Expression and clinical significance of placenta-specific 1 in pancreatic ductal adenocarcinoma.

The limited efficacy of conventional therapies for pancreatic ductal adenocarcinoma has led to the growing interest for identifying potential antigenic targets for immunotherapy. Placenta-specific 1 (PLAC1) is a new member of cancer-testis antigens with restricted expression in normal tissues. Ectopic activation of PLAC1 has been found in different types of cancers, but its role in pancreatic ductal adenocarcinoma remains unknown. This study evaluated the protein expression of PLAC1 and its clinical significance in pancreatic ductal adenocarcinoma. We examined PLAC1 expression in 93 pancreatic ductal adenocarcinoma samples by immunohistochemistry. The expression of PLAC1 was detected in 41 (44.1%) patients. Among patients' clinicopathological characteristics, PLAC1 expression was only significantly correlated with tumor differentiation (p = 0.028). Univariate analysis revealed that PLAC1 expression (p = 0.016) and tumor differentiation (p = 0.003) were significantly correlated with poor survival in the whole cohort. Subgroup analysis showed that PLAC1 expression was an independent prognostic biomarker in the perineural invasion positive subgroup (p < 0.05). This study demonstrated that the protein expression of PLAC1 was significantly associated with decreased overall survival in patients with pancreatic ductal adenocarcinoma, indicating that it was a valuable prognostic marker for pancreatic ductal adenocarcinoma and might be a potential target for immunotherapy.