ViiV Healthcare Ltd. said the U.S. Food and Drug Administration rejected its investigational two-drug regimen for treating HIV-1 infection in virologically suppressed adults.

GlaxoSmithKline PLC-backed ViiV received a complete response letter from the U.S. regulator regarding its application for its long-acting combination of ViiV's cabotegravir and Johnson & Johnson's Edurant, or rilpivirine. The company said the reasons stated in the letter for the rejection relate to chemistry manufacturing and controls.

The company's new drug application was based on late-stage studies Atlas and Flair, which evaluated the two-drug regimen in 1,100 patients from 16 countries. The trials showed the combination worked as well as a standard-of-care, three-drug regimen in maintaining viral suppression throughout a 48-week period.

ViiV said it will work with the FDA to determine the next steps to take regarding the drug application.

U.K.-based ViiV and New Brunswick, N.J.-based Johnson & Johnson are developing the injectable regimen under a collaboration they entered in 2016. The drug combination was previously shown to be effective as an injection administered every two-months in a late-stage study.

ViiV is also seeking EU and Canada approval for the regimen. Pfizer Inc. and Shionogi & Co. Ltd. also own a stake in ViiV Healthcare.