Optimization of a T cells education protocol to treat hematological cancers

Abstract Allogeneic hematopoietic stem cell transplantation is the sole curative treatment for patients with high-risk hematological cancers. Most of its activity relies on the ability of engrafted T cells to recognize minor histocompatibility antigens (MiHAs) expressed on malignant cells resulting in their elimination. However, donor lymphocytes can also recognize MiHAs expressed on non-hematopoietic cells leading to graft-versus-host disease. Hence, the expansion of T lymphocytes displaying potent cytotoxic activity toward MiHA(s) preferentially expressed on leukemic cells would be greatly beneficial for engrafted patients. Using a proteo-genomic approach, novel MiHAs that are predominantly expressed on hematopoietic cells have been identified. We previously showed that these novel MiHAs can be exploited for ex vivo expansion of the antigen specific T cells. However, the frequencies of these MiHA specific T cells are extremely low. Thus it is challenging to generate an optimal ex vivo expansion of antigen specific T cells to a single MiHA. In this context, we aim to improve this complex manufacturing process by using simultaneously multiple MiHAs to enhance the probability of obtaining response to at least one MiHA. This approach allowed us to expand T cells populations with distinct MiHAs specificities. Further, upon restimulation, MiHA specific T cells express high levels of inflammatory cytokines Interferon-γ and Tumor Necrosis Factor-α thus suggesting their functionality. In conclusion, multipeptide T cell stimulation allows for simultaneous expansion of functional T cells specific for several MiHA. This could be translated in improved therapeutical approach reducing the probability of immune escape of malignant cells.