U.S. Army, GSK's P. vivax malaria vaccine fails to protect in early trial

A vaccine developed in collaboration between GlaxoSmithKline ($GSK) and the U.S. Army failed to protect subjects in an early trial against the world's most prevalent malaria parasite. Researchers will press forward, however, saying the knowledge gained may assist future development.

In the Phase I/IIa study, conducted by the U.S. Army's Walter Reed Army Institute of Research, the institute's VMP001 vaccine formulated with GlaxoSmithKline's AS01B adjuvant failed to protect volunteers from the Plasmodium vivax malaria parasite. The team used a controlled human malaria infection (CHMI) technique, bringing P. vivax-infected mosquitoes from Thailand to the WRAIR in Silver Spring, MD, to test the vaccine candidate's ability to protect in a human challenge.

Despite the vaccine's trial miss, a "small but significant delay in time to parasitemia was seen in 59% of vaccinated subjects," leading the researchers to conclude that the "availability of a P. vivax CHMI model will accelerate the process of P. vivax vaccine development, allowing better selection of candidate vaccines for advancement to field trials."

WRAIR's trial reportedly was the first worldwide using the CHMI technique in P. vivax malaria.

"Findings from the analysis of the immune response of vaccinated subjects have given us clues to improve vaccine candidates, and studies are now underway at WRAIR to develop next-generation vivax vaccines," Lt. Col. Robert Paris, M.D., director of the WRAIR's U.S. Military Malaria Research Program, told Genetic Engineering & Biotechnology News.

GlaxoSmithKline's Mosquirix, the world's first approved malaria vaccine, protects against the Plasmodium falciparum parasite, which causes the most malaria deaths worldwide but is not the most prevalent species. The vaccine received EMA approval last summer but has since experienced a setback, with the agency in October calling for pilot projects to test its efficacy in the real world instead of widespread rollouts. The vaccine is seen as far from perfect, with a four-dose regimen conferring only 40% efficacy, which wanes over time.

PLOS Neglected Tropical Diseases published the results.

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