Drug developed by GSK in collaboration with Medicines for Malaria Venture would be the first single-dose treatment for the prevention of a relapse.
Plasmodium vivax malaria is a disease transmitted to humans through the bite of mosquitoes infected with the Plasmodium parasite. The first reaction is an acute malaria episode, after which the parasite can lie dormant in the liver (in a form known as hypnozoite) and cause periodic relapses of P. vivax malaria. Approximately 8.5 million people are infected with P. vivax malaria each year, largely in South-Asia, South-East Asia, Latin America and the horn of Africa.
The dormant form is not treatable with common anti-malarial drugs because they are designed to attack the parasite in its blood-stage form. Only one drug (primaquine) is approved by the US Food and Drug Administration (FDA) for the prevention of a relapse, and it must be taken for 14 days to be effective. This type of drug, which attacks the dormant form of the parasite to prevent relapse is referred to as a “radical cure.”
There may be a new medicine available soon that will offer a simplified “radical cure.” Tafenoquine (proposed proprietary name Krintafel), a new treatment developed by GlaxoSmithKline (GSK) in collaboration with Medicines for Malaria Venture (MMV), received a favorable decision from the FDA’s Antimicrobial Drugs Advisory Committee (AMDAC). All 13 members voted that there is substantial evidence of its effectiveness and 12 out of 13 voted that there is adequate evidence of its safety for the prevention of relapse of P. vivax malaria in patients 16 years of age and older.
GSk submitted the new drug application (NDA) for tafenoquine with FDA in November 2017. It also filed a submission with the Australian Therapeutic Goods Administration (TGA) in December 2017. Approvals decisions are expected from both agencies in the next few months.
Tafenoquine, which was first synthesized by researchers at the Walter Reed Army Institute of Research in 1978, is an 8-aminoquinoline derivative with activity against all stages of the P. vivax lifecycle, including hypnozoites. GSK has been developing the candidate as a treatment for malaria for over 20 years. It has been collaborating with MMV since 2008.