• Histologic diagnosis of AL amyloidosis and typed with immunohistochemistry/ immunofluorescence, immunoelectron microscopy, or mass spectrometry. In patients with biopsy-confirmed amyloidosis, ambiguous amyloid typing results, and cardiac involvement alone, a negative pyrophosphate (PYP) or technetium-99m (99mTc) and 3,3-diphosphono-1,2-propanodicarboxylic acid (DPD-Tc99m) bone scan is required to distinguish cardiac involvement due to AL amyloidosis from amyloid transthyretin (ATTR) amyloidosis. Data from the initial diagnosis are accepted.

• Genetic testing must be negative for transthyretin mutations associated with hereditary amyloidosis, or immunohistochemistry/ immunofluorescence/ immunoelectron microscopy/ mass spectrometry of amyloid deposits must provide clear evidence of κ or λ light chains in patients who present with peripheral neuropathy or heart as the dominant organ involvement. Data from the initial diagnosis are accepted.

• Eastern Cooperative Oncology Group (ECOG) performance status 0,1 or 2

• Mayo stage I-IIIA cardiac disease at Screening

• Relapsed patients must have received at least 1 line of treatment, including Dara and bortezomib. Patients must have received at least two cycles of therapy. However, patients who have received high-dose therapy with melphalan as their only therapy are also eligible.

• Measurable hematologic disease: a dFLC \>20 mg/L with an abnormal κ/λ ratio (with Freelite® test kits, The Binding Site) or presence of a monoclonal spike ≥0.5 g/dL.

• Adequate bone marrow function, without transfusion or growth factors within 5 days prior to the first drug intake (C1D1), defined as:

• Absolute neutrophils ≥1,000/mm3,

• Platelets ≥75,000/mm3,

• Hemoglobin ≥8.5 g/dL.

• Adequate organ function, defined as:

• Serum creatinine clearance (CKD-EPI formula) ≥20 mL/min,

• Serum SGPT/ALT \<5.0 x Upper Limit of Normal (ULN),

• Serum total bilirubin \<2.0 mg/dL or direct bilirubin ≤30% of the total, unless the patient has Gilbert's syndrome, where direct bilirubin should then be \<2.0 mg/dL,

• Serum albumin ≥\<2.5 gr/dl (medication to correct serum albumin levels is permitted).