Extended follow-up of outcome measures in multiple myeloma patients treated on a phase I study with bortezomib and pegylated liposomal doxorubicin.

A phase I study of a combination of the proteasome inhibitor bortezomib and pegylated liposomal doxorubicin showed significant anti-tumor activity against advanced multiple myeloma, with 36% of patients achieving a complete or near-complete response and 73% having a partial response or better. Given this encouraging efficacy, it was therefore of interest to update the prior experience and define parameters such as time to progression, time to retreatment, and overall survival. Additional follow-up was collected on all evaluable multiple myeloma patients and revealed a median time to progression of 9.3 months versus 3.8 months on whatever had been the patient's prior therapy. Time to retreatment was prolonged from 5.9 months after the patient's prior therapy to 24.2 months after bortezomib with pegylated liposomal doxorubicin. The median overall survival after therapy with bortezomib and pegylated liposomal doxorubicin was 38.3 months. These findings compare favorably with results reported for bortezomib alone and support the possibility that the bortezomib/pegylated liposomal doxorubicin regimen may provide superior efficacy against relapsed/refractory multiple myeloma.