A phase 3, double-blinded, multicentre, randomised study to evaluate the safety and efficacy of twice yearly long-acting subcutaneous Lenacapavir, and daily oral Emtricitabine/Tenofovir Alafenamide for pre-exposure prophylaxis in cisgender men, transgender women, transgender women, transgender men and gender non-binary at risk of HIV infection.


Both daily oral emtricitabine/tenofovir disoproxil fumarate (F/TDF; Truvada®; TVD) and emtricitabine/tenofovir alafenamide (F/TAF; Descovy®; DVY) have demonstrated high effectiveness for PrEP, with F/TDF recommended by the World Health Organization (WHO) for HIV prevention. However, the need for strict daily adherence has limited their population-level impact on reducing HIV incidence. Lower adherence has been linked to reduced PrEP efficacy, despite estimates of significant usage in the US.

Lenacapavir (LEN) offers a novel approach, as its long-acting subcutaneous administration every six months can address the challenges of daily oral regimens, stigma, and adherence issues. This could substantially increase PrEP uptake and persistence, benefiting individuals who prefer less frequent dosing and those who find daily oral PrEP challenging.

Long-acting PrEP is anticipated to be highly desirable for current users seeking less frequent dosing and for individuals at high HIV risk who have not considered or discontinued daily oral PrEP. This includes marginalized groups disproportionately affected by HIV. LEN’s potential efficacy and reduced adherence requirements make it a crucial alternative, aiming to enroll diverse populations historically underrepresented in HIV trials.

Early clinical and preclinical data suggest LEN’s potent antiviral activity and the potential to eliminate daily adherence needs, addressing a significant unmet need in HIV prevention and potentially accelerating population-level reductions in new infections, particularly in marginalized and disproportionately affected communities.


  • 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 Ismail (Co-Investigator)

Latest Update

April 2024

For more details about PURPOSE 2 please email

Click here for further details regarding the PURPOSE 2 study.

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