Bortezomib retreatment in relapsed multiple myeloma - results from a retrospective multicentre survey in Germany and Switzerland.

OBJECTIVES This multicenter, retrospective survey evaluated the efficacy and safety of bortezomib retreatment in patients with relapsed multiple myeloma who had responded to initial bortezomib treatment. METHODS Clinical records of 94 patients receiving bortezomib retreatment in Germany and Switzerland were reviewed. RESULTS Sixty patients were included according to prespecified criteria. Patients had received a mean 3.7 ± 2.3 therapies prior to initial bortezomib. Overall response rate to bortezomib retreatment was 63.3%; 8 (13.3%), 3 (5.0%) and 27 (45.0%) patients achieved complete response (CR), near-CR and partial response, respectively. Response to retreatment was associated with response to initial treatment (75.0% of patients with CR to initial treatment responded to retreatment) and treatment-free interval (TFI) after initial treatment (76.9 vs. 38.1% overall response rate for patients with TFI >6 vs. ≤ 6 months). After retreatment, median time to progression was 9.3 months. Median TFI was 5.7 months; 31.7, 25.0 and 15.0% of patients experienced a TFI longer than 6, 9 and 12 months, respectively. Reported adverse drug reactions were consistent with the known safety profile of bortezomib and most resolved completely. CONCLUSIONS These results demonstrate that relapsed multiple myeloma patients who respond to initial bortezomib treatment have a sustained susceptibility to bortezomib and do not experience uncommon toxicity to retreatment.