Elranatamab in Patients With Relapsed or Refractory AL Amyloidosis

Inclusion Criteria: * Previously diagnosed with AL amyloidosis based on IMWG criteria who have relapsed or refractory disease after treatment with at least one prior line of therapy (minimum 2 cycles). * Participants must have progression of light chain disease, defined as dFLC \>20mg/L. * For Phase 2 only, measurable hematologic disease, satisfying one of the following criteria: Difference between involved and uninvolved free light chain (FLC) over 40 mg/L; Abnormal level of FLC with an abnormal κ/λ ratio (except in participants with CKD stage 3 or higher where a rise of lambda FLC to an abnormal level and of at least 50% over the nadir with a normal κ/λ ratio is acceptable); A serum M spike measuring ≥ 0.5 g/dL * Age ≥ 18 years * ECOG performance status ≤2 or Karnofsky ≥60% * Participants must meet the following organ and marrow function as defined below: Absolute leukocyte count ≥3,000/mcL , Absolute neutrophil count ≥1,000/mcL, Absolute platelet count ≥75,000/mcL , Direct bilirubin ≤1.5 × institutional upper limit of normal (ULN) AST(SGOT)/ALT(SGPT) ≤3 × institutional ULN, Creatinine: Calculated clearance ≥30 mL/min using Cockcault-Groft equation * Participants who received belantamab mafodotin are eligible if discontinued due to intolerance or adverse event. * For participants with evidence of chronic hepatitis B virus (HBV) infection, the HBV viral load must be undetectable on suppressive therapy, if indicated. * Participants with a history of hepatitis C virus (HCV) i…