Werewolf Therapeutics and Ambros agree all-stock merger to advance Phase III CRPS therapy

The combination will create a Nasdaq-listed Ambros Therapeutics focused on neridronate, backed by a concurrent $150 million private placement expected to fund the programme through Phase III results and a planned FDA submission.

Werewolf Therapeutics and Ambros Therapeutics have entered a definitive all-stock merger agreement based on implied pre-financing equity values of $500 million for Ambros and $47.5 million for Werewolf, alongside a $150 million concurrent private placement.

The combined company will operate as Ambros Therapeutics and focus on the Phase III development of neridronate for complex regional pain syndrome type 1 (CRPS-1), with the financing expected to provide cash runway into the first half of 2029.

Field	Content
Alert Type	Deal
Companies	Werewolf Therapeutics; Ambros Therapeutics
Deal Type	All-stock merger and concurrent private placement
Asset or Company	Ambros Therapeutics, principally neridronate
Therapy Area(s)	Neurology; Pain; Rare diseases
Technology or Modality	Bisphosphonate
Deal Value	The merger exchange ratio is based on an implied $500 million value for Ambros Therapeutics and $47.5 million for Werewolf Therapeutics, before giving effect to a concurrent $150 million private placement. The financing is separate from the merger consideration. (GlobeNewswire)
Development Stage	Phase III – neridronate is being evaluated in the pivotal CRPS-RISE trial for CRPS-1. (Werewolf Therapeutics, Inc.)
Geography	United States; combined company to be Nasdaq-listed
What Happened	On 21 August 2026, Werewolf Therapeutics and Ambros Therapeutics entered into a definitive agreement to combine in an all-stock transaction. Ambros will become a wholly owned subsidiary of Werewolf, with the combined business operating as Ambros Therapeutics and expected to trade on Nasdaq under the ticker AMBX. Pre-merger Ambros shareholders are expected to own approximately 71.7%, existing Werewolf shareholders approximately 6.8%, and investors in the concurrent financing approximately 21.5% of the combined company. The companies have also secured commitments for a $150 million private placement expected to close concurrently with the merger. (Werewolf TX Investors)
Why It Matters	The transaction provides Ambros with a public-market vehicle and additional capital to advance neridronate through its pivotal Phase III programme and towards a potential FDA submission. Neridronate is being developed for CRPS-1, for which there is currently no FDA-approved therapy, giving the combined company a late-stage programme addressing a defined treatment gap. (Ambros Therapeutics, Inc.)
Supporting Context	Neridronate has received FDA Breakthrough Therapy, Fast Track and Orphan Drug designations for CRPS-1. The companies state that the FDA has agreed that a single successful pivotal trial could potentially support an application for approval, while Phase III CRPS-RISE topline results are expected in 2028. (Ambros Therapeutics, Inc.)
Strategic Rationale	Ambros gains access to the public markets and financing intended to fund neridronate through Phase III results and a planned NDA submission, while Werewolf shareholders retain an interest in the combined company. Eligible pre-merger Werewolf shareholders will also receive a contingent value right linked to potential proceeds from dispositions of Werewolf's legacy assets. (GlobeNewswire)
Potential Impact	If the CRPS-RISE trial is successful and neridronate subsequently secures FDA approval, the combined company could bring forward the first FDA-approved treatment for CRPS-1. This remains dependent on successful Phase III development and regulatory review. (Werewolf Therapeutics, Inc.)
Key Takeaway	The merger shifts the combined company's focus to Ambros' late-stage neridronate programme, with $150 million in new financing providing funding towards its pivotal CRPS-1 readout and planned FDA submission. (Werewolf Therapeutics, Inc.)
What to Watch	Completion of the merger and private placement, CRPS-RISE Phase III topline results expected in 2028, and a potential subsequent NDA submission for neridronate in CRPS-1. (Ambros Therapeutics, Inc.)
Primary Source	Werewolf Therapeutics and Ambros Therapeutics merger announcement
Relevant Date	21 August 2026

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