Concurrent upregulation of immune checkpoint molecule genes in colorectal cancer

Background: A simultaneous gene expression pattern of immune checkpoint molecules might exist in colorectal cancer. This hypothesis has rarely been tested in human in vivo samples. Objective: We investigated the gene expression patterns of immune checkpoint molecules in human colorectal cancer tissues using quantitative polymerase chain reaction (qPCR) with a focus on concurrent gene expression. Results: We included 14 females and 16 males with a mean age was 68.5 years. The mean number of all immune checkpoint molecules did not differ significantly between normal and tumor tissues. Histological grade 3 tumors were more common in the PDCD1-expressing group [3 (25.0%) vs. 0 (0%) (p = 0.042)]. All six and four immune checkpoint molecules were expressed in eight and three PDCD1-positive patients, respectively. Specifically, CD274 was expressed in 11 of 12 PDCD1-positive patients, while LAG3 and IDO1 were expressed simultaneously in all patients expressing CD274. Conclusion: Colorectal cancers more commonly express multiple immune checkpoint molecules simultaneously than single molecules. This suggests that blocking multiple immune checkpoint pathways may serve as a potential strategy for immunotherapy.