Study Evaluating the Safety and the Efficacy of Human T Lymphoid Progenitor (HTLP) Injection to Accelerate Immune Reconstitution After Umbilical Cord Blood (UCB) Transplantation in Adult Patients With Hematologic Malignancies (HTLP-ONCO)

This is an open-labelled and non-controlled Phase I/II clinical trial, evaluating the safety and the efficacy of Human T Lymphoid Progenitor (HTLP) injection to accelerate immune reconstitution after umbilical cord blood (UCB) transplantation in adult patients with hematologic malignancies. The dose limiting toxicity of HTLP injection will be evaluated using a model-based design.

Allogeneic bone marrow transplantation (AlloSCT) is the treatment of choice for high- risk acute myeloid leukemias in complete first remission after induction therapy and other high-risk hematological malignancies. Umbilical cord blood grafts are frequently used for patients lacking an HLA- matched family donor (Matched-sibling donor, MSD) as well as in the absence of an appropriate unrelated donor (10/10 MUD). As any HSCT, UCB transplantations are associated with the risk of acute and chronic GVHD, post- transplant immunodeficiency with increased risk of infections as well as relapse. Especially the risk of infection and therefore non- relapse mortality (NRM) or transplant- related mortality (TRM) is significantly higher in UCB transplantations as compared to MSD or 10/10 MUD transplantations. All of these risks have been linked to a significant delay in immune reconstitution including various immune cell populations like CD4 and CD8 T cells, Treg, NK, iNKT, pDC and others. The investigators therefore make the hypothesis that if T-cell-mediated immunity was rapidly generated after a partially HLA-compatible UCB transplantation will reduce the risk of infection and to prevent relapse without increasing the risk of GVHD.