Objectives: Immune therapy targeting cancer/testis (CT) antigens improve the survival in several types of solid tumours. The expression of CT antigens is related to poor survival in non-small-cell lung cancer (NSCLC). The epidermal growth factor receptor (EGFR) mutation is the best predictive factor for the sensitivity to tyrosine kinase inhibitors in lung adenocarcinoma. The aim of this study was to elucidate the correlation between the expression of CT antigens and clinicopathological factors, including the EGFR mutation, and to analyse the prognosis in lung adenocarcinoma.
Methods: Data were collected from a total of 281 lung adenocarcinoma patients who underwent surgery. Among them, 125 cases, whose specimens were too small to extract sufficient DNA and/or RNA, and 2 cases with the coexistence of another histological lung cancer were excluded. A total of 154 patients were reviewed. The expression of CT antigens (melanoma-associated antigen gene [MAGE]-A4 and KK-LC-1) and the EGFR-activating mutation (L858R point mutation in exon 21 and inframe deletion in exon 19) was evaluated by using polymerase chain reaction amplification.
Results: The expression of MAGE-A4 and KK-LC-1 was detected in 14 (9%) and 54 patients (35%) with adenocarcinoma. The EGFR-activating mutation was found in 64 patients (42%). Univariate and multivariate analyses demonstrated that tumours expressing at least one CT antigen were associated with no EGFR mutation (odds ratio = 0.3; 95% confidence interval, 0.14-0.71; P < 0.01). A survival analysis was performed in 135 patients who underwent complete resection and the 5-year overall survival rate was 71.1% in those with any expression of CT antigens and 83.2% in those without expression of the genes (P < 0.04).
Conclusion: Two different therapeutic targets, EGFR-activating mutation and CT antigen, have a negative relationship with each other.