Molecular targets for diagnostic and intraoperative imaging of pancreatic ductal adenocarcinoma after neoadjuvant FOLFIRINOX treatment

Abstract

Neoadjuvant systemic treatment is increasingly being integrated in the standard treatment of pancreatic ductal adenocarcinoma (PDAC) patients to improve oncological outcomes. Current available imaging techniques remain unreliable in assessing response to therapies, as they cannot distinguish between (vital) tumor tissue and therapy induced fibrosis (TIF). Consequently, resections with tumor positive margins and subsequent early post-operative recurrences occur and patients eligible for potential radical resection could be missed. To optimize patient selection and monitor results of neoadjuvant treatment, PDAC-specific diagnostic and intraoperative molecular imaging methods are required. This study aims to evaluate molecular imaging targets for PDAC after neoadjuvant FOLFIRINOX treatment. Expression of integrin α_vβ₆, carcinoembryonic antigen cell adhesion molecule 5 (CEACAM5), mesothelin, prostate-specific membrane antigen (PSMA), urokinase-type plasminogen activator receptor, fibroblast activating receptor, integrin α5 subunit and epidermal growth factor receptor was evaluated using immunohistochemistry. Immunoreactivity was determined using the semiquantitative H-score. Resection specimens from patients after neoadjuvant FOLFIRINOX treatment containing PDAC (n = 32), tumor associated pancreatitis (TAP) and TIF (n = 15), normal pancreas parenchyma (NPP) (n = 32) and tumor positive (n = 24) and negative (n = 56) lymph nodes were included. Integrin α_vβ₆, CEACAM5, mesothelin and PSMA stainings showed significantly higher expression in PDAC compared to TAP and NPP. No expression of α_vβ₆, CEACAM5 and mesothelin was observed in TIF. Integrin α_vβ₆ and CEACAM5 allow for accurate metastatic lymph node detection. Targeting integrin α_vβ₆, CEA, mesothelin and PSMA has the potential to distinguish vital PDAC from fibrotic tissue after neoadjuvant FOLFIRINOX treatment. Integrin α_vβ₆ and CEACAM5 detect primary tumors and tumor positive lymph nodes.

Figure 1

Overview of immunohistochemical staining. Representative images of HE (A–C), integrin α_vβ₆ (D–F), CEACAM5 (G–I), mesothelin (J–L) and PSMA (M–O) expression on normal pancreatic parenchyma, tumor induced pancreatitis and PDAC. All images are at 5 × magnification, zoom images in (C,F,I,L,O) at 40 × magnification. HE, hematoxylin eosin; α_vβ₆, integrin α_vβ₆; CEACAM5, carcinoembryonic antigen cell adhesion molecule 5; MSLN, mesothelin; PSMA, prostate-specific membrane antigen.

Figure 2

H-scores of selected molecular targets. Representative diagrams of H-scores of integrin α_vβ₆, CEACAM5, mesothelin and PSMA on tumor (PDAC), normal and tumor induced pancreatitis. H-scores were determined as described in Material and Methods. CEACAM5, carcinoembryonic antigen cell adhesion molecule 5; PSMA, prostate-specific membrane antigen.

Figure 3

Overview of immunohistochemical stainings on a tumor positive lymph node. Representative images of a metastatic lymph node stained for HE (A), integrin α_vβ₆ (B), CEACAM5 (C), mesothelin (D) and PSMA (E). All images are at 2 × magnification, zoom images at 10 × magnification. CEACAM5, carcinoembryonic antigen cell adhesion molecule 5; PSMA, prostate-specific membrane antigen.