Haploidentical Hematopoietic Stem Cell Transplantation Using A Novel Clofarabine Containing Conditioning Regimen For Patients With Refractory Hematologic Malignancies

Inclusion Criteria: * Age less than or equal to 21 years old; may be greater than 21 years old if a previously treated St. Jude patient and within 3 years of completion of most recent prior disease specific therapy. * One of the following refractory hematologic malignancies (chemoresistant relapse or primary induction failure) or diagnoses: * ALL * AML (\>25% blasts in the bone marrow) * secondary AML/MDS * CML in accelerated phase or blast crisis * juvenile myelomonocytic leukemia (JMML) * myelodysplastic syndrome (MDS) * Hodgkin or non-Hodgkin lymphoma (NHL) with residual or recurrent disease following autologous HSCT, who are unable to undergo autologous HSCT due to chemo-resistant disease or inability to have an acceptable quantity of tumor-free stem cells collected (\> 1 x 108 TNC/kg marrow or \> 1 x 106 CD34+/kg PBS * patients with a hematologic malignancy who have undergone prior allogeneic HSCT or who have a co-morbid condition that in the medical opinion of medical faculty (Division of Bone Marrow Transplantation and Cellular Therapy) makes standard myeloablation prohibitive * Does not have any other active malignancy other than the one for which this transplant is indicated * Cardiac shortening fraction greater than or equal to 25% * For pediatric patients, creatinine clearance greater than or equal to 90 ml/min/1.73 m2 according to the Schwartz formula for estimated GFR (ml/min/1.73m2) = k\*height (cm)/serum creatinine (mg/dL). k is a proportionality constant that varies with age and is a function of urinary creatinine clearance per unit of body size; 0.45 up to 12 months of age; 0.55 children and adolescent girls; and 0.70 for adolescent boys * For adolescent or adult patients, serum creatinine 1.0 mg/dL; if serum creatinine 1.0 mg/dL, then the estimated glomerular filtration rate (GFR) must be 60 mL/min/1.73 m2 as calculated by the Modification of Diet in Renal Disease equation where predicted GFR (ml/min/1.73 m2) = 186 x (serum creatinine)-1.154 x (age in years)-0.023 x (0.742 if patient is female) x (1.212 if patient is black) * Forced vital capacity (FVC) greater than or equal to 40% of predicted value or pulse oximetry greater than or equal to 92% on room air. * Karnofsky or Lansky (age-dependent) performance score of greater than or equal to 50 (See APPENDIX A) * Does not have active acute or active chronic GVHD defined as requiring medical therapy. * Does not have active acute bronchiolitis obliterans (BO) or bronchiolitis obliterans organizing pneumonia (BOOP). * Has a suitable HLA partially matched family member donor available for stem cell donation * Bilirubin less than or equal to 1.5 times the upper limit of normal for age. * Alanine aminotransferase (ALT) less than or equal to 1.5 times the upper limit of normal for age. * Aspartate aminotransferase (AST) less than or equal to 1.5 times the upper limit of normal for age. * Not pregnant (confirmed by negative serum or urine pregnancy test within 14 days prior to enrollment). * Not lactating Inclusion criteria (stem cell donor): * Partially HLA-matched family member. * At least 18 years of age. * HIV negative * Not pregnant (confirmed by negative serum or urine pregnancy test within 14 days prior to enrollment). * Not lactating