DOR/ISL Phase III data points to shift toward two-drug STRs in HIV.

A 96-week Phase III trial presented at CROI 2026 reported that switching to doravirine+islatravir (DOR/ISL) maintained viral suppression and showed consistent safety through week 96. The article says the regimen is at pre-registration in the US with a potential 2026 launch if approved.

A Phase III study of doravirine plus islatravir (DOR/ISL) reported sustained viral suppression and tolerability through 96 weeks in adults who were previously virologically suppressed on oral antiretroviral therapy. The article mentions Merck (MSD) as the developer of the fixed-dose DOR/ISL single-tablet regimen. The trial results were presented at the 33rd Conference on Retroviruses and Opportunistic Infections (CROI 2026) and reflect interest in two-drug single-tablet regimens as an alternative to larger combinations. Study details: - The randomised trial enrolled 551 adults, with 366 switching to DOR/ISL at baseline and 185 continuing their existing regimen; by week 48 nearly all remaining participants switched, leaving 543 who received DOR/ISL. - The study followed participants for 96 weeks and was presented at CROI 2026 in Denver, Colorado. - Reported virologic suppression and safety outcomes through weeks 48–96 were consistent with earlier findings from the program. - Mean changes in CD4+ T-cell counts and total lymphocyte counts were similar across treatment groups and no discontinuations were attributed to immune cell declines. - Weight changes were modest overall, with larger increases observed among participants who switched from efavirenz- or tenofovir disoproxil fumarate–containing regimens, consistent with past observations after stopping weight-suppressive therapies. - The article says DOR/ISL is at pre-registration in the US and in Phase III development in the EU, and cites a GlobalData projection for the drug across major markets. Summary: The data reinforce a reported industry trend toward two-drug single-tablet regimens that aim to simplify HIV treatment and reduce cumulative drug exposure. Regulatory review in the US is underway with a potential 2026 launch if approved, and additional Phase III activity is ongoing in the EU.