Gilead and Merck's experimental weekly HIV pill suppresses virus in late‑stage trials

Gilead Sciences and Merck reported that their experimental once‑weekly HIV pill, combining Merck’s islatravir with Gilead’s lenacapavir, kept viral loads undetectable in two late‑stage trials involving adults whose HIV was already controlled with daily therapy. In one study none of the participants switching to the weekly regimen had detectable virus after 48 weeks, compared with 0.3% on daily Biktarvy; in the second trial 0.3% on the weekly pill showed detectable levels versus 1.3% on standard daily regimens.

The companies said the weekly treatment was non‑inferior to existing daily options, with side‑effect profiles similar to those regimens (headache, nausea, diarrhea) and no new safety concerns. Results support regulatory filings for what could become the first once‑weekly HIV regimen. Investors are watching the rollout of lenacapavir, marketed as Yeztugo, while Merck’s daily pill Idvynso received FDA approval earlier this year.