65,000 Patients a Year, Zero Approved Drugs, One Phase 3 Trial

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Friday, August 21, 2026

Biotech mergers can completely remake small public companies overnight, particularly when a transaction brings together a late-stage clinical asset, institutional capital and a clear regulatory path. Add an orphan disease with no FDA-approved drug therapy, and investors suddenly have a very different company to value than the one that existed the day before.

Shares of Werewolf Therapeutics, Inc. (Nasdaq: HOWL) are soaring Friday after the immuno-oncology company announced a definitive all-stock merger with privately held Ambros Therapeutics alongside an oversubscribed $150 million private placement. Werewolf's conditionally activated INDUKINE cancer programs become legacy assets, and the combined company will focus on neridronate, a Phase 3 drug candidate targeting Complex Regional Pain Syndrome Type 1, or CRPS-1.

CRPS-1 is a debilitating orphan disease that typically follows a limb injury and affects an estimated 65,000 newly diagnosed patients in the United States annually. There are currently no FDA-approved medicines for the condition, which can cause continuous, severe pain along with swelling, hypersensitivity and other symptoms.

Neridronate is not a new molecule. The bisphosphonate is approved in Italy for CRPS and other indications and has been administered to approximately 600,000 patients across its approved indications there. In the United States, the FDA has granted the drug Breakthrough Therapy, Fast Track and Orphan Drug designations for CRPS.

The ongoing CRPS-RISE Phase 3 trial is evaluating approximately 270 patients with warm CRPS-1. The randomized, triple-blind, placebo-controlled study measures change in pain intensity at 12 weeks as its primary endpoint. Based on interactions with the FDA, Ambros believes positive results from a single pivotal trial could potentially support U.S. approval, with topline results expected in 2028.

The $150 million private placement, co-led by RA Capital Management and Janus Henderson Investors, is expected to fund the combined company through Phase 3 topline results and a planned New Drug Application submission, providing a projected cash runway into the first half of 2029.

Under the merger terms, Ambros carries an implied value of $500 million compared with $47.5 million for Werewolf. Existing Werewolf shareholders, excluding financing participants, are expected to own approximately 6.8% of the combined company, with Ambros shareholders owning 71.7% and private placement investors 21.5%. Werewolf shareholders will also receive a contingent value right tied to potential proceeds from dispositions of the company's legacy assets.

The transaction is expected to close by the first quarter of 2027, subject to stockholder approval and customary closing conditions. The combined company will operate as Ambros Therapeutics and is expected to trade under the Nasdaq ticker AMBX.

Shares of HOWL are up 102.7% to $0.87 in Friday morning trading.

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