Inclusion of Strep-tag II in design of antigen receptors for T-cell immunotherapy

Adoptive transfer of chimeric antigen receptor (CAR) and T cell receptor (TCR)-engineered T cells has shown striking efficacy for the treatment of particular human malignancies1–5. Current approaches administer cell products comprising a mixture of transduced and non-transduced T cells, and expression of introduced receptors on T cells is variable. Ideally, engineered receptors would be designed to facilitate purification or selective expansion of receptor bearing T cells and enable thei in vivo tracking and reisolation for functional analysis. Here we design such multifunctional receptors through incorporation of modified Strep-tag II sequences at various locations in the extracellular region of the CAR or TCR (Strep-tag CAR; Strep-tag TCR)6. We selected Strep-tag II to evaluate as a receptor intrinsic marker because binding reagents for Strep-tag are used in clinical cell processing7.