Multiple myeloma (MM) typically follows a relapsing course with many
patients requiring multiple therapies. This single-arm phase 2 study
prospectively evaluated the efficacy and safety of bortezomib
retreatment in MM patients who had relapsed after achieving at least a
partial response (PR) to prior bortezomib-based therapy. Patients aged
18years, with measurable, secretory MM, who relapsed 6months after prior
bortezomib treatment were eligible. Patients received up to eight cycles
of bortezomib (+/- dexamethasone). The primary endpoint was best
confirmed response at retreatment; secondary endpoints included duration
of response (DOR), time to progression (TTP), and safety. Adverse events
(AEs) were graded by National Cancer Institute Common Terminology
Criteria for Adverse Events version 3.0. A total of 130 patients (median
of two prior lines of therapy) were enrolled and received retreatment.
At retreatment, 28% and 72% of patients received bortezomib and
bortezomib-dexamethasone, respectively. Overall response rate was 40%.
In patients who achieved PR, median DOR and TTP were 6 center dot 5 and
8 center dot 4months, respectively. Thrombocytopenia was the most common
grade 3 AE (35%). Forty percent of patients experienced neuropathy
events, which improved and resolved in a median of 1 center dot 5 and 8
center dot 9months, respectively. In conclusion, bortezomib retreatment
was effective and tolerable in relapsed MM patients, with no evidence of
cumulative toxicities