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First-in-Human, Phase 1, Randomized, Double-Blind, Placebo-Controlled Study of TNX-1500, an Fc-Modified anti-CD154 Monoclonal Antibody, Evaluating the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of Single-Ascending Doses in Healthy Adults

Seth Lederman, B. Daugherty, Nancy Herje, Gregory M. Sullivan

Journal of Clinical Immunology, 2026

26 participants

Abstract

Blocking CD154 (CD40L) has the potential to prolong transplanted solid organ graft survival and treat autoimmune diseases. However, first-generation anti-CD154 IgG1 monoclonal antibodies (mAbs) were associated with an increased risk of thrombosis linked to Fc binding to FcγRIIa (CD32A). Here, we describe a first-in-human, phase 1 clinical trial of TNX-1500, a novel Fc-modified IgG4 anti-CD154 mAb designed to decrease binding to FcγRIIa. Healthy volunteers (N = 26) were enrolled into single-ascending dose (3, 10, and 30 mg/kg) cohorts and received TNX-1500 intravenously. TNX-1500 was generally well tolerated. Among participants receiving TNX-1500 3, 10, and 30 mg/kg, 1 (25%), 3 (38%), and 3 (38%) participants, respectively, reported ≥ 1 treatment-emergent adverse event; all were mild or moderate in severity, and none resulted in study discontinuation. There were no thromboembolic events. Pharmacokinetic analyses of TNX-1500 demonstrated a mean half-life of 37.8 and 33.8 days for 10 and 30 mg/kg, respectively, supportive of monthly dosing; dose-proportional exposure was suggested over the 3 to 30 mg/kg range. TNX-1500 blocked the primary T cell–dependent antibody response to keyhole limpet hemocyanin (KLH) at all doses and blocked the secondary response at the 10 and 30 mg/kg doses. At 3 mg/kg, TNX-1500 reduced peak secondary response to KLH by ~ 70% relative to placebo. TNX-1500 administration was associated with immediate and sustained reduction in soluble CD154. Overall,…

How strong is the evidence?

Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 3 of 5 (Moderate · trial / cohort / secondary analysis). Trials without a large randomized design, cohorts and secondary analyses give moderate evidence. Reported size: 26 participants or records.

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