Reduced Intensity Conditioning Before Partially Matched Donor Stem Cell Transplant in Treating Patients With Advanced Cutaneous T Cell Lymphoma

Inclusion Criteria:

1. Stage IIB-IV mycosis fungoides and sezary syndrome who have failed at least one standard systemic therapy or are not candidates for standard therapy.
2. Patient should have a responsive skin disease including complete remission (CR) and partial remission (PR) (close to CR; 75%-99% clearance of skin disease from baseline without new tumors (T3) in patients with T1, T2 or T4 only skin disease) and should not have visceral organ or lymph node involvement prior to transplantation.
3. Patients must have a related donor who is a two or more allele mismatch at the HLA-A; B; C; DR and DQ loci. Patients who have sibling donors with a one antigen mismatch due to recombination will not be enrolled in this protocol.
4. Patients must have adequate organ function:

   * Left Ventricular Ejection Fraction (LVEF) of \>50%
   * Carbon Monoxide Diffusing Capacity (DLCO) \>50% of predicted corrected for hemoglobin
   * Adequate liver function as defined by a serum bilirubin \<2.0 (unless hemolysis or Gilbert disease), Aspartate aminotransferase (AST) or Alanine aminotransferase (ALT) \< 2.5 X upper limit of normal
   * Creatinine clearance of \> 60 ml/min
5. Performance status \> 80% (Karnofsky)
6. Hematopoietic Cell Transplantation Specific Comorbidity Index (HCT-CI) \<5 for age \< 65, HCT-CI \<4 for age \>65
7. Patients must be willing to use contraception if they have childbearing potential
8. Able to give informed consent, or their legally authorized representative can give informed consent.

Exclusion Criteria:

1. Performance status of \< 80% (Karnofsky)
2. HIV positive
3. Active involvement of the central nervous system with malignancy
4. Psychiatric disorder that would preclude patients from signing an informed consent
5. Pregnancy, or unwillingness to use contraception if they are have childbearing potential.
6. Patients with life expectancy of \< 6 months for reasons other than their underlying hematologic/oncologic disorder or complications there from.
7. Patients who have received alemtuzumab within 8 weeks of transplant admission, or who have recently received horse or rabbit anti-thymocyte globulin (ATG) and have ATG levels of \> 2 μgm/ml.
8. Patients who cannot receive cyclophosphamide
9. Patients with evidence of another malignancy (exclusive of a skin cancer that requires only local treatment);

   * Patients with prior malignancies diagnosed\> 5 years ago without evidence of disease are eligible.
   * Patients with prior malignancy treated \< 5 years ago but have a life expectancy of \> 5 years for that malignancy are eligible.
10. Uncontrolled active infection