Pfizer has added to big pharma’s gene therapy deal streak, by announcing a collaboration with Vivet on the development of a potential breakthrough therapy for Wilson disease.

The company will acquire 15% ownership stake in Vivet, with an exclusive option to acquire all outstanding shares.

The companies will collaborate on the development of VTX-801, the French firm's proprietary treatment for Wilson disease.

Existing therapies for Wilson disease have sub-optimal efficacy or significant side effects for many patients, meaning that the search for an efficient medicine is still essential.

Under the terms of the deal, Pfizer paid approximately 45 million Euros (£39 million) upon signing, and may pay up to 560 million Euros (£485.6 million) inclusive of the option exercise payment and subject to certain clinical, regulatory, and commercial milestones.

Mikael Dolsten, Pfizer chief scientific officer and president, Worldwide Research, Development, and Medical, said: “Pfizer strives to provide meaningful enhancements to the lives of patients with rare diseases. Our partnership with Vivet offers an important expansion of Pfizer’s commitment to collaborate with the scientific community and to accelerate our leading AAV-directed gene therapy portfolio.”

Wilson disease is a devastating, rare, chronic, and potentially life-threatening liver disorder of impaired copper transport that causes serious copper poisoning. Untreated, the disease results in various combinations and severity of hepatic (fibrosis and cirrhosis), neurologic and psychiatric symptoms, which can be fatal and that can only be cured by liver transplantation.