Safety, Tolerability and Pharmacokinetics of NTM-1632, a Novel Mixture of Three Monoclonal Antibodies against Botulinum Toxin B.

ObjectiveBotulism is a rare, life-threatening paralytic disease caused by Clostridium botulinum neurotoxin (BoNT). Available treatments including an equine antitoxin and human immune globulin are given post-exposure and challenging to produce and administer. NTM-1632 is an equimolar mixture of 3 human IgG monoclonal antibodies, B1, B2, and B3, targeting BoNT serotype B (BoNT/B). This first-in-human study assessed the safety, tolerability, pharmacokinetics (PK), and immunogenicity of NTM-1632.MethodsThis double-blind, single-center, placebo-controlled dose escalation study, randomized 3 cohorts of healthy volunteers to receive a single intravenous dose of NTM-1632 (0.033, 0.165, or 0.330 mg/kg) or saline placebo. Safety monitoring included physical examinations, clinical laboratory studies, and vital signs. Blood sampling was performed at pre-specified time points for PK and immunogenicity analyses.ResultsTwenty-four subjects received study product (18 NTM-1632; 6 placebo), and no deaths or serious adverse events were reported. Adverse events in the NTM-1632 groups were generally mild and similar in frequency and severity to the placebo group, and no safety signal was identified. NTM-1632 has a favorable PK profile with a half-life >20 days for the 0.330 mg/kg dose and an approximately linear relationship with respect to maximum concentration and area under the concentration-time curve (AUC0→t). NTM-1632 demonstrated low immunogenicity with only a few treatment-emergent anti-drug antibody responses in the low and middle dosing groups and none at the highest dose.InterpretationNTM-1632 is well-tolerated at the administered doses. The favorable safety, PK, and immunogenicity profile of NTM-1632 supports further clinical development as a treatment for BoNT/B intoxication and post-exposure prophylaxis.