Werewolf Therapeutics Inc (NASDAQ: HOWL) shares jumped 120% in premarket trading on Friday after the biotech company agreed to merge with Ambros Therapeutics Inc in an all-stock transaction backed by a $150 million private placement.
The combined entity, to be named Ambros Therapeutics and trade under the ticker AMBX, will focus on advancing neridronate, Ambros’s late-stage treatment candidate for Complex Regional Pain Syndrome Type 1 (CRPS-1). The merger, expected to close in the first quarter of 2027, remains subject to shareholder approval and customary closing conditions.
Under the deal terms, Ambros shareholders will hold approximately 71.7% of the combined company, while Werewolf shareholders will retain about 6.8%. Private placement investors will own roughly 21.5% of the new entity. The merger implies a $500 million valuation for Ambros and a $47.5 million valuation for Werewolf, based on exchange ratios outlined in the agreement.
The private placement, which was oversubscribed, was led by RA Capital Management and Janus Henderson Investors, with participation from Aberdeen Investments, Adage Capital Partners, Affinity Asset Advisors, Arkin Bio Capital, Balyasny Asset Management, Patient Square Capital’s Enavate Sciences, SilverArc Capital, Sphera Healthcare, and Woodline Partners LP.
Neridronate, Ambros’s lead candidate, has received FDA Breakthrough Therapy, Fast Track, and Orphan Drug designations. The drug has been administered to approximately 600,000 patients in Italy for approved indications. CRPS-1, a condition with no FDA-approved therapy, affects an estimated 65,000 newly diagnosed patients annually in the United States.
The combined company’s cash runway is projected to extend into the first half of 2029. Topline results from the pivotal CRPS-RISE Phase 3 clinical trial are anticipated in 2028, with a planned New Drug Application submission to follow.
