Islatravir is an antiviral agent in the nucleoside reverse transcriptase translocation inhibitor (NRTTI) class developed for HIV treatment. Clinical development has included standalone and fixed-dose combination programs, with a marketed doravirine/islatravir tablet approved in 2026. The active triphosphate metabolite inhibits reverse transcriptase with immediate and delayed chain-termination effects.
The FDA is set to make decisions on four drug applications in April 2026, including Orca-T for hematological malignancies, orforglipron for obesity, sparsentan for kidney disease, and a doravirine/islatravir combination for HIV-1.
Merck announced Phase 3 trial results for its investigational once-daily, two-drug HIV regimen doravirine/islatravir at CROI 2026, demonstrating non-inferiority to standard treatment in treatment-naïve adults with viral suppression rates of 91.8% at Week 48.
Merck stock reached a 52-week high at $122.69, rising 46.25% over 12 months and 7.4% in the past month following strong Q4 results and improved long-term pipeline outlook beyond Keytruda's 2028 patent expiration.
| NCT ID | Title | Status | Phase |
|---|---|---|---|
| NCT06719570 |
A Study of Doravirine and Islatravir as a Single Entity or Combination Therapy and the Effect of Food in Healthy Adult Participants (MK-8591A-055) |
COMPLETED | PHASE1 |
| NCT06619678 |
A Study of MK-8507 and Islatravir (MK-8591) in Healthy Adult Participants (MK-8507-016) |
COMPLETED | PHASE1 |
| NCT05130086 |
A Study of Islatravir (MK-8591) in Trans and Gender Diverse Participants (MK-8591-035) |
WITHDRAWN | PHASE2 |
| NCT05115838 |
Radiopaque Matrix MK-8591 Implant in Participants at Low-Risk for Human Immunodeficiency Virus Type 1 (HIV-1) Infection (MK-8591-043) |
WITHDRAWN | PHASE2 |
| NCT04644029 |
Oral ISL QM as PrEP in Cisgender Women at High Risk for HIV-1 Infection (MK-8591-022) |
TERMINATED | PHASE3 |
| NCT04568603 |
Islatravir and Methadone Pharmacokinetics (MK-8591-029) |
COMPLETED | PHASE1 |
| NCT04564547 |
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] |
COMPLETED | PHASE2 |
| NCT04515641 |
Single-Dose Islatravir in Moderate Hepatic Impairment (MK-8591-030) |
COMPLETED | PHASE1 |
| NCT04303156 |
Pharmacokinetics of Islatravir in Participants With Severe Renal Impairment (MK-8591-026) |
COMPLETED | PHASE1 |
| NCT04003103 |
Safety and Pharmacokinetics of Oral Islatravir (MK-8591) Once Monthly in Participants at Low Risk of Human Immunodeficiency Virus 1 (HIV-1) Infection (MK-8591-016) |
COMPLETED | PHASE2 |
