A phase I/II study of escalating doses of thalidomide in conjunction with bortezomib and high-dose melphalan as a conditioning regimen for autologous stem cell transplantation in patients with multiple myeloma

A regimen of escalating doses of thalidomide, in combination with bortezomib and high-dose melphalan (mel/vel/thal), was evaluated as a conditioning regimen for autologous stem cell transplantation (ASCT) in multiple myeloma (MM) patients with a prior transplant who had relapsed or achieved less than a complete remission following a prior ASCT. Thalidomide was dose escalated starting from 600 mg to 1000 mg on days −5 to −1 in a 3 × 3 design, bortezomib was administered at 1.6 mg/m² intravenously on days −4 and −1 and melphalan 200 mg/m² was administered on day −2. No dose-limiting toxicity was seen in the phase I portion of the trial. An additional 20 patients were enrolled at the maximum tolerated dose of thalidomide of 1000 mg daily. The overall response rate was 69% with 38% complete remission. Median PFS and OS were 9.3 and 65.4 months, respectively, with a median follow-up of 17.8 months. The most common grade 3–4 adverse events (AEs) were neutropenic fever (58.6%), mucositis (6.9%), and diarrhea (6.9%). Serious AEs included somnolence (13.8%) and tumor lysis syndrome (3.4%). The addition of high-dose thalidomide to bortezomib and melphalan as conditioning for salvage ASCT was well tolerated and was an effective conditioning regimen.