The relentless pursuit of innovative treatments in the pharmaceutical industry continues to reshape the landscape of chronic disease management. Merck & Co. Inc. (NYSE:MRK) on Wednesday announced additional data from two Phase 3 studies of a two-drug regimen of doravirine/islatravir (DOR/ISL) in adults with virologically suppressed HIV-1 infection.
In the MK-8591A-052 trial, the suppression was on bictegravir/emtricitabine/tenofovir alafenamidei (BIC/FTC/TAF) and baseline antiretroviral therapy (bART) in trial MK-8591A-051.
BIC/FTC/TAF is sold as Biktarvy by Gilead Sciences Inc. (NASDAQ:GILD).
These additional findings will be shared at the 20th European AIDS Conference.
Phase 3 data presented at CROI 2025 showed that the investigational DOR/ISL maintained viral suppression and demonstrated non-inferiority to the three-drug regimen BIC/FTC/TAF in MK-8591A-052 and baseline ART in MK-8591A-051, with no observed treatment-emergent resistance to DOR or ISL.
In trial MK-8591A-052, adults living with virally suppressed HIV-1 infection who switched to DOR/ISL from BIC/FTC/TAF showed minimal changes in weight and body composition at Week 48.
The mean weight change from baseline for the DOR/ISL treatment group was -0.03 kg vs. +0.28 kg for the BIC/FTC/TAF group, and the mean percentage weight change from baseline was 0.10% for DOR/ISL (n=316), compared to 0.39% for BIC/FTC/TAF (n=163).
At Week 48, 14.6% and 3.5% of participants who switched to DOR/ISL experienced a ≥5% and ≥10% weight gain from baseline, respectively, compared with 16.0% and 2.5% of participants who continued BIC/FTC/TAF.
Additionally, mean percent changes in lean body mass, peripheral fat, and trunk fat, and mean changes in body mass index and waist-to-hip ratio were small and comparable between the two treatment groups.
In both trials, adults who switched to DOR/ISL from their current regimen saw no clinically meaningful changes in fasting lipids or in the homeostatic model assessment of insulin resistance (HOMA-IR).
Across both trials, the pooled DOR/ISL group’s mean changes from baseline in fasting lipids, including total cholesterol, HDL, LDL, and triglycerides, were minimal, with no substantial differences from comparator groups.
The proportion of participants with type 2 diabetes who modified their diabetic medication was <5% across treatment groups.
A comparable proportion of participants initiated lipid-lowering therapy (pooled DOR/ISL 4.8%, BIC/FTC/TAF 4.1%, bART 5.9%) across the two trials.
Earlier this year, the U.S. Food and Drug Administration (FDA) accepted the New Drug Application for DOR/ISL and has set a target action date of April 28, 2026.
MRK Price Action: Merck & Co shares were down 0.96% at $83.89 at the time of publication on Wednesday, according to Benzinga Pro data.
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