aibioSynlogic to merge with Caldera Therapeutics in all-stock deal
Tickers SYBX
The combined company would operate as Caldera Therapeutics. A concurrent private placement of approximately $278 million is expected to close alongside the merger, which is expected to close by early 2027.
Key facts
- Company
- SYNLOGIC, INC. (OTC: SYBX)
- News type
- Mergers
- Primary source
- Form 8-K, SEC EDGAR
Synlogic, Inc. (OTC: SYBX) and Caldera Therapeutics, Inc. announced on July 29, 2026 that they entered into a definitive merger agreement to combine in an all-stock transaction. Both companies would become wholly owned subsidiaries of a newly formed holding company. After closing, the combined company plans to operate as Caldera Therapeutics, Inc. and intends to apply to trade on the Nasdaq Capital Market under the ticker symbol CALD.
The terms
As of closing, the expected ownership of the combined company is about 2.3% for pre-merger Synlogic stockholders, about 62.8% for pre-merger Caldera stockholders, and about 34.9% for investors in the concurrent private placement. The Synlogic percentage will be adjusted based on the estimated amount of Synlogic's net cash immediately before closing, so current Synlogic holders would keep a small slice of the combined company.
Both boards of directors approved the transaction. Closing depends on approval by each company's stockholders, the effectiveness of a registration statement on Form S-4 that the new company will file, and other customary conditions. The release says the transaction is expected to close by early 2027. Praveen Tipirneni, MD, MBA, Caldera's chief executive officer, will lead the combined company, and Caldera's board will become the board of the combined company.
Mary Beth Dooley, principal executive officer and principal financial officer of Synlogic, said in the release that "we believe this transaction represents the best path forward for our shareholders."
What Caldera is developing
Caldera is a privately held clinical-stage biotechnology company developing CLD-423, which the release describes as a potential first-in-class TL1A x IL-23p19 bispecific antibody for inflammatory bowel disease and other immune-mediated diseases. Caldera holds exclusive worldwide rights to develop and commercialize CLD-423 under a license agreement with Qyuns Therapeutics Co., Ltd.
The release says CLD-423 is in a Phase 1 healthy volunteer trial in Australia that started in January 2026 and has completed dosing. Unblinded data from the first four single ascending dose cohorts support the trial objectives. The company says the molecule was generally well tolerated with no dose-limiting toxicities in those cohorts.
The release also reports a serum half-life exceeding 40 days within the anticipated therapeutic exposure range, and approximately 80% subcutaneous bioavailability. Caldera says these properties support a convenient maintenance regimen of once every 8 or 12 weeks in IBD patients.
Financing and advisers
The upsized concurrent private placement is expected to generate approximately $278 million in gross proceeds from a syndicate of institutional investors and mutual funds. The release names Bain Capital Life Sciences, TCGX, Atlas Venture, venBio Partners, Omega Funds, Blackstone Multi-Asset Investing, LAV, Wellington Management, Janus Henderson Investors, Sirenia Capital Management LP and Vivo Capital among them.
The release names Jefferies, TD Cowen, Guggenheim Securities, UBS Investment Bank and LifeSci Capital as placement agents to Caldera. Lucid Capital Markets is exclusive financial advisor to Synlogic, and Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C. is its legal counsel. Fenwick & West LLP is legal counsel to Caldera, and Cooley LLP is legal counsel to the placement agents.
Financial position
In its annual report for 2025, Synlogic reported no revenue for 2025, against $8,000 for 2024. The net loss was $1.0 million for 2025 and $23.4 million for 2024. Cash used in operations was $4.4 million in 2025 and $31.7 million in 2024. Year-end 2024 cash and cash equivalents were $18.9 million.
What is unproven
The lead drug, CLD-423, has been tested only in healthy volunteers. The release reports data from the first four of five single ascending dose cohorts in a Phase 1 trial, and no patient with inflammatory bowel disease has been dosed, so the half-life and bioavailability figures say nothing yet about whether it works. The tolerability finding and the dosing interval are Caldera's own account, and the release gives no placebo comparison or safety table. The funding runway into 2029 is the companies' expectation and depends on the private placement closing with the merger, approval by both sets of stockholders and an effective Form S-4. The combined company only intends to apply for the Nasdaq listing. Caldera expects more data later in 2026.