Randomized Trial Comparing Double Versus Triple Bortezomib-Based Regimen in Patients With Multiple Myeloma and Acute Kidney Injury Due to Cast Nephropathy

PURPOSE We report a multicenter controlled trial comparing renal recovery and tolerance profile of doublet versus triplet bortezomib-based regimens in patients with initial myeloma cast nephropathy (CN) and acute kidney injury (AKI) without need for dialysis. METHODS After symptomatic measures and high-dose dexamethasone, patients were randomly assigned to receive bortezomib plus dexamethasone (BD), or BD plus cyclophosphamide (C-BD). In patients with < 50% reduction of serum free light chains (sFLCs) after 3 cycles, chemotherapy was reinforced with either cyclophosphamide (BD group) or thalidomide (C-BD group). RESULTS Ninety-two patients were enrolled in each group. At random assignment, characteristics of the 2 groups were similar, including median age (68 years) and serum creatinine level (305.5 and 273.5 mu mol/L in BD and C-BD group, respectively). At 3 months, renal response rate (primary end point) was not different (41 v 47 responders in the BD and C-BD groups, respectively; relative risk [RR], 0.87; P = .46). Very good partial response (free light chain reduction >= 90%) or more was achieved in 36 and 47 patients, respectively (RR, 0.76; P = .10). After 1 cycle of chemotherapy, 69 in the BD group and 67 patients in the C-BD group had achieved sFLC level <= 500 mg/L. Serious adverse events were recorded in 30 and 40 patients, respectively. At 12 months, 19 patients had died (9 in the BD group v 10 in the C-BD group), including 10 (6 in the BD group and 4 in the C-BD group) from myeloma progression and 3 (0 in the BD group and 3 in the C-BD group) from infection. Within median follow-up of 27 months, 43 and 42 patients switched to new therapy, respectively. Overall, 50 patients (24 in the BD group and 26 in the C-BD group) had died. CONCLUSION This randomized study did not show any benefit of C-BD compared with BD on renal recovery of patients with initial CN not requiring dialysis. Adding cyclophosphamide did not sufficiently improve the efficacy-toxicity balance. Patients with myeloma with AKI are fragile, and indication for doublet or triplet regimen should be adapted to frailty.