Pentostatin, Cyclophosphamide, and Rituximab Followed By Campath-1H in Patients With Relapsed or Refractory B-Cell CLL

RATIONALE: Drugs used in chemotherapy, such as pentostatin, cyclophosphamide, and CAMPATH-1H work in different ways to stop cancer cells from dividing so they stop growing or die. Monoclonal antibodies, such as rituximab can locate cancer cells and either kill them or deliver cancer-killing substances to them without harming normal cells. Combining chemotherapy with monoclonal antibody therapy may kill more tumor cells. PURPOSE: This phase II trial is studying how well pentostatin, cyclophosphamide, rituximab, and CAMPATH-1H work in treating patients with relapsed or refractory B-cell chronic lymphocytic leukemia.