Synlogic and Caldera Therapeutics have announced a definitive all-stock merger agreement, with the combined entity to operate as Caldera Therapeutics and seek a NASDAQ listing under the ticker CALD. The merger is supported by an upsized USD 278 million private placement from leading healthcare investors including Bain Capital Life Sciences, TCGX, Atlas Venture, venBio Partners, Omega Funds, Blackstone, LAV, Wellington Management, and others.

The combined company expects cash runway into 2029, funding Phase II development of CLD-423 in ulcerative colitis and Crohn's disease. CLD-423 is a potential first-in-class bispecific antibody (BsAb) simultaneously targeting TL1A and IL-23p19, designed with a monovalent 1+1 IgG format incorporating YTE half-life extension to enable every-8-to-12-week subcutaneous dosing.

Phase I healthy-volunteer data from the first four single-ascending-dose cohorts showed favourable tolerability, dose-proportional pharmacokinetics, serum half-life exceeding 40 days, approximately 80% bioavailability, and low anti-drug antibody incidence.

Caldera holds exclusive worldwide rights under a licence from China-based Qyuns Therapeutics. Pre-merger Synlogic stockholders will hold approximately 2.3% of the combined company, with Caldera stockholders at 62.8% and institutional investors at 34.9%.