PRIMARY OBJECTIVES:~I. Arm A: To assess the rate of complete response using pentostatin, cyclophosphamide, and ofatumumab in patients with previously untreated chronic lymphocytic leukemia (CLL) or small lymphocytic lymphoma (SLL) requiring therapy.~II. Arm B: To assess the treatment-free survival rate at 18 months using pentostatin, cyclophosphamide, and ofatumumab induction therapy followed by ofatumumab consolidation in patients with previously untreated CLL or SLL requiring therapy.~SECONDARY OBJECTIVES:~I. Arm A and Arm B: To assess the rate of overall response in patients with previously untreated CLL or SLL requiring therapy and to determine the proportion of patients who achieve a minimal residual disease (MRD) negative state as assessed by flow cytometry in each arm independently.~II. Arm A and Arm B: To monitor and assess toxicity in patients with previously untreated CLL or SLL in each arm independently.~III. Arm A and Arm B: To determine the progression-free survival, treatment-free survival, and duration of response in each arm independently.~IV. Arm A and Arm B: To determine if molecular prognostic parameters (zeta-chain-associated protein [ZAP]-70, cluster of differentiation [CD]38, cytogenetic abnormalities identified by fluorescence in situ hybridization [FISH], immunoglobulin heavy-chain variable-region [IgVH] mutation status, etc) relate to response to therapy in each arm independently.~V. Arm B: To assess the rate of complete response using pentostatin, cyclophosphamide, and ofatumumab induction followed by ofatumumab consolidation in patients with previously untreated CLL or SLL requiring therapy.~VI. Arm B: To evaluate whether consolidation therapy with ofatumumab after pentostatin, cyclophosphamide, and ofatumumab (PCO) induction improves the depth of response.~TERTIARY OBJECTIVES:~I. Arm A and Arm B: To assess the complete and overall response as well as treatment free survival in each arm as compared to a historic control of patients treated with pentostatin, cyclophosphamide, and rituximab in an exploratory manner.~II. Arm A and Arm B: To assess the complete and overall response as well as treatment free survival of patients treated with PCO induction followed by ofatumumab consolidation (Arm B) as compared to patients treated with PCO induction who did not receive ofatumumab consolidation (Arm A) in an exploratory manner.~III. Arm A and Arm B: Assess the mechanisms of ofatumumab induced cell death and explore methods to enhance ofatumumab cytotoxicity.~OUTLINE: Patients are assigned to 1 of 2 treatment arms.~ARM A (closed to accrual as of 8/23/2011): Patients receive induction therapy comprising ofatumumab intravenously (IV) on day 1 (days 1-2 of course 1 only), pentostatin IV over 30 minutes on day 1, and cyclophosphamide IV over 30 minutes on day 1. Treatment repeats every 21 days for 6 courses in the absence of disease progression or unacceptable toxicity.~ARM B: Patients receive induction therapy as in Arm A. Patients then receive consolidation therapy comprising ofatumumab IV on day 1. Treatment repeats every 28 days for 6 courses in the absence of disease progression or unacceptable toxicity.~After completion of study treatment, patients are followed up every 90 days for 1 year.
This phase II trial studies how well giving ofatumumab together with pentostatin and cyclophosphamide works in treating patients with untreated chronic lymphocytic leukemia or small lymphocytic lymphoma. Monoclonal antibodies, such as ofatumumab, can block the ability of cancer cells to grow and spread. Drugs used in chemotherapy, such as pentostatin and cyclophosphamide, work in different ways to stop the growth of cancer cells, either by killing the cells, by stopping them from dividing, or by stopping them from spreading. Giving ofatumumab together with pentostatin and cyclophosphamide may be a better way to block cancer growth.