An HIV-prevention group called PrEP4All Collaboration filed a petition Wednesday with the U.S. Patent and Trademark Office contending Gilead knew its new, improved drug — approved in 2015 and now part of Gilead’s combination therapies Genvoya and Descovy — was safer. But it alleged Gilead postponed development so it could continue to gain monopoly profits from its older combination HIV drugs, including Viread and Truvada, for a longer period,before those drugs went off patent and faced generic competition.

The group is asking the Patent and Trademark Office to reject Gilead’s request for three extra years of patent life on the newer drug, called tenofovir alafenamide, or TAF. Odds of success are steep because the patent office will review such third-
party petitions only in “extraordinary’’ circumstances, according to its rules.