Immtech concludes malaria prevention trial

The exploratory study was designed to determine whether the company should focus on commercializing a blood-stage or a liver-stage malaria prevention drug. Participants in the randomized placebo controlled trial were treated with placebo, one dose of pafuramidine that was expected not to be effective (administered eight days before subjects were exposed to malaria), and one dose of pafuramidine that was considered to be potentially effective (administered one day prior to exposure).

In this study a single dose of 100mg of pafuramidine was administered once only to prevent malaria infection in the liver, which represents the earliest stage of infection. Healthy volunteers were recruited for the trial because they are representative of travelers to malaria-endemic areas.

The 100mg dosing was determined based on results of blood levels of the active drug form of pafuramidine recorded in previous human and animal model studies. The low dosages and rigorous study design were used to help distinguish the effect of pafuramidine on liver-stage infection versus the effect demonstrated on blood-stage infection.

The malaria parasite initially travels to the liver where it grows for about seven days before spreading to the blood. Malaria prevention drugs can work by preventing the infection in the liver or in the blood stream. A liver stage regimen would continue for seven days after travel and a blood stage regimen would continue for 30 days after travel. The results of this study indicate that the company should commercialize a prevention drug to target the blood stage form of malaria, Immtech said.