Safety and Efficacy of Two Doses of ATIR101, a T-lymphocyte Enriched Leukocyte Preparation Depleted of Host Alloreactive T-cells, in Patients With a Hematologic Malignancy Who Received a Hematopoietic Stem Cell Transplantation From a Haploidentical Donor

The purpose of this study is to determine whether a repeat dose administration of ATIR101 is safe and effective when infused in patients with a hematologic malignancy following a T-cell depleted stem cell graft from a related haploidentical donor. All patients are planned to receive two ATIR101 doses of 2×10E6 viable T-cells/kg, unless the second dose is reduced or halted for safety reasons.

Study CR-AIR-008 is an exploratory, open-label, multicenter study. After signing informed consent, patients will receive a hematopoietic stem cell transplantation (HSCT) from a related, haploidentical donor, followed by a first ATIR101 infusion at a dose of 2×10E6 viable T-cells/kg between 28 and 32 days after the HSCT. Patients will receive a second ATIR101 infusion at a dose of 2×10E6 viable T-cells/kg between 70 and 74 days after the HSCT. To evaluate safety of the second dose administration, the first 6 patients treated will be evaluated for the occurrence of dose limiting toxicity (DLT), defined as acute GvHD grade III/IV within 120 days post HSCT (or within 42 days after the second ATIR101 infusion in case of prior dose delays). If within the first 6 patients no DLT is observed, treatment of the remaining 9 patients will continue with two ATIR101 doses of 2×10E6 viable T cells/kg. If within the first 6 patients at least 2 patients show DLT, the second ATIR101 infusion will be adjusted to a dose of 1×10E6 viable T cells/kg. If in one of the next 3 patients treated at this lower dose again DLT is observed, the second ATIR101 infusion will be halted and the remaining patients will be given only a single dose of ATIR101. All patients treated with ATIR101 will be followed up until 12 months after the HSCT. Assessments will be performed at weekly visits from the day of the first ATIR101 infusion (Week 4) until 6 weeks after the second ATIR101 infusion (Week 16), at monthly visits from 4 until 6 months after the HSCT, and every 3 months from 6 until 12 months after the HSCT.