Isatuximab as Upfront Therapy for the Treatment of High Risk AL Amyloidosis

PRIMARY OBJECTIVES: 1. Test the safety and feasibility of isatuximab-based drug treatment. 2. Evaluate the preliminary efficacy of a slow-go approach in high risk AL amyloid patients. STUDY TREATMENT Each patient starts by receiving increasing intensity of treatment for AL Amyloidosis up to maximum tolerance, and then maintenance Isatuximab thereafter for a specified period. All patients will receive Isatuximab (weekly x 4 then every other week) plus dexamethasone 4 mg PO/IV days weekly. If tolerating Isatuximab/Dex4 (earliest time to escalate C1D15), add Velcade to 1 mg/m2 SQ weekly. If tolerating Isa/Vel1.0/Dex4 (earliest time to escalate C2D1), increase dexamethasone to 12 mg weekly. If tolerating Isa/Velcade1.0/Dex12 (earliest time to escalate C3D1), increase Velcade to 1.3 mg/m2 SQ. If tolerating Isa/Velcade1.3/Dex12 (earliest time to escalate C4D1), add cyclophosphamide 300 mg IV weekly. If tolerating Isa/Velcade1.3/Cy300/Dex12 (earliest time to escalate C5D1), increase cyclophosphamide to 400 mg IV weekly. If tolerating Isa/Velcade1.3/Cy400/Dex12 (earliest time to escalate C6D1), increase cyclophosphamide to 500 mg IV weekly. Tolerance determined by the patient not reaching an escalation limiting toxicity AND patient approval to dose escalate. Patients then receive dexamethasone and isatuximab as maintenance treatment twice per month for 12 months in the absence of disease progression or unacceptable toxicity.