Inclusion Criteria for Transplant Recipient:

          -  Age less than or equal to 21 years.

          -  Any of the following hematologic malignancies that has relapsed or remains refractory
             after prior allogeneic HCT (this includes any stage of disease - such as refractory
             due to induction failure, refractory in relapse, or in any CR - as long as the
             hematologic malignancy remained persistent or returned after a previous allogeneic
             HCT):

               -  ALL, AML, Myeloid Sarcoma, CML, Juvenile myelomonocytic leukemia (JMML),
                  myelodysplastic syndrome (MDS), non-Hodgkin lymphoma (NHL)

          -  Has a suitable single haplotype matched (≥ 3 of 6) family member donor.

          -  Does not have any other active malignancy other than the one for which this transplant
             is indicated.

          -  If prior CNS leukemia, it must be treated and in CNS CR

          -  Does not have current uncontrolled bacterial, fungal, or viral infection.

          -  There is no minimum time from the previous transplant, but patients must meet the
             following criteria:

               -  Left ventricular ejection fraction > 40%, or shortening fraction ≥ 25%.

               -  Creatinine clearance (CrCl) or glomerular filtration rate (GFR) ≥ 50
                  ml/min/1.73m2.

               -  Forced vital capacity (FVC) ≥ 40% of predicted value; or pulse oximetry ≥ 92% on
                  room air if patient is unable to perform pulmonary function testing.

               -  Karnofsky or Lansky (age-dependent) performance score ≥ 50 (See Appendix A).

               -  Bilirubin ≤ 3 times the upper limit of normal for age.

               -  Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) ≤ 5 times the
                  upper limit of normal for age.

               -  Not pregnant. If female with child bearing potential, must be confirmed by
                  negative serum or urine pregnancy test within 14 days prior to enrollment.

               -  Not breast feeding

        Inclusion Criteria for Haploidentical Donor:

          -  At least single haplotype matched (≥ 3 of 6) family member

          -  At least 18 years of age.

          -  HIV negative.

          -  Not pregnant as confirmed by negative serum or urine pregnancy test within 14 days
             prior to enrollment (if female).

          -  Not breast feeding.

          -  Regarding donation eligibility, is identified as either:

               -  Completed the process of donor eligibility determination as outlined in 21 CFR
                  1271 and agency guidance; OR

               -  Does not meet 21 CFR 1271 eligibility requirements, but has a declaration of
                  urgent medical need completed by the principal investigator or physician
                  sub-investigator per 21 CFR 1271.