DISEASE CHARACTERISTICS:

• Diagnosis of B-cell chronic lymphocytic leukemia or B-cell small lymphocytic lymphoma according to the International Workshop on Chronic Lymphocytic Leukemia (IWCLL) 2008 criteria

• Meets 1 of the following criteria:

  • Early disease cohort:

    • Meets ≥ 1 of the following criteria:

      • FISH showing deletion 17p in ≥ 20% of cells (either at diagnosis or any time before study entry) either alone or in combination with other cytogenetic abnormalities
      • FISH showing deletion 11q in ≥ 20% of cells (either at diagnosis or any time before study entry) either alone or in combination with other cytogenetic abnormalities, unless the patient has achieved a complete remission, according to IWCLL 2008 criteria which includes CT scan, bone marrow morphology, and flow cytometry
      • Failed to achieve a partial response to initial therapy but lack of disease progression (may receive a second therapy to improve response before transplant)

    • Received ≥ 2 courses of induction therapy (it is expected that patients will receive ≥ 4 months of therapy prior to enrollment, but this is not required)

      • Suggested regimens include, but are not limited to, the following:

        • Fludarabine phosphate and rituximab
        • Fludarabine phosphate, cyclophosphamide, and rituximab
        • Pentostatin, cyclophosphamide, and rituximab
        • Bendmustine and rituximab
        • Alemtuzumab alone or in combination with other agents
    • Stable disease or better after most recent therapy (i.e., no prior progression), according to the revised IWCLL 2008 criteria
    • Nodes ≤ 5 cm

  • Advanced disease cohort:

    • Meets ≥ 1 of the following criteria:

      • First disease progression < 24 months after completing (this includes progression on initial therapy)
      • Second or subsequent progression
    • Stable disease or better after most recent chemotherapy, according to the revised IWCLL 2008 criteria
    • Nodes ≤ 5 cm
    • FISH showing deletion of 17p in ≥ 20% of cells (regardless of interval from initial therapy) either alone or in combination with other cytogenetic abnormalities

• Has an HLA-matched related or unrelated donor available

  • 6/6 HLA-matched related donor by low-resolution typing at HLA A, B, C, and DR
  • 8/8 HLA-matched unrelated donor by molecular typing at both HLA class I and class II (A, B, C, and DR loci)
  • No syngeneic donors

PATIENT CHARACTERISTICS:

• ECOG performance status 0-2
• Serum creatinine < 2 mg/dL
• Calculated creatinine clearance ≥ 40 mL/min
• AST < 3 times upper limit of normal
• Total bilirubin < 2 mg/dL (except for patients with Gilbert syndrome)
• DLCO ≥ 40% predicted
• LVEF ≥ 30% by ECHO or MUGA
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception
• HIV negative
• Hepatitis B surface antigen negative
• Anti-hepatitis B core antigen negative
• Hepatitis C antibody negative
• No uncontrolled diabetes mellitus or active uncontrolled serious infections
• No history of Richter transformation

PRIOR CONCURRENT THERAPY:

• See Disease Characteristics
• At least 4 weeks after day 1 of the last course since prior cytotoxic chemotherapy or alemtuzumab