Pharmacokinetics and Safety of SAR441236

This study evaluated the safety, tolerability, pharmacokinetics, and antiviral activity of SAR441236, a tri-specific broadly neutralizing antibody against HIV. The study included three arms. In Arm A, three dose cohorts (1, 3, and 10 mg/kg) of antiretroviral-treated, virologically suppressed participants were randomized (2:1, active to placebo) to receive a single intravenous (IV) dose of SAR441236 or placebo on Day 0. After Cohort 1 (1 mg/kg, lowest Arm A dose), each subsequent, higher-dose, cohort opened for enrollment only after an evaluation of safety outcomes for all participants in the previous cohort indicated it was safe to increase the dose of SAR441236. All participants in Cohorts 1-3 were followed for up to 24 weeks. In Arm A, Cohort 4, participants were randomized (2:1, active to placebo) to receive an IV infusion of 30 mg/kg SAR441236 or placebo once every 12 weeks beginning at entry, for a total of 4 infusions. The first six Cohort 4 participants were enrolled after the safety evaluation of Cohort 3 participants and the rest of the Cohort 4 participants were accrued after a safety evaluation of the first 6 participants. The time between infusions was prolonged for some participants due to the COVID-19 pandemic, which occurred during the course of the study. Participants in this cohort were followed for up to 36 weeks after their final infusion. Participants in Arm A continued taking non-study-provided antiretroviral treatment throughout the study. In Arm B, two cohorts of viremic participants received a single IV dose of SAR441236 on Day 0. Cohort 5 (1 mg/kg, lowest planned Arm B dose) opened first. After reviewing the safety data from that cohort, as well as that from all Arm A cohorts (which had fully enrolled), and taking into consideration enrollment challenges, the study was redesigned to be a dose de-escalation study in Arm B only. With this redesign, the study began enrollment into the highest dose (Cohort 8, 30 mg/kg) after closing Cohort 5 enrollment. Each subsequent Arm B cohort (of lower doses) was planned to open for enrollment only after an evaluation of efficacy data from Day 14 for all participants in the previous cohort was completed. However, the highest dose cohort never fully enrolled, and no subsequent cohorts were opened. All Arm B participants were followed for up to 24 weeks. Participants in Arm B initiated or re-initiated non-study-provided combination antiretroviral therapy (ART) (selected by their primary HIV clinician) on or before Day 28. A later version of the protocol changed the duration of SAR441236 monotherapy to no more than 14 days, however, no participants enrolled under that version. In Arm C, two cohorts of ART-treated, virologically suppressed participants were randomized (2:1, active to placebo) to receive a single subcutaneous (SC) dose of SAR441236 or placebo on Day 0. Cohort 11 (1 mg/kg) opened for enrollment only after an evaluation of safety outcomes from Day 14 for all participants in Cohort 10 (0.3 mg/kg) and the cumulative data from that cohort indicated it was safe to dose escalate. All Arm C participants were followed for 24 weeks. Participants in Arm C continued taking non-study-provided ART throughout the study. The study closed to enrollment and follow-up in May 2023 due to the expiration of the available study product, despite failing to meet its enrollment targets in Arm B. There had been no enrollment to the study since October 2021, despite the team's revision of the protocol (Version 4.0) to adjust eligibility criteria to facilitate enrollment of participants with viremia. At the time of study closure, Arm A and C were fully enrolled. Two Arm B cohorts (1 mg/kg and 30 mg/kg) achieved partial enrollment. Although protocol version 4.0 was released in September 2022, the last participant was enrolled under protocol version 3.0 and completed study follow-up in April 2022.