For Immediate Release
Calixis Announces $45 Million Series A Financing to Advance Its Pipeline of Oral KIT Inhibitors for Mast-Cell–Driven Disease
Financing from blue-chip life-science investors — Atlas Venture, OrbiMed, and Aditum Bio — will support development of lead candidate THB335 through Phase 2 in chronic spontaneous urticaria and advance the company's broader pipeline.
Calixis, Inc., a clinical-stage biopharmaceutical company developing oral therapies for mast cell–driven diseases, today announced the closing of a $45 million Series A financing from blue-chip life-science investors, including Atlas Venture, OrbiMed, and Aditum Bio.
Calixis is developing oral small molecules that inhibit wild-type KIT, the receptor tyrosine kinase essential for the survival and function of mast cells — the central effector cells that drive a range of allergic and inflammatory diseases. Proceeds from the financing will be used to advance the company's lead candidate, THB335, an oral wild-type KIT inhibitor, through its Phase 2 study in chronic spontaneous urticaria (CSU), to progress the company's broader pipeline, and for general corporate purposes.
“This financing, and the support of a syndicate of leading life-science investors, allows us to advance THB335 through a rigorous Phase 2 study and to build a pipeline around a simple idea: that targeting mast cells at their source can change the course of allergic and inflammatory disease. We are grateful for our investors' partnership as we work toward new oral options for patients.”
— Eben Tessari, Chief Executive Officer of CalixisAbout THB335
THB335 is an investigational, orally administered, potent and selective small-molecule inhibitor of KIT being developed by Calixis for mast cell–driven diseases, beginning with CSU. THB335 is currently being evaluated in a Phase 2, randomized, double-blind, placebo-controlled study (NCT07766499). THB335 has not been approved by any regulatory authority, and its safety and efficacy have not been established.
About Calixis
Calixis, Inc. is a clinical-stage biopharmaceutical company based in Cambridge, Massachusetts, developing oral therapeutics targeting mast cells for immunologic and inflammatory diseases, led by its lead program THB335 in chronic spontaneous urticaria. Calixis was formed in 2025 and has raised $45M in Series A capital from blue-chip life-science investors. For more information, visit www.calixisbio.com.
Media & investor contact
info@calixisbio.com
Forward-looking statements. This press release contains forward-looking statements regarding Calixis's financing, clinical development plans, and the potential of its programs. Such statements involve risks and uncertainties, and actual results may differ materially. Calixis's investigational compounds have not been approved by the U.S. Food and Drug Administration or any other regulatory authority; their safety and efficacy have not been established. Calixis undertakes no obligation to update these statements except as required by law.