Abstract 3147A: The use of the sTRA glycan for predicting responses to neoadjuvant therapy in patients with pancreatic ductal adenocarcinoma

Abstract

Abstract The sTRA glycan has been validated as a serological and cell-surface biomarker of pancreatic ductal adenocarcinoma (PDAC). In previous work, a biomarker panel using sTRA and CA19-9 performed significantly better than CA19-9 for distinguishing PDAC from benign diseases of the pancreas; here we explored whether the subgroup identified by sTRA has a different prognosis than other subgroups. We examined the plasma levels of sTRA and CA19-9 in two cohorts of patients with resectable or borderline-resectable PDAC. In each cohort, two samples per patient were collected: one prior to any therapy, and another after neoadjuvant therapy but before surgery. In the first cohort (n = 54), the ratio of post-therapy to pre-therapy plasma sTRA was statistically higher (p < 0.05, student’s t-test using logged ratios) in patients with poor response, as assessed by surgical pathology. CA19-9 had higher ratios in a subset of the poor-response subjects but without statistical significance. In the second cohort (n = 75), the pre-treatment and post-treatment levels of sTRA were significantly higher (p < 0.01, Wilcoxon Rank-Sum test) in patients with shorter survival (<2 years). In contrast, CA19-9 did not show statistical significance in the pre-treatment or post-treatment levels, but the post:pre ratios were substantially higher in a subset of the short-survival group. In both cohorts, sTRA identified a subset of poor responders that was non-identical to the one identified by CA19-9. As a result, a biomarker panel combining the markers provided better accuracy for identifying poor responders than either marker alone. In an analysis of 24 cell line models of PDAC, the cell lines that secreted sTRA had a statistically higher resistance to chemotherapy than those not secreting sTRA, whereas the cell lines secreting CA19-9 showed no such association. Therefore, pancreatic cancers that produce sTRA may be a distinct subtype with higher resistance to chemotherapy, and sTRA in combination with CA19-9 could be a valuable serological predictor of responsiveness to chemotherapy. Citation Format: Ben Staal, Ying Liu, Peter Hsueh, Mohammed Aldakkak, Herbert Zeh, Douglas Evans, Randall E. Brand, Susan Tsai, Brian B. Haab. The use of the sTRA glycan for predicting responses to neoadjuvant therapy in patients with pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3147A.