A combination of islatravir and doravirine (Pifeltro), taken once daily as a two-drug treatment, showed virologic suppression at 96 weeks in patients with HIV-1 who had not previously received treatment, according to recent research from a phase 3 trial presented at the virtual 2020 International Congress on Drug Therapy in HIV Infection.
“Our commitment to medical advances in HIV can be seen in the important data we are presenting at HIV Glasgow 2020, including islatravir’s potential for use in combination with doravirine as a once-daily, two-drug treatment,” Joan Butterton, MD, vice president, infectious diseases, Global Clinical Development, Merck Research Laboratories, said in a press release. “We continue to pursue new methods for treating HIV, as shown by our growing body of clinical research, and we look forward to sharing new data from our ongoing, global Phase 3 clinical trials for islatravir with doravirine in the future.”
Patients in the trial were randomly assigned to receive islatravir at a dose of 0.25 mg (29 patients), a dose of 0.75 mg (30 patients), a dose of 2.25 mg (31 patients) in addition to receiving doravirine (100 mg) and lamivudine (3TC) (300 mg), or doravirine/lamivudine/tenofovir disoproxil fumarate (Delstrigo) (31 patients). At 24 weeks or more, patients in the islatravir groups could receive combination islatravir and doravirine (100 mg) without 3TC if they reached HIV-1 RNA < 50 copies/mL.
Results from 96 weeks showed 86.2% of patients in the 0.25 mg group, 90.0% of patients in the 0.75 mg group, and 67.7% of patients in the 2.25 mg islatravir group had HIV-1 RNA < 50 copies/mL compared with 80.6% of patients receiving Delstrigo. The researchers noted the lower response rate in the 2.25 mg dose islatravir group was due to discontinuations up to 48 weeks. Overall, 7 participants in the trial discontinued due to virologic failure, defined as HIV-1 RNA levels < 80 copies/mL. No participant in either the islatravir groups or the Delstrigo group required resistance testing based on criteria, as all the participants were under HIV-1 RNA levels < 80 copies/mL.
Regarding adverse events, 7.8% of participants in the islatravir groups and 22.6% of participants in the Delstrigo group experienced drug-related adverse events at 96 weeks. There were no additional adverse events between 48 weeks and 96 weeks. The researchers noted there were no renal safety issues, and there were no treatment discontinuations based on renal adverse events.