The U.S. Food and Drug Administration has approved bortezomib (Velcade) for the retreatment of adult patients with multiple myeloma who had previously responded to bortezomib therapy and relapsed at least 6 months following completion of prior bortezomib treatment. The labeling update includes dosing guidelines as well as safety and efficacy findings for single-agent use or use in in combination with dexamethasone in patients previously treated with bortezomib. Bortezomib retreatment may be started at the last tolerated dose.
The approved retreatment supplemental New Drug Application consisted of a phase II study and other supportive data. The phase II international RETRIEVE trial was a single-arm, open-label trial enrolling 130 adult patients with myeloma who had previously responded to bortezomib-based therapy and relapsed at least 6 months after prior treatment with bortezomib. Patients received a median of two prior therapies, and dexamethasone was administered in combination with bortezomib in 94 patients.
The RETRIEVE trial showed an overall response rate of 38.5%, with one patient achieving complete response and 49 achieving partial response. In the 50 responding pateints, the median duration of response was 6.5 months (range, 0.6–19.3 months).
The safety profile seen with bortezomib retreatment was consistent with the known safety profile of intravenous bortezomib in relapsed multiple myeloma; no cumulative toxicities were observed upon retreatment. ■