Bortezomib and high-dose melphalan as conditioning regimen before autologous stem cell transplantation in patients with de novo multiple myeloma: a phase 2 study of the Intergroupe Francophone du Myelome (IFM).

Autologous stem cell transplantation (ASCT) is recommended for younger patients with newly diagnosed multiple myeloma. Achieving complete response (CR) or at least very good partial response (VGPR) is a major prognostic factor for survival with 20% to 30% of patients achieving CR after ASCT. Bortezomib has shown synergistic effects with melphalan and no prolonged hematologic toxicity. In this Intergroupe Francophone du Myélome (IFM) phase 2 study, 54 untreated patients were enrolled between July and December 2007 to receive bortezomib (1 mg/m(2) x 4) and melphalan (200 mg/m(2)) as conditioning regimen (Bor-HDM). Overall, 70% of patients achieved at least VGPR, including 17 patients with CR (32%) after ASCT. No toxic deaths were observed. Bortezomib did not increase hematologic toxicity. Only 1 grade 3 to 4 peripheral neuropathy was reported. A matched control analysis was conducted comparing our cohort with patients from the IFM 2005-01 trial (HDM alone). Patients were matched for response to induction therapy and type of induction: CR was higher in the Bor-HDM group (35% vs 11%; P = .001), regardless of induction therapy. These results suggest that Bor-HDM is a safe and promising conditioning regimen. Randomized studies are needed to assess whether this conditioning regimen is superior to HDM alone. This trial was registered at www.clinicaltrials.gov as NCT00642395.