S1304, Carfilzomib and Dexamethasone for Treating Patients With Relapsed or Refractory Myeloma

PRIMARY OBJECTIVES: I. To evaluate and compare progression free survival (PFS) of two different doses of carfilzomib with dexamethasone in multiple myeloma (MM) patients with relapsed and/or refractory disease. SECONDARY OBJECTIVES: I. To evaluate and compare response rates (RR) for each arm. II. To evaluate response rates (RR) for patients that relapse on low dose carfilzomib and subsequently cross-over to high dose carfilzomib. III. To evaluate the safety of this combination for this patient population. IV. To evaluate overall survival (OS). TERTIARY OBJECTIVES: I. To explore the molecular variability in MM cells obtained from extramedullary bone marrow relapse sites. II. To explore the role of positron emission tomography (PET) scanning in assessing disease burden and as a tool to assess treatment response. III. To explore changes in left ventricular ejection fraction (LVEF) in patients with relapsed or refractory multiple myeloma treated with low dose carfilzomib or high dose carfilzomib plus dexamethasone. OUTLINE: Patients are randomized to 1 of 2 treatment arms. ARM I: Patients receive dexamethasone intravenously (IV) and low-dose carfilzomib IV over 2-10 minutes on days 1, 2, 8, 9, 15, and 16. Patients with progression cross-over to Arm II. ARM II: Patients receive dexamethasone IV and high-dose carfilzomib IV over 30 minutes on days 1, 2, 8, 9, 15, and 16. Note that for the first course of treatment on both arms carfilzomib is given at a reduced rate to assess toxicity. In both arms, treatment repeats every 28 days for up to 12 courses in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up every 3 months for 3 years from initial registration.