Intermediate-dose melphalan compared with myeloablative treatment in multiple myeloma: long-term follow-up of the Dutch Cooperative Group HOVON 24 trial.

BACKGROUND AND OBJECTIVES The Dutch-Belgian HOVON group performed a randomized phase 3 trial to compare single non-myeloablative intensive treatment with double, intensive treatment in previously untreated patients with multiple myeloma (MM). DESIGN AND METHODS Three hundred and three patients with stage II/III MM were randomized after VAD induction chemotherapy to receive two cycles of non-myeloablative intermediate-dose melphalan (70 mg/m2) (single treatment) or the same regimen followed by cyclophosphamide 120 mg/kg iv plus total body irradiation (TBI) 9 Gy and autologous stem cell transplantation (double, intensive treatment). In both treatment arms interferon .IIa was given as maintenance until relapse/progression. RESULTS A significantly higher proportion of patients achieved a complete remission (CR) on protocol treatment with double, intensive therapy (32 % vs 13 %, p<0.001). Double treatment produced better outcome in terms of event-free survival (median 22 vs 21 months, 28% vs 14% at 4 years and 15% vs 7% at 6 years after randomization; logrank p=0.013; univariate HR 0.74, 95% CI, 0.58-0.94), progression-free survival (median 27 vs 24 months, 33% vs 16% at 4 years, and 17% vs 9% at 6 years after randomization; logrank p=0.006; HR=0.71, 95% CI 0.56-0.91), but not overall survival (median 50 vs 55 months, 52% vs 56% at 4 years and 39% vs 36% at 6 years after randomization; logrank p=0.51; HR=1.10, 95% CI 0.83-1.46). The achievement of a CR had a favorable prognostic impact on event-free survival (HR=0.60 , 95% CI=0.44 -0.82 , p=0.001) and progression-free survival (HR=0.62 , 95% CI=0.45 -0.84, p=0.002). INTERPRETATION AND CONCLUSIONS Double, intensive treatment resulted in a better CR rate, event-free survival and progression-free survival but not overall survival compared to single non-myeloablative treatment in previously untreated patients with multiple myeloma.