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Utility of bortezomib retreatment among patients with refractory multiple myeloma.

17549 Background: Bortezomib (VELCADE; Vc) has emerged as the standard of care for patients with relapsed or refractory multiple myeloma (MM). However, following initial Vc therapy, its utility in recurrent disease is unclear. This retrospective case series provides preliminary evidence of the safety and efficacy of Vc in the retreatment of patients with recurrent MM.


METHODS
An observational case series was developed based on a medical records review of all patients (N = 10) who completed Vc retreatment following completion of initial Vc therapy. Best response was measured as the greatest mean % reduction in the treatment response measure: serum/urine M-protein or plasma cells. Differences between initial treatment and retreatment efficacy and Vc-related hospitalizations were assessed using descriptive statistics.


RESULTS
During initial treatment 44% of patients responded to Vc (≥50% M-protein (3/9) or plasme cell reduction (1/9, 1 pt NA). At retreatment 50% of patients responded (5/10). Following initial Vc therapy, the median treatment-free interval was just over 13 months (56.6 weeks). One patient experienced a dose reduction due to peripheral neuropathy (grade 2) during retreatment, compared to two patients with neuropathy (grade 3) during initial treatment. Termination of therapy due to any unmanageable toxicity was much lower during retreatment (14.3% vs 62.5%). Finally, none of the patients were hospitalized for Vc-related events during retreatment, compared with two patients during initial treatment.


CONCLUSIONS
Vc retreatment appears to be as effective as initial treatment in terms of response, and may actually yield less toxicity and hospitalizations. Even though this small sample size precluded statistical testing, the observed patterns are instructive and additional prospective trials are currently ongoing. However, based on these preliminary data, prolonged disease control may be achieved with repeated use. [Table: see text].