Use of T-allo10 in Hematopoietic Stem Cell Transplantation (HSCT) for Blood Disorders

Patients ages 3-30 years, with hematologic malignancies undergoing mismatched related or unrelated donor transplant will receive conditioning chemotherapy with Total body radiation and cyclophosphamide, according to the standard procedure. The investigators plan to infuse the donor T-allo10 product one day before HSCT so that the Tr1 cells contained within the T-allo10 product will be able to prevent anti-host alloreactivity of the T cells present within the unmanipulated HSC graft. Indeed, Tr1 cells best exert their suppressive activity at the time of effector T cell activation, occurring when the T cells present in the HSC graft will be transferred to the patient ; therefore, the investigators expect that the early infusion of T-allo10 cells will optimally modulate anti-host alloreactivity of the donor T cells and prevent GvHD. Immunosuppression will also be administered at the time of HSCT. Up to 27 eligible patients will be given the T-allo10 product sequentially in 3 escalating dose cohorts to determine the maximum tolerated dose (or the highest dose tested if no maximum tolerated dose is reached). Each cohort will begin by evaluating 3 patients. The patients in each cohort will be staggered by 28 days and each succeeding patient will be enrolled no sooner than the 29 day after the preceding patient's infusion of T-allo10. * If no patient in a cohort develops a dose limiting toxicity (DLT) following infusion of the investigational cellular product, the investigators will start enrolling patients at the next higher cell dose after completing the 28-day safety evaluation of the 3rd patient in the dose cohort. * If one out of 3 patients in a cohort has a DLT, 3 additional patients will be evaluated at the same dose level. * If one out of 6 patients experiences a DLT, dose escalation will occur. * If 2 out of ≤ 6 patients experience a DLT, dose escalation will cease and that dose will be designated the maximally administered dose. * Up to three (3) additional patients will be entered at the next lowest dose level if only 3 patients were treated previously at that dose