APJ Is Associated with Treatment Response in Gastric Cancer Patients Receiving Concurrent Chemoradiotherapy and Endostar Therapy.

BACKGROUND Endostar combined with concurrent chemoradiotherapy (CRT) has been used in patients with gastric cancers (GCs). However, there are no reliable markers to predict the treatment response and prognosis of these patients. Apelin and its receptor (APJ) are involved in angiogenesis in tumor tissues. We aimed to study whether Apelin and Apelin receptor (APJ) tumor expression can predict the treatment response of combination therapy of endostar and CRT. MATERIALS AND METHODS We enrolled patients with locally advanced GC receiving CRT only and CRT+endostar combination therapy. Apelin receptor (APJ) in tumor samples was determined by immunohistological staining and scored by measuring staining area and signal intensity. RESULTS The high APJ expression has significantly higher rates of tumor invasion, local lymph node, and distant metastasis (all p < 0.001). In the CRT only group, the distribution of high and low APJ expression in patients with good and poor treatment response to CRT is not significantly different (p = 0.235). However, in the CRT+endostar group, the chance of having poor response to combined treatment is 3.645-fold higher in those having high APJ expression levels than those who have low APJ expression levels. Our prognostic analysis shows that in the CRT+endostar group, high APJ expression had significantly shorter overall survival (OS) period than those with low APJ expression (p < 0.001). Furthermore, multivariate survival analysis reveals that the APJ expression is an independent predictor for the OS period in GC patients treated with CRT+endostar. CONCLUSION Tumor APJ can be used to predict the therapy response and prognosis in GC patients receiving CRT+endostar therapy.