 This is a phase 2 study of Rituximab in combination with Methotrexate, Doxorubicin, Cyclophosphamide, Leucovorin, Vincristine, Ifosfamide, Etoposide, Cytarabine and Mesna R-MACLOIVAM in subjects with previously untreated Mantle Cell Lymphoma MCL. Treatment will consist of up to 4 cycles of therapy. Response assessment by CT and PET scans will be performed post Cycle 2. Once the final cycle of therapy is completed, response evaluation will be performed based on pre-study CT scans, PET Scanendoscopy or any staging scans that were positive at baseline. PI approval required if treating with less than 4 cycles. 