• Patient age \< 25 years. Both genders and all races eligible.

• Disease eligibility

‣ Acute myeloid leukemia, primary or secondary - Disease status: MRD negative (flow MRD ≤ 0.1%)

⁃ Myelodysplasia

⁃ Acute lymphoblastic leukemia - Disease status: MRD negative

⁃ Chronic myelogenous leukemia - Disease status: chronic phase, accelerated phase or blast crisis now in second chronic phase

⁃ Mixed lineage or biphenotypic acute leukemia- Disease status: MRD negative

⁃ Lymphoblastic lymphoma - Disease status: in remission

⁃ Burkitt's lymphoma/leukemia - Disease status: in remission

⁃ Lymphoma after relapse - Disease status: in remission

⁃ Other malignant hematologic diseases in remission (to be approved by PI)

• Karnofsky Performance Status ≥ 60% for patients 16 years and older and Lansky Play Score ≥ 60 for patients under 16 years of age (Appendix 1)

• Evaluation of organ status as per MCW BMT SOP

• Infectious disease criteria: No active untreated infection. Patients with possible fungal infections must have had at least 2 weeks of appropriate anti-fungal antibiotics and be asymptomatic.

• Signed consent by parent/guardian or able to give consent if ≥18 years.

• Negative pregnancy test for patients capable of childbearing potential

• Sexually active patients capable of child-bearing potential must agree to use adequate contraception (diaphragm, birth control pills, injections, intrauterine device \[IUD\], surgical sterilization, subcutaneous implants, or abstinence, etc.) for the duration of treatment. Sexually active men must agree to use barrier contraceptive for the duration of treatment.

• Donor Eligibility:

• Unrelated donor meets National Marrow Donor Program criteria for donation

• Infectious disease testing

• MCW BMT procedures apply for determining donor eligibility, including donor screening and testing for relevant communicable disease agents and diseases.

• Only Peripheral blood stem cells will be used for stem cell source on this study therefore donor must be willing to undergo G-CSF mobilization and stem cell apheresis. Donor matching. High resolution typing at all loci to be performed.

• Unrelated Donor:

• a. HLA typing of at least 10 alleles is required. Donor must be matched at 9/10 or 10/10 alleles (HLA A, B, C, DRB1, DQB1).Donor and collection center willing to undergo mobilization and apheresis

• Haploidentical Related Donor:

∙ Haploidentical parent or other related donor: Minimum match level full haploidentical (at least 5/10; HLA A, B, C, DRB1, DQB1 alleles), but use of haploidentical donors with extra matches (e.g. 6, 7, or 8/10) encouraged.