Leucine Zipper-based Cell Sorting for Purification of Dual-vector-transduced Cells

Adoptive T cell therapies, including chimeric antigen receptor (CAR) T cells, have demonstrated impressive clinical activity against hematologic malignancies and are showing promise in treating solid tumor malignancies. Despite these successes, multiple mechanisms of resistance to T cell immunotherapy have been identified that limit therapeutic success, including loss of or weak expression of target antigens, development of T cell exhaustion, and the presence of an immunosuppressive tumor microenvironment. Multiple cell engineering strategies have been developed to overcome these mechanisms of resistance. However, multiple mechanisms of resistance can occur simultaneously, necessitating a combination of multiple engineering strategies to optimize anti-tumor activity. Vector packaging constraints limit the delivery of large amounts of genetic information to T cells and present a challenge in co-expressing multiple engineered constructs. Here, we describe a protocol for co-transducing T cells with two vectors to encode multiple transgenes, thereby increasing the number of engineered functions. By co-expressing a leucine zipper-based cell sorting methodology, termed Zip-sort, we direct selective immunomagnetic purification of dual-transduced cells that have incorporated two distinct vectors.