The combination of Merck & Co.’s islatravir and Gilead’s lenacapavir has been successful in two Phase 3 trials and is expected to be the first long-acting oral HIV treatment that can be taken weekly.
Both trials of combination therapy containing a 2 mg dose of islatravir and a 300 mg dose of lenacapavir included virologically suppressed HIV-infected individuals, and both met their primary efficacy endpoints.
The Islend-1 study showed that the combination was non-inferior in patients who switched off Gilead’s once-daily tablet Biktarvy. In Eilend-2, this combination therapy was effective in patients who stopped standard-of-care antiretroviral therapy. Neither study identified any new safety concerns.
Gilead and Merck said they plan to submit the data to regulatory authorities around the world and present the findings at a future scientific conference.
“Long-acting oral therapies are the next wave of transformative innovation in HIV drug development and have the potential to change the face of treatment,” Jared Baeten, M.D., Gilead’s SVP, Clinical Development and Head of Virology Therapeutics, said in the release. “Innovative oral HIV treatment options that allow for less frequent dosing have the potential to make a meaningful difference to the lives of people living with the virus, offering more flexibility and discretion.”
In a note to clients, Jefferies analysts said they viewed the data as “positive,” but said they expected Biktarvy to remain the standard of care because its efficacy is well established. Five-year data on Biktarvy shows that 97% of patients remain suppressed, but questions remain about the long-term safety and tolerability 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 dosing for patients with drug-resistant HIV. Twelve months ago, the FDA approved the use of lenacapavir as a pre-exposure prophylaxis (PrEP). Commercially known as Eztugo.
Less than two months later, islatravir was first approved by the FDA in combination with the company’s doravirine. This regimen, commercially known as Idovinso, was approved to replace current antiretroviral regimens among HIV-infected adults who are virologically suppressed and have no history of alternative treatment due to virologic treatment failure or doravirine resistance.
Islatravir is a new nucleoside reverse transcriptase translocation inhibitor (NRTI), while doravirine is an older non-nucleoside reverse transcriptase inhibitor (NNRTI). Doravirine has been commercialized since 2018 as part of Merck’s HIV treatments Pifeltro and Delstrigo.
Gilead dominates the HIV market, with Biktarvy posting sales of $14.3 billion last year. HIV is part of Merck’s infectious diseases portfolio, and the company projects it could generate $15 billion in annual sales by the middle of the next decade, according to a recent presentation.
