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

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.

Inclusion criteria

• Any of the following hematologic malignancies:

• Acute myeloid leukemia (AML) in first remission with high-risk features or in second or higher remission
• Acute lymphoblastic leukemia (ALL) in first remission with high-risk features or in second or higher remission
• Myelodysplastic syndrome (MDS): transfusion-dependent, or intermediate or higher IPSS-R risk group
• Karnofsky performance status ≥ 70%
• Eligible for haploidentical stem cell transplantation according to the investigator
• Male or female, age ≥ 18 years and ≤ 65 years

Exclusion criteria

• Availability of a fully matched related or unrelated donor following a donor search
• Diffusing capacity for carbon monoxide (DLCO) < 50% predicted
• Left ventricular ejection fraction < 50% (evaluated by echocardiogram or MUGA)
• AST > 2.5 x ULN (CTCAE grade 2)
• Bilirubin > 1.5 x ULN (CTCAE grade 2)
• Creatinine clearance < 50 mL/min (calculated or measured)
• Positive HIV test
• Positive pregnancy test (women of childbearing age only)
• Prior allogeneic HSCT
• Estimated probability of surviving less than 3 months
• Known allergy to any of the components of ATIR101 (e.g., dimethyl sulfoxide)
• Known presence of HLA antibodies against the non-shared donor haplotype
• Any other condition which, in the opinion of the investigator, makes the patient ineligible for the study

Inclusion criteria

Donor:

• Haploidentical family donor with 2 to 3 mismatches at the HLA-A, -B and/or -DR loci of the unshared haplotype
• Male or female, age ≥ 16 and ≤ 75 years (If applicable, local legal requirements for donors under the age of 18 will be followed)
• Eligible for donations of human blood and blood components according to local requirements and regulations
• Eligible for donation according to the transplantation center

Exclusion criteria

Donor:

• Positive pregnancy test or nursing (women of childbearing age only)
• Positive viral test for HIV-1, HIV-2, HBV, HCV, Treponema pallidum, HTLV 1 (if tested), HTLV-2 (if tested), or WNV (if tested)