Abstract
BACKGROUND: Immunoglobulin light chain (AL) cardiac amyloidosis carries high mortality, particularly when refractory to standard plasma cell-directed therapy. Deep hematologic remission is essential for heart transplant eligibility. CASE SUMMARY: A 37-year-old woman with advanced AL cardiomyopathy and refractory plasma cell dyscrasia did not respond to daratumumab-based therapy and could not tolerate venetoclax. She developed rapidly progressive, inotrope-dependent heart failure. Salvage therapy with a B-cell maturation antigen-directed bispecific antibody, teclistamab, induced a rapid, minimal residual disease-negative complete hematologic response within 2 weeks. This enabled successful heart transplantation during the same hospitalization, with excellent early post-transplant outcomes and sustained remission. DISCUSSION: B-cell maturation antigen-directed bispecific antibodies can achieve rapid and profound hematologic responses in refractory AL amyloidosis, even in patients with advanced cardiac involvement, thereby restoring transplant eligibility. TAKE-HOME MESSAGE: Teclistamab achieved a rapid minimal residual disease-negative complete response within weeks, demonstrating its potential as a fast-acting salvage therapy capable of restoring heart transplant eligibility in advanced cardiac AL amyloidosis.