Prothena Reports 2025 Results as Partners Advance Phase 3 Trials in Parkinson's, ATTR-CM
Prothena reported Q4 and full year 2025 financial results with $308.4 million in cash as partners Roche and Novo Nordisk initiated Phase 3 trials for prasinezumab and coramitug, both expected to complete in 2029.
Prothena Corporation plc reported financial results for the fourth quarter and full year 2025, with quarter-end cash and restricted cash position of $308.4 million. Net cash used in operating and investing activities was $23.3 million and $163.7 million for the fourth quarter and full year of 2025, respectively.
In 2025, partner Roche initiated the Phase 3 PARAISO clinical trial evaluating prasinezumab in early Parkinson's disease and Novo Nordisk initiated the Phase 3 CLEOPATTRA clinical trial evaluating coramitug in ATTR amyloidosis with cardiomyopathy, both with primary completions expected in 2029. These partnered programs have the potential to earn up to approximately $3 billion in future aggregate milestones in addition to potential future royalties.
Roche is evaluating prasinezumab in the ongoing Phase 3 PARAISO clinical trial in ~900 participants with early-stage Parkinson's disease (NCT07174310). Prasinezumab is a potential first-in-class antibody for the treatment of Parkinson's disease that is designed to target a key epitope within the C-terminus of alpha-synuclein and is the focus of a worldwide collaboration with Roche. Roche has stated that prasinezumab has peak sales potential greater than $3.5 billion (unadjusted) and could be the first disease-modifying treatment for a condition that affects 10 million people worldwide.
Novo Nordisk is evaluating coramitug in the ongoing Phase 3 CLEOPATTRA clinical trial in ~1280 participants with ATTR-CM with primary completion expected in 2029 (NCT07207811). Coramitug (formerly PRX004) is a potential first-in-class amyloid depleter antibody for the treatment of ATTR amyloidosis with cardiomyopathy designed to deplete the pathogenic, non-native forms of the transthyretin (TTR) protein, and is being developed by Novo Nordisk as part of its up to $1.2 billion acquisition of Prothena's ATTR amyloidosis business and pipeline. Novo Nordisk presented Phase 2 results during a late-breaking session at the American Heart Association Scientific Sessions on November 10, 2025. Prothena has potential to earn a clinical milestone in 1H 2026 when prespecified enrollment criteria are met in the ongoing Phase 3 clinical trial by Novo Nordisk.
Bristol Myers Squibb fully enrolled the Phase 2 TargetTau-1 trial evaluating BMS-986446 in early Alzheimer's disease with primary completion expected in 1H 2027. Bristol Myers Squibb is conducting the Phase 2 TargetTau-1 clinical trial in approximately 310 patients with early Alzheimer's disease (NCT06268886). BMS-986446 (formerly PRX005) is a potential best-in-class antibody for the treatment of Alzheimer's disease that specifically targets a key epitope within the microtubule binding region (MTBR) of tau, a protein implicated in the causal pathophysiology of Alzheimer's disease. Bristol Myers Squibb completed a Phase 1 trial evaluating a subcutaneous formulation of BMS-986446 and conducted a Phase 1 open-label single-dose clinical trial to assess subcutaneous administration (NCT06955741). BMS-986446 was granted Fast Track designation by the U.S. FDA as a treatment for Alzheimer's disease.
Prothena is conducting a Phase 1 first-in-human clinical trial to evaluate the safety, tolerability, immunogenicity, and pharmacokinetics of single ascending and multiple doses of PRX019 in healthy adults with completion expected in 2026. Bristol Myers Squibb obtained the exclusive global license for PRX019 in 2024. Prothena has potential to earn a clinical milestone by end of 2026 should Bristol Myers Squibb decide to further develop PRX019, a potential treatment of neurodegenerative diseases in development in collaboration with Bristol Myers Squibb.
Prothena presented preclinical data on its TDP-43 CYTOPE program at Neuroscience 2025 (Society for Neuroscience) and at the International Symposium on ALS/MND demonstrating the potential of Prothena's CYTOPE technology to target intracellular disease pathways. TDP-43 CYTOPE is a proprietary preclinical program enabling precision intracellular targeting of TDP-43 pathology, a defining pathogenic feature of ALS and other TDP-43 proteinopathies. Prothena is evaluating PRX012-TfR, a once-monthly, subcutaneous anti-Aβ antibody combined with transferrin receptor technology for the treatment of Alzheimer's in preclinical studies.
Prothena has potential to earn up to $105 million in aggregate clinical milestone payments by end of 2026 related to the advancement of both coramitug for ATTR amyloidosis with cardiomyopathy by Novo Nordisk and PRX019 for neurodegenerative diseases by Bristol Myers Squibb.
Prothena expects the full year 2026 net cash used in operating and investing activities to be $50 to $55 million and expects to end the year with approximately $255 million in cash (midpoint). Financial guidance does not include the potential to earn up to $105 million in aggregate clinical milestone payments from strategic partners in 2026. At the Extraordinary General Meeting on November 19, 2025 Prothena obtained shareholder approval to reduce share capital to create distributable reserves to support a share redemption program to be conducted in 2026 if deemed appropriate.