Third Harmonic Bio (THRD) 7th Annual Evercore ISI HealthCONx Healthcare Conference summary

Company overview and lead program status

• Focused on therapies for mast cell-mediated inflammatory diseases, with lead compound THB335 targeting chronic spontaneous urticaria (CSU).

• THB335 is a once-daily oral KIT inhibitor, currently in phase I trials with data expected in Q1 2025.

• Strong financial position with $296 million in cash as of September 30, sufficient to fund through phase II data and beyond.

Differentiation and clinical rationale

• Oral KIT inhibitors offer patient and physician convenience over antibody injections, with reduced risk of anaphylaxis.

• Oral formulation allows for rapid discontinuation if needed and potential for dose titration to optimize efficacy and safety.

• Prior data with first-generation compound (THB001) showed promising efficacy but was halted due to liver toxicity.

Transition from THB001 to THB335

• THB001 discontinued after liver toxicity observed in early trials, despite high response rates.

• Root cause identified as metabolic liability leading to toxic metabolite formation; THB335 designed to avoid this issue.

• Preclinical and cross-species testing of THB335 showed no toxic metabolite formation and improved safety profile.

• Patent coverage for THB335 extends through end of 2043.