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Gilead’s Twice-Yearly Shot To Prevent HIV Succeeds In Phase 3 Trial

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Gilead’s Twice-Yearly Shot To Prevent HIV Succeeds In Phase 3 Trial

For the very first time, an HIV PrEP drug candidate has shown zero infections in a late-stage trial

An experimental twice-a-year injection of a new antiviral drug to prevent HIV, called lenacapavir, was 100 per cent effective in a late-stage trial, according to Gilead Sciences Canada.

In its Phase 3 PURPOSE 1 trial, which was conducted in South Africa and Uganda, none of the 2,134 cisgender women aged 16-25 who received lenacapavir contracted HIV after using the twice-a-year injections. The exciting results bring Gilead one step closer to introducing a new form of pre-exposure prophylaxis, or PrEP, and broadening its HIV prevention offerings.

“With early data showing zero infections and 100 per cent efficacy, twice-yearly lenacapavir has potential as a new option to prevent HIV transmission,” said Wendy Arnott, executive director of medical affairs at Gilead. “We remain focused on our goal of ending the HIV epidemic globally and here in Canada. We look forward to seeing further results from the PURPOSE clinical program.”

The age group targeted by the trial is the worst affected by HIV in southern Africa. In 2022, more than three quarters of infections in 15- to 24-year-olds in the region were in girls and women, according to UNAIDS.

Every week in 2022, 4,000 adolescent girls and young women aged 15–24 years became infected with HIV globally, and 3,100 of these infections occurred in sub-Saharan Africa, according to UNAIDS.

The announcement of the trial’s success has been widely hailed as a huge breakthrough in the HIV sector, where a vaccine has been elusive.

The next steps for the pharmaceutical company will be to replicate these results. Later this year or early next year, Gilead expects to share data from an ongoing Phase 3 study of men who have sex with men. That trial, PURPOSE 2, is assessing twice-yearly lenacapavir for PrEP in men who have sex with men, transgender people and non-binary people, and is currently underway in Argentina, Brazil, Mexico, Peru, South Africa, Thailand and the United States. If the results from that trial are positive, the pharmaceutical company could bring lenacapavir for PrEP to market as soon as late 2025.

More than a decade ago, Gilead’s Truvada became the first approved PrEP for people without HIV who are at high risk of acquiring it. Daily pills dominate the market, but drug manufacturers are now focusing on developing longer-acting shots.

Health policymakers and advocates hope to better prevent the spread of HIV with longer-acting options that could reach people who either can’t or don’t want to take a daily pill. HIV remains an epidemic in Canada, with six Canadians dying on average every week of HIV-related illnesses, and 35 more diagnosed with HIV every single week, according to surveillance data from the Government of Canada. While the currently available oral HIV prevention options can reduce the risk of acquiring sexually transmitted HIV by more than 90 per cent when taken as prescribed, barriers remain, including recurring medication use, stigma, discrimination, and low awareness of transmission behaviours and prevention.

For more information about Gilead Sciences Canada, visit

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