Prothena Partners Present Data Supporting Next Generation Treatments for Parkinson’s and Alzheimer’s Disease at AD/PD™ 2026

Key Takeaways

• Prasinezumab shows ~2‑year disease progression delay in PD models
• PADOVA OLE data indicate sustained motor slowing and biomarker benefits
• Digital health metrics favor prasinezumab in OFF‑L‑DOPA state
• BMS‑986446 safe, dose‑proportional in Japanese and global participants
• Data support continued Phase III PARAISO and Alzheimer trials

Summary

Prothena and its partners Roche and Bristol Myers Squibb presented late‑stage data on two neurodegenerative candidates at AD/PD™ 2026. Prasinezumab demonstrated a roughly two‑year delay in Parkinson’s disease progression, sustained motor benefits in the PADOVA open‑label extension, and favorable imaging and digital health biomarkers. BMS‑986446, a tau‑targeting antibody, was shown to be safe and dose‑proportional in a diverse healthy‑participant cohort, including Japanese subjects. The findings underpin the upcoming Phase III PARAISO trial for Parkinson’s and continued Alzheimer’s development programs.

Pulse Analysis

Neurodegenerative disorders remain among the most pressing unmet medical needs, with Parkinson’s and Alzheimer’s affecting tens of millions worldwide. Industry players are increasingly turning to protein‑dysregulation strategies, leveraging monoclonal antibodies to intervene early in disease pathways. Prothena’s collaborative model—pairing its CYTOPE® platform with established partners—allows rapid progression from discovery to late‑stage trials, positioning the company as a key innovator in the space.

The prasinezumab data presented at AD/PD 2026 provide compelling evidence of disease modification. Modeling analyses estimate a two‑year “time saved” in disease progression, while the PADOVA open‑label extension shows consistent motor slowing and preservation of neuromelanin and iron‑sensitive MRI signals. Complementary digital health assessments further reinforce clinical signals, suggesting that the antibody may deliver measurable benefits even in the OFF‑L‑DOPA state. These results have set the stage for the Phase III PARAISO trial, which could deliver the first approved therapy to slow Parkinson’s progression.

BMS‑986446’s safety profile, demonstrated across ethnic groups, removes a major barrier for global Alzheimer’s trials. By targeting multiple tau microtubule‑binding domains and engaging microglial clearance pathways, the antibody addresses a central driver of neurofibrillary tangle formation. The dose‑proportional pharmacokinetics and lack of anti‑drug antibodies support flexible dosing regimens, accelerating enrollment in upcoming efficacy studies. If successful, BMS‑986446 could become a cornerstone of tau‑focused therapeutic strategies, offering investors and clinicians a new avenue to combat cognitive decline.