Topline results were announced from a phase 3 trial evaluating birtamimab in patients with amyloid light chain (AL) amyloidosis.
Birtamimab is an investigational monoclonal antibody designed to clear the amyloid that accumulates and causes organ damage in patients with AL amyloidosis by binding to a defined epitope on kappa and lambda AL protein.
The double-blind, placebo-controlled, time-to-event AFFIRM-AL trial (ClinicalTrials.gov Identifier: NCT04973137) assessed the safety and efficacy of birtamimab in 207 newly diagnosed, treatment-naïve patients with Mayo Stage IV AL amyloidosis.
Study participants were randomly assigned 2:1 to receive birtamimab or placebo intravenously every 28 days, in addition to standard of care (bortezomib-containing chemotherapy regimen).
Findings showed the trial did not meet its primary endpoint of time to all-cause mortality (hazard ratio, 0.915; P =.7680). Significant improvements on secondary endpoints, including 6-minute walk test distance (nominal P =.5288) and Short Form-36 version 2 Physical Component Score (nominal P =.9597), were also not observed with birtamimab.
Based on these results, Prothena has made the decision to discontinue the AFFIRM-AL trial, including the open-label extension portion.
“This is not the outcome that we expected, and we are surprised and disappointed by these results for patients, their families and caregivers, and for the entire AL amyloidosis community,” said Gene Kinney, PhD, President and Chief Executive Officer, Prothena. “With these results, we believe that the most appropriate action is to discontinue all development of birtamimab.”