Safety and efficacy of bortezomib and melphalan combination in patients with relapsed or refractory multiple myeloma: updated results of a phase 1/2 study after longer follow-up.

Bortezomib synergizes with melphalan in preclinical and early clinical studies. Updated data from our phase 1/2 study assessing the safety and efficacy of bortezomib plus melphalan in relapsed/refractory multiple myeloma (MM) are presented. Bortezomib (0.7, 1.0, or 1.3 mg/m(2)) on days 1, 4, 8, and 11 and oral melphalan (0.025-0.25 mg/kg) on days 1-4 of a 28-day cycle were administered. Hematologic toxicities defined the maximum tolerated dose as bortezomib 1.0 mg/m(2) and melphalan 0.10 mg/kg. Because dose-limiting toxicities were attributed to the more myelosuppressive melphalan, cohorts 9 and 10 with higher bortezomib (1.3 mg/m(2)) and lower melphalan (0.025 and 0.10 mg/kg) doses were added. Responses occurred in 32/46 (70%) evaluable patients: two complete (4%), five near-complete (11%), 16 partial (35%), and nine minimal (20%). Complete and near-complete responses were observed only with higher bortezomib doses. Response rates were similar in patients with prior melphalan or bortezomib. Median progression-free survival was 9 months (range, 1-24), and overall survival was 32 months (range, 1-54). The most common grade 3/4 hematologic adverse events (AEs) were neutropenia (31%/0%), thrombocytopenia (25%/2%), and anemia (13%/0%). Grade 4 tumor lysis syndrome was reported in one patient. Fewer grade 3/4 hematologic AEs were reported in cohorts 9 and 10 than in cohorts receiving lower bortezomib and higher melphalan doses. In conclusion, bortezomib plus melphalan is a steroid- and immunomodulatory drug-free regimen that may provide a treatment alternative for elderly patients and patients with significant comorbidity.

Phase I/II trial assessing bortezomib and melphalan combination therapy for the treatment of patients with relapsed or refractory multiple myeloma.

PURPOSE: Bortezomib has shown synergy with melphalan in preclinical models. We assessed the safety, tolerability, and response rate in a dose-escalation study of this combination for relapsed or refractory multiple myeloma patients. METHODS: Bortezomib was administered from 0.7 to 1.0 mg/m(2) on days 1, 4, 8, and 11 of a 28-day cycle for up to eight cycles. Oral melphalan was administered in escalating doses from 0.025 to 0.25 mg/kg on days 1 to 4. RESULTS: Thirty-five patients with relapsed or refractory myeloma were enrolled, 34 of whom were assessable for response. Dose-limiting toxicity of grade 4 neutropenia in two of six patients in the highest dose cohort led to the assignment of bortezomib 1.0 mg/m2 and melphalan 0.10 mg/kg as the maximum-tolerated dose (MTD). Responses (minimal [MR], partial [PR], or complete [CR]) occurred in 23 of 34 patients (68%), including two CRs (6%), three immunofixation-positive CRs (9%), 11 PRs (32%), and seven MRs (21%). Responses were observed in five of six assessable patients (83%) at the MTD. Median progression-free survival for all patients was 8 months (range, 2 to 18 months). Grade > or = 3 toxicities were related mostly to myelosuppression. Among the 15 patients with grade 1/2 neuropathy at baseline, it resolved during treatment in one, worsened in four, and remained stable in 10 patients. Eight other patients developed grade 1/2 neuropathy during the study. CONCLUSION: Bortezomib plus melphalan given on a 28-day schedule showed encouraging activity with manageable toxicity and represents a promising treatment for myeloma patients.