Weekly treatment with bortezomib for patients with recurrent or refractory multiple myeloma: a phase 2 trial of the Minnie Pearl Cancer Research Network.

BACKGROUND

The purpose of the current study was to evaluate the efficacy and toxicity of weekly bortezomib in the treatment of patients with recurrent/refractory multiple myeloma.

METHODS

A total of 40 patients with multiple myeloma who had received either 1 or 2 previous treatment regimens were treated with bortezomib at a dose of 1.6 mg/m(2) intravenously for 4 consecutive weeks, followed by 1 week without treatment. Responses were measured using International Myeloma Working Group criteria.

RESULTS

Twenty-two patients (55%; 95% confidence interval, 40%-70%) achieved objective responses to treatment, with a median response duration of 16 months. The median progression-free survival for all patients was 9.6 months, with a 1-year progression-free survival rate of 39%. The 1-year and 2-year overall survival rates were 75% and 51%, respectively. Weekly bortezomib was generally well tolerated; grade 3/4 (using the National Cancer Institute Common Toxicity Criteria [version 3.0]) neutropenia (13%), thrombocytopenia (20%), fatigue (15%), diarrhea (13%), and neuropathy (10%) were experienced by a minority of patients.

CONCLUSIONS

In the current study, a schedule of weekly bortezomib was found to be effective and well tolerated in patients with previously treated multiple myeloma. Although the response rate and duration appear comparable to those achieved with twice-weekly bortezomib, the relative efficacy of these 2 schedules cannot be determined definitively on the basis of this phase 2 study. A weekly schedule of bortezomib is a reasonable option for patients who have logistic difficulties receiving a twice-weekly schedule, and is an attractive schedule for incorporation into combination regimens.