Enhanced gene editing strategies for the next generation of T cell therapies

T cell gene therapies (GT) including CD19 chimeric antigen receptor T cells (CAR-T) have dramatic results in haematological malignancies. Expansion and persistence are driven by abundant target expression on malignant and normal B cells. However, similar clinical efficacies have not been replicated for non-malignant indications and solid tumours. I hypothesise that "epitope engineering” gene editing of T cell surface protein (e.g. CD52) epitopes, targeted by monoclonal antibodies (mAb) such as alemtuzumab could be used to selectively protect engineered T cells following mAb administration. Single amino acid substitutions generated with base editing could abrogate mAb binding whilst preserving protein function. T cells would be conferred with a transient selective advantage in the presence of mAb. I hypothesise that this approach will improve two aspects of T cell GT: For ex vivo manufactured therapies, this approach will facilitate less toxic antibody-mediated lymphodepleting conditioning and, in disease settings lacking abundant antigenic stimulus (e.g. solid tumours and autoimmune diseases), improve T cell expansion and persistence. For in vivo genetic modification of T cells (directly in the body), I hypothesise that epitope engineering will improve in vivo editing frequencies, via selective expansion, to biologically relevant frequencies thus transforming the translational potential of T cell GT.