BSB-1001 in Patients Undergoing HLA-Matched Allogenic Hematopoietic Stem Cell Transplant for AML, ALL or MDS

This is a first-in-human, multicenter, open-label, dose-finding study for the evaluation of an HA-1 minor histocompatibility antigen (miHA)-reactive TCR-modified T cell product (BSB-1001) derived from an HLA-matched allogenic donor, in patients with AML, ALL or MDS undergoing an HLA-matched alloHSCT who are at a high risk for relapse post-HSCT. BSB-1001 targets the HLA-A\*02:01-restricted HA-1 miHA. Enrolled patients must be HLA-A\*02:01 and HA-1-positive (H/H or H/R), with an identified HLA-matched, HA-1-negative (R/R) donor. Patients will undergo one of the following myeloablative conditioning regimens, according to standard institutional procedures, which include either fludarabine+thiotepa+total body irradiation, or busulfan+ melphalan+ fludarabine. After conditioning is completed, patients will receive the CD34-selected alloHSCT followed by BSB-1001 on day 0, without any prophylactic immunosuppression. The study is an adaptive dose escalation design with 1 to 3 cohorts to evaluate single doses of BSB-1001. Three to six patients will be enrolled in each cohort and enrolled patients will be followed until completion of the study. If the maximum tolerated dose (MTD) is reached or if a dose is deemed promising, the Sponsor may determine to either cease enrollment or open an expansion cohort at the desired dose level. The optional expansion part of the study is planned to include approximately 20 additional AML patients at the recommended dose.