Merck-Gilead's weekly HIV combo maintains viral suppression

Early results show that a weekly combination of Merck & Co.’s islatravir and Gilead’s approved HIV med Sunlenca maintained a high rate of viral suppression in patients with HIV, and just one patient out of 100 missed on the primary endpoint that measured viral load.

The open-label phase 2 study is testing islatravir 2 mg and lenacapavir 300 mg once a week against Gilead’s oral Biktarvy daily in 104 virologically suppressed adults.

The main goal calculated the number of patients who had an HIV RNA viral load greater than or equal to 50 copies/ML at week 24. On that measure, just one patient did not meet that bar with a viral load more than 50 copies/ML, but later went on to achieve suppression at week 30.

On the secondary endpoint, which Gilead and Merck highlighted in their Wednesday release, the islatravir combo maintained a high rate of viral suppression with 94% of the group reporting less than 50 copies/ML. This shows that patients who switched to the weekly combo, compared to Biktarvy’s daily dosing schedule, maintained comparable rates of HIV suppression, the companies explained.

No patients in the Biktarvy arm of the study had viral loads of more than 50 copies/ML at week 24.

Grade 1 and 2 cases of dry mouth and nausea were reported in the islatravir combo group, while there were no grade 1 or 2 treatment-related adverse events in the Biktarvy group. There were also no grade 3 or 4, which would represent more serious, adverse events in any group of the study. Two patients in the islatravir group discontinued due to adverse events unrelated to the drug, the companies said.

The snippet of data also showed no changes in CD4+ T cell counts or absolute lymphocyte counts, which is key after islatravir was placed on hold in December 2021 in a study combining it with a different med. Merck lowered the islatravir dose in future trials. The islatravir/Sunlenca trial resumed in April 2023. 

The phase 2 study will continue on to week 48 with longer-term follow up data to be reported at a future medical conference.

Gilead and Merck are hoping to offer a weekly option for patients with HIV.

“HIV treatment is not one size fits all—developing once-weekly treatment options could help meet the needs of each individual, aiming toward maximizing long-term outcomes for people with HIV,” said Jared Baeten, M.D., Ph.D., HIV Clinical Development, Gilead.

The data reported today at the 31st Conference on Retroviruses and Opportunistic Infections support continued development of the combo, the companies said

Editor's note: This story was updated at 4:39 p.m. ET on March 6, 2024, to clarify that a single patient missed the primary endpoint, which measures viral load.