Anti-FAP CAR-NK cells as a novel targeted therapy against cervical cancer and cancer-associated fibroblasts

Abstract

The tumor microenvironment (TME) has a central role in many cancers, particularly by fostering an immunosuppressive milieu. Chimeric antigen receptor (CAR)-based immunotherapy displays a promising strategy to re-direct immune cells toward specific antigens, thereby inducing targeted cytotoxicity. The fibroblast activation protein (FAP) is overexpressed in various cancer types and has shown promise in CAR-based therapies. However, its application in gynecological cancers remains unexplored. This study evaluates the efficacy of anti-FAP CAR-NK cells as a targeted immunotherapy for cervical cancer and cancer-associated fibroblasts (CAFs). FAP expression was quantified on cervical cancer cell lines, primary cervical cancer tissues, and cells isolated from these tissues. Alpharetroviral SIN vectors were used to transduce NK-92 cells and primary cord blood-derived NK cells with 3rd-generation anti-FAP CARs. Immunohistochemistry and flow cytometry revealed high FAP expression on CaSki cells, cervical cancer tissues, and primary cervical CAFs. In 2D co-cultures with FAP-positive target cells, anti-FAP CAR-NK cells exhibited significantly enhanced cytotoxicity and elevated degranulation compared to control NK cells, with no observed effects against FAP-negative target cells. Primary NK cells revealed high cytotoxicity against cervical cancer cells with a high release of cytolytic enzymes. Anti-FAP CAR-NK cells also showed efficient elimination of cervical cancer cells and CAFs in 3D tumor spheroid models. These findings underscore the potential of anti-FAP CAR-NK cells as a potent therapeutic approach for cervical cancer and suggest broader applicability in diseases characterized by high FAP expression.