PD-L1 expression in pancreatic adenosquamous carcinoma: PD-L1 expression is limited to the squamous component

• Published in: Pathology, research and practice research and practice, 2018-12, Vol.214 (12), p.2069-2074
• Main Authors: Tanigawa, Masahiko, Naito, Yoshiki, Akiba, Jun, Kawahara, Akihiko, Okabe, Yoshinobu, Ishida, Yusuke, Ishikawa, Hiroto, Hisaka, Toru, Fujita, Fumihiko, Yasunaga, Masafumi, Shigaki, Takahiro, Sudo, Tomoya, Mihara, Yutaro, Nakayama, Masamichi, Kondo, Reiichiro, Kusano, Hironori, Shimamatsu, Kazuhide, Okuda, Koji, Akagi, Yoshito, Yano, Hirohisa
• Format: Article
• Language: English
• Subjects: Aged; Aged, 80 and over; B7-H1 Antigen - biosynthesis; Biomarkers, Tumor - analysis; Carcinoma, Adenosquamous - pathology; Female; Humans; Immunohistochemistry; Keyword; Male; Middle Aged; Pancreas; Pancreatic adenosquamous carcinoma; Pancreatic cancer; Pancreatic Neoplasms; Pancreatic Neoplasms - pathology; PD-L1, EUS-FNA
• ISSN: 0344-0338; 1618-0631
• DOI: 10.1016/j.prp.2018.10.006

•These showed positive PD-L1 expression in the squamous cell carcinoma component, and the TPS indicated a high expression.•In contrast, only one case (3%) was positive for PD-L1 in PDACs.•On the other hand, PD-L1 expression in EUS-FNA samples was seldom observed.•PD-L1/PD-1 pathway inhibition may be a treatment strategy for PASC, although the expression in the whole tumor was low. We examined the programmed death-ligand 1 (PD-L1) expression in surgically resected pancreatic adenosquamous carcinoma (PASC) samples. Furthermore, the detection rate was also assessed using biopsy cases obtained from endoscopic ultrasound-guided fine needle aspiration (EUS-FNA). Fifteen cases of PASC (six resected and nine EUS-FNA biopsied) from the Kurume University Hospital between 2009 and 2016 were used for the evaluation of PD-L1 expression. As a control group, 34 cases of pancreatic ductal adenocarcinomas (PDACs) were selected. To compare　the positivity and intensity of PD-L1, two types of clones (SP263, E1L3N) were examined for immunostaining. Only the membrane expression of PD-L1 was regarded as positive. The PD-L1 expressions in the squamous cell carcinoma component (SCc), adenocarcinoma component (ACc), and immune cells were assessed separately. The ratio of PD-L1 expression was calculated by counting the positive tumor cells, and tumor proportion score (TPS) was applied (TPS; Null < 1%, low expression; 1 ≤ TPS ≤ 49% and high expression; ≥ 50%). PD-L1 expression was observed in five surgical PASC samples (83%). This shows that SCc presented a high expression in these cases. However, the overall TPS indicated a low expression. In contrast, only one case (3%) was positive for PD-L1 in PDACs, and the TPS indicated a low expression. No differences in PD-L1 expression were observed between the two clones, SP263 and E1L3N. High PD-L1 expression in the EUS-FNA sample was found in only one case (11%). Although assessment using the tumor cells of PASC samples obtained from EUS-FNA was difficult, this study suggests the selective expression of PD-L1 in the SCc of PASC. Furthermore, it was considered that immune checkpoint inhibitors could provide therapeutic effects selectively on the SCc for the entire range of TPSs, though the PD-L1 expression was low.