Lenalidomide, Dexamethasone, and Elotuzumab With or Without Cyclophosphamide in Treating Patients With Relapsed Primary Amyloidosis

PRIMARY OBJECTIVES: I. To assess the rate of hematologic response of very good partial response (VGPR) or better according to the International Society of Amyloidosis (ISA) hematologic response criteria. SECONDARY OBJECTIVES: I. To assess duration of hematologic response. II. To assess time to hematologic progression. III. To assess overall hematologic response rate. IV. To assess complete hematologic response rate. V. To assess organ response (according to ISA organ response criteria). VI. To assess overall survival (OS). OUTLINE: Patients are randomized to 1 of 2 arms. ARM I: Patients receive lenalidomide orally (PO) on days 1-21 and dexamethasone intravenously (IV) on days 1, 8, 15, and 22. Patients also receive elotuzumab IV over 1 hour on days 1, 8, 15, and 22 of courses 1 and 2 and days 1 and 15 of subsequent courses. Treatment repeats every 28 days for up to 6 courses in the absence of disease progression or unacceptable toxicity. ARM II: Patients receive lenalidomide, dexamethasone, and elotuzumab as in Arm I. Patients also receive cyclophosphamide IV on days 1, 8, and 15. Treatment repeats every 28 days for up to 6 courses in the absence of disease progression or unacceptable toxicity. MAINTENANCE THERAPY: All patients receive lenalidomide PO on days 1-21 and dexamethasone IV on days 1, 8, 15, and 22. Patients also receive elotuzumab IV over 1 hour on day 1. Courses repeat every 28 days for up to 2 years in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up every 3 months for 24 months.