Efficacy and Safety of Bortezomib Based Regimens Retreatment in Relapsed Multiple Myeloma Patients: Results from a Retrospective Study.

Objective: To evaluate the efficacy and safety of bortezomib retreatment in relapsed multiple myeloma (MM) patients, who previously responded to bortezomib. Methods: This retrospective observational study included data from 45 patients and evaluated the efficacy and safety of bortezomib based retreatment in these patients, who had achieved at least a partial response (PR) on initial bortezomib therapy in our hospital from May 2006 to May 2013. Results: The overall response rate (ORR) was 71.2%, among them 9% patients achieved CR, 11.1% patients achieved very good partial response (VGPR), 51.1% patients achieved PR. All patients were divided into 3 groups according to the response of initial bortezomib therapy, including CR group, VGPR group and PR group. After bortezomib retreatment, the ORR of the 3 groups was 76.9%, 75% and 62.5%, respectively. According to the response of bortezomib retreatment, the patients were divided into 2 groups: group 1 who at least achieved PR, group 2 who showed no response. The median progression-free survival (PFS) after bortezomib retreatment for group 1 and 2 was 9( 95% confidence interval 7.947~10.051) and 10 (95% confidence interval 8.381∼11.619) months, respectively (P>0.05), while the median overall survival (OS) after bortezomib retreatment was 71 (95% confidence interval 66.694∼75.306)) and 37 (95% confidence interval 1-28) months, respectively (P<0.05). In patients with bortezomib retreatment had different degrees of adverse events (AE) , the most AE for grade 1~2. The most common grade ≥3 AE was thrombocytopenia, neutropenia and anemia. The incidence rate of grade ≥3 AE peripheral neuropathy bortezomib was 15%. Conclusion: Bortezomib based regimens retreatment was effective and tolerable in relapsed MM patients, who had achieved at least a partial response (PR) on initial therapy. The incidence rate of AE was not significantly increased.