• Mirum expands potential opportunities across rare disease pipeline
• Vivet to lead preclinical development of its two gene therapy programs for PFIC3 and PFIC2
• Mirum gains option to license VTX-803 and VTX-802

FOSTER CITY, Calif. and PARIS, France - March 12, 2021 - Mirum Pharmaceuticals, Inc. (Nasdaq: MIRM) and Vivet Therapeutics (“Vivet”) announced today an agreement whereby Mirum has the exclusive option to develop and subsequently commercialize Vivet’s two proprietary AAV gene therapy programs for progressive familial intrahepatic cholestasis (PFIC), subtypes 3 and 2. The two programs, VTX-803 and VTX-802, are currently being evaluated in preclinical studies by Vivet, a privately-held gene therapy biotechnology company.

Under the terms of the agreement, Vivet will continue to advance the preclinical studies for VTX-803 and VTX-802 for PFIC3 and PFIC2, respectively. Mirum has the exclusive option to license the programs after which Mirum would lead the clinical development and any future commercialization of the programs. Until that time, Mirum will provide funding to support the continued research and development costs associated with the two gene therapy programs.

“This gene therapy collaboration will work to address the root cause of PFIC3 and PFIC2 and provide an option for patients who do not respond to ASBT inhibition,” said Chris Peetz, president and chief executive officer at Mirum. “We are encouraged by the expertise and dedication of the Vivet team to develop next-generation gene therapies that have the potential to transform the lives of patients and their families. There are clear synergies in our combined missions to help the people who need it the most.”

“Mirum’s dedication to the treatment of cholestatic liver diseases and those rare diseases for which there are limited medications make them a great partner to potentially develop and bring to market VTX-803 and VTX-802,” said Jean-Philippe Combal, chief executive officer and co-founder of Vivet. “Their leadership in rare liver disease and in particular PFIC, is important as they not only understand the urgent need for patients but also that today’s treatment options will never be enough. Gene therapy is a transformative approach, potentially benefiting more patients.”

VTX-803 and VTX-802 are two proprietary AAV gene therapy programs of Vivet currently being evaluated in preclinical studies for progressive familial intrahepatic cholestasis (PFIC), subtypes 3 and 2. It is thought that successful correction by gene therapy of the defective MDR3 transporter and bile salt export pump (BSEP) functions for PFIC3 and PFIC2, respectively, may ultimately provide a cure for patients living with these rare liver diseases. Such an approach carries the potential to overcome the main limitations of current standard of care for PFIC3 and PFIC2. It may provide long-lasting benefits by restoring physiological bile secretion and preventing severe hepatic complications of the diseases and outweighing its related significant costs.

Vivet has received Orphan Drug Designation for VTX-803 by the U.S. Food and Drug Administration (FDA) and the European Medicines Agency (EMA). Additionally, preclinical proof-of-concept studies highlighting VTX-803 were published in Nature Communications in 2019. The data demonstrated sustained and significant reversal of PFIC3 disease biomarkers in a model of PFIC3.