infection.

Methods: This study was an analysis of the haemoglobin, red cell counts, and parasitaemia data from 315 participants enrolled in IBSM-VIS between 2012 and 2019, including 269 participants inoculated with the 3D7 strain of P.

Seeking an optimal dosing regimen for OZ439/DSM265 combination therapy for treating uncomplicated falciparum malaria.

Background: The efficacy of artemisinin-based combination therapies (ACTs), the first-line treatments for uncomplicated falciparum malaria, has been declining in malaria-endemic countries due to the emergence of malaria parasites resistant to these compounds. Novel alternative therapies are needed urgently to prevent the likely surge in morbidity and mortality due to failing ACTs.

Objectives: This study investigates the efficacy of the combination of two novel drugs, OZ439 and DSM265, using a biologically informed within-host mathematical model.

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

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.

Liver Function Test Abnormalities in Experimental and Clinical Infection.

Liver transaminase elevations after treatment in malaria volunteer infection studies (VISs) have raised safety concerns. We investigated transaminase elevations from two human VISs where subjects were treated with chloroquine ( = 24) or artefenomel ( = 8) and compared them with studies in Thailand ( = 41) and Malaysia ( = 76). In the VISs, alanine transaminase (ALT) increased to ≥ 2.

A Plasmodium vivax experimental human infection model for evaluating efficacy of interventions.

BACKGROUNDInterventions that interrupt Plasmodium vivax transmission or eliminate dormant P. vivax liver-stage parasites will be essential for malaria elimination. Development of these interventions has been hindered by the lack of P.

An in vitro toolbox to accelerate anti-malarial drug discovery and development.

Background: Modelling and simulation are being increasingly utilized to support the discovery and development of new anti-malarial drugs. These approaches require reliable in vitro data for physicochemical properties, permeability, binding, intrinsic clearance and cytochrome P450 inhibition. This work was conducted to generate an in vitro data toolbox using standardized methods for a set of 45 anti-malarial drugs and to assess changes in physicochemical properties in relation to changing target product and candidate profiles.

PCR correction strategies for malaria drug trials: updates and clarifications.

Malaria drug trials conducted in endemic areas face a major challenge in their analysis because it is difficult to establish whether parasitaemia in blood samples collected after treatment indicate drug failure or a new infection acquired after treatment. It is therefore vital to reliably distinguish drug failures from new infections in order to obtain accurate estimates of drug failure rates. This distinction can be achieved for Plasmodium falciparum by comparing parasite genotypes obtained at the time of treatment (the baseline) and on the day of recurring parasitaemia.

Increased stress associated with head-out plethysmography testing can exacerbate respiratory effects and lead to mortality in rats.

Introduction: DSM421, a dihydroorotate dehydrogenase inhibitor, was in preclinical development as a potential treatment option for malaria. When tested in a core battery of safety pharmacology assays, DSM421 did not produce any effects at oral doses up to 750 mg/kg in an Irwin test in rats, but a respiratory study in rats using head-out plethysmography resulted in substantial changes in respiratory function as well as moribundity and mortality at that and lower doses. An investigation was performed to determine the source of this discrepancy.

Efficacy and Safety of Fosmidomycin-Piperaquine as Nonartemisinin-Based Combination Therapy for Uncomplicated Falciparum Malaria: A Single-Arm, Age De-escalation Proof-of-Concept Study in Gabon.

Background: Fosmidomycin-piperaquine is being developed as nonartemisinin-based combination therapy to meet the challenge of emerging artemisinin resistance.

Methods: The study was a phase 2, single-arm, proof-of-concept study of the efficacy, tolerability, and safety of fosmidomycin-piperaquine for the treatment of uncomplicated Plasmodium falciparum monoinfection in Gabon. Adults and children of both sexes with initial parasite counts between 1000 and 150000/µL received oral treatment with fosmidomycin (twice daily doses of 30 mg/kg) and piperaquine (once daily dose of 16 mg/kg) for 3 days and followed-up for 63 days.

Characterization of Novel Antimalarial Compound ACT-451840: Preclinical Assessment of Activity and Dose-Efficacy Modeling.

Background: Artemisinin resistance observed in Southeast Asia threatens the continued use of artemisinin-based combination therapy in endemic countries. Additionally, the diversity of chemical mode of action in the global portfolio of marketed antimalarials is extremely limited. Addressing the urgent need for the development of new antimalarials, a chemical class of potent antimalarial compounds with a novel mode of action was recently identified.

Safety, tolerability and pharmacokinetic profile of single and multiple oral doses of arterolane (RBx11160) maleate in healthy subjects.

