Bispecific antibody activated T cells: A newly developed T cells with enhanced proliferation ability and cytotoxicity

Adoptive cell therapy using ex vivo expanded lymphocytes has shown remarkable efficacy in tumor immunotherapy recently. Among various transfused immune cells, T lymphocytes are the most widely used since they are critical mediators of the immune system and have the capacity to kill tumor cells. However, there are drawbacks in the expanded T cells for transfusion including limited cytotoxicity, limited proliferation and lack of specificity. To improve the quality of these ex vivo expanded T cells, we have designed a new method to expand a group of T cells which are named bispecific antibodies activated T cells. It is the first time that such cells are induced by introducing the bispecific antibody drug (blinatumomab) and feeder cells (normal B cells and irradiated B cell originated lymphoma cells) to the traditional T cells culture system. Culture of freshly isolated human peripheral blood mononuclear cells in this newly designed cell culture system enabled these expanded T cells that (a) displayed a robust proliferation ability; (b) showed fully activated phenotype and enhanced cytokines production; (c) had a low proportion of CD4⁺CD25⁺ T regulatory cells and (d) exhibited strengthened cytotoxicity at relatively low effector: target ratios. This work further confirmed the feasibility of rapid induction and expansion of large amounts of human T cells in vitro by using bispecific antibodies and feeder cells. This strategy could also be used for other immune cells rapid expansion and help to improve the quality of these expanded immune cells for adoptive transfusion.