• Overall response rate [ Time Frame: Every 3 months ] [ Designated as safety issue: No ]
  
• Assess side effects [ Time Frame: Day 1 of each cycle ] [ Designated as safety issue: Yes ]
  

• Progression and overall survival [ Time Frame: 2 years ] [ Designated as safety issue: No ]
  
• Correlative studies [ Time Frame: During induction (weeks 1-15); PK every 2 months during maintenance. ] [ Designated as safety issue: No ]
  

Drug: Velcade

Induction: 1.3 mg/m2 IV days 1 and 4 of weeks 1, 2, 4, 5, 7, 8, 10, 11, 13 & 14.

Maintenance: 1.3 mg/m2 IV day 1 weekly x 2 weeks beginning week 20 and continuing every 6 months until month 23.

Drug: Rituximab

Induction: 375 mg/m2 IV day 1 of weeks 4, 5, 7, 8, 10, 11, 13 and 14 prior to Velcade administration.

Maintenance: 375 mg/m2 day 1 weekly x 4 weeks.

Rationale: Previous studies testing bortezomib and rituximab separately indicate these agents have some efficacy against mantle cell lymphoma (MCL). Bortezomib is a targeted cancer drug that blocks proteasomes. The proteasome is an enzyme complex existing in all cells that influences proteins controlling cellular processes. By blocking the proteasome, bortezomib disrupts biologic pathways such as those related to the growth and survival of cancer cells. Rituximab is a monoclonal antibody that attaches to a protein called the CD20 antigen that is found almost exclusively on the surface of B-cells with leukemia. Once rituximab attaches to the protein, the immune system activates to kill the malignant B-cells. The current study combines bortezomib and rituximab in patients with relapsed or refractory MCL.

Purpose: This study will evaluate the safety and efficacy of bortezomib and rituximab in patients with relapsed or refractory MCL. Blood, molecular, and tumor analysis will be conducted to provide researchers with information about areas such as rituximab resistance, the effects of bortezomib on cells associated with immune function, and protein alterations related to the cellular growth and death of MCL. In addition, the role of maintenance therapy and timing of administration in MCL will be assessed.

Treatment: Patients in this study will receive bortezomib and rituximab. Both drugs will be administered through intravenous infusions. There are two treatment periods in this study. The first is considered induction therapy where patients will receive bortezomib and rituximab intermittently over an eighteen week period. Lower dosages of rituximab will be given to patients at the beginning of the study to ensure no severe toxicity occurs. Those patients without disease growth after the eighteen weeks of treatments will continue with maintenance therapy. During this time period, patients will be given bortezomib and rituximab for up to one year and a half. Several tests and exams will be conducted throughout the study to closely monitor patients. Treatments will be discontinued due to disease growth or unacceptable side effects.