Malaria, Vivax

The aim of this study is to collect efficacy and safety data to support the registration of tafenoquine in India.

The resilience of P. vivax to malaria elimination efforts is due to its ability to form dormant liver stages (hypnozoites) that reactivate weeks to months after the initial infection causing recurrent episodes of malaria (relapses) and ongoing parasite transmission. Relapses account for a majority of recurrent infections and clinical cases of P. vivax malaria, and therefore have a significant effect on morbidity at the individual level. With current technology, it is not possible to directly measure hypnozoite biomarkers. Rather than directly detecting hypnozoites, our team developed an indirect approach by measuring antibodies induced by the primary blood-stage infection. Antibodies to different blood-stage antigens decay at different rates. Measuring antibodies to a carefully selected panel of P. vivax antigens can aid to identify individuals who have been infected within the previous 9 months (approximately the lifespan of hypnozoites). A serological test based on selected P. vivax antigens can detect recent exposure and predict future relapses. Coupling this test with a safe and efficacious primaquine treatment regimen, results in a population-based intervention to target the hypnozoite reservoir. This intervention is referred to as Plasmodium vivax Serological Testing and Treatment (PvSeroTAT). PvSTATEM is a cluster randomised trial in Madagascar and Ethiopia. This study will provide insights into the feasibility, acceptability, and efficacy of the PvSeroTAT approach. In this study, individuals, randomised by clusters, will be tested for the presence of serological markers of a recent P. vivax infection, followed by a targeted drug treatment intervention aimed at killing P. vivax hypnozoites.

The goal of this Phase 2b study is to examine the safety and efficacy of the combination of SJ733, an investigational agent, and tafenoquine for the radical cure of uncomplicated P. vivax malaria monoinfection in adult participants and determine the contributions of SJ733 to the effect. SJ733 will be administered in a 1-, 2-, or 3-day treatment schedule in combination with a single dose of tafenoquine.

Phase 1 clinical trial to evaluate the safety, reactogenicity, and immunogenicity of a malaria vaccine named Vivaxin against the protozoan Plamodium vivax in participants with no prior malaria infection

In this area of Greater Mekong Subregion (GMS), vivax malaria is the most common kind of malaria. It can stay very long in the liver, and come out later to make another episode of illness. This can happen many times even without a mosquito bite. Only 8-aminoquinoline drugs can kill the liver forms of the malaria parasite. One of these drugs is called primaquine, and it has been used all over the world for a long time. There is now a new formulation of this 8-aminoquinoline drug called tafenoquine that can also treat the malaria in the liver. The main benefit of this drug is that it is a single dose, which makes much convenient for the patients as well as for the malaria control program than conventional 14 days of primaquine. Recent research suggests that ACT (Artemisinin Combination Therapy) may antagonise the efficacy of tafenoquine (Baird et al. 2020 ASTMH Annual Meeting) . This could prevent the use of tafenoquine in areas with chloroquine resistant P. vivax parasites where national malaria programmes recommend ACTs for vivax malaria. Also, currently recommended tafenoquine dose is sub-optimal: 300 mg dose proved significantly inferior to low dose primaquine in a meta-analysis of the phase 3 studies when restricted to the Southeast Asian region (Llanos-Cuentas et al. 2019 NEJM; Watson et al. 2022a Elife). A tafenoquine dose of 450mg is predicted to provide \>90% of the maximal effect. The objective of this research is to find out whether 450 mg dose of tafenoquine can be combined effectively with ACT providing a short course treatment for P. vivax malaria.