Evaluation of tumour biomarkers associated with invasion, metastasis and immune escape in cats with exocrine pancreatic carcinoma.

In humans and cats, pancreatic carcinoma (PC) arising from the exocrine pancreas is considered an aggressive cancer associated with a poor prognosis due to its high metastatic rate. The aim of this retrospective multi-institutional study was to investigate tissue expression of biomarkers of tumour invasiveness, metastasis and immune escape in cats with PC. A secondary aim was to correlate the overall immunohistochemical scores (OISs) with histological characteristics, presence of metastasis and survival. Immunohistochemistry for COX-2, E-cadherin, CD44, c-KIT and PD-L1 was performed on 40 PC tissue samples. CD44 was expressed in all PCs with 27 (67 %) having a moderate to high OIS. PD-L1, E-cadherin, COX-2 and c-KIT expression was seen in 20 (50 %), 21 (52 %), 18 (45 %) and 14 (35 %) cases, respectively, with predominantly low OISs. Metastasis was present in 43 % of cats with a median survival time (MST) of 7 days (95 % CI 0-20; range, 1-1,094) and a 1-year survival rate of 13.8 %. When excluding cats that died or were euthanized at diagnosis, the MST was 19 days (95 % CI 0-99; range, 2-1,094). No statistical associations were found between COX-2, E-cadherin, PD-L1, CD44 or c-KIT OIS and histological subtype, necrosis, vascular invasion, mitotic count, presence of metastasis or survival. Positive E-cadherin expression was significantly associated with the presence of perineural invasion (P = 0.009; OR 1.50 [95 % CI 1.11-2.03]).