Prothena’s Partner Roche to Advance Prasinezumab into Phase III Development for Early-Stage Parkinson's Disease

Prothena Corporation plc (NASDAQ:PRTA) today announced partner Roche will advance prasinezumab, an investigational anti-alpha-synuclein antibody, into Phase III development in early-stage Parkinson’s disease. This decision is informed by data from the Phase IIb PADOVA study and ongoing open-label extensions (OLE) from both PADOVA and the Phase II PASADENA study.

“As pioneers in developing the first anti-alpha-synuclein targeting antibody, we are excited to see Roche advancing prasinezumab into Phase III development, with the potential to deliver the first disease-modifying treatment option to the millions of individuals living with Parkinson’s disease and their families,” stated Gene Kinney, Ph.D., President and Chief Executive Officer, Prothena.

Multiple endpoints from the PADOVA and OLE studies suggest a potential clinical benefit of prasinezumab when added to effective symptomatic treatment in early-stage Parkinson’s disease. Prasinezumab showed potential clinical efficacy in the primary endpoint of time to confirmed motor progression, although missed statistical significance. Positive trends towards reduced motor progression at 104 weeks (two years) were observed; these effects appear to be sustained over longer treatment periods based on additional OLE data. The PADOVA study also provided the first biomarker evidence of prasinezumab impacting the underlying disease biology.

The PASADENA and PADOVA OLE studies, which are evaluating the long-term safety and efficacy of prasinezumab in over 750 people with early-stage Parkinson’s disease, are ongoing.

About Prasinezumab

Prasinezumab is an investigational monoclonal antibody designed to bind aggregated alpha-synuclein and thereby reduce neuronal toxicity. By reducing the build-up of alpha-synuclein protein in the brain, prasinezumab can potentially prevent further accumulation and spreading between cells, which may slow progression of the disease.

Data from the Phase IIb PADOVA study suggest the possible clinical benefit of prasinezumab on top of effective symptomatic treatment in early-stage Parkinson’s disease. PADOVA investigated prasinezumab in 586 people with early-stage Parkinson’s disease, treated for a minimum of 18 months while on stable symptomatic treatment. Prasinezumab showed potential clinical efficacy in the primary endpoint of time to confirmed motor progression with a HR=0.84 [0.69-1.01], although the study missed statistical significance (p=0.0657). In a pre-specified analysis, the effect of prasinezumab was more pronounced in the population treated with levodopa (75% of participants), HR=0.79 [0.63-0.99], p=0.0431 (nominal). Consistent positive trends across multiple secondary and exploratory endpoints were also observed. Trends towards reduced motor progression at 104 weeks (two years) were observed, showing 30-40% relative reduction versus placebo across the overall and levodopa-treated populations.