Inclusion Criteria

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