Third Harmonic Bio Initiates Strategic Review, Lays Off 50% Staff Citing Competitive Landscape

On Tuesday, Third Harmonic Bio, Inc. THRD revealed results from its Phase 1 single and multiple ascending dose (SAD/MAD) trial of THB335 in healthy volunteers.

The company says the data are expected to support the advancement of THB335 into a Phase 2 trial in chronic spontaneous urticaria (CSU).

Dose-dependent reductions in serum tryptase, a biomarker of mast cell activation, were observed in the MAD cohorts, with mean reductions from baseline ranging from 13% to 84% at Day 15.

THB335 was generally safe and well tolerated in the SAD cohorts. There were 3 subjects in the MAD cohorts with isolated, transient asymptomatic transaminase elevations. Two of the three subjects received a placebo (1 subject in the 21 mg cohort and 1 subject in the 164 mg cohort), and 1 active subject received THB335 in the 164 mg cohort.

Transaminase elevations in the 164 mg cohort were largely consistent in time course and magnitude for the placebo and active subjects.

The company intends to continue THB335 development activities through the first half of 2025 to prepare for the initiation of a 12-week, placebo-controlled Phase 2 study in CSU by mid-year 2025.

The company also initiated a strategic review process to run in parallel with Phase 2 readiness activities to identify opportunities to maximize shareholder value.

“As we evaluate the competitive landscape and current market dynamics, we believe the right thing for our stakeholders is to evaluate a full range of strategic transactions and/or business combinations to maximize value creation across all assets in the company…” said Natalie Holles, Chief Executive Officer of Third Harmonic Bio.

In conjunction with this announcement, the company is halting all non-THB335 related research and discovery activities and undertaking a reduction in workforce of approximately 50%. As of December 31, 2024, the company had approximately $285 million in cash and cash equivalents.

After accounting for expenses related to THB335 Phase 2 readiness activities, continuing operations, and restructuring costs, Third Harmonic Bio estimates it will have cash and cash equivalents of approximately $262 million to $267 million on June 30, 2025.

In December 2022, Third Harmonic discontinued the Phase 1b study of THB001 in chronic inducible urticaria after observing asymptomatic liver transaminitis in two subjects enrolled in the first dose cohort of 200mg BID.

Price Action: THRD stock closed at $3.56 on Wednesday.

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