Phase II Trial of Prophylactic Rituximab Therapy for Prevention of CGVHD

Inclusion Criteria:(A) Patients age greater than 17 and less than 76. (B) CLL patients with unmutated IgG VH gene status are immediately eligible and patients with mutated IgG VH genes (>2% nucleotide change compared to somatic sequence) are eligible if they are considered appropriate by their HSCT physician. CLL patients in complete remission benefit most from allogeneic HSCT, and physicians will be encouraged to provide aggressive chemotherapy prior to nonmyeloablative transplantation.

(C) MCL patients who their BMT physicians believe would benefit from allogeneic HSCT.

(D) Adequate renal (Cr < 2.4 mg/dl) and hepatic (Bilirubin < 3.0 mg/dl, AST < 100 IU) function. Patients with lab results in excess of these can be enrolled with approval of PI.

(E) Men and women of reproductive potential must agree to use an acceptable method of birth control during treatment and for six months after completion of treatment.

(F) All subjects must provided written informed consent

Donor Inclusion Criteria (A) Genotypically or phenotypically HLA-identical. (B) Donor age < 75 unless cleared by institutional P.I (C) Capable of giving written, informed consent. (D) Donor must consent to PBSC mobilization with G-CSF and apheresis

Exclusion Criteria:(A) Patient age less than 18 or greater than 75 (B) Patient does not have a 9/10 or 10/10 HLA identical donor (high resolution molecular genotyping at HLA A, B, C and DrB1, and DQ) (C) Standard exclusions for any allogeneic transplantation including: i. Pregnancy or lactation ii. Serious uncontrolled infection iii. HIV seropositivity iv. Hepatitis B or C seropositivity v. Cardiac function: ejection fraction <40% or uncontrolled cardiac failure vi. Pulmonary: DLCO <50% predicted vii. Liver function abnormalities: elevation of bilirubin to >= 3 mg/dl and/or AST>100 viii. Renal: creatinine >2.4 ix. Karnofsky performance score <= 60% x. Patients with poorly controlled hypertension (SBP>150 or DBP>90 repeatedly). (D) Known life-threatening hypersensitivity to Rituximab or other anti-B cell antibody is an exclusion criterion. Previous Rituximab therapy is neither required, nor is it an exclusion criterion, but will be carefully assessed and correlated with outcome.

(E) Inability to comply with the allogeneic transplant treatment. (F) Uncontrolled CNS involvement with disease

Donor Exclusion Criteria (A) Identical twin (B) Any contra-indication to the administration of subcutaneous G-CSF at a dose of 16mg/kg/d for five consecutive days (C) Serious medical or psychological illness (D) Pregnant or lactating females (E) Prior malignancy within the preceding five years, with the exception of non-melanoma skin cancers.

(F) HIV seropositivity