Bortezomib plus dexamethasone is highly effective in relapsed and refractory myeloma patients but responses are short-lived.

Objectives Bortezomib has proven to be effective as single agent in myeloma patients. Aim of this study was to evaluate the efficacy and toxicity of bortezomib in combination with dexamethasone in a cohort of MM relapsed/refractory patients treated in a single centre. Patients and Methods In this single center study 70 patients were treated with bortezomib alone (9) or in combination with dexamethasone (61). Results Forty-one patients (59%) achieved at least a partial response (PR), including 7% complete response (CR), 36% very good partial response (VGPR) reaching the best response within 4 cycles. The duration of response (DOR) was significantly longer for patients achieving CR/VGPR than for those achieving PR (7.3 versus 3.8 months, p=0.03). Likewise, time to progression (TTP), time to alternative treatment (TTAT), and treatment free interval (TFI) were significantly better for patients obtaining CR/VGPR (6.8, 9.4, 6.5 months respectively) as compared to PR (4.9, 6.3, 2 months respectively). The only dose-limiting toxicity was peripheral neuropathy (PN), which occurred in 38/70 patients (55%) and was of grade 3-4 in 12 (17%). PN led to a dose reduction or treatment discontinuation in 17 (24%) patients. Complete resolution or improvement of PN occurred in 29/38 (76%) after a median time of 100 days (range: 17-202). Conclusions Bortezomib in combination to dexamethasone is highly effective in relapsed/refractory MM producing an impressive rate of CR/VGPR, but responses are short-lived