A Clinical Trial Investigating the Safety and Biological Activity of the Antibody BNT351 in Adults Living Without and With HIV

The study will consist of two parts (Parts A and B). Part A will be a randomized, double-blind, placebo-controlled, single ascending dose, first-in-human study part. Part A will enroll people living without HIV (PLWOH). Four cohorts are planned in Part A (Cohorts A1, A2, A3, and A4). Cohort A1 will evaluate one dose of BNT351 administered subcutaneously (SC). Cohorts A2 to A4 will evaluate three different doses of BNT351 administered intravenously (IV). For each cohort, participants will be randomized to BNT351 or placebo. Part B will be single-dose, open-label, proof-of concept study part. Part B will enroll PLWH. Part B comprises two cohorts (Cohorts B1 and B2) and will be non-randomized. Parts A and B will use a sentinel participant/staggered dosing approach in which dosing will start with a lower dose of BNT351 and then progress to the next dose level. The study will start with recruitment into Part A. Depending on the available safety, pharmacokinetics, and/or viral kinetics data generated within this study, any of the Part A or B cohorts may not be initiated or may be terminated earlier by sponsor decision. In Part A, for each participant, there will be an \~4-week screening period, one dose of BNT351 or placebo, and an \~38-week follow-up period. In total, Part A will last up to \~42 weeks per participant. In Part B, for each participant, there will be an \~4-week screening period, one dose of BNT351, and an up to 8-week observation period with HIV viral load assessments, after which combination antiretroviral therapy (cART) will be started. Overall, participants will be followed for \~38 weeks after IMP administration and in total, Part B will last up to \~42 weeks per participant.