GRP78 expression and clinical outcomes in pancreatic cancer: A single institution review.

Abstract

e16767 Background: Pancreatic Ductal Adenocarcinoma (PDAC) has one of the lowest 5-year survival rates of all cancers. Poor prognosis can be attributed in part to late detection and chemoresistance. Perioperative chemotherapy with or without radiation is the standard treatment for resectable PDAC, however recurrence rates remain high. GRP78 (HSPA5/BiP) is an endoplasmic reticulum (ER) chaperone protein involved in regulation of the ER stress response that leads to pro-survival pathway activation and chemoresistance in tumor cells. Prior studies of suppression of GRP78 expression in PDAC cell lines led to increased pancreatic cell apoptosis in response to gemcitabine. In vivo studies of human PDAC xenografts showed that tumors with higher GRP78 expression were associated with increased chemoresistance. Methods: We conducted a single institution retrospective review of 53 patients who underwent resection of PDAC from 1/1/2009-7/1/2016. Archived tumor tissue expression of GRP78 was assessed by immunohistochemistry (IHC) and scored as 0-3+. GRP78 IHC scores of 0-1+ were categorized as low and scores of 2-3+ as high. Corresponding clinical data were collected. Adjusted effects of GRP78 expression on the hazard of treatment failure or death were estimated using Cox proportional hazards models. Type III Wald Chi-square p-values are reported for the overall effect in each model. Results: GRP78 expression level demonstrated a significant effect on disease free survival (DFS) in unadjusted analyses (HR 2.00, p = 0.05), as well as after adjusting for performance status (p = 0.03), initial overall stage (p = 0.05), pathological tumor stage (p = 0.02), pathological node stage (p < 0.01), resection margins (p = 0.05), and neoadjuvant therapy (p = 0.05) in separate models. In unadjusted analysis, high GRP78 expression showed a trend towards worsened overall survival (OS), but did not reach statistical significance (HR 1.8, p = 0.11). The effect on OS was significant when adjusting for pathological tumor stage (p = 0.04) and pathological node stage (p = 0.01). (575). Conclusions: Consistent with prior animal studies, our retrospective review revealed that high GRP78 expression was associated with worsened DFS in patients with resectable PDAC. When adjusting for pathological staging, high GRP78 expression had a similar impact on OS. These findings warrant further evaluation of the role of GRP78 in prognosis, response to therapy and as a potential treatment target.