Arterolane (RBx11160, OZ277) maleate is a rapidly acting synthetic trioxolane anti-malarial. This randomized, placebo controlled study was a phase I study to evaluate the clinical safety and tolerability as well as pharmacokinetics (PKs) of arterolane maleate including food effect. Eight single rising oral doses of arterolane (25, 50, 100, 150, 200, 300, 400, 600 mg), food effect under fed and fasting conditions at 100 mg dose and four multiple oral dose regimens (25, 50, 100, 200 mg) were administered once daily for 7 days in 64 healthy young males (Caucasian).

The global pipeline of new medicines for the control and elimination of malaria.

Over the past decade, there has been a transformation in the portfolio of medicines to combat malaria. New fixed-dose artemisinin combination therapy is available, with four different types having received approval from Stringent Regulatory Authorities or the World Health Organization (WHO). However, there is still scope for improvement.

Assessing the utility of an anti-malarial pharmacokinetic-pharmacodynamic model for aiding drug clinical development.

Background: Mechanistic within-host models relating blood anti-malarial drug concentrations with the parasite-time profile help in assessing dosing schedules and partner drugs for new anti-malarial treatments. A comprehensive simulation study to assess the utility of a stage-specific pharmacokinetic-pharmacodynamic (PK-PD) model for predicting within-host parasite response was performed.

Methods: Three anti-malarial combination therapies were selected: artesunate-mefloquine, dihydroartemisinin-piperaquine, and artemether-lumefantrine.

First-in-man safety and pharmacokinetics of synthetic ozonide OZ439 demonstrates an improved exposure profile relative to other peroxide antimalarials.

Aims: To assess the safety and pharmacokinetics of a new synthetic ozonide antimalarial, OZ439, in a first-in-man, double-blind study in healthy volunteers.

Methods: OZ439 was administered as single oral daily doses of a capsule formulation (50-1200 mg) or an oral dispersion (400-1600 mg, fed and fasted states) and for up to 3 days as an oral dispersion (200-800 mg day(-1)). Plasma concentrations of OZ439 and its metabolites were measured by LC-MS.

Pharmacokinetics and pharmacodynamics of arterolane maleate following multiple oral doses in adult patients with P. falciparum malaria.

Arterolane (RBx 11160) maleate is a novel, rapidly acting synthetic trioxolane antimalarial compound being developed by Ranbaxy Research Laboratories (Haryana, India). It is presently under phase III in combination with piperaquine phosphate. The present work reports the relationship between pharmacokinetic (PK) parameter (AUC(0-8h) on day 0/day 6) and indices of pharmacodynamic (PD) response (50% parasite clearance [PC(50)], 90% parasite clearance [PC(90)], parasite clearance time [PCT], recrudescence) from a phase II, double-blind, multicenter, randomized, parallel-group, dose-ranging trial.

Comparative embryotoxicity of different antimalarial peroxides: in vitro study using the rat whole embryo culture model (WEC).

Three groups of compounds: (i) active peroxides (artemisinin and arterolene), (ii) inactive non-peroxidic derivatives (deoxyartemisinin and carbaOZ277) and (iii) inactive peroxide (OZ381) were tested by WEC system to provide insights into the relationship between chemical structure and embryotoxic potential, and to assess the relationship between embryotoxicity and antimalarial activity. Deoxyartemisinin, OZ381 and carbaOZ277 did not affect rat embryonic development. Artemisinin and arterolane affected primarily nucleated red blood cells (RBCs), inducing anemia and subsequent tissue damage in rat embryos, with NOELs for RBC damage at 0.

Arterolane, a new synthetic trioxolane for treatment of uncomplicated Plasmodium falciparum malaria: a phase II, multicenter, randomized, dose-finding clinical trial.

Background: Drug-resistant Plasmodium falciparum malaria necessitates development of novel drugs for treatment.The present study assessed the efficacy and safety of 3 dose levels of arterolane (RBx 11160), a synthetic trioxolane, for treatment of acute uncomplicated falciparum malaria.

Methods: In this randomized, double-blind, multicenter, parallel-group, dose-finding, phase II trial, 230 patients from 4 centers in Thailand, India, and Tanzania (mainland and Zanzibar) received either 50 mg (n=78), 100mg (n=76), or 200 mg (n=76) of arterolane once daily for 7 days.

Safety, tolerability, and single- and multiple-dose pharmacokinetics of piperaquine phosphate in healthy subjects.

Piperaquine phosphate is an orally active bisquinolone antimalarial drug that has been used for the past 3 decades. The authors report the safety, tolerability, and pharmacokinetics of piperaquine from a classical controlled phase I study. It was a double-blind, randomized, parallel-group, placebo-controlled, and single- and multiple-dose study.