Inclusion Criteria:

• Aged ≥ 18 years.
• Newly diagnosed and AL amyloidosis treatment-naïve with cardiac involvement.
• Confirmed diagnosis of AL amyloidosis.
• Confirmed Mayo Stage IV AL Amyloidosis as defined by -NT-proBNP ≥ 1800 pg/mL and -Troponin-T > 0.03 ng/mL and -dFLC ≥ 18 mg/dL.
• Planned first-line chemotherapy contains bortezomib administered subcutaneously weekly.

Exclusion Criteria:

• Non-AL amyloidosis.
• NT-proBNP > 8500 pg/mL.
• Meets the International Myeloma Working Group (IMWG) definition of multiple myeloma.
• Subject is eligible for and plans to undergo ASCT or organ transplant during the study.
• Myocardial infarction, uncontrolled angina, severe uncontrolled ventricular arrhythmias, or ECG evidence of acute ischemia, within 6 months prior to the Month 1-Day 1 Visit.
• Severe valvular stenosis (e.g., aortic or mitral stenosis with a valve area < 1.0 cm^2) or severe congenital heart disease.
• ECG evidence of acute ischemia or active conduction system abnormalities.
• Prior treatment with hematopoietic growth factors, transfusions of blood or blood products within 1 week of Month 1-Day 1.
• Prior radiotherapy within 4 weeks of Month 1-Day 1.
• Prior treatment with plasma cell-directed chemotherapy, birtamimab, daratumumab, 11- 1F4, anti-serum amyloid P antibody, doxycycline for amyloid, or other investigational treatment directed at amyloid.
• Waldenström's macroglobulinemia and/or immunoglobulin M monoclonal gammopathy.