USA – Merck has announced a positive top-line results from two pivotal Phase 3 trials of the investigational, once-daily oral fixed dose combination pill of doravirine/islatravir (DOR/ISL) in adults with HIV-1 infection who are virologically suppressed on different antiretroviral therapy regimens.
The drugmaker has announced that the trials met their safety and efficacy endpoints at 48 weeks in adults with HIV-1 infection who are currently receiving antiretroviral therapy.
According to the company, the endpoint is defined as a percentage of participants with HIV-1 RNA levels greater than 50 copies per milliliter.
Both Merck trials met their primary endpoint on the percentage of participants with HIV-1 RNA levels at or below 50 copies/mL, demonstrating that antiviral efficacy was comparable between the drug combination and antiretroviral therapies.
For reference, any level of HIV-1 RNA below 50 copies/mL is considered optimal for patients — in fact, that number is sometimes considered undetectable in a blood test.
Similarly, a “lower viral load” is defined as any number less than 10,000 copies/mL, while a “high viral load” is defined as any number between 100,000 and a million copies of RNA/per mL of blood.
The pharmaceutical giant revealed top-line results from pivotal Phase III trials of a once-daily oral pill combining Merck’s FDA-approved anti-HIV treatment doravirine with islatravir.
The first trial looked at switching from antiretroviral therapy to doravirine/islatravir. According to the company, the second trial looked at switching from bictegravir/emtricitabine/tenofovir to doravirine/islatravir.
Merck said it will present detailed findings from the studies at a future scientific congress.
“We will continue to study doravirine/islatravir in diverse populations of people living with HIV and look forward to sharing data from these trials,” said Joan Butterton, a vice president at Merck Research Laboratories.
Merck has been a consistent runner-up in HIV, a field dominated by Gilead and then ViiV, which is majority-owned by GSK.
Regardless of what happens with the Merck combination now that it’s on its way to regulators, analysts don’t expect anything to overtake Gilead’s market leader.
Ronny Gal of Bernstein evaluated Merck and Gilead’s alliance a few months ago, concluding that:
“For HIV treatment it will be hard to unseat Biktarvy. HIV treatments have effectively reached the upper-limit on efficacy and tolerability. From here, new products will try to differentiate based on quality-of-life enhancements like less frequent dosing and lower associated weight gain. These value propositions are real, but patient turnover in HIV is relatively low and we believe it would a tough sell to switch virally suppressed patients of Biktarvy. As a result, we model only 30% peak market share for ISL/LEN combinations – material, but less than Biktarvy.”
During the trials, the safety and tolerability profile of DOR/ISL were consistent with previously reported phase 2 studies.
Individuals with HIV-1 who are virologically suppressed on ART, those with extensive treatment experience, and those who are new to HIV treatment were all included in the ILLUMINATE clinical trials.
The program also included pediatric HIV-1 patients who weighed at least 77.1 pounds and were virologically suppressed and treated.