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SAMRC contributes to the 100% efficacy of twice-yearly injectable medication for HIV Prevention

PURPOSEThe South African Medical Research Council (SAMRC), through its five sites under HIV and Other Infectious Diseases Research Unit (HIDRU), contributed to an international multicentre study that resulted in a 100% efficacy for HIV prevention injectable Pre-exposure prophylaxis (PrEP).

The Independent Data Monitoring Committee (IDMC) recently recommended that Gilead Sciences, Inc. (Nasdaq: GILD) stop the Blinded Phase of the PURPOSE 1 Trial at Interim Analysis and Offer Open-Label Lenacapavir to all Participants with immediate effect.

Gilead announced the main results from an interim analysis of the Phase 3 PURPOSE 1 double-blind, randomised  trial indicating that the company’s twice-yearly injectable HIV-1 capsid inhibitor, lenacapavir, demonstrated 100% efficacy for the investigational use of HIV prevention in cisgender women. The PURPOSE program comprises five HIV prevention trials around the world that are focused on innovation in science, trial design, community engagement and health equity.

PURPOSE 1 was evaluating the safety and efficacy of twice-yearly, subcutaneous lenacapavir for pre-exposure prophylaxis (PrEP) and once-daily oral Descovy® (emtricitabine 200mg and tenofovir alafenamide 25mg; F/TAF) in more than 5,300 cisgender women and adolescent girls aged 16-25 across 25 sites in South Africa and three sites in Uganda.

The study objectives of the PURPOSE 1 trial were achieved as the key efficacy endpoints of superiority of twice-yearly lenacapavir to once-daily oral Truvada® (emtricitabine 200mg and tenofovir disoproxil fumarate 300mg; F/TDF) and background HIV incidence (bHIV) was met. In the trial, lenacapavir was well-tolerated and no significant or new safety concerns were identified.

These are the first data generated from Gilead’s landmark PURPOSE program, which is the most comprehensive and diverse HIV prevention trial program ever conducted.

“This first-ever 100% efficacy result signifies a positive step in the direction of HIV eradication and our participants and communities are extremely excited,” said Dr Nishanta Singh, one of the SAMRC HIDRU Principal Investigators at the Verulam site in KwaZulu-Natal.

The SAMRC HIDRU five clinical trial sites contributed 13% of participants to the efficacy results.

“We are eternally grateful to our study volunteers for their contribution to this milestone results. We thank our research team members, community stakeholders, partners and collaborators for their ongoing support and dedication to the trial. Collectively, the study volunteers and researchers remain dedicated to HIV prevention research efforts and advocate choice to the populations. Young women vulnerable to acquiring HIV will benefit from this injectable HIV prevention option, giving them a choice,” said Dr Spooner,  Investigator at Bothas Hill site.

“I am excited that I was able to help get this good results that will protect us young women from getting HIV as we are not able to protect ourselves with condoms” said a study volunteer at the dissemination meeting held with all volunteers in Verulam.   

What were the results in the study arms?

There were 0 incident cases of HIV infection among 2,134 women in the lenacapavir group (incidence 0.00 per 100 person-years). There were 16 incident cases among 1,068 women in the Truvada group (incidence 1.69 per 100 person-years). The results demonstrated the superiority of twice-yearly lenacapavir over bHIV (primary endpoint, incidence 2.41 per 100 person-years) and superiority of twice-yearly lenacapavir over once-daily Truvada (secondary endpoint), with p<0.0001 for both endpoints.

HIV incidence in the Descovy group was numerically similar (39 incident cases among 2,136 women, incidence 2.02 per 100 person-years) to that in the Truvada group and was not statistically superior to bHIV. Previous clinical trials among cisgender women have commonly found challenges with adherence to daily oral pills for PrEP, and adherence analyses for Descovy and Truvada from PURPOSE 1 are ongoing. In the trial, both Descovy and Truvada were well-tolerated and no new safety concerns were identified.

More information about the PURPOSE program, including individual trial descriptions, populations and locations, can be found at

For more information

  1. Dr Nishanta Singh
    Study PI
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