Brazil and Thailand have become the first malaria-endemic nations to launch tafenoquine, a new single-dose medication aimed at preventing the relapse of Plasmodium vivax (P. vivax) malaria. This medicine, administered alongside chloroquine, marks a significant step forward in global malaria eradication efforts. Developed through a collaboration between GSK plc and Medicines for Malaria Venture (MMV), tafenoquine is designed to tackle both the blood and liver stages of P. vivax malaria, offering a radical cure.
Addressing P. vivax Malaria
P. vivax is the predominant malaria parasite in regions outside sub-Saharan Africa. It is notorious for causing repeated clinical relapses, which can severely impact patients' health, economic stability, and social wellbeing. These relapses also exacerbate the disease burden, increasing the risk of transmission and hindering global malaria elimination initiatives.
Tafenoquine, an 8-aminoquinoline antimalarial drug, specifically targets the liver stage of P. vivax malaria. When used with chloroquine to treat the blood stage of the infection, it achieves a radical cure. However, tafenoquine can induce acute hemolytic anemia in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency, necessitating a G6PD test before administration.
Implementation in Brazil and Thailand
The Ministries of Health in Thailand and Brazil have conducted feasibility studies, supported by MMV, on the routine use of tafenoquine following point-of-care G6PD testing. These studies have informed their decision to integrate tafenoquine into their public health systems as part of their malaria elimination strategies.
In Brazil, the government expedited the introduction of tafenoquine in March 2024, particularly in response to a public health emergency in the Yanomami Special Indigenous Health District, where P. vivax accounts for nearly 70% of malaria cases. The rollout of this new treatment option has now commenced within the broader public health system.
Thailand has also seen a significant rise in malaria cases in recent years, particularly in regions bordering Myanmar, where displaced populations have increased the demand for malaria diagnosis and treatment. The introduction of tafenoquine in Thailand is expected to make a substantial impact on controlling the disease.
Global Approvals and Future Prospects
Tafenoquine has received regulatory approvals in several countries, including the US, Australia, Brazil, Ethiopia, Guyana, Peru, Thailand, Colombia, and the Philippines. It is currently undergoing evaluation for marketing authorization in other P. vivax-endemic regions. Submissions for approval include comprehensive data on safety, efficacy, feasibility, patient and health worker perceptions, and cost-effectiveness.
About Tafenoquine
First synthesized by the Walter Reed Army Institute of Research in 1978, tafenoquine is an 8-aminoquinoline derivative effective against all stages of the P. vivax lifecycle, including the dormant liver stage (hypnozoites). GSK began developing tafenoquine as a potential antimalarial over 20 years ago and partnered with MMV in 2008 to advance it as a treatment for P. vivax relapses. The development of tafenoquine is part of GSK's global health initiative to enhance healthcare for vulnerable populations.
The STANDARD G6PD test, developed in collaboration between SD Biosensor and PATH, is a portable device that measures G6PD enzyme activity using a drop of blood from a finger prick. This test provides results within two minutes, ensuring safe administration of tafenoquine.
Conclusion
The introduction of tafenoquine in Brazil and Thailand represents a major advancement in the fight against malaria. By preventing relapses of P. vivax malaria, this new treatment has the potential to significantly reduce the disease burden and support global eradication efforts. With ongoing evaluations and approvals, tafenoquine may soon become a vital tool in the global battle against malaria.
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