A carcinoembryonic antigen-specific cell therapy selectively targets tumor cells with HLA loss of heterozygosity in vitro and in vivo

gene product carcinoembryonic antigen (CEA) is an attractive target for colorectal cancer because of its high expression in virtually all colorectal tumors and limited expression in most healthy adult tissues. However, highly active CEA-directed investigational therapeutics have been reported to be toxic, causing severe colitis because CEA is expressed on normal gut epithelial cells. Here, we developed a strategy to address this toxicity problem: the Tmod dual-signal integrator. CEA Tmod cells use two receptors: a chimeric antigen receptor (CAR) activated by CEA and a leukocyte Ig-like receptor 1 (LIR-1)-based inhibitory receptor triggered by human leukocyte antigen (HLA)-A*02. CEA Tmod cells exploit instances of HLA heterozygous gene loss in tumors to protect the patient from on-target, off-tumor toxicity. CEA Tmod cells potently killed CEA-expressing tumor cells in vitro and in vivo. But in contrast to a traditional CEA-specific T cell receptor transgenic T cell, Tmod cells were highly selective for tumor cells even when mixed with HLA-A*02-expressing cells. These data support further development of the CEA Tmod construct as a therapeutic candidate for colorectal cancer.