Dose Ranging, Switch Study of Islatravir (MK-8591) and Ulonivirine (MK-8507) Once-Weekly in Virologically-Suppressed Adults With Human Immunodeficiency Virus Type 1 (HIV-1) [MK-8591-013]

Based on laboratory findings of decreased lymphocyte and CD4+ T-cell counts across the islatravir program and as described in protocol amendment 2 (approved 01-Dec-2021), participants in study Part 1 (double-blind treatment period) were unblinded, discontinued all study interventions, and switched to standard of care non-study antiretroviral (ART) therapy. Participants who received ISL + ulonivirine (Groups 1 to 3) may have then entered into an unblinded safety monitoring period and were monitored for ≥6 months. As specified in protocol amendment 2, study Parts 2 and 3 were no longer planned or initiated for any participant.