Werewolf Therapeutics and Ambros Merge to Target Complex Regional Pain Syndrome Market

Werewolf Therapeutics, Inc. and Ambros Therapeutics, Inc. announced Friday an agreement to merge in an all-stock transaction. The companies also secured commitments for $150 million in private financing.

The combined company will operate as Ambros Therapeutics and is expected to trade on Nasdaq under the ticker "AMBX." It will focus on developing neridronic acid, a potential therapy for treating complex regional pain syndrome type 1.

$150 Million Financing Extends Cash Runway

The oversubscribed private placement is co-led by RA Capital Management and Janus Henderson Investors. Other investors include Aberdeen Investments, Adage Capital Partners, and Balyasny Asset Management.

The financing is expected to support operations through the top-line results of the CRPS-RISE Phase 3 trial in 2028. It will also support the submission of a New Drug Application to the U.S. Food and Drug Administration. The combined company expects its cash reserves to sustain operations into the first half of 2029.

Neridronic Acid Takes Center Stage

Neridronic acid is being evaluated in the Phase 3 CRPS-RISE trial for patients with warm-type CRPS-1. The U.S. Food and Drug Administration has granted the drug Breakthrough Therapy, Fast Track, and Orphan Drug designations.

Approximately 65,000 new CRPS-1 cases are diagnosed annually in the U.S., and no FDA-approved drug currently exists for the condition. Neridronic acid, already approved in Italy for CRPS and other indications, has been administered to approximately 600,000 patients.

Ambros Therapeutics stated that its intellectual property portfolio, combined with neridronic acid's Orphan Drug designation, supports U.S. market exclusivity through 2045.

Merger Expected to Close in 2027

The transaction implies a valuation of $500 million for Ambros and $47.5 million for Werewolf.

Ambros shareholders are expected to hold approximately 71.7% of the combined company, while Werewolf shareholders will hold approximately 6.8%. Private placement investors are expected to hold approximately 21.5%.

The companies expect the merger to close by the first quarter of 2027, subject to shareholder approval and other customary conditions.

Werewolf Monetizes Preclinical Assets via EMD Serono Deal

Separately, Werewolf Therapeutics entered into an asset purchase agreement with EMD Serono Research & Development Institute, a subsidiary of Merck KGaA, signed August 14, according to an August 20 filing.

EMD agreed to pay Werewolf $28 million upfront, plus $5 million upon completion of technology transfer. The deal covers Werewolf's preclinical INDUCER platform and certain INDUKINE assets.

Werewolf retained rights needed to continue developing its WTX-124 and WTX-330 clinical programs. EMD also granted Werewolf an exclusive license to certain transferred patents supporting these programs.

HOWL stock performance: Werewolf Therapeutics shares rose 126.77% to $0.9780, based on Friday premarket trading data.