By Colin Kellaher

Gyre Therapeutics has agreed to buy privately held, clinical-stage biopharmaceutical company Cullgen in an all-stock transaction valued at about $300 million, upending plans by Pulmatrix to merge with Cullgen.

Gyre on Monday said the acquisition of Cullgen will create a U.S.- and China-based fully integrated biopharmaceutical company with revenue-producing commercial assets and a pipeline of degraders, targeting inflammatory diseases and cancers.

San Diego-based Gyre said it expects to complete the acquisition early in the second quarter.

Pulmatrix, a Framingham, Mass., biopharmaceutical company, in late 2024 agreed to merge with China-based Cullgen, but the deal encountered regulatory delays in China, and Pulmatrix on Monday said Cullgen had terminated the agreement.

Pulmatrix said it has been working to identify an alternative reverse merger opportunity, adding that it is encouraged by the interest it has received and a recent increase in deal activity within its industry.

Write to Colin Kellaher at colin.kellaher@wsj.com

(END) Dow Jones Newswires

March 02, 2026 10:23 ET (15:23 GMT)

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