Synlogic is merging with the private biotech Caldera Therapeutics in an all-stock deal that will take Caldera public and fund its lead drug for inflammatory bowel disease.
Under the agreement, both companies become wholly owned subsidiaries of a new Caldera Therapeutics holding company, which will trade on Nasdaq under the ticker “CALD.” The structure is effectively a reverse merger: Caldera shareholders will own 62.8% of the combined company, private-placement investors 34.9%, and existing Synlogic shareholders just 2.3%. A concurrent private placement will bring in $278 million in gross proceeds, backed by investors including Atlas Venture, Bain Capital Life Sciences, Blackstone, Janus Henderson, venBio Partners and Wellington Management.
The lead program
The centerpiece is CLD-423, a bispecific antibody that targets two inflammatory pathways at once — TL1A and IL-23p19 — for ulcerative colitis, Crohn’s disease and other immune-mediated conditions. The drug is in a Phase 1 study in healthy volunteers in Australia that began in January 2026; the company says it has been generally well tolerated with no dose-limiting toxicities so far.
What the combined company plans
Management intends to advance CLD-423 into Phase 2 development for inflammatory bowel disease while exploring additional immune-mediated indications. Cash on hand plus the private-placement proceeds are expected to fund operations through 2029. The deal is expected to close by early 2027, subject to shareholder approvals and customary conditions.
“These transactions provide the capital and public company platform to advance our vision as we move into Phase 2 development in IBD,” said Caldera chief executive Praveen Tipirneni.