Werewolf and Ambros to tie the knot in $150M rare disease deal
August 21, 2026 |
2 min read |
Michael Gibney
The merger, which would create a new company bearing Ambros’ name, will help support development of Ambros’ non-opioid painkiller for patients with debilitating limb injuries
Immunotherapy biotech Werewolf Therapeutics and rare disease specialist Ambros Therapeutics are joining forces in pursuit of a treatment for complex regional pain syndrome type 1
The companies revealed their merger plans alongside a $150 million private placement that is expected to help fund operations through a late-stage study of the potential CRPS-1 therapy neridronate into regulatory submission with enough runway to last into the first half of 2029, according to a Friday release from Werewolf
The combined company will operate under Ambros’ name and with the company’s leadership team intact, led by CEO Jay Hagan. The merger has been approved by both companies’ boards of directors
Ambros’ neridronate program, which holds the FDA’s breakthrough therapy, fast track and orphan drug designations, is currently being studied in an ongoing Phase 3 trial. The primary endpoint is a change in pain intensity from baseline to week 12 in patients with CRPS-1. Ambros licensed neridronate, originally developed by Italy’s Abiogen Pharma, before debuting at the end of last year with a $125 million series A round. The company was cofounded by former biotech executive and U.S. presidential candidate Vivek Ramaswamy, currently the Republican nominee for governor of Ohio.
A non-opioid pain treatment called a bisphosphonate analgesic, neridronate has gained the attention of U.S. regulators looking to introduce new non-addictive options in the wake of the opioid crisis. Vertex Pharmaceuticals leads the charge, receiving an FDA nod in January 2025 for its non-opioid painkiller Journavx for the treatment of moderate-to-severe acute pain
There is currently no FDA-approved treatment specifically for CRPS-1, which causes severe pain following a limb injury. Neridonate is designed to address pain and other CRPS-related symptoms. It has been approved in Italy
Werewolf primarily focuses on immunotherapies for cancer with a technology platform that stimulates the immune system against solid tumors. Its most advanced clinical programs, which address the signaling proteins interleukin-2 and interleukin-12, are each in Phase 1b clinical trials
Pre-transaction values of Ambros and Werewolf are $500 million and $47.5 million, respectively, according to the release. Werewolf stockholders who held shares before the announcement are expected to own about 6.8% of the combined company, while Ambros stockholders will own about 71.7%
Mergers & acquisitionsPainRare diseases
Werewolf Therapeutics
Michael Gibney
