Prothena Corporation Reports Q1 2026 Financial Results and Business Highlights

Prothena Corporation Reports Strong First Quarter 2026 Results, Boosted by Milestone Payments and Clinical Progress

By Robert Mitchell, Staff Reporter, News Directory 3

DUBLIN — Prothena Corporation plc (NASDAQ: PRTA), a late-stage clinical biotechnology company specializing in protein dysregulation therapies, today reported a significant turnaround in its first quarter 2026 financial results, marking a dramatic shift from net losses in the same period last year. The company posted a net income of $32.7 million, compared to a net loss of $60.2 million in Q1 2025, driven by a $50 million milestone payment from Novo Nordisk and strong collaboration revenues.

Financial Performance and Cash Position For the quarter, Prothena reported total revenue of $51.1 million, up sharply from $2.8 million in Q1 2025. The company also updated its full-year 2026 net cash guidance, now projecting net cash used in operating and investing activities to be between $18 million and $23 million—down from the previous estimate of $50 million to $55 million. Prothena expects to end the year with approximately $273 million in cash, cash equivalents, and restricted cash, an improvement from prior guidance of $255 million.

The company’s cash position was further bolstered by the $50 million milestone payment from Novo Nordisk, related to the Phase 3 enrollment of coramitug (PRX004), an antibody for the treatment of ATTR amyloidosis with cardiomyopathy (ATTR-CM). Prothena also initiated a share repurchase program in 2026, with up to $100 million allocated for repurchasing shares.

Clinical Progress and Partnership Highlights Prothena’s strong financial performance reflects significant progress in its clinical pipeline. Roche, a key partner, presented several updates at the International Conference on Alzheimer’s and Parkinson’s Diseases and Related Neurological Disorders (AD/PD™ 2026) supporting the potential of prasinezumab, a potential first-in-class antibody for Parkinson’s disease. Key findings included:

• A “time saved” analysis from the PASADENA open-label extension study, indicating that prasinezumab may delay disease progression by approximately two years over a five-year period.
• Longer-term data from the PADOVA open-label extension study, demonstrating a sustained effect of prasinezumab on disease progression.
• Exploratory biomarker analyses suggesting prasinezumab may impact the underlying biology of Parkinson’s disease.

Novo Nordisk received Fast Track designation from the U.S. FDA for coramitug in ATTR-CM, further accelerating its development. Prothena also completed a Phase 1 study for PRX019, a potential treatment for neurodegenerative diseases, and could earn a $55 million clinical milestone payment if Bristol Myers Squibb advances the program, with a decision expected by year-end 2026.

Pipeline and Future Outlook Prothena’s pipeline includes several promising candidates:

• Prasinezumab (Parkinson’s disease, partnered with Roche)
• Coramitug (ATTR amyloidosis with cardiomyopathy, partnered with Novo Nordisk)
• BMS-986446 (Alzheimer’s disease, partnered with Bristol Myers Squibb)
• TDP-43 CYTOPE® (preclinical program for ALS and other TDP-43 proteinopathies)

The company continues to explore additional research collaborations and licensing partnerships to advance its programs, including its proprietary CYTOPE® technology, designed for precision intracellular targeting of disease pathways.

Investor Conference and Leadership Prothena’s senior management team will participate in one-on-one investor meetings at the H.C. Wainwright 4th Annual BioConnect Investor Conference on May 19, 2026, in New York.

Gene Kinney, Ph.D., President and Chief Executive Officer of Prothena, commented on the quarter’s results: “We were encouraged by updates on our partnered Phase 3 clinical programs. Roche’s presentations at AD/PD 2026 highlighted the potential of prasinezumab, and Novo Nordisk’s Fast Track designation for coramitug is a significant milestone. We remain focused on advancing our pipeline and exploring new collaborations to bring innovative therapies to patients.”

Conclusion Prothena’s first quarter 2026 results underscore the company’s strong operational execution and the potential of its clinical pipeline. With robust financials, key regulatory milestones, and ongoing clinical progress, Prothena is well-positioned to continue its mission of developing groundbreaking therapies for devastating neurodegenerative and rare peripheral amyloid diseases.

For more information, visit Prothena’s website at www.prothena.com.

Contact: Mark Johnson, CFA, Senior Vice President, Head of Investor Relations and Corporate Communications, Prothena Corporation plc Email: IR@prothena.com | Media@prothena.com