DOSE-DENSE AND HIGH DENSITY CHEMOTHERAPY PLUS RITUXIMAB WITH AUTOLOGOUS STEM CELL TRANSPLANTATION FOR PRIMARY TREATMENT OF DIFFUSE LARGE B-CELL LYMPHOMA AT POOR PROGNOSIS: A PHASE II MULTICENTER STUDY

BACKGROUND: We investigated the addition of rituximab to dose-dense and high-dose chemotherapy with autologous stem cell transplantation in patients with untreated poor-prognosis diffuse large B-cell lymphoma. DESIGN AND METHODS: Ninety-four young patients (age, 18-60) with stage III-IV diffuse large B-cell lymphoma at intermediate/high or high risk according to the age-adjusted International Prognostic Index were enrolled into a phase II trial. The treatment was as follows: four courses of bi-weekly rituximab-cyclophosphamide-epirubicin-vincristine-prednisone (R-MegaCEOP14), two courses of rituximab-mitoxantrone-cytarabine-dexamethasone (R-MAD) and carmustine-etoposide-cytarabine-melphalan (BEAM) with autologous stem cell transplantation. RESULTS: The complete response and toxic death rates were 82% and 5%, respectively. Failure-free survival and overall survival rates at 4 years were 73% and 80%, respectively. The outcomes of these patients were retrospectively compared to those of 41 patients with similar characteristics enrolled into a previous phase II trial of high-dose chemotherapy without rituximab. This historical group was treated with eight weekly infusions of methotrexate-doxorubicin-cyclophosphamide-vincristine-prednisone-bleomycin (MACOP-B), two courses of MAD and BEAM with autologous stem cell transplantation. The 4-year failure-free survival rates for the rituximab and historical groups were 73% versus 44%, respectively (p=0.001); the 4-year overall survival rates were 80% and 54%, respectively (p=0.002). A Cox's multivariable model was applied to adjust the effect of treatment for unbalanced or important prognostic factors: failure and death risks were significantly reduced in the rituximab group compared to the historical group, with an adjusted hazard ratio of 0.44 (p=0.01) for failure-free survival and 0.46 (p=0.02) for overall survival. CONCLUSIONS: These results suggest that the addition of rituximab to high-dose chemotherapy is effective and safe in diffuse large B-cell lymphoma with a poor-prognosis and such regimens need to be compared to dose-dense chemoimmunotherapy without autologous stem cell transplantation in randomized trials.