FDA Approval

Doravirine/Islatravir (IDVYNSO) FDA Approval for Virologically Suppressed HIV-1 In Adults

Edited by:
Anthony Calabro, MA

Key Highlights

  • The FDA approved doravirine/islatravir (IDVYNSO) for adults with virologically suppressed HIV-1 on a stable antiretroviral regimen without prior treatment failure or doravirine resistance–associated substitutions.
  • The approval was supported by Phase 3 randomized, active-controlled noninferiority trials (Trial 052 and Trial 051).
  • Doravirine/islatravir demonstrated noninferior efficacy compared with bictegravir/emtricitabine/tenofovir alafenamide and baseline antiretroviral therapy based on HIV-1 RNA thresholds at Week 48.
  • The most common adverse events included diarrhea, dizziness, fatigue, abdominal distention, headache, and weight increase.

On April 21, 2026, the FDA approved doravirine 100 mg/islatravir 0.25 mg (IDVYNSO), a once-daily, fixed-dose, 2-drug oral regimen, for the treatment of HIV-1 infection in adults who are virologically suppressed (HIV-1 RNA <50 copies/mL) on a stable antiretroviral regimen. The indication applies to patients with no history of virologic treatment failure and no known substitutions associated with doravirine resistance. IDVYNSO is a complete regimen and should not be coadministered with other antiretroviral medications for HIV-1 treatment.

The approval was supported by Week 48 data from 2 of the Phase 3 randomized, active-controlled, noninferiority trials (Trial 052 [NCT05630755] and Trial 051 [NCT05631093]) in virologically suppressed adults.

In Trial 052, 1% of participants who switched to doravirine/islatravir (n = 342) and 1% who continued bictegravir/emtricitabine/tenofovir alafenamide (n = 171) had HIV-1 RNA ≥50 copies/mL at Week 48 (treatment difference, 0.9%; 95% CI, −1.9% to 2.9%). Viral suppression (HIV-1 RNA <50 copies/mL) was maintained in 92% and 94% of participants, respectively.

In Trial 051, 1% of participants receiving doravirine/islatravir (n = 366) and 5% receiving baseline antiretroviral therapy (n=185) had HIV-1 RNA ≥50 copies/mL (treatment difference, −3.6%; 95% CI, −7.8% to −0.8%), with viral suppression maintained in 96% and 92%, respectively.

The safety profile of doravirine/islatravir was comparable to that of comparator regimens across both trials. Adverse events leading to discontinuation occurred in 3% of participants receiving doravirine/islatravir vs 2% receiving bictegravir/emtricitabine/tenofovir alafenamide in Trial 052 and in 0.5% vs 2%, respectively, in Trial 051.

The most common adverse events (≥2% in any treatment group) included diarrhea (up to 3%), dizziness (up to 2%), fatigue (up to 2%), abdominal distention (up to 2%), headache (up to 2%), and weight increase (up to 2%). Severe skin reactions, including Stevens-Johnson syndrome/toxic epidermal necrolysis, and drug rash with eosinophilia and systemic symptoms were reported. A single case of severe immune thrombocytopenia was observed.

Doravirine/islatravir is administered orally as a once-daily single-tablet regimen containing doravirine 100 mg and islatravir 0.25 mg.

Reference
Merck & Co., Inc. FDA approves Merck’s once-daily IDVYNSO (doravirine/islatravir) for adults with virologically suppressed HIV-1. News release. April 23, 2026. Accessed April 23, 2026. https://www.merck.com/news/fda-approves-mercks-once-daily-idvynso-doravirine-islatravir/