Prime Medicine Restructures, Halts Clinical Program Amid Leadership Change

Prime Medicine, a Cambridge-based biotech company specializing in gene editing, has announced significant changes to its operations and leadership. The company is discontinuing its sole clinical-stage program and reducing its workforce by 25% as it pivots to focus on preclinical liver-targeted therapies.

CEO Departure and Clinical Program Shelved

Keith Gottesdiener, M.D., has resigned from his position as CEO of Prime Medicine. The company's board has appointed Chief Financial Officer Allan Reine, M.D., to take the helm while retaining his current responsibilities. This leadership transition comes as Prime Medicine makes the strategic decision to shelve PM359, its only clinical-stage genetic medicine.

Despite reaching what the company described as a clinical "milestone," Prime Medicine is ending further internal development of PM359, an autologous hematopoietic stem cell therapy for chronic granulomatous disease. The therapy, which uses "prime editors" to modify cells ex vivo, showed promising preliminary results in its phase 1/2 trial. No serious adverse events were reported, and the treatment demonstrated restoration of NADPH oxidase activity in 66% of neutrophils by Day 30, exceeding the threshold for clinical benefit.

Shift in Focus and Workforce Reduction

As part of its restructuring, Prime Medicine will redirect its efforts towards its preclinical in vivo liver franchise. The company anticipates submitting an Investigational New Drug (IND) application for a program in this area in the first half of 2026.

The workforce reduction will impact 25% of Prime Medicine's staff, affecting roles across various departments including R&D, CMC, and G&A. Allan Reine emphasized that the restructuring aims to create a "lean, nimble biotech" focused on key data readouts in Wilson's Disease and Alpha-1 Antitrypsin Deficiency.

Financial Implications and Future Outlook

The announcement has had a significant impact on Prime Medicine's stock, which dropped 19% to $1.28 per share following the news. However, the company retains a strong cash position, with $190 million on hand as of the end of last year, expected to fund operations into the first half of 2026.

Prime Medicine will continue its collaboration with Bristol Myers Squibb, focusing on developing CAR-T products for hematology, immunology, and oncology. This partnership, established last fall with a $110 million upfront payment from Bristol Myers Squibb, offers Prime Medicine the potential to earn up to $3.5 billion in milestone payments.

As the biotech industry faces ongoing challenges, particularly in the gene therapy sector, Prime Medicine's restructuring reflects a broader trend of companies reevaluating their priorities and resource allocation in a difficult market environment.