Dufort, F. J. | Search bioRxiv

bioRxiv2024

Conditional activation of NK cell function using chemically synthetic constrained bicyclic peptides directed against NKp46 and tumor-expressed antigens

Natural killer (NK) cells have the unique potential to recognize and kill tumor cells independently of MHC-I presentation of antigens, as well as to secrete cytokines that engage adaptive anti-tumor immunity and the function of cytolytic T cells. We have discovered and characterized chemically synthetic, constrained bicyclic peptides that bind with high affinity and specificity to NKp46, an activating receptor expressed selectively on NK cells in the tumor microenvironment. Chemical coupling to other bicyclic peptides specific for the tumor antigens EphA2 or MT-1 created NKp46 agonists whose function was completely conditional on binding to the tumor antigen. These chemical conjugates effectively convert the tumor antigen into a "kill me" signal for NK cells. Not only did these newly created tumor-immune cell agonists (TICAs) direct potent and efficient killing of human tumor cells by primary human NK cells in vitro, but they also caused secretion of the pro-inflammatory cytokines TNF and IFN{gamma}. Importantly, the TICAs directed production of FLT3 ligand, an essential mitogen for conventional dendritic cells which are central to the development of anti-tumor immunity in cancer. We illustrate the TICA-directed interaction of NK cells with tumor cells using confocal microscopy and we show that TICAs enable sustained function over multiple rounds of killing. These novel tools are well positioned to harness the potential of NK cells in the treatment of cancer.

cancer biology↗

bioRxiv2020

CD19-targeting CAR T cells potently redirected to kill solid tumor cells

Successful CAR T cell therapy for the treatment of solid tumors requires exemplary CAR T cell expansion, persistence and fitness, and the ability to target tumor antigens safely. Here we address this constellation of critical attributes for successful cellular therapy by using integrated technologies that simplify development and derisk clinical translation. We have developed a CAR-CD19 T cell that secretes a CD19-anti-Her2 bridging protein. This cell therapy strategy exploits the ability of CD19-targeting CAR T cells to interact with CD19 on normal B cells to drive expansion, persistence and fitness. The secreted bridging protein potently binds to Her2-positive tumor cells, mediating CAR-CD19 T cell cytotoxicity in vitro and in vivo. Because of its short half-life, the secreted bridging protein will selectively accumulate at the site of highest antigen expression, ie. at the tumor. Bridging proteins that bind to multiple different tumor antigens have been created. Therefore, antigen-bridging CAR-CD19 T cells incorporate critical attributes for successful solid tumor cell therapy. This platform can be exploited to attack tumor antigens on any cancer.

cancer biology↗