Cancer/testis antigens (CTAs) are a group of proteins ectopically expressed in a wide range of cancer types. The highest frequency of CTAs is found in non-small-cell lung cancer (NSCLC), ovarian cancer and melanoma. Because of their cancer specificity and immunogenic features, CTAs serve as potential targets for highly specific immunotherapy and cancer elimination.
In a previous study1, 90 CTAs were identified based on a systematic approach using quantitative transcriptomics of tissues from 199 NSCLC patients compared to 142 normal tissues corresponding to 32 different organ sites. The CTAs were defined as having at least 5 times higher gene expression in NSCLC than any other tissue (excluding testis and placenta), and expression in at least in 2% of NSCLC cases. Thirty-five of the CTAs have previously been reported in the CTdatabase resource, while the remaining 55 were defined as novel CTAs. Here, we performed an in-depth evaluation of the CTA landscape of NSCLC by further analysis of the 90 CTAs on the protein level. The CTAs were categorized based on previous literature, level of protein existence (PE status) and cell type-specific expression using Human Protein Atlas immunohistochemistry data2. Ten CTA targets were chosen for further characterization by immunohistochemistry on a well-characterized NSCLC cohort to link the CTA protein profiles to both clinical and survival data, mutation pattern (82 genes) as well as nine different in situ immune profiles (PD-L1, CD4, CD8, FOXP3, CD45Ro, CD20, CD138, CD163 and Npk146). This in-depth characterization provides a unique opportunity for extending the knowledge of CTAs in lung cancer and identification of novel potential targets for immunotherapy in NSCLC.