• ≥ 18 years of age

• MM patients (for Arm A and Arm B): Patients with Relapsed/Refractory MM per 2016 IMWG criteria, previously treated with at least 1 but not more than 4 prior lines of therapy for MM. Refractory MM, meanwhile, is defined as disease that progresses on salvage therapy or progresses within 60 days of the last treatment.

• AL amyloidosis patients (for Arm C ONLY): Patients with AL amyloidosis when meeting:

• i. histochemical diagnosis based on detection by polarizing microscopy of green birefringent material in Congo red-stained tissue specimens, the type must have been confirmed unequivocally.

• ii. have symptomatic organ involvement. Only purpura and/or carpal tunnel syndrome are not acceptable.

• iii. have at least one prior line of systemic therapy for AL. Patients who do not achieve at least a PR to frontline therapy in 3 months are eligible.

• iv. All MM/AL patients should have measurable disease of AL amyloidosis as defined by at least ONE of the following:

⁃ Serum monoclonal protein ≥1.0 g/dl by protein electrophoresis

⁃ \>200 mg of monoclonal protein in the urine on 24-hour electrophoresis

⁃ Serum differential FLC concentration (dFLC, difference between amyloid forming \[involved\] and nonamyloid forming \[uninvolved\] free light chain \[FLC\]) \> 5 mg/dL; OR serum FLC of 7.5 mg/dL provided the κ/λ FLC ratio is abnormal (κ/λ \<0.26 for patients with monoclonal λ FLC, κ/λ \>1.65 for patients with monoclonal κ FLC).

• Eastern Cooperative Oncology Group (ECOG) ≤ 2

• Life expectancy ≥ 6 months

• Adequate hematologic function defined as:

∙ ANC ≥1.0 x 10\^9/L independent of growth factor support within 7 days of the first dose with study drug

‣ Hemoglobin ≥8 g/dL without transfusion or growth factor support within 7 days of the first dose of study drug

‣ Platelet count ≥ 50 x 10\^9/L without transfusion support within 7 days of the first dose of study drug (for MM patients); or platelet count ≥ 100 x 10\^9/L or ≥ 50 x 10\^9/L if bone marrow involvement independent of transfusion support in either (for AL amyloidosis patients).

• Adequate hepatic and renal function defined as:

∙ AST and ALT \< 3 x upper limit of normal (ULN)

‣ Creatinine clearance \>30 mL/min (for MM patients); or Creatinine ≤3 mg/dL and CrCL ≥25 ml/min using the Cockcroft-Gault formula (for AL amyloidosis patients)

‣ Bilirubin\< 1.5 x ULN (Except if considered secondary to Gilbert's syndrome and primarily indirect bilirubinemia)

• PT/INR ≤2 x ULN and PTT (or aPTT) ≤2 x ULN

• Female subjects who are of non-reproductive potential (i.e., post-menopausal by history: no menses for ≥2 year; or history of hysterectomy; or history of bilateral tubal ligation; or history of bilateral oophorectomy). Female subjects of childbearing potential must have a negative serum pregnancy test upon study entry.

• Male and female subjects who agree to use highly effective methods of birth control (e.g., condoms, implants, injectables, combined oral contraceptives, some intrauterine devices\[IUDs\], sexual abstinence, or sterilized partner) during the period of therapy and for 90 days after the last dose of study drug

⁃ Ability to complete questionnaire(s) by themselves or with assistance (For AL amyloidosis patients only)