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.