Third Harmonic Bio announced positive Phase 1 results for THB335, an oral KIT inhibitor, paving the way for a Phase 2 trial in chronic spontaneous urticaria (CSU). Concurrently, the company is initiating a strategic review to explore options for maximizing shareholder value, including potential business combinations. With approximately $285 million in cash as of December 31, 2024, Third Harmonic Bio is halting non-THB335 research and reducing its workforce by 50%.
The positive Phase 1 results and subsequent move towards a Phase 2 trial in CSU represent a crucial step for both Third Harmonic Bio and patients suffering from this often debilitating condition. Current CSU treatments have limitations, and a safe, effective oral therapy could address a significant unmet medical need. The strategic review, combined with the company’s healthy cash position, may attract potential partners or acquirers interested in THB335’s market potential. This creates a unique opportunity for accelerated development and potentially faster access for patients.
In the Phase 1 trial, THB335 demonstrated a 40-hour half-life, supporting once-daily dosing. Dose-dependent exposure increases and tryptase reductions, a biomarker of mast cell activation, were observed, reaching levels potentially beneficial for CSU treatment. The drug was generally safe and well-tolerated, with isolated transaminase elevations deemed unrelated to THB335. Other adverse events, such as hair color change, hemoglobin and neutrophil count reductions, were dose-dependent and resolved during follow-up. The company projects having between $262 million and $267 million in cash by June 30, 2025, after accounting for THB335’s Phase 2 preparation, ongoing operations, and restructuring costs.
The combined news of positive clinical data and the strategic review signals a pivotal moment for THB335 and Third Harmonic Bio. While the strategic review’s outcome remains uncertain, the company’s focus on advancing THB335 into Phase 2 and its substantial cash reserves position it well for navigating the upcoming stages of development, potentially leading to a much-needed new treatment option for CSU patients. The initiation of the Phase 2 trial in mid-2025 will be a critical inflection point, providing further insights into the drug’s efficacy and safety profile.
Jon Napitupulu is Director of Media Relations at The Clinical Trial Vanguard. Jon, a computer data scientist, focuses on the latest clinical trial industry news and trends.
