US pharmaceutical group Pfizer has bought a 15% stake in Vivet Therapeutics and now has an exclusive option to buy out the rest of the privately-held French gene therapy company.
Pfizer said in a statement that it will collaborate with Vivet on the development of its proprietary treatment for Wilson disease – a potentially life-threatening liver disorder – VTX-801.

Mikael Dolsten, Pfizer's chief scientific officer and president of 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.”

Under the terms of the deal, Pfizer paid about €45m upon signing and may pay up to €560m inclusive of the option exercise payment and subject to certain clinical, regulatory, and commercial milestones.

Pfizer can exercise its option to acquire Vivet following the company's delivery of certain data from the Phase I/II clinical trial for VTX-801.

Vivet's co-founder and chief executive Jean-Phillippe Combal said: “We welcome Pfizer as a shareholder and partner that can help us advance our efforts to develop therapies for patients burdened with inherited liver disorders.

“This investment demonstrates the clear value of Vivet's innovative approaches to gene therapy.”

In addition to its Wilson disease programme, Vivet is also advancing liver-directed gene therapy programmes for progressive familial intrahepatic cholestasis for bile excretion defects and citrullinemia for defects in the urea cycle, which leads to the build-up of ammonia and other toxic substances in the blood.