---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-25-141098"
form_type: "8-K"
ticker: "PRTA"
cik: "0001559053"
company_name: "PROTHENA CORP PUBLIC LTD CO"
filed_at: "2025-06-16T23:59:59+00:00"
generated_at: "2026-05-19T06:27:02.716917+00:00"
event_type: "other_material"
sentiment: "positive"
materiality_score: 0.75
calibrated_materiality_score: 0.75
confidence: "high"
source: SEC EDGAR
---

# Roche to advance prasinezumab to Phase III for Parkinson’s; Phase IIb data missed primary endpoint

## Summary
- Partner Roche advancing prasinezumab into Phase III for early-stage Parkinson’s disease.
- Phase IIb PADOVA study missed statistical significance on primary endpoint but showed positive trends in motor progression.
- Open-label extension data suggest sustained clinical benefit over longer treatment periods.
- First biomarker evidence from PADOVA indicates impact on underlying disease biology.
- Over 10 million people affected globally; potential first disease-modifying treatment.

## SEC filing metadata
- accession: 0001193125-25-141098
- form_type: 8-K
- ticker: PRTA
- cik: 0001559053
- company_name: PROTHENA CORP PUBLIC LTD CO
- filed_at: 2025-06-16T23:59:59+00:00
- event_type: other_material
- sentiment: positive
- materiality_score: 0.75
- calibrated_materiality_score: 0.75
- confidence: high
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/1559053/000119312525141098/0001193125-25-141098-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/1559053/000119312525141098/d13247d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-25-141098
- JSON: https://secwatch.observer/filing/0001193125-25-141098.json
- Plain text: https://secwatch.observer/filing/0001193125-25-141098.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.