Current and Emerging Immunotherapies for Systemic AL Amyloidosis

Abstract

Systemic light-chain (AL) amyloidosis is a rare and complex clonal plasma cell neoplasm characterized by the production of misfolded and unstable immunoglobulin light-chains leading to multisystem amyloid deposition, which progresses to organ dysfunction and eventual failure. The importance and urgency of AL amyloidosis depends on its potential to induce significant organ impairment, progressive course, risk of life-threatening complications, and the limited treatment options available. Treatment options and prognosis depend on the number and severity of organ involvement at the time of diagnosis with cardiac involvement carrying the worst outcomes. The treatments aim to target eliminating the underlying clonal plasma cell neoplasm and prevent the production and deposition of amyloid precursor immunoglobulin light-chain protein in the affected vital organs. Strategies for treating systemic AL amyloidosis have incorporated anti-plasma cell therapies approved in the management of multiple myeloma due to their shared cellular derivation. Quadruplet therapy of cyclophosphamide, bortezomib, dexamethasone and daratumumab (DaraCyborD) is the currently approved first-line induction therapy for systemic AL amyloidosis. Some patients need upfront autologous hematopoietic stem cell transplantation (HSCT) after high-dose melphalan conditioning particularly if DaraCyborD is not able to achieve complete hematologic response (CHR). Additionally, a promising treatment option involves disassembling amyloid deposits from the vital organs using monoclonal antibodies such as CAEL 101 or Birtamimab with the expectation of restoring damaged tissues of the vital organs affected thereby improving or reversing patients' symptoms. Both CAEL 101 and Birtamimab are currently being tested in phase 3 clinical trials for systemic AL amyloidosis patients with advanced cardiac involvement. This comprehensive review provides an up-to-date overview of AL amyloidosis therapy, with a particular focus on recent advances and future directions of immunotherapeutic strategies.

Keywords: AL amyloidosis; immunoglobulin light-chain; immunotherapy; monoclonal antibodies; plasma cell dyscrasia.