MSD confirms changes to Step study

Merck, Sharp and Dohme (MSD) has confirmed that study volunteers on the Step study for its HIV vaccine (V520) will be informed whether they received vaccine or placebo in the trials.

The decision to unblind volunteers came from the Step Study Oversight Committee which comprises off the three study sponsors – MSD, the HIV Vaccine Trial Network (HVTN) and the National Institute of Allergy and Infectious Diseases.

The oversight committee assessed Step results at a HVTN meeting last week and decided that volunteers should be told whether they were receiving placebo or vaccine.

MSD stated that all volunteers would be encouraged to continue returning to their study sites for ongoing risk reduction counselling and other study-related tests.

Study investigators are also being advised to provide this information to the volunteers and also give additional data about the unblinding process directly from the study sites.

Earlier this year, MSD confirmed that one of two Phase II Step study trials showed that the investigational HIV vaccine was not effective in two areas.

Study results demonstrated that the vaccine failed to prevent infection in volunteers not previously infected with HIV as well as failing to reduce the viral load in volunteers who became infected with HIV during the trial.