Pfizer said it has acquired a 15 percent stake in privately-held French gene therapy developer Vivet Therapeutics along with an option to acquire the rest of the company.

The deal also includes a collaboration to develop Vivet’s lead therapy VTX-801, a potential breakthrough therapy for Wilson disease, a rare, chronic, and potentially life-threatening liver disorder of impaired copper transport that causes serious copper poisoning.

In patients with Wilson disease, a mutation in the gene encoding the ATP7B protein, which reduces the ability of the liver and other tissues to regulate copper levels, causes severe hepatic damage, neurologic symptoms and potentially death. Currently it can only be cured by liver transplantation. Existing therapies for Wilson disease do not work well or have the potential for significant side effects.

Vivet is using a modified AAV vector to move a truncated version of the ATP7B gene into liver cells. Its technology was developed through partnerships and exclusive licenses with the Fundación para la Investigación Médica Aplicada, a not-for-profit foundation at the Centro de Investigación Medica Aplicada, University of Navarra based in Pamplona, Spain.

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

“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,” said Jean-Phillippe Combal, co-founder and CEO of Vivet. This investment demonstrates the clear value of Vivet’s innovative approaches to gene therapy.”

Under the terms of the deal, Pfizer paid approximately $51.1 million (€45 million) upfront and may pay up to $635.8 million (€560 million), which includes the option exercise payment and is subject to certain clinical, regulatory, and commercial milestones. Pfizer can exercise its option to acquire all of Vivet following the company’s delivery of certain data from the mid-stage clinical trial for VTX-801.

 “VTX-801 could provide a potentially transformative therapeutic option for patients with Wilson disease by directly addressing the underlying cause of the disease—the inability to excrete copper owing to a mutation in the gene that codes for that function,” said Seng Cheng, senior vice president and chief scientific officer of Pfizer’s Rare Disease Research Unit.

Photo: Jean-Phillippe Combal, co-founder and CEO of Vivet

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