In a two-year study of Merck’s islatravir, the vast majority of people with HIV both achieved and sustained a fully suppressed viral load on the experimental antiretroviral.

One of the study’s authors, Jean-Michel Molina, MD, of Hôpital Saint-Louis in Paris, notes that the highly potent islatravir, which is the first nucleoside reverse transcriptase translocation inhibitor, is currently being evaluated “for treatment and prevention of HIV, with daily, weekly and monthly regimens and also as a twice-yearly implant.”

The recent study enrolled 121 people with HIV who had never been treated for the virus. They were randomized initially to receive either 0.25 milligrams, 0.75 mg or 2.25 mg of islatravir plus Pifeltro (doravirine) and lamivudine daily or to receive Delstrigo (doravirine/tenofovir disoproxil fumarate/lamivudine).

Those in the islatravir groups who had a fully suppressed viral load at week 20 or later were taken off lamivudine.

At week 96, a respective 86%, 90% and 68% of those who received 0.25 mg, 0.75 mg and 2.25 mg of islatravir had a fully suppressed viral load, as did 81% of those who received Delstrigo.

During the first 48 weeks of the trial, six participants discontinued treatment due to not achieving and sustaining a fully suppressed viral load.

This included two people each in the 0.25 mg and 0.75 mg islatravir groups, one in the 2.25 mg group and one in the Delstrigo group. Following the 48-week mark, one additional participant stopped treatment for this reason.