AstraZeneca Drug Shows Promise in Subgroup of Rare Disease

AstraZeneca's anti-fibril therapy, anselamimab, has shown a notable benefit in a specific subgroup of patients with light chain amyloidosis. While the overall Phase III trial did not meet its primary endpoint, the drug demonstrated significant improvements in adults with advanced kappa light chain (AL) amyloidosis when used as a first-line therapy. This subgroup, comprising patients with a kappa predominant light chain isotype, experienced a 62% improvement in survival and a 71% reduction in cardiovascular hospitalizations compared to placebo.

These positive results for the kappa subgroup were presented at the American Society of Clinical Oncology (ASCO) Annual Meeting, which took place from May 29 to June 1, 2026. In contrast, the overall study population and patients with the lambda isotype did not show a similar benefit. AstraZeneca acquired the drug, then owned by Alexion, in a significant £39bn deal in 2020.

This development follows previous setbacks for monoclonal antibody approaches in AL amyloidosis, with another drug, birtamimab, failing to meet its trial endpoint. Currently, Darzalex Faspro is the only FDA-approved treatment for AL amyloidosis. Other therapies, such as Immix Biopharma's NXC-201, are in development and have received orphan drug designation.