Roche Holding AG / Prothena Corporation plc

Parkinson's Disease

90K US cases/yr · $82.2B US total economic burden of Parkinson's disease, 2024 (direct + indirect)

Disease Overview

Parkinson's disease is a progressive neurodegenerative disorder driven by loss of dopaminergic neurons in the substantia nigra and accumulation of misfolded alpha-synuclein into Lewy bodies. Patients experience tremor, rigidity, bradykinesia and postural instability that worsen over decades; existing therapies (levodopa, dopamine agonists, MAO-B inhibitors, DBS) are symptomatic only and do not slow underlying neurodegeneration.

Competitive Landscape

At the 2013 deal date, all approved Parkinson's therapies were symptomatic — Sinemet/levodopa (generic, branded by Merck/Sun), Mirapex (pramipexole, BI/Pfizer), Requip (ropinirole, GSK), Azilect (rasagiline, Teva) and Xadago (later 2017). The disease-modifying race centered on alpha-synuclein, with Roche/Prothena's prasinezumab (PRX002) competing against Biogen's cinpanemab, AbbVie/BioArctic's ABBV-0805, and small-molecule aggregation inhibitors. Through 2024, every direct alpha-synuclein antibody competitor failed in Phase 2: Biogen discontinued cinpanemab (SPARK trial, 2021), AbbVie shelved ABBV-0805. Prasinezumab itself missed the primary endpoint in PASADENA (Phase 2, 2020) and PADOVA (Phase 2b, December 2024), but Roche advanced it into Phase 3 in June 2025 citing exploratory motor-progression signals on MDS-UPDRS Part III, particularly in rapidly progressing subgroups. Jefferies analysts have publicly questioned whether an extracellular antibody can meaningfully engage an intracellular protein. The Prothena license gave Roche the only surviving anti-aggregated-α-synuclein antibody in late development, structurally elevating the deal's strategic value despite mixed data — but financial returns to Prothena have been limited to $135M cumulative through mid-2025 of the up to $630M total package.