Pfizer Secures Exclusive Option to Acquire Gene Therapy Company Vivet Therapeutics

Pfizer and Vivet to collaborate on development of potential
breakthrough therapy for Wilson disease

Pfizer acquires 15% ownership stake in Vivet

PARIS & NEW YORK–(BUSINESS WIRE)–Vivet Therapeutics (“Vivet”), a privately held gene therapy biotech
company dedicated to developing gene therapy treatments for inherited
liver disorders with high unmet medical need, and Pfizer Inc. (NYSE:
PFE) announced today that Pfizer has acquired a 15% equity interest in
Vivet and secured an exclusive option to acquire all outstanding shares.
Pfizer and Vivet will collaborate on the development of VTX-801, Vivet’s
proprietary treatment for Wilson disease.

Wilson disease is a devastating, rare, chronic, and potentially
life-threatening liver disorder of impaired copper transport that causes
serious copper poisoning. In patients with Wilson disease, a monogenetic
mutation disables the normal copper biliary excretion pathway leading to
excess copper accumulation in the liver and other organs including the
central nervous system. Untreated, Wilson 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. Existing therapies for Wilson
disease have sub-optimal efficacy or significant side effects for many
patients.

Jean-Phillippe Combal, Co-Founder & CEO of Vivet, 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.”

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.”

Bringing together Pfizer’s and Vivet’s expertise in liver-directed AAV
gene therapy for metabolic diseases creates an opportunity to develop a
breakthrough medicine that can meaningfully improve the lives of
patients with Wilson disease. “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.

Under the terms of the transaction, Pfizer paid approximately €45
million (US$51 million) upon signing and may pay up to €560 million
(US$635.8 million) inclusive of the option exercise payment and subject
to certain clinical, regulatory, and commercial milestones. Pfizer can
exercise its option to acquire 100% of Vivet following the company’s
delivery of certain data from the Phase I/II clinical trial for VTX-801.
As part of the transaction, Pfizer senior executive Monika Vnuk, M.D.,
Vice President, Worldwide Business Development, will join Vivet’s Board
of Directors. Other terms of the transaction were not disclosed.

Vivet Co-Founder and Chief Scientific Officer Gloria
Gonzalez-Aseguinolaza said, “The potential of VTX-801 has already been
demonstrated in preclinical models and our partnership with Pfizer will
help accelerate development of VTX-801 and expand our other innovative
technologies.”

In addition to its Wilson disease program, Vivet is also advancing
liver-directed gene therapy programs for progressive familial
intrahepatic cholestasis (PFIC) 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.

About Vivet Therapeutics

Vivet Therapeutics is an emerging biotechnology company developing novel
gene therapy treatments for rare, inherited metabolic diseases.

Vivet is building a diversified gene therapy pipeline based on novel
adeno-associated virus (AAV) technologies developed through its
partnerships with, and exclusive licenses from, the Fundación para la
Investigación Médica Aplicada (FIMA), a not-for-profit foundation at the
Centro de Investigación Medica Aplicada (CIMA), University of Navarra
based in Pamplona, Spain.

Vivet’s lead program, VTX-801, is a novel investigational gene therapy
for Wilson disease which has been granted Orphan Drug Designation (ODD)
by the Food and Drug Administration (FDA) and the European Commission
(EC). This rare genetic disorder is caused by mutations in the gene
encoding the ATP7B protein, which reduces the ability of the liver and
other tissues to regulate copper levels causing severe hepatic damage,
neurologic symptoms and potentially death.