Safety and pharmacokinetics of N6LS, a broadly neutralising monoclonal antibody for HIV: a phase 1, open-label, dose-escalation study in healthy adults.

Background: Broadly neutralising antibodies (bNAbs) have shown promise as both prevention and treatment strategies against HIV-1. The clinical effectiveness of bNAbs depends on enhancing their neutralisation breadth and extending their serum half-lives. In this study, we aimed to assess the safety, tolerability, pharmacokinetic profile, and neutralisation activity in serum of N6LS, a HIV-1 bNAb.

Methods: In this first-in-human, dose-escalation, open-label, phase 1 trial, healthy adult participants (aged 18-50 years) who were HIV-1 negative were recruited to the National Institutes of Health Clinical Center (Bethesda, MD, USA). Three groups received one intravenous administration of N6LS at 5 mg/kg (n=3), 20 mg/kg (n=3), or 40 mg/kg (n=3); one group received one subcutaneous administration of 5 mg/kg N6LS (n=3); two groups received three administrations of either 5 mg/kg subcutaneous (n=5) or 20 mg/kg intravenous (n=5) N6LS every 12 weeks; and two groups received one subcutaneous administration of either 5 mg/kg (n=5) or 20 mg/kg (n=5) N6LS with ENHANZE drug product (EDP), recombinant human hyaluronidase PH20. The primary objectives were the safety and tolerability of N6LS with and without EDP. All participants who received N6LS were included in the primary safety analyses. This trial is registered at ClinicalTrials.gov, NCT03538626, and is complete.

Findings: Between June 18, 2018, and April 11, 2022, we enrolled 33 healthy adults (19 female individuals and 14 male individuals). One participant did not receive N6LS and one participant was lost to follow-up after 8 weeks. N6LS had an encouraging safety profile similar to other HIV-1 bNAbs, with no serious adverse events. Local reactogenicity was observed after administration of N6LS, with the most common symptom being mild to moderate injection site pain or tenderness in subcutaneous groups, reported in six of eight participants. All ten participants who received N6LS with EDP had mild to severe injection site erythema, which, despite being graded as severe in size, was generally not noticed by participants or deemed bothersome, and resolved without intervention. Systemic reactogenicity was mild in all groups. N6LS had an overall mean serum half-life of 48·6 days and retained its broad and potent neutralisation characteristics in serum. EDP administration increased N6LS bioavailability. No functional anti-drug antibodies to N6LS were detected following administration.

Interpretation: N6LS showed a promising safety and pharmacokinetics profile while retaining its potent neutralisation characteristics in serum, making it a promising candidate for inclusion in HIV-1 prevention and therapeutic combination strategies. The addition of EDP can enable safe subcutaneous administration of higher doses and larger volumes of N6LS, supporting additional methods for prophylactic and therapeutic bNAb administration.

Funding: US National Institute of Allergy and Infectious Diseases Intramural Research Program, National Institutes of Health.