Prothena Corporation plc (PRTA) SEC Filings & Earnings Calls

Loss of key development executive to a partner may impact partnered program oversight and internal capabilities.

“CDO leaving to join strategic partner and lead a partnered program.”

Pre-revenue biotech with ongoing cash burn.

“Net cash used in operating and investing activities was $25.7 million in the second quarter.” · word for word

Dependence on partner milestones and clinical trial outcomes.

“Partnered programs could generate up to approximately $3 billion in aggregate future milestone payments, plus potential royalties.” · word for word

Pipeline Dependency Risk

“Our success is largely dependent on the success of our research and development programs. Our drug candidates are in various stages of development and we may not be able to successfully discover, develop, obtain regulatory approval for, or commercialize any drug candidates.” · word for word

Cash Runway Risk

“We anticipate that we will require additional capital in order to continue the research and development, and eventual commercialization, of our drug candidates.” · word for word

Collaboration Dependency Risk

“We are dependent upon Roche with respect to further development of prasinezumab. We are dependent upon Novo Nordisk with respect to further development of coramitug. We are dependent upon BMS with respect to further development of moponetug.” · word for word

Accumulated Deficit Risk

“As of June 30, 2026, we had an accumulated deficit of $1.3 billion.” · word for word

No revenue; pre-commercial biotech reliant on partnership milestones and cash runway

“No revenue reported; cash burn guidance improved but still negative; pipeline dependency on partnered programs”

Dependence on partnership milestones for revenue

“Revenue is highly dependent on milestone payments from partners; without such payments, the company would have minimal revenue.”

Accumulated deficit and need for future capital

“As of March 31, 2026, the Company had an accumulated deficit of $1.3 billion.” · word for word

Phase 3 trial failure

“the trial did not meet its primary or secondary endpoints and, as such, we subsequently discontinued the development of birtamimab” · word for word

Workforce reduction and restructuring

“in June we commenced a corporate restructuring, including an approximate 63% reduction in workforce to substantially reduce our operating costs.” · word for word

Negative net income

“Net Income (Loss) ($ in thousands) 2025: (244,092)”

Dependence on partnered programs

“prasinezumab ... is the focus of the worldwide collaboration with Roche. ... coramitug ... is being developed by Novo Nordisk ... BMS-986446 ... Bristol Myers Squibb”

ARIA-E safety signal for PRX012

“the robust plaque clearance was associated with non-competitive rates of ARIA-E.” · word for word

Buyback reduces cash for R&D; clinical trial risks remain.

“Excluding any potential purchases... expects to end the year with approximately $255 million in cash”

Clinical Trial Failure Risk

“There is no assurance that the results of the Phase 3 clinical trial for prasinezumab, the Phase 3 clinical trial for coramitug, the Phase 2 clinical trial for BMS-986446, and the Phase 1 clinical trial for PRX019 will support further development of these drug candidates.” · word for word

Funding Dependency Risk

“We anticipate that we will require additional capital in order to continue the research and development, and eventual commercialization, of our drug candidates.” · word for word

Key Personnel Dependency Risk

“We are highly dependent on key personnel, including Dr. Gene G. Kinney, our President and Chief Executive Officer.” · word for word

Collaboration Dependency Risk

“We are dependent upon Roche with respect to further development of prasinezumab. ... We are dependent upon Novo Nordisk with respect to further development of coramitug ... We are dependent upon BMS with respect to further development of BMS-986446” · word for word

Clinical trial risk: partnered programs may fail or be delayed, impacting milestone and royalty potential.

“Phase 3 trials for prasinezumab and coramitug have primary completion expected in 2029, long timeline.”

Cash burn risk: despite guidance, company has no approved products and relies on partnerships for funding.

“Net cash used in operating and investing activities was $163.7M in FY2025; guidance for FY2026 is $50-55M.” · word for word

Board departure may signal governance transition, but no disagreement indicates low risk.

“Resignation not due to disagreement; no operational or financial impact disclosed.”

Clinical trial failure risk; net loss increased significantly in first nine months of 2025 due to restructuring charges.

“first nine months of 2025 includes $33.1 million of restructuring charges associated with the discontinuation of the birtamimab program” · word for word

Revenue collapse and dependency on collaboration milestones

“Total revenue was $9.7 million and $133.0 million for the nine months ended September 30, 2025, and 2024, respectively. Collaboration revenue of $133.0 million for the nine months ended September 30, 2024 included $107.9 million from the PRX019 Global License Agreement and PRX019 Phase 1 Clinical Trial Obligation and $25.0 million was related to BMS’s materi”

Cash burn and limited runway

“Net cash used in operating activities was $140.3 million for the nine months ended September 30, 2025. Cash and cash equivalents: $330.8 million as of September 30, 2025.” · word for word

Pipeline setbacks and restructuring

“In June 2025, we commenced a restructuring plan following our decision in May 2025 to discontinue further development of birtamimab. We have incurred aggregate restructuring charges of approximately $0.5 million and $33.1 million for the three and nine months ended September 30, 2025.” · word for word

Need for additional capital

“We anticipate that we will require additional capital in order to continue the research and development, and eventual commercialization, of our drug candidates.” · word for word

Dependence on key personnel

“We are highly dependent on key personnel, including Dr. Gene G. Kinney, our President and Chief Executive Officer.” · word for word