A long-acting, two-drug HIV regimen being co-developed by ViiV Healthcare and Janssen Sciences Ireland UC has shown comparable viral suppression rates to a three-drug regimen in a Phase II trial, indicating its potential to reduce the dosing burden for patients and thus improve treatment adherence.

The LATTE-2 study assessed long-acting, injectable formulations of cabotegravir (ViiV) and rilpivirine (Janssen, branded Edurant), given every four or eight weeks to patients with HIV-1 infection who had already achieved viral suppression with a daily three-drug oral regimen of cabotegravir plus two nucleoside reverse transcriptase inhibitors (NRTIs).

Following 96 weeks of maintenance treatment, viral suppression rates for the two-drug regimen dosed every eight weeks (94 percent) or every four weeks (87 percent) were comparable to the rate observed in patients continuing with a three-drug oral regimen (84 percent).

In the study, data from which were published in The Lancet and presented at the annual conference of the International AIDS Society in Paris, France, two patients in the eight-week dosing group and one patient in the oral regimen group met protocol-defined virologic failure criteria, but neither had evidence of resistance at failure.

Injection site pain was the most commonly reported injection site reaction reported by patients receiving the injectable two-drug therapy, but ISRs were mild (84 percent) or moderate (15 percent) in severity, with a median symptom duration of three days.

John C Pottage Jr, chief scientific and medical officer for ViiV, said the study findings are important because they show durability and tolerability of long-acting viral suppression for a two-drug regimen out to 96 weeks.

“Administration of long-acting parenteral medication removes the daily dosing burden for patients and the LATTE-2 results showed that long-acting cabotegravir and rilpivirine maintained viral suppression, with no virologic failures in the four-week dosing group,” he noted.

All eyes will now be on results of a Phase III trial assessing the two-drug regimen, which are expected next year.

ViiV Healthcare is majority owned by GSK, with Pfizer and Shionogi as shareholders.