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 the publication related to the mechanism of action, pharmacological characteristics, and clinical utility of birtamimab, a potential best-in-class anti-amyloid treatment for AL amyloidosis. The publication can be found in the latest issue of Leukemia & Lymphoma, an international peer-reviewed journal that publishes research on all aspects of hematological malignancies.

AL amyloidosis is an idiopathic, rare, progressive and often fatal disease characterized by amyloid deposits that build up in vital organs leading to damage, dysfunction and failure. The risk of early mortality is especially high in patients with significant cardiac involvement as there are no current treatment options that target existing amyloid deposits in these patients.

Birtamimab binds to a highly conserved cryptic epitope which is only exposed in misfolded kappa and lambda light chain (LC) protein. Birtamimab binds and neutralizes soluble, toxic LC aggregates and binds and clears insoluble AL amyloid deposits, without affecting normally folded LC proteins. This mechanism of action is complementary to the current standard of care therapy for AL amyloidosis which does not target the existing toxic LC aggregates and amyloid deposits.

“Birtamimab was designed to clear deposited amyloid from vital organs and is the only treatment that has shown a significant survival benefit in patients with Mayo Stage IV AL amyloidosis, which was demonstrated in a post hoc analysis of the Phase 3 VITAL placebo-controlled clinical trial,” said Hideki Garren, M.D., Ph.D., Chief Medical Officer, Prothena. “Birtamimab is being evaluated in patients with Mayo Stage IV AL amyloidosis, who are at high risk of early mortality, in the ongoing confirmatory Phase 3 AFFIRM-AL clinical trial.”

A copy of the peer-reviewed article can be found here in Leukemia & Lymphoma:

https://www.tandfonline.com/doi/full/10.1080/10428194.2024.2337803

About Birtamimab

Birtamimab is an investigational, humanized monoclonal antibody designed to specifically and selectively target and clear the amyloid that accumulates and causes organ dysfunction and failure in patients with AL amyloidosis. Birtamimab specifically binds to a defined epitope on kappa and lambda AL protein involved in the disease process. Birtamimab is the only investigational drug that has shown a significant survival benefit in patients with Mayo Stage IV AL amyloidosis post-hoc in a placebo-controlled clinical trial. Birtamimab has been granted orphan drug designation for AL amyloidosis by both the U.S. Food and Drug Administration (FDA) and the European Medicines Agency and has been granted Fast Track designation by the FDA. A Special Protocol Assessment (SPA) was agreed to between Prothena and the FDA for the AFFIRM-AL clinical trial which represents FDA’s agreement that the design and planned analysis for the primary endpoint of time to all-cause mortality adequately address the objectives necessary to support a regulatory submission. Results from confirmatory Phase 3 AFFIRM-AL clinical trial are expected between 4Q 2024 and 2Q 2025 (NCT04973137). Final marketing approval is predicated upon FDA’s complete review of the entire application.

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 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.

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