A combination of Merck’s islatravir and Gilead’s lenacapavir has succeeded in two phase 3 trials and is in line to become the first long-acting oral HIV treatment that can be taken weekly.
Both trials of the combination regimen—which includes a 2 mg dose of islatravir and a 300 mg dose of lenacapavir—included people with HIV who are virologically suppressed and both achieved their primary efficacy endpoint.
In the Islend-1 study, the combo showed its non-inferiority in those who had switched off Gilead’s once-daily pill Biktarvy. In Islend-2, the combo measured up in those who had switched off standard-of-care antiretroviral regimens. No new safety concerns were identified in either study.
Gilead and Merck said they plan to submit the data to regulatory authorities around the world and present the findings at a future scientific congress.
“Long-acting oral therapies represent a new wave of transformational innovation in HIV drug development, with the potential to reshape the landscape of care,” said Jared Baeten, M.D, Ph.D, Gilead’s SVP, Clinical Development, Virology Therapeutic Area Head, said in a release. “Innovative oral HIV treatment options that allow for less frequent dosing may make a meaningful difference in the lives of people living with the virus, potentially offering more flexibility and discretion.”
In a note to clients, analysts from Jefferies said that they viewed the data as a “plus,” but that they expect Biktarvy to remain the standard of care because of its well-established efficacy. While five-year data on Biktarvy has shown that 97% of patients remain suppressed, questions remain about the long-term safety and resistance of ISL/LEN.
Gilead’s lenacapavir has been on the market since 2022, when it was approved in the U.S. as Sunlenca for twice-yearly administration for those with drug-resistant HIV. Twelve months ago, the FDA signed off on lenacapavir for pre-exposure prophylaxis (PrEP). It is known commercially in that indication as Yeztugo.
Less than two months ago, islatravir was approved for the first time by the FDA in combination with the company’s doravirine. The regimen, known commercially as Idvynso, was endorsed to replace current antiretroviral regimens among adults with HIV who are virologically suppressed and who have no history of virologic treatment failure or treatment substitutions due to doravirine resistance.
While islatravir is a newer nucleoside reverse transcriptase translocation inhibitor (NRTTI), doravirine is an older non-nucleoside reverse transcriptase inhibitor (NNRTI). Doravirine has been commercialized since 2018 as part of Merck’s HIV meds Pifeltro and Delstrigo.
Gilead dominates the HIV market, recording sales of $14.3 billion last year for Biktarvy. HIV is part of Merck's infectious disease portfolio, which the company projects can generate $15 billion in annual sales by the middle of the next decade, according to a recent presentation.