An outbreak of cholangiocarcinoma in a printing company was reported in Japan, and these cases were regarded as an occupational disease (occupational cholangiocarcinoma). This study examined the expression status of programmed death-1 (PD-1) and programmed death-ligand 1 (PD-L1) in occupational cholangiocarcinoma. Immunostaining of PD-1, PD-L1, CD3, CD8, and CD163 was performed using tissue sections of occupational cholangiocarcinoma (n = 10), and the results were compared with those of control cases consisting of intrahepatic (n = 23) and extrahepatic (n = 45) cholangiocarcinoma. Carcinoma cells expressed PD-L1 in all cases of occupational cholangiocarcinoma, whereas the detection of PD-L1 expression in cholangiocarcinoma cells was limited to a low number of cases (less than 10%) in the control subjects. In cases of occupational cholangiocarcinoma, occasional PD-L1 expression was also noted in precancerous/preinvasive lesions such as biliary intraepithelial neoplasia and intraductal papillary neoplasm of the bile duct. Additionally, tumor-associated macrophages and tumor-infiltrating T cells expressed PD-L1 and PD-1, respectively. The number of PD-L1-positive mononuclear cells, PD-1-positive lymphocytes, and CD8-positive lymphocytes infiltrating within the tumor was significantly higher in occupational cholangiocarcinoma compared with that in control cases. These results indicate that immune escape via the PD-1/PD-L1 axis may be occurring in occupational cholangiocarcinoma.

Diversity in cell differentiation, histology, phenotype and vasculature of mass-forming intrahepatic cholangiocarcinomas Aims: Mass-forming intrahepatic cholangiocarcinomas (MF-iCCAs), involving small bile ducts, bile ductules or canals of Hering, remain