Gilead’s twice-yearly HIV PrEP 100% effective, says study

twice-yearly injection

Gilead Sciences’ already dominant position in HIV pre-exposure prophylaxis (PrEP) has been consolidated by a new study showing that its twice-yearly injectable drug was 100% effective in protecting African women.

It is the first time that a PrEP trial has been shown to prevent any HIV infections from slipping through the net, according to Gilead, and showed a subcutaneous injection with lenacapavir every six months was more effective than its widely-used oral PrEP drug Truvada (emtricitabine/tenofovir disoproxil fumarate).

PrEP is used to protect at-risk people such as an HIV-negative individual with an HIV-positive partner and requires high levels of adherence to be effective, which can be tricky to achieve with daily oral therapies.

The result – which prompted a 5% rise in Gilead’s share price – led the independent data monitoring committee to recommend that the 5,300-subject PURPOSE 1 trial be unblinded and the lenacapavir shot offered to all participants. The study involved women and adolescent girls in South Africa and Uganda.

Gilead still needs to replicate the findings in a second phase 3 trial before seeking FDA approval, but that could come within the next few months. 

The company is expecting results of the PURPOSE 2 study in cisgender men who have sex with men, transgender men, transgender women, and gender non-binary individuals around the end of 2024 or in early 2025, which if positive could set up regulatory filings before the end of next year. That is running at sites in Argentina, Brazil, Mexico, Peru, South Africa, Thailand, and the US.

According to Linda-Gail Bekker, who is director of the Desmond Tutu HIV Center at the University of Cape Town, South Africa, a twice-yearly injection could provide a “critical new choice” for PrEP that is particularly relevant to cisgender women.

“While we know traditional HIV prevention options are highly effective when taken as prescribed, twice-yearly lenacapavir for 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,” she said.

The result also keeps Gilead’s nose in front of its main rival in the HIV category, ViiV Healthcare, which has regulatory approval for an injectable PrEP option – Apretude (cabotegravir) – which needs to be dosed six times a year. 

Apretude was approved in the US in 2021 and Europe last September and made £149 million ($1) in sales in full-year 2023 – all from the US market – and £54 million in the first quarter of 2024. It still has a long way to go to challenge Gilead’s PrEP franchise, however, which has raked in billions of dollars since Truvada first reached the market for PrEP in 2012.

It is thought that around two-thirds of Truvada’s peak sales of $3 billion came from PrEP, with the remainder from its use as a treatment for HIV infection, before generic competition started to have an effect. 

Gilead is shifting its oral PrEP business to follow-up Descovy (emtricitabine/tenofovir alafenamide), also approved for HIV treatment, which made total sales of $2 billion last year. Analysts at RBC Capital Markets have predicted twice-yearly lenacapavir could also become a $2 billion product.

In its statement, Gilead noted that it intends to outline a strategy on facilitating access to the injectable in “high-incidence, resource-limited countries, which are primarily low- and lower-middle-income countries.”

Twice-yearly lenacapavir is already approved to treat resistant HIV infection under the Sunlenca brand name.