Retrospective Analysis of Weekly Administration of Bortezomib in Multiple Myeloma.

Background: Currently the standard treatment of multiple myeloma (MM) with the proteasome inhibitor bortezomib (Velcade) is by twice weekly administration of the drug. We present a retrospective study of bortezomib therapy by weekly dosing in MM patients unable to tolerate the standard regimen.

Methods: Since January 2004, five patients (3 male and 2 female, age 47 – 81) have been treated at our center by weekly, and one (male, 86) by every-two-week administration of bortezomib. This approach was selected primarily due to low performance status and/or comorbidities. All patients had failed at least one prior treatment modality. Each cycle of the weekly schedule consisted of one dose every week for two weeks, followed by two weeks of rest. Mainly for convenience purposes, two patients while stable on weekly treatment, were switched to even less frequent treatment of once every-three-weeks. Furthermore, five patients received a plain dose of 2.0 mg rather than regular dose calculation per body surface area.

Results: All 5 patients on weekly schedule had an initial moderate to major response, followed by a stable course. None of them, however, achieved a complete remission. 2/5 demonstrated progression of disease after they were switched to every-three-week dosing. The patient on every-two-week treatment had an initial favorable response, and is currently being switched to the weekly schedule due to excellent tolerance.

Conclusion: Our retrospective analysis indicates that weekly bortezomib therapy is a promising alternative approach to the treatment of MM in those patients intolerant to standard regimen. It seems reasonable, therefore, to attempt a larger prospective study of bortezomib administration with less frequent dosing, mainly in this group of MM patients.