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.