José Gadelha da Silva Júnior (Fiocruz Rondônia)
“For the first time in almost 70 years, Brazil has achieved the Anvisa [the Brazilian agency for food and drug administration] registration of a new drug against malaria vivax” - this was how Dhélio Batista Pereira, public health researcher at Fiocruz Rondônia and at the Center for Tropical Medicine Research (Cepem), announced the most recent victory in the fight against a disease that affects about 7.5 million people worldwide, according to WHO. Developed by British pharmaceutical company GlaxoSmithKline, tafenoquine registration was accepted (10/29) by Anvisa. According to the researcher, clinical trials coordinated by Fiocruz prove that the new drug shortens treatment time, which helps increase patience compliance. The next step to be taken by the institution is the application of viability tests in endemic regions before fully including the new drug in Brazilian Public Health System.
Unlike primaquine, a drug used in Brazil for over 60 years and administrated to patients daily for up to 14 days, “tafenoquine can be applied in a single dose, as its action lasts for more than 20 days and has chances of a radical cure. The new drug is effective directly on the hepatic form of malaria vivax (hypnozoites), avoiding the so-called relapses, the term used to describe a disease that returns to a patient due to infection in the bloodstream”, the tropical medicine specialist explained.
With the Anvisa approval, Brazil has become the first country with endemic malaria to regulate tafenoquine as a drug to be made available to the general population by the Ministry of Health. The use of tafenoquine was first cleared in July 2018 by the American Food and Drug Administration, and in September 2018 by the Australian Therapeutic Goods Administration. These regulatory approvals were based on efficacy and safety data of a widely encompassing global clinical development program for the radical cure of the form of malaria caused by Plasmodium vívax, carried out in nine countries with endemic cases of the disease, including Brazil.
Trials with tafenoquine began with the American army at least 30 years ago. However, in the past ten years a partnership between the NGO Medicines for Malaria Venture (MMV) and British giant GlaxoSmithKline, with support from the Bill and Melinda Gates Foundation, made the clinical phase of the trials possible in Peru, India, Vietnam, Ethiopia and in Brazil, in the cities of Porto Velho/RO and Manaus/AM.
The next step is a study by the Ministry of Health, in a partnership with Fiocruz and other institutions, to assess the implementation of the use of the new drug in malaria patients in Brazil. Dhélio Pereira explains that “the main goal is to evaluate the inclusion of the G6PD enzyme activity test in the body and the choice of treatment, as about 5% of the Brazilian population has a deficiency in the activity of this enzyme, to some degree”.
The researcher adds: “If the test shows normal parameters, the patient is cleared to take tafenoquine; if enzyme activity is moderate or light, the patient can take primaquine; if the deficiency is high, the patient can take primaquine on a weekly basis and under close monitoring”, stating the deficit in this enzyme can lead to severe side effects, when not identified. The idea is to offer differentiated treatment after a malaria diagnosis and to guide professionals working at the public health network regarding the new treatment model. The final survey will be able to guide states and municipalities towards effective actions to diagnose and treat malaria.