Prothena Corporation plc announced a significant corporate restructuring involving an approximate 63% reduction in its workforce, as the clinical-stage biotechnology company moves to substantially reduce operating costs while maintaining support for its remaining wholly owned programs and partnered collaborations.
The Dublin-based company, which specializes in protein dysregulation therapeutics for neurodegenerative and rare peripheral amyloid diseases, made the announcement as multiple pipeline milestones approach across its partnered programs.
Strategic Pipeline Developments Drive Restructuring Decision
The restructuring comes amid several key developments in Prothena's pipeline. Earlier this week, Roche announced it will advance prasinezumab into Phase 3 development for early-stage Parkinson's disease, marking a significant milestone for the partnered program.
"We have incredible Prothenians who are among the industry's most talented professionals and have dedicated their careers to advancing new treatments for patients," said Gene Kinney, Ph.D., President and Chief Executive Officer of Prothena. "I want to express my sincere gratitude to each Prothenian being affected by today's announcement and thank them for their passion toward our mission to treat diseases caused by protein dysregulation."
The company expects initial data in August 2025 from Phase 1 ASCENT clinical trials of its wholly owned PRX012 program in Alzheimer's disease. Additionally, Novo Nordisk expects to share data from its Phase 2 clinical trial evaluating coramitug for ATTR-CM in the second half of 2025.
Partnered Programs Continue with Significant Milestone Potential
Despite the workforce reduction, Prothena maintains its obligations to partnered programs that represent substantial future value. The company expects to complete a Phase 1 clinical trial for PRX019 in collaboration with Bristol Myers Squibb in 2026, while Bristol Myers Squibb expects to complete a Phase 2 TargetTau-1 clinical trial evaluating BMS-986446 in Alzheimer's disease in 2027.
These partnered programs hold significant financial potential, with the company positioned to receive up to $105 million in 2026 for clinical milestones from various partnered programs.
Revised Financial Guidance Reflects Operational Changes
Based on the reorganization, Prothena revised its full year 2025 financial guidance. The company expects its 2025 net cash burn from operating and investing activities to be $170 to $178 million and to end the year with approximately $298 million in cash, cash equivalents, and restricted cash.
The estimated 2025 net cash burn is primarily driven by an estimated net loss of $240 to $248 million, which includes an estimated $36 million of non-cash share-based compensation expense and a $45 million non-cash income tax expense to book a full valuation allowance against its U.S. deferred tax assets.
The estimated 2025 net loss includes $105 to $110 million of operating expenses associated with birtamimab and the company's reorganization, including research, development, manufacturing and pre-commercial expenses, severance costs and contract termination fees related to manufacturing obligations, and approximately $12 million of non-cash share-based compensation expense.
Strategic Options Under Evaluation
The company's board, management, and financial advisors are collectively evaluating a comprehensive range of business options to best serve shareholder interests. These evaluations consider the implications of the multiple recent and upcoming milestones across Prothena's pipeline.
The discontinuation of birtamimab development is expected to result in an approximate decrease of $96 million in annualized net cash burn, providing the company with improved financial flexibility as it navigates this transition period.
Prothena's pipeline includes both wholly owned and partnered programs being developed for diseases including ATTR amyloidosis with cardiomyopathy, Alzheimer's disease, Parkinson's disease, and other neurodegenerative conditions, leveraging the company's expertise in protein dysregulation and misfolded protein biology.
