Merck Inc., announces clinical holds on studies evaluating islatravir for the treatment and prevention of HIV-1 infection

The FDA’s clinical hold is based on previously announced observations of decreases in total lymphocyte and CD4+ T-cell counts in some participants receiving islatravir in clinical studies.

As previously announced, Merck has stopped dosing in the Phase II IMAGINE-DR clinical trial of islatravir in combination with MK 8507 (MK 8591-013) and paused enrollment in the once-monthly Phase III PrEP studies, (MK 8591-022 and MK 8591-024). With the FDA’s clinical hold, no new studies may be initiated.

Participants who are currently receiving islatravir as part of the studies for PrEP, including oral and implant formulations, as well as injectable islatravir for treatment and prophylaxis, will no longer receive the study drug; CD4+ T-cell and total lymphocyte counts will be monitored for recovery (full clinical hold). Participants in the PrEP studies will be offered approved, once-daily, oral PrEP. Additionally, participants in studies of DOR/ISL who were started on treatment will continue to receive study medication (partial clinical hold). No new participants will be screened or randomized in DOR/ISL studies for treatment during the partial clinical hold. Investigators have been informed of these actions.