Birtamimab has been tested in nearly 300 patients with AL amyloidosis at the intended clinical dose of 24 mg/kg and was shown to be generally safe and well tolerated in the clinical studies conducted to date. Birtamimab was previously evaluated in the Phase 3 VITAL Study, a global multi-center, randomized, double-blind, placebo-controlled clinical study of newly diagnosed, treatment naïve patients with AL amyloidosis and cardiac involvement. Results from the analysis of patients categorized as Mayo Stage IV at baseline in the VITAL study revealed a significant survival benefit favoring birtamimab in these patients, with 74% of birtamimab-treated patients alive at 9 months versus 49% of patients in the control group.
Birtamimab is the only investigational therapeutic that has shown a significant survival benefit in Mayo Stage IV patients with AL amyloidosis in a placebo-controlled study. Based on multiple in-depth discussions with the U.S. Food and Drug Administration (FDA) regarding these results, Prothena is advancing birtamimab into the confirmatory Phase 3 AFFIRM-AL study in patients with Mayo Stage IV AL amyloidosis. This registration-enabling study will be conducted with a primary endpoint of all-cause mortality at p≤0.10 under a Special Protocol Assessment (SPA) agreement with FDA.
Birtamimab has been granted orphan drug designation for AL Amyloidosis by both the FDA and the European Medicines Agency and has been granted Fast Track designation by the FDA.