Abstract B012: TP53 missense mutations and keratin 17 are negative prognostic biomarkers in pancreatic ductal adenocarcinoma

Abstract

Abstract Background: Cancer patients with similar clinical and pathologic characteristics may have different responses to treatments and survival, which may be attributable to distinct molecular properties of their tumors. In pancreatic ductal adenocarcinomas (PDACs), there is a pressing need to identify prognostic biomarkers that could help us to predict disease progression and patient survival. Our group previously reported that keratin17 (K17) expression is a hallmark of PDACs of patients with the shortest patient survival. Furthermore, there is some evidence suggesting that missense mutations in TP53 are associated with worse survival in patients with PDAC. To date, however, no studies have addressed the differential prognostic value of molecular characterization of TP53 coupled with K17 expression for predicting survival in patients with PDAC. Objective and methods: To fill this gap, we assessed the effect of different TP53 mutations and K17 expression on patient survival, using a clinically annotated cohort of 128 patients containing molecular profiling on patient tumors. K17 Immunohistochemistry (IHC) staining on patient’s formalin-fixed, paraffin-embedded (FFPE) tissue blocks were performed to assess the expression of this marker in tumor cells. K17 IHC scoring was conducted based on a subjective assessment of the overall proportion of stained cells relative to the overall number of tumor cells present in a single representative section from each case. Kaplan-Meier and Cox proportional hazards regression models were analyzed to determine survival differences of patients with PDACs harboring different TP53 mutations and levels of K17 IHC expression, adjusting for patient demographics (age at diagnosis, sex, race/ethnicity) and tumor characteristics (presence of distant metastasis at diagnosis). Results: Tumors were classified as high for K17 when ≥90% of tumor cells showed strong staining. High-K17 cases (n=16;12.50%) had shorter survival compared with low-K17 cases (n=112; 87.50%) (26.80 vs. 16.77 months; P=0.035). The majority of cases harbored missense mutations in TP53 (42.19%), while about one-third harbored truncating TP53 (27.34%) mutations. We found that PDACs with missense TP53 mutations and high K17 were associated with worse patient survival compared to tumors with missense TP53 and low K17 expression (HR=5.27; 95% CI, 1.76-15.82; P=0.003). Similarly, compared with patients with wild-type TP53 and low K17, patients with both missense TP53 mutations and high K17 had significantly worse survival (HR=3.51, 95% CI, 1.45-8.51; P=0.005). Conclusions: Our findings suggest that molecular characterization of specific TP53 mutations coupled with K17 IHC staining may help to determine differences in patient prognosis and identify subgroups with worse patient survival, therefore, potentially guiding future clinical management of patients. Citation Format: Carlos Mauricio Mejia Arbelaez, Gabriella Baraks, Lyanne Oblein, Michael Horowitz, Lynn Matrisian, Kenneth Shroyer, Luisa Fernanda Escobar-Hoyos. TP53 missense mutations and keratin 17 are negative prognostic biomarkers in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B012.