Prothena Announces Promising New Preclinical and Clinical Data from its Neurodegenerative Programs Selected for Oral Presentations at AD/PD 2021

• Robust preclinical data support the benefit of PRX005, a novel anti-tau antibody, for the potential treatment Alzheimer’s disease
• New pre-specified exploratory subgroup analyses and new digital biomarker data from Part 1 of the Phase 2 PASADENA study of prasinezumab in patients with early Parkinson’s disease will be featured in two separate presentations

DUBLIN, Ireland, Feb. 24, 2021 (GLOBE NEWSWIRE) -- Prothena Corporation plc (NASDAQ:PRTA), a late-stage clinical company with expertise in protein dysregulation and a pipeline of investigational therapeutics for rare peripheral amyloid and neurodegenerative diseases, today announced three oral presentations and participation in a live forum at The 15^th International Conference on Alzheimer’s and Parkinson’s Diseases (AD/PD 2021). Prothena will present new preclinical data demonstrating that targeting a novel epitope with PRX005, an anti-tau antibody, resulted in superior attributes for the potential treatment of Alzheimer’s disease. PRX005 is being developed as part of the Company’s global neuroscience collaboration with Bristol Myers Squibb. In addition, Roche will present new pre-specified exploratory subgroup analyses from Part 1 of the Phase 2 PASADENA study of prasinezumab in patients with early Parkinson’s disease and, separately, new digital biomarker data from its remote monitoring technology used in the study. Prasinezumab is being developed as part of the Company’s worldwide collaboration with Roche.

“Our proven protein dysregulation scientific platform continues to advance novel therapeutics that specifically target the forms of proteins that cause disease,” stated Wagner Zago, PhD. Prothena’s Chief Scientific Officer. “Our scientific platform encompasses an unbiased approach to identify optimal regions to target on pathogenic proteins, and expertise in engineering drugs to specifically or selectively engage mechanisms of neutralization and clearance while leaving the normal, healthy protein structure intact. This approach has translated into clinical proof of concept on endpoints that are meaningful to patients across a number of programs. We are looking forward to highlighting new data at AD/PD for PRX005, one of several programs in our Alzheimer’s disease portfolio, as well as the two new clinical analyses being presented by Roche from the Phase 2 PASADENA study of prasinezumab.”

PRX005, Anti-Tau Immunotherapy

Neurofibrillary tangles composed of misfolded tau proteins, along with A plaques, are pathological hallmarks of Alzheimer’s disease. Antibodies targeting various tau epitopes are currently being investigated for their ability to disrupt this pathogenic process and treat Alzheimer’s disease. Our preclinical research indicates that antibodies developed to target key epitopes within the microtubule binding region (MTBR) of tau may result in superior attributes.

Prothena has employed its unbiased epitope mapping and selection strategy to define this critical region of the tau protein involved in the pathological spread in Alzheimer’s disease. Antibodies targeting epitopes along the tau protein were developed and tested in a variety of in vitro and in vivo models. Among these, the murine precursor of PRX005, an antibody targeting an epitope within the MTBR of tau, demonstrated significant inhibition of cell-to-cell transmission and neuronal internalization in vitro and in vivo, and slowed pathological progression in a tau transgenic mouse model.

The oral presentation is scheduled as follows:

• Title: Microtubule Binding Region (MTBR)-Specific Antibody PRX005 Prevents Pathological Tau Progression Via Blockade of Neuronal Internalization
• Session: Tau Pathology and Therapeutic Strategies 1
• Date and Time: Thursday, March 11, 13:30 - 13:45 CET
• Presenter: Philip J. Dolan, PhD, Director, Protein Sciences, Prothena

Phase 2 PASADENA Study of Prasinezumab in Patients with Early Parkinson’s Disease

New pre-specified exploratory subgroup analyses from the PASADENA study as well as results from the digital biomarker mobile application used in PASADENA to continuously monitor symptoms of Parkinson’s disease will be presented by Roche at AD/PD.

The oral presentations are scheduled as follows:

• Title: A Phase 2 Study to Evaluate the Safety and Efficacy of Prasinezumab in Early Parkinson’s Disease (PASADENA): Results from Part 1, Week-52
• Session: Treatment Strategies for PD and DLB
• Date and Time: Thursday, March 11, 9:00 - 09:15 CET
• Presenter: Gennaro Pagano, MD, MSc, PhD, Senior Principal Medical Director, Translational Medicine, Neuroscience and Rare Diseases Discovery and Translational Area, Roche Pharma Research and Early Development

• Title: Roche PD Mobile Application V2 Detects Slowing of Early Parkinson’s Disease Progression Under Prasinezumab: PASADENA Phase 2 Part 1 Results
• Session: Treatment Strategies for PD and DLB
• Date and Time: Thursday, March 11, 9:15 - 09:30 CET
• Presenter: Kirsten I. Taylor, PhD, Group Leader, Neurocognitive and Digital Biomarkers, Biomarkers and Translational Technology, Neuroscience and Rare Diseases, Roche

In addition, Gene Kinney, PhD, Chief Executive Officer, Prothena, will participate in the following live forum:

• Title: Forum on Translational Drug Discovery in Parkinson’s Disease/Lewy Body Disease Phase I-III – Recent Updates
• Date and Time: Friday, March 12, 18:30 – 19:30 CET

About Prothena

Prothena Corporation plc is a late-stage clinical company with expertise in protein dysregulation and a pipeline of novel investigational therapeutics with the potential to change the course of devastating rare peripheral amyloid and neurodegenerative diseases. Fueled by its deep scientific expertise built over decades of research, Prothena is advancing a pipeline of therapeutic candidates for a number of indications and novel targets for which its ability to integrate scientific insights around neurological dysfunction and the biology of misfolded proteins can be leveraged. Prothena’s pipeline includes both wholly-owned and partnered programs being developed for the potential treatment of diseases including AL amyloidosis, ATTR amyloidosis, Alzheimer’s disease, Parkinson’s disease and a number of other neurodegenerative diseases. For more information, please visit the Company’s website at www.prothena.com and follow the Company on Twitter @ProthenaCorp.

Forward-looking Statements

This press release contains forward-looking statements. These statements relate to, among other things, the treatment potential, designs, and proposed mechanisms of action of PRX005 and prasinezumab; potential indications and the potential superior attributes and efficacy of novel epitopes and antibodies we have identified in our PRX005 program; the expected timing of reporting data from the Phase 2 clinical study of prasinezumab and preclinical studies of PRX005; and the continued advancement of our discovery, preclinical, and clinical pipeline. These statements are based on estimates, projections and assumptions that may prove not to be accurate, and actual results could differ materially from those anticipated due to known and unknown risks, uncertainties and other factors, including but not limited to the effects on our business of the worldwide COVID-19 pandemic and the risks, uncertainties and other factors described in the “Risk Factors” sections of our Annual Report on Form 10-K filed with the Securities and Exchange Commission (SEC) on March 3, 2020; discussions of potential risks, uncertainties, and other important factors in our subsequent filings with the SEC; and our Annual Report on Form 10-K to be filed with the SEC for our fiscal year 2020. Prothena undertakes no obligation to update publicly any forward-looking statements contained in this press release as a result of new information, future events or changes in Prothena’s expectations.

Contacts:

Media
Ellen Rose, Head of Communications
650-922-2405, ellen.rose@prothena.com

Investors
Jennifer Zibuda, Director, Investor Relations & Communications
650-837-8535, jennifer.zibuda@prothena.com