Abstract C063: Keratin 17 as a predictor of chemotherapy response in pancreatic ductal adenocarcinoma

Abstract

Abstract Background: Two chemotherapies based on either gemcitabine- or 5-fluorouracil (5-FU) remain standard-of-care for pancreatic ductal adenocarcinomas (PDACs). Patients, however, differ in response and thus many clinical trials for experimental drugs have failed. Therefore, there is an urgent need to establish clinically deployable and rapid biomarkers to decide the best chemotherapeutic regimen for subgroups of patients and prevent toxic side effects. We previously reported that keratin 17 (K17) expression, detected at either the level of messenger RNA or protein by immunohistochemistry (IHC), is as accurate as molecular subtyping to identify subgroups of PDAC patients with shortest survival. In this work, we determined the predictive value of K17 testing for both chemotherapeutic approaches to treat PDAC. Methods: We profiled keratin 17 (K17) expression, a hallmark biomarker of the basal molecular subtype of PDAC, using immunohistochemistry in two cohorts of formalin-fixed paraffin-embedded PDACs (total n=305). These cases were collected through the Know Your Tumor® initiative and three high-volume treating institutions in the U.S. We performed multivariate predictive analyses and determined the threshold to define positive vs negative test. Results: Patients with advance stage disease, low K17, and treated with 5-FU- chemotherapy had three-times longer survival rates compared to counterparts treated with gemcitabine-based chemotherapy. These results contrast to those found in cases with high K17, where no differences were seen with either regimen. Based on RECIST, 72% of low K17 cases responded to treatment compared to 24% of high K17 cases. Predictive value of K17 was independent of mutation status and clinical variables. Conclusions: Our findings indicate that 5-FU-, rather than gemcitabine- based therapies are more likely to extend survival for patient's tumors expressing low rather than high K17. A K17 IHC test rapid test in PDACs has been patented (US11,092,603) and it is currently being tested in prospective phase II clinical trials (NCT04469556, NCT02047474 and NCT03991962). Results from these trials will test the presented findings. Citation Format: Lyanne Oblein, Lucia Roa, Sruthi Babu, Michael Horowitz, Emanuel Petricoin, Lynn M. Matrisian, Edik Blais, Natalia Marchenko, Felicia Allard, Ali Alkalin, Wei Jiang, Brent Larson, Andrew Hendifar, Vincent Picozzi, Minsig Choi, Luisa Escobar-Hoyos, Kenneth Shroyer. Keratin 17 as a predictor of chemotherapy response 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 C063.