A double-blinded, multicenter, randomized Phase 3 study aimed at assessing the safety and effectiveness of twice-yearly long-acting subcutaneous Lenacapavir, in combination with daily oral Emtricitabine/Tenofovir Alafenamide, for pre-exposure prophylaxis among adolescent girls and young women vulnerable to HIV infection.


Daily use of F/TDF has proven highly effective for PrEP and is the recommended standard for women at risk of HIV. However, the need for strict adherence to a daily regimen has limited its overall impact on reducing HIV incidence across populations. PrEP’s efficacy hinges on adherence, evident in studies where lower adherence correlated with reduced effectiveness. Maintaining daily adherence is especially challenging for certain at-risk groups, including adolescent girls and young women (AGYW) in sub-Saharan Africa aged 15 to 25.

In 2018, despite over 730,000 new HIV infections in East and Southern Africa, only about 84,000 people in the region used PrEP at least once. This suboptimal uptake among women underscores the need for new PrEP options to overcome existing challenges. If proven safe and effective, F/TAF and LEN could offer crucial alternatives for AGYW at risk of HIV acquisition, addressing some of the limitations of current PrEP regimens.

F/TAF has demonstrated comparable efficacy to F/TDF with more favorable effects on bone density and renal safety biomarkers, particularly in cisgender male individuals and transgender women (TGW) who have sex with men. However, its effectiveness for HIV prevention in cisgender women (CGW) remains unclear. If shown to be similarly effective in CGW, F/TAF could be a valuable PrEP option for transvaginal HIV prevention, especially for those with renal or bone health concerns.

LEN presents another important PrEP option for CGW due to its pharmacokinetic profile supporting a subcutaneous injection every 6 months (Q6M). Its non-reliance on daily oral dosing could overcome barriers such as stigma, disclosure concerns, and limited access to healthcare services in sub-Saharan Africa. This long-acting PrEP option may be preferred by current PrEP users seeking less frequent dosing, aligning with the preferences of young women in South Africa and Kenya for injectables over tablets or rings.

Overall, long-acting PrEP options like LEN hold promise for increasing PrEP uptake and reducing new HIV infections among AGYW by addressing adherence challenges and offering alternatives to daily oral regimens.


  • Wits RHI
  • Prof. Thesla Palanee-Phillips (Co-Principal Investigator)
  • Dr. Nkosiphile Ndlovu (Co-Investigator)
  • Dr. L Kew (Co-Investigator)
  • Dr. L Kgoa (Co-Investigator)
  • Dr. H Ishmail (Co-Investigator)

Latest Update

April 2024

For more details about PURPOSE 1 please email

Click here for further details regarding the PURPOSE 1 study.

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