Gilead Sciences and Tibotec Pharmaceuticals announced earlier this week that two Phase III clinical trials have found rilpivirine (TMC278) to be non-inferior to Sustiva (efavirenz) in people living with HIV beginning antiretroviral (ARV) therapy for the first time.

Studies are under way to coformulate Tibotec’s rilpivirine with Gilead’s Truvada (tenofovir plus emtricitabine), ultimately allowing for one-pill, once-daily dosing. 

In a conference call with investors on April 20, Gilead reported that there was no significant difference in the percentage of Phase III study volunteers with viral loads below 50 copies/mL after 48 weeks of treatment while taking Truvada in combination with either rilpivirine or Sustiva.

The study investigators plan to formally present the 48-week data at a scientific meeting later this year, potentially this summer at the 18th International AIDS Conference in Vienna.

Tibotec plans to submit a new drug application (NDA) in support of rilpivirine’s approval to the U.S. Food and Drug Administration (FDA) this summer. Approval for the coformulated version of rilpivirine and Truvada will likely be requested once Gilead and Tibotec have successfully completed necessary studies proving both drugs can be safely and effectively combined.

The companies are also working toward an agreement to make the fixed-dose combination of Truvada and rilpivirine available in the developing world.