Plasmodium vivax malaria: GSK and MMV present positive data on pediatric treatment

November 19, 2020

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GSK and Medicines for Malaria Venture (MMV) today presented positive data from the TEACH study of tafenoquine, an 8-aminoquinoline, for the prevention of relapse (radical cure) of Plasmodium vivax (P. vivax) malaria in children and adolescents.

The results of the Tafenoquine Exposure Assessment in Children (TEACH) study were presented during the American Society of Tropical Medicine & Hygiene 2020 virtual annual meeting.

TEACH evaluated dosages of tafenoquine based on weight in children and adolescents between the age of 6 months and up to 15 years. The safety profile was consistent with previous clinical studies with the exception of early post-dose vomiting. Ninety-five percent of the study’s 60 subjects had no recurrence of P. vivax malaria during four months of follow-up.

The current standard of care for prevention of P. vivax relapse requires a 7- or 14-day course of treatment and at present there is no age-specific pediatric formulation. Tafenoquine is a single dose treatment for radical cure and is already licensed in people aged 16 and older. TEACH investigated the use of a novel 50 mg dispersible tablet, which was developed to facilitate use in children. The study also used the approved 150 mg tablet.

Pauline Williams, Head of Global Health R&D, GSK, said: “The results presented today represent an encouraging step forward in the fight against P. vivax malaria in children, providing evidence to support a pediatric formulation of tafenoquine. Poor compliance with the current standard of care can allow P. vivax malaria to relapse from its dormant stage, causing terrible suffering in the young people disproportionately affected by the disease and enabling ongoing malaria transmission, undermining malaria elimination efforts. These data underscore GSK’s dedication to combatting infectious disease, especially in children, and our commitment to discover and develop interventions to tackle malaria.”

David Reddy, MMV’s Chief Executive Officer, said, “Children are particularly at risk of P. vivax malaria infections, which is why the development of a pediatric formulation of tafenoquine was critical. At MMV we aim to deliver treatments for the most vulnerable populations, and are proud to have worked together with GSK to meet this unmet need with a single-dose treatment for the prevention of relapse for children from 6 months of age.”

The TEACH study evaluated tafenoquine in children and adolescents with P. vivax malaria weighing at least 10 kilograms. All subjects received a single dose of tafenoquine and a course of chloroquine administered per local or national treatment guidelines to treat the acute blood stage of the illness.

Different doses of tafenoquine were administered depending on weight. Data from TEACH show that subjects weighing between 10 kg and 20 kg should receive 100 mg in dispersible tablets; and those between 20 kg and 35 kg should receive 200 mg in dispersible tablets. Those weighing over 35 kg should receive 300 mg in the form of two, 150 mg tablets, currently approved for older populations. Although no subjects were recruited into the lowest weight band (≥6 months to <2 years, weighing ≥5 kg to ≤10 kg), the pharmacokinetic (PK) modelling data from TEACH indicate a child in that weight band should receive a 50 mg dose of tafenoquine.

The relapse-free efficacy rate of 95 percent at four months is in line with studies of tafenoquine in adults and older adolescents. The safety profile was consistent with previous clinical studies, with the exception of early post-dose vomiting. No drug-related, serious adverse events were reported.

Data from TEACH will support regulatory filings in Australia and malaria-endemic countries.