Prothena Scraps Birtamimab After Phase 3 Miss

Prothena says it will discontinue the development of birtamimab, its investigational treatment for AL amyloidosis, after the drug failed to meet the primary or secondary endpoints in a Phase 3 clinical trial. AL amyloidosis, which also known as immunoglobulin light chain amyloidosis, is a condition where abnormal protein deposits (amyloid) build up in various organs and tissues, causing damage and organ dysfunction.

The company says its AFFIRM-AL study, which evaluated birtamimab in 207 patients with newly diagnosed Mayo Stage 4 AL amyloidosis, did not show a statistically significant benefit in reducing all-cause mortality compared to placebo. Secondary measures, including a six-minute walk test and a physical health score, also failed to show improvement.

In addition, the company said it will shut down the open-label extension of the AFFIRM-AL trial and begin taking steps to cut operating costs, including a significant reduction in workforce.