Effective response with bortezomib retreatment in relapsed multiple myeloma – a multicentre retrospective survey in Switzerland

Previous studies have shown that retreatment of relapsed/refractory multiple myeloma (MM) with a second course of bortezomib therapy could be effective in heavily pre-treated patients. In this study, the results of a multicentre, retrospective survey were reported involving patients in Switzerland with MM who responded to initial bortezomib therapy; 43 patients were enrolled and 42 were evaluated for response. The overall response rate (complete response [CR] + near CR [nCR] + partial response [PR]) to bortezomib retreatment was 64.3%, and the clinical benefit rate (CR + nCR + PR + stable disease) for retreatment was 83%. The response rate to bortezomib retreatment in the subgroup with a first treatment-free interval (TFI) >6 months was higher than that in the subgroup with first TFI ≤6 months (74.1% vs. 46.7%) and lower in patients who received concomitant dexamethasone with bortezomib retreatment (57.1% vs. 78.6%). The median overall survival (OS) from first diagnosis of MM was 9.3 years, and after retreatment with bortezomib the median OS was 1.7 years. In total, 85.7% of patients who achieved CR or nCR with initial bortezomib treatment achieved CR or nCR with retreatment. Bortezomib as retreatment was well tolerated, and the safety profile was consistent with previous studies of bortezomib in relapsed MM. The most common adverse drug reaction attributed to bortezomib was peripheral neuropathy in 5 patients. In conclusion, bortezomib retreatment was a well-tolerated, effective therapeutic option for relapsed MM patients in the Swiss clinical setting who have previously responded to bortezomib, particularly for those who experienced an initial TFI of >6 months.