Clinical development of tacrolimus-resistant regulatory T cells to enable simultaneous immunosuppression and support of immune regulation

Adoptive transfer of regulatory T cells (Tregs) offers a strategy to restore immunological balance and reduce long-term adverse effects of generalized immunosuppression. However, while Tregs can potently inhibit incipient immune activation, they struggle to suppress established memory effector T cells, necessitating the continued use of immunosuppression.

Calcineurin inhibitors such as Tacrolimus effectively control both, newly activated and pre-existing effector-T-cells, but unfortunately, they also impair Treg function. Therefore, we hypothesized that gene-editing of Tregs inducing Tacrolimus resistance (FKBP12KO) would enable combined therapy that curbs effector T-cell responses without compromising Treg efficacy. Here, we developed FKBP12KO-Tregs using a ribonucleoprotein-based CRISPR/Cas9 approach and characterized them extensively in-vitro.