Prothena (PRTA) Piper Sandler 37th Annual Healthcare Conference summary

Pipeline strategy and near-term focus

• Two late-stage programs in Phase III: Prasinezumab for early Parkinson's (with Roche) and Coramitug for ATTR cardiomyopathy (with Novo), both advancing in 2024-2026.

• Ongoing Phase II and I programs with Bristol targeting Alzheimer's and neurodegeneration, with key data and decisions expected in 2025-2026.

• Focus on achieving $105 million in clinical milestones for Coramitug and PRX019 by end of 2025.

• Plans to partner unpartnered programs and CYTOPE technology in 2026.

• Share repurchase program targeted for announcement in Q4 2026.

Prasinezumab in Parkinson's disease

• Prasinezumab targets alpha-synuclein, aiming to slow disease progression and potentially be the first disease-modifying therapy for Parkinson's.

• Phase III trial design incorporates learnings from Phase II, with a larger sample size (900 patients) and longer duration (2 years).

• Roche estimates a potential market opportunity of $3.5 billion for this asset.

• Economic terms include $135 million received, $620 million in remaining milestones, and tiered royalties up to high double-digit teens.

Coramitug in ATTR cardiomyopathy

• Coramitug targets deposited amyloid in the heart, differentiating from therapies that inhibit or stabilize transthyretin.

• Phase II data showed significant NT-proBNP reduction and cardiac remodeling, even on top of standard stabilizer therapy.

• Phase III CLEOPATRA study includes all NYHA classes, with a composite primary endpoint and up to four years of follow-up.

• Remaining economic terms include $1.13 billion in milestones, structured as lump sums for sales thresholds due to tax advantages.