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A Phase 3, Double-Blinded, Multicenter, Randomized PrEP Trial

Backgroud of PURPOSE 1 Study

AMBSO in partnership with Makerere University John Hopkins University Research Collaboration (MU-JHU) and Makerere University School of Public Health MUSPH) are in the final stages of preparing to conduct a study funded by Gilead Sciences Inc. titled, A Phase 3, Double-Blinded, Multicenter, Randomized Study to Evaluate Safety and Efficacy of Twice Yearly Long-Acting Subcutaneous Lenacapavir, and Daily Oral Emtricitabine/Tenofovir Alafenamide for Pre-Exposure Prophylaxis in Adolescent Girls and Young Women at Risk of HIV Infection.

Primary Objective

The primary objective of the study is to evaluate the safety and efficacy of twice-yearly long acting subcutaneous Lenacapavir (LEN) and the daily oral Emtricitabine/Tenofovir Alafenamide (F/TAF) in preventing the risk of Human Immunodeficiency Virus (HIV) infection relative to the background HIV incidence rate in the region.

Study Population

The study will be conducted among Adolescent Girls and Young Women (AGYWs) aged ≥ 16 to ≤ 25 years that are at risk of HIV infection.

Where the study will be conducted

In Uganda, the study will conducted at 3 sites. The AMBSO site will cover greater Masaka and during the six years of conducting the study, participants will be drawn from the Greater Masaka areas; specifically in the districts of Kalungu, Masaka, Lyantonde, Rakai, and Kyotera

End Points

This Phase 3, double-blind, multi-site, randomized study is to compare HIV incidence in each of the LEN and F/TAF study drug groups with the external control of background HIV incidence, defined as the estimated HIV incidence without PrEP in the population studied. F/TDF will serve as the internal active control.

Phases of the Study

The study has 2 parts which includes a cross-sectional HIV incidence study (Incidence Phase) and a double-blinded, randomized study (Randomized Phase). The Incidence Phase will include initial assessments that will provide an estimate of the concurrent background HIV incidence rate (the counterfactual rate), using a recency assay. The Randomized Phase of the study will have a Blinded Phase, a LEN Open-label Extension (OLE) Phase, and a Pharmacokinetic (PK) Tail Coverage Phase. Participants eligible for the Randomized Phase will be randomized, in a blinded fashion, in a 2:2:1 ratio to receive LEN, F/TAF, or F/TDF, respectively, in the Blinded Phase


The study team will enroll approximately 500 AGYW in the incidence phase, and 250 in the randomization phase, who will be followed for 6 years working along with community local leaders, the CAB, implementing partners, the District Health Officers and closely with in-charges of health facilities or their designees among others to recruit participants from within communities.