Evaluation of MTX-463 Administered Subcutaneously in Healthy Adult Males

This is a randomized, double-blind, placebo-controlled, study to assess the safety, tolerability, and PK of MTX-463 when administered via SC injection in healthy adult males. The study will consist of a single cohort comprising 8 healthy male participants, who on Day 1 will be randomly assigned to receive MTX-463 or matched placebo. Randomization will be in a 3:1 ratio such that 6 participants will receive MTX-463 and 2 will receive placebo. Participants randomized to MTX-463 will receive a dose of 250 mg of MTX-463. Participants randomized to placebo will receive SC injections containing sodium chloride 0.9%. The injections will be given under the skin of the abdominal wall on Day 1. Blood will be drawn pre-dose on Day 1 for PK and antidrug antibodies (ADAs) and post-dose for PK at 6 and 24 hours. Participants will remain in the clinical research unit (CRU) for 24 hours after their injections, and then they will return for outpatient PK blood draws on Days 3 through 8, 15, and 22, with blood drawn for ADA assessment on Days 15 and 22. Each participant will undergo assessments at specified timepoints on Days 1 through 22 as detailed in Table 1. End-of-study procedures will be completed on Day 22 or upon early termination (ET). Local safety and tolerability at the injection site will be assessed at the time of the injections and for 24 hours afterward, and on Days 5, 8, 15 (±1 day), and 22 (±2 days) (EOS/ET).