Prothena Provides Updates on PRX012, PRX123, Birtamimab and Portfolio Programs

Prothena Corporation plc (NASDAQ:PRTA), a late-stage clinical biotechnology company with a robust pipeline of investigational therapeutics built on protein dysregulation expertise, provided a business update on portfolio programs.

Key Business Updates and Upcoming Milestones

Neurodegenerative Diseases Portfolio

Alzheimer’s Disease (AD)

PRX012, a wholly-owned potential best-in-class, next-generation subcutaneous antibody for the treatment of AD that targets a key epitope at the N-terminus of amyloid beta (Aβ) with high binding potency. The U.S. Food and Drug Administration (FDA) has granted Fast Track Designation for PRX012 for the treatment of AD.

• Encouraging amyloid reduction seen following six months of treatment at 70mg and ARIA-E rate consistent with placebo
• Data supports once-monthly subcutaneous treatment and dose escalation in multiple-ascending dose cohorts (200mg and up to 400mg)
• Ongoing Phase 1 trial continues as planned and expect to update in 2024

BMS-986446 (formerly PRX005), a potential best-in-class antibody for the treatment of AD that specifically targets a key epitope within the microtubule binding region (MTBR) of tau, a protein implicated in the causal human biology of AD. BMS-986446 is part of a Global Neuroscience Research and Development Collaboration with Bristol Myers Squibb.

• Bristol Myers Squibb reported that Phase 1 data supports rapidly moving BMS-986446 into a Phase 2 clinical trial in 1H 2024

PRX123, a wholly-owned potential first-in-class dual Aβ/tau vaccine designed for the treatment and prevention of AD, is a dual-target vaccine targeting key epitopes within the N-terminus of Aβ and MTBR-tau designed to promote amyloid clearance and block the transmission of pathogenic tau.

• Investigational new drug (IND) application cleared by FDA
• Fast Track designation granted by FDA
• Phase 1 timeline update expected in 2024 in order to optimize capital allocation across robust clinical portfolio

Parkinson’s Disease (PD)

Prasinezumab, a potential first-in-class antibody for the treatment of PD designed to target a key epitope within the C-terminus of alpha-synuclein and is the focus of a worldwide collaboration with Roche.

• Roche completed enrollment for the Phase 2b PADOVA clinical trial in patients with early PD (NCT04777331); topline results expected in 2024

Rare Peripheral Amyloid Diseases Portfolio

AL Amyloidosis

Birtamimab, a wholly-owned potential best-in-class amyloid depleter antibody for the treatment of AL amyloidosis designed to directly neutralize soluble toxic aggregates and promote clearance of amyloid that causes organ dysfunction and failure. Among patients with AL amyloidosis, a rare, progressive, and fatal disease, newly diagnosed individuals with advanced disease (e.g., Mayo Stage IV) are at the highest risk for early death. Birtamimab has been granted Fast Track Designation by the FDA for the treatment of patients with Mayo Stage IV AL amyloidosis to reduce the risk of mortality and has been granted Orphan Drug Designation by both the FDA and European Medicines Agency. A significant survival benefit was observed in the analysis of birtamimab-treated patients categorized as Mayo Stage IV at baseline in the previous Phase 3 VITAL clinical trial (Blood 2023).