Prothena (PRTA) investor relations material

Company overview and pipeline highlights

• Focuses on diseases caused by dysfunctional proteins, with a differentiated scientific approach and both partnered and unpartnered programs since its 2012 spin-out.

• Multiple phase III programs are ongoing, including partnerships with Roche (Parkinson’s, alpha-synuclein), Novo Nordisk (ATTR cardiomyopathy), and Bristol Myers Squibb (tau protein, MTBR region).

• Data from two phase III studies are expected around 2029, with phase II data from the tau program anticipated in the first half of next year.

• The PRX-019 program, partnered with Bristol Myers Squibb, is completing phase I in 2024, with a decision on phase II advancement expected by year-end.

• Proprietary pipeline includes reformulated anti-Abeta antibody (PRX012) and the CYTOPE platform targeting previously undruggable intracellular proteins.

Financial milestones and partnership economics

• Earned $50 million milestone from Novo for enrollment achievement, with payment expected within 30 days.

• Potential $55 million milestone from Bristol Myers Squibb if PRX019 advances to phase II by year-end.

• Announced a share repurchase program of up to $100 million for 2026, not included in current year-end cash guidance.

• Roche partnership includes $755 million in milestones (with $135 million received to date) and tiered royalties up to high double-digit teens; peak sales projected at over $3.5 billion.

• Bristol Myers Squibb partnerships total $1.55 billion in potential milestones plus royalties, with $135 million received for the tau program and $80 million for PRX019.

Clinical and scientific updates

• Roche’s prasinezumab program in Parkinson’s is progressing, with new five-year open-label extension data and additional six-month PADOVA trial data to be presented at AD/PD 2026.

• PADOVA phase IIb showed continued separation from placebo at 24 months, especially in levodopa-treated patients, increasing phase III success probability.

• Novo’s ATTR cardiomyopathy program showed nearly 50% NT-proBNP reduction at the highest dose, with additional benefits on top of standard of care, prompting phase III advancement.

• Tau program targets the MTBR region, with phase II data expected in the first half of next year; primary outcome is change in tau PET, with secondary functional endpoints.

• CYTOPE technology enables targeting of intracellular proteins like TDP-43, showing clearance of cytosolic aggregates and normalization of splice variants in preclinical models.