A GlaxoSmithKline (GSK) logo is seen at the GSK research centre in Stevenage, Britain November 26, 2019. REUTERS/Peter Nicholls

(Reuters) - GlaxoSmithKline’s HIV drugs division ViiV Healthcare said on Saturday that the U.S. Food and Drug Administration declined to approve its long acting HIV injection.

ViiV, in which Pfizer and Shionogi have small stakes, said it received a so-called complete response letter (CRL) from the FDA in which the regulator questioned the treatment’s chemistry, manufacturing and controls process, but not its safety.

The monthly injection to suppress the virus that causes AIDS was aimed as an alternative to daily pills.

The unit of the British drugmaker, which is challenging HIV drug market leader Gilead Sciences, said it will work with the FDA to determine the next steps for the new drug application.

A GSK spokesman said it was not yet clear by when ViiV would be able to address the FDA’s concerns.

The CRL for the Cabenuva injection, containing two active ingredients cabotegravir and Janssen’s rilpivirine, follows U.S. market approval in April for its once-a-day pill Dovato, also a two-drug combination.

The injection has previously proven to be as effective as standard daily pills with three active ingredients when administered monthly and also once every two months.

U.S. drugmaker Gilead dominates the HIV market and it will keep up the pressure with fast-growing Biktarvy, which was approved early last year.