04:42 PM EDT, 05/23/2025 (MT Newswires) -- Prothena ( PRTA ) said late Friday that it will discontinue the development of birtamimab after the phase 3 Affirm-Al trial of monoclonal antibody failed to meet the primary endpoint in treating patients with AL amyloidosis, or amyloid light chain amyloidosis.

The company said it will also stop the open-label extension of the Affirm-Al clinical trial.

Prothena ( PRTA ) said it expects to provide details of its plans to reduce ongoing operating expenses, which include job cuts, in June and the results of its review of business options once finalized.