Factors Affecting Post-transplant Cyclophosphamide (PTCy) Efficacy

Inclusion Criteria Recipients and donors must meet all of the following applicable inclusion criteria to participate in this study: 1. Informed consent and HIPAA authorization for release of personal health information signed by the subject. 2. Age ≥ 18 years at the time of consent. 3. Subject is scheduled as a recipient or respective donor (Donor consent/participation is not required for subjects undergoing matched unrelated donor HCT) for the following hematopoietic stem cell transplants (HCT) procedures using a non-myeloablative regimen at Levine Cancer Institute (LCI), and has been deemed a qualified candidate by his/her physician, per LCI medical standards: haplo-identical donor HCT, match related donor (MRD) HCT, matched unrelated donor (MUD) HCT. 4. Recipient only: Planned post-transplant cyclophosphamide 5. As determined by the enrolling physician, ability of the subject to understand and comply with study procedures for the entire length of the study Exclusion Criteria Subjects meeting any of the criteria below may not participate in the study: 1. Recipient only (applies only to haplo-identical and MRD HCT recipients; not required for MUD HCT recipients): Does not have a respective donor who is willing to sign informed consent for participation in this study. 2. Recipient only: Treatment with any investigational drug within 30 days prior to day -6 of treatment 3. Donor only (applies only to haplo-identical and MRD HCTs; donor participation is not required for MUD HCTs): Does not have a respective recipient who is willing to sign informed consent for participation in this study.