An Observational, Retrospective Analysis of Retreatment with Bortezomib for Multiple Myeloma

PurposeThe aim of this retrospective chart review of patients with multiple myeloma (MM) was to describe patterns of retreatment with bortezomib-based therapy and responses to retreatment in a community-based setting.Patients and MethodsData were retrospectively extracted from the medical records of patients treated in US Oncology—affiliated community oncology clinics who received 2 separate treatments with bortezomib-based therapy. Eligible patients had ≥ 60 days between treatments and ≥ 4 bortezomib doses during initial treatment. Responses were determined primarily by laboratory values. Response categories included (1) very good partial response (VGPR), ≥ 90% M-protein decrease; (2) partial response (PR), 50%–89% decrease; and (3) less than PR (< PR), < 50% decrease, excluding progressive disease (PD).ResultsRetreatment response data were available for 82 patients; 5 (6%) had VGPR, 12 (15%) had PR, 52 (63%) had < PR, 5 (6%) had PD, and 8 (10%) died. Among 62 patients with response assessments for initial treatment and retreatment, VGPR/PR rates to retreatment were 44%, 23%, and 13% among patients with VGPR, PR, and < PR to initial treatment, respectively. Median time between bortezomib treatments was 9.7 months; 29% of patients received non-bortezomib therapy between treatments. The most common treatment pattern (58% of patients) was single-agent bortezomib at initial treatment and retreatment. Toxicity contributed to discontinuation in 38% of patients during initial treatment and 22% during retreatment; rates of neuropathy contributing to discontinuation were 18% and 6%, respectively.ConclusionRetreatment with bortezomib-based therapy is feasible, with predictable toxicities. This observational analysis supports bortezomib alone or in combination as a retreatment option after initial bortezomib treatment in patients with relapsed MM.