Belgian Hematological Society

Bone disease is a key presenting feature of myeloma. This post hoc analysis of the phase III VISTA trial of bortezomib plus melphalan-prednisone (VMP) vs. MP in previously untreated myeloma patients assessed clinical bone disease events and changes in alkaline phosphatase (ALP), a marker for osteoblast activation, and serum Dickkopf-1 (DKK-1), an inhibitor of osteoblast differentiation, during treatment. Patients received nine 6-wk cycles of VMP (bortezomib 1.3 mg/m(2) , days 1, 4, 8, 11, 22, 25, 29, 32, cycles 1-4, days 1, 8, 22, 29, cycles 5-9, plus melphalan 9mg/m(2) and prednisone 60mg/m(2) , days 1-4, cycles 1-9; N=344) or MP alone (N=338). Rates of bisphosphonates use during treatment (73% vs. 82%), progression because of worsening bone disease (3% vs. 11%), and requirement for subsequent radiotherapy (3% vs. 8%) were lower with VMP vs. MP. Median maximum ALP increase was significantly higher with VMP vs. MP overall (49.7% vs. 30.3%, P=0.029), and higher by response group (complete response [CR]: 68.7% vs. 43.9%; partial response [PR]: 41.5% vs. 31.2%). Greater maximum ALP increase was strongly associated with achievement of CR (P≤0.0001) and CR/PR (P≤0.01). Median DKK-1 decreased with VMP by 694.4pg/mL and increased with MP by 1273.3pg/mL from baseline to day 4 (P=0.0069). Available radiologic data revealed evidence of bone healing in 6/11 VMP-treated patients, who achieved best responses of three CR, one PR, and two stable disease. These results suggest a positive effect of bortezomib on bone metabolism and potentially bone healing in myeloma.

The standard treatment for patients with multiple myeloma who are not candidates for high-dose therapy is melphalan and prednisone. This phase 3 study compared the use of melphalan and prednisone with or without bortezomib in previously untreated patients with multiple myeloma who were ineligible for high-dose therapy. We randomly assigned 682 patients to receive nine 6-week cycles of melphalan (at a dose of 9 mg per square meter of body-surface area) and prednisone (at a dose of 60 mg per square meter) on days 1 to 4, either alone or with bortezomib (at a dose of 1.3 mg per square meter) on days 1, 4, 8, 11, 22, 25, 29, and 32 during cycles 1 to 4 and on days 1, 8, 22, and 29 during cycles 5 to 9. The primary end point was the time to disease progression. The time to progression among patients receiving bortezomib plus melphalan-prednisone (bortezomib group) was 24.0 months, as compared with 16.6 months among those receiving melphalan-prednisone alone (control group) (hazard ratio for the bortezomib group, 0.48; P<0.001). The proportions of patients with a partial response or better were 71% in the bortezomib group and 35% in the control group; complete-response rates were 30% and 4%, respectively (P<0.001). The median duration of the response was 19.9 months in the bortezomib group and 13.1 months in the control group. The hazard ratio for overall survival was 0.61 for the bortezomib group (P=0.008). Adverse events were consistent with established profiles of toxic events associated with bortezomib and melphalan-prednisone. Grade 3 events occurred in a higher proportion of patients in the bortezomib group than in the control group (53% vs. 44%, P=0.02), but there were no significant differences in grade 4 events (28% and 27%, respectively) or treatment-related deaths (1% and 2%). Bortezomib plus melphalan-prednisone was superior to melphalan-prednisone alone in patients with newly diagnosed myeloma who were ineligible for high-dose therapy. (ClinicalTrials.gov number, NCT00111319.)