Update on B‐cell maturation antigen‐directed therapies in AL amyloidosis

Systemic light chain (AL) amyloidosis is a rare clonal plasma cell disorder characterized by the production of amyloidogenic immunoglobulin light chains, which causes the formation and deposition of amyloid fibrils, leading to multi-organ dysfunction. Current treatment is directed at the underlying plasma cell clone to achieve a profound reduction in the monoclonal free light chain production. The standard-of-care first-line therapy is a combination of daratumumab, cyclophosphamide, bortezomib and dexamethasone (D-VCd regimen), resulting in high rates of haematological and organ responses. However, AL amyloidosis remains incurable, and all patients inevitably relapse. Hence, novel treatment options are needed for patients with an inadequate response or relapsed/refractory disease. B-cell maturation antigen (BCMA) is a tumour necrosis factor (TNF receptor superfamily receptor overexpressed on plasma cells in multiple myeloma (MM) and AL amyloidosis. Recently, several novel anti-BCMA immunotherapies have been approved for the treatment of relapsed/refractory MM, including antibody-drug conjugate belantamab mafodotin, bispecific antibodies teclistamab and elranatamab and chimeric antigen receptor T-cell therapies idecabtagene vicleucel and ciltacabtagene autoleucel. Despite lower expression than in MM, BCMA is also a promising target in AL amyloidosis. This review aims to provide up-to-date information on the efficacy and toxicity of anti-BCMA therapy in AL amyloidosis.