Abstract C064: Prognostic impact of an immunomorphological signature integrating immune, fibroblast and tumor markers in a series of 217 patients operated on for pancreatic adenocarcinoma

Abstract An integrative approach taking into consideration the tumor microenvironment, in particular cancer-associated fibroblasts (CAFs) and tumor-infiltrating lymphocytes (TILs) and its interaction with tumor cells offers a more precise reflect of pancreatic ductal adenocarcinomas (PDACs) biology. In this setting, an immunomorphological signature established from bioinformatics data could thus represent an attractive approach. Moreover to molecular signatures, on which there is still no consensus. This study aimed to evaluate the prognostic value of a panel of morphological and immunohistochemical (IHC) markers on the immune, fibroblastic and epithelial contingents of PDACs for overall (OS) and relapse-free (RFS) survival. Two hundred and seventeen patients operated for PDAC between 2000 and 2017 were included for a tissue microarray (TMA) analysis. A panel of antibodies and special stains was selected based on a previous bioinformatics study (under review) literature data. Slides were digitized and lymphocytes expressing CD3, CD8 and CD20 were quantified. A pixel classifier was used to assess the percentage of collagen and fibroblasts expressing anti-LRRC15, HSP47, α-SMA and FAP antibodies involved in the stroma reaction. Due to the co-marking of stromal and epithelial cells of PTK7 and β-catenin, respectively implicated in embryogenesis and the canonical Wnt pathway, these markers were interpreted semi-quantitatively in a double-blind fashion. After dichotomization using the maximized log-rank method, the association of these parameters with OS and RFS was assessed by univariate and multivariate Cox models. Five years after surgical resection, 26 patients (12.0%) were free of recurrence and 56 (25.8%) were alive. In multivariate analysis, the following parameters were associated with reduced OS and RFS: poor differentiation, lymph node ratio greater than 0.2, loss of tumor β-catenin on tumor cells, a low density of tumor-infiltrating CD3 T lymphocytes and a high percentage of HSP47 fibroblasts. Reduced OS was also associated with an age greater than 65 years at the time of surgery and the absence of adjuvant treatment. In order to evaluate the joint effects of the three tumor compartments markers independentely related to OS and RFS (β-catenin, HSP47, CD3), we grouped them into 3 classes (0/1+, 2+, 3+) according to the number of good prognosis criteria (class 3+ with the greatest number of good prognosis criteria). The multivariate analysis shows an additive effect of these parameters in OS and RFS compared to class 3+ patients. These data underline the interest of simultaneously characterizing the three epithelial, immune and fibroblastic compartments in PDAC. Furthermore, we highlight for the first time the prognostic impact of HSP47 by immunohistochemistry and confirm the β-catenin one. This tissue approach with an IHC panel studied on an operating specimen could be a first step towards applicability on biopsies and lead to a better patient stratification in a therapeutic setting. Citation Format: Franck Monnien, Chloé Molimard, Marine Abad, Marie-Paule Algros, Sophie Félix, Nikolaus Zirganos, Bruno Heyd, Angélique Vienot, Christophe Borg, Frédéric Bibeau. Prognostic impact of an immunomorphological signature integrating immune, fibroblast and tumor markers in a series of 217 patients operated on for pancreatic adenocarcinoma [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer; 2022 Sep 13-16; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2022;82(22 Suppl):Abstract nr C064.