RESUMEN
The purpose of this study was to evaluate the efficacy and safety of short-course bortezomib, melphalan, prednisone (VMP) in previously untreated multiple myeloma as frontline therapy for transplant-ineligible patients and induction prior to autologous stem cell transplantation (ASCT). Patients received up to 6 28-day cycles of bortezomib 1.3 mg/m(2), days 1, 4, 8, and 11, plus melphalan 6 mg/m(2) and prednisone 60 mg/m(2), days 1-7. After 2-6 cycles, eligible and consenting patients could proceed to ASCT. Responses were assessed by International Uniform Response Criteria. The primary endpoint was complete response (CR) rate with VMP. Forty-five patients were enrolled. Among 44 evaluable patients, response rate was 95%, including 18% >or=CR (9% stringent CR), 27% very good partial responses (VGPR), and 50% partial responses (PR). Twenty patients proceeded to ASCT. Stem cell collection was successful in all; median yield was 5.6 x 10(6) CD34(+) cells/kg. Posttransplant response rates were 30% >or=CR (10% stringent CR), 65% VGPR, and 5% PR. After median follow-up of 14.0/14.6 months, median time to progression and progression-free survival were both 19.8/27.9 months in non-ASCT/ASCT patients. Seven patients have died; 1-year survival rates were 82%/95% in non-ASCT/ASCT patients. The most common grade 3/4 toxicities were thrombocytopenia (20%), neutropenia (28%), and infection (9%). Peripheral neuropathy grade 2-4 was the most common nonhematopoietic side effect occurring 17 patients (38%), although it was typically reversible, and only 5 patients (11%) discontinued therapy as a result of it. Short-course VMP is highly effective and generally well tolerated, both as initial treatment in non-ASCT patients and induction prior to ASCT. VMP did not negatively affect stem cell collection. Longer follow-up and prospective phase III trials are required to validate these initial observations.