Twice-yearly shots of Gilead HIV drug effective in large prevention study

Dive Brief:

  • Twice-yearly shots of a Gilead Sciences HIV drug were so effective at preventing infections in a large late-stage clinical trial that study monitors recommend the company stop testing early and offer the drug to all participants.
  • The trial, called Purpose 1 and run in South Africa and Uganda, compared Gilead’s medicine lenacapavir to once-daily Truvada and background HIV infection rates among cisgender women. Lenacapavir proved superior to both, with zero HIV infections reported in the study group, Gilead said Thursday.
  • Gilead hopes testing of twice-yearly lenacapavir will prove it an effective and more convenient preventive option for people at risk of HIV infection. The company expects data late this year or early next from another study that involves cisgender men who have sex with men as well as certain groups of people who are transgender or gender non-binary.

Dive Insight:

Gilead has made oncology a focus of its dealmaking in recent years, investing tens of billions of dollars in acquisitions of cancer drugs and their developers.

But the bulk of Gilead’s business remains in HIV, a field it has long led with a portfolio of pills approved to prevent or treat infections. Lenacapavir is its latest entrant and, as an injection given twice per year, could represent a more convenient way for people to protect against the disease.

“While we know traditional HIV prevention options are highly effective when taken as prescribed, twice-yearly lenacapavir for [pre-exposure prophylaxis, or PrEP] could help address the stigma and discrimination some people may face when taking or storing oral PrEP pills, as well as potentially help increase PrEP adherence and persistence given its twice-yearly dosing schedule,” said Linda-Gail Bekker, director of the Desmond Tutu HIV Center at the University of Cape Town, South Africa, in a statement provided by Gilead.

Gilead released only summary results from the Purpose 1 trial Thursday, indicating fuller details will be presented at a future medical conference.

More than 5,300 women and adolescent girls were enrolled in the study, which randomized participants to receive either preventive lenacapavir, once-daily oral Descovy or once-daily oral Truvada. Both Descovy and Truvada are approved PrEP options.

Lenacapavir and Descovy were then compared to Truvada and, because offering a placebo is now considered unethical in HIV prevention studies, background HIV rates. Researchers reported 0 incident cases of HIV infection in the women who were given lenacapavir, compared to the background incidence rate of 2.41 per 100 person-years.

Lenacapavir was also superior to once-daily Truvada, Gilead said, although the company did not reveal the incidence rate for the Truvada group in its Thursday statement.

HIV incidence among those on once-daily Descovy was similar to that of the Truvada group, but didn’t meet the statistical threshold to show superiority to background HIV incidence. Gilead attributed the latter finding as possibly related to known adherence challenges with once-daily pills.

Brian Abrahams, an analyst at RBC Capital Markets, described the readout in a Thursday note to clients as a “near best-case” outcome. While a positive result had been expected, Abrahams noted that uncertainty remained because Gilead had not conducted a mid-stage study beforehand.

The company will need to obtain positive results from its ongoing Purpose 2 study to support an approval application for lenacapavir in this use. The drug is already approved as Sunlenca in the U.S. and Europe to treat, alongside other therapies, resistant HIV infections in people whose drug regimens no longer keep the disease at bay.

In its statement Thursday, Gilead said that it will soon share more information on its plans for supporting access to lenacapavir, if approved for PrEP, in countries with high infection incidence but limited resources.

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