Prothena Corporation plc (NASDAQ:PRTA), a late-stage clinical biotechnology company with a robust pipeline of investigational therapeutics built on protein dysregulation expertise, today announced that Paula Cobb will step down from Prothena's Board of Directors to join Manifold Bio as its Chief Operating Officer. During her six-year tenure, Ms. Cobb played a significant role in which she made key contributions to the Company's vision and strategy.

"I would like to thank Paula for her many contributions during the past six years. As a biotechnology executive with wide-ranging global development, business strategy and commercial expertise, she provided valuable insights to the board and leadership," said Daniel G. Welch, Chair of Prothena's Board of Directors. "The entire board of directors appreciates Paula's strategic expertise and impact since joining the board in 2019 and we wish her continued success in her new role."

"I have been honored to serve on the Prothena Board during these past six years," said Cobb. "I am proud of what we accomplished together and remain confident in the company's strategic vision to develop transformative medicines for patients suffering from devasting diseases caused by protein dysregulation."

With the departure of Ms. Cobb, Prothena has 8 Directors on its board.

About Prothena

Prothena Corporation plc is a late-stage clinical biotechnology company with expertise in protein dysregulation and a pipeline of investigational therapeutics with the potential to change the course of devastating neurodegenerative and rare peripheral amyloid 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 ATTR amyloidosis with cardiomyopathy, 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 X (formerly Twitter) @ProthenaCorp.

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Mark Johnson, CFA

Vice President, Investor Relations

650-837-8550

IR@prothena.com

Media@prothena.com

Prothena Announces Board of Directors Update