6529 Background: Sequential chemotherapy by CHOP and DHAP regimens followed by ASCT improves complete response (CR) rate and EFS in younger patients with MCL (Lefrère et al, Leukemia, 2002). Since Rituximab (R) may induce significant response in relapsing MCL, we conduct a pilot, multicentric study to determine the impact of the CHOP/DHAP protocol plus R followed by ASCT as a first line therapy in the treatment of MCL at advanced stage. METHODS Patients under 66 years with histologically proven, stage III-IV MCL were included. Treatment consisted of two courses of CHOP, one R-CHOP (Rituximab : 375 mg/m2) and three R-DHAP. Peripheral blood stem cells harvest was performed at the end of the third R-DHAP. Responding pts were eligible for an ASCT after high dose therapy with TBI (10 Gy), Aracytine (6g/m2) and Melphalan (140 mg/m2) (TAM 6) or BEAM if TBI could not be performed. RESULTS From May 2000 to November 2003, 56 pts were included in this study. Median age is 57 years. Fourty-eight pts are evaluable for treatment response. Characteristics of patients are as follow : bone marrow involvement (42/48), leukemic disease (23/48), PS>1 (3/48), extramedullary involvement (20/48) included gastrointestinal (10/22 tested), LDH > 1N (15/48). Fourty-four pts are evaluable after the three courses of (R)-CHOP. Response rates were as follow : CR (4/44), PR > 50% (37/44) and stable disease (3/44). Fourty patients have completed the three courses of R-DHAP. After the R-DHAP, response rates were : PR (14/40), CR (23/40) and SD (3/40). PBSC harvest was successful in 39/40 patients. Thirty patients were autografted with a TAM 6 (28 pts) or a BEAM regimen (2 pts). After ASCT, all patients but one were in CR. Currently, with a median follow up of 25 months, 28/30 pts were in CR 1 and only one relapse was observed. One patient died from unrelated cause. CONCLUSIONS Chemotherapy with DHAP followed by a Aracytine containing regimen provide a high response rate in untreated MCL. However, longer follow-up is needed to assess impact of Rituximab on EFS and survival. Multicentric European study is currently ongoing to test this approach against R-CHOP induction therapy. No significant financial relationships to disclose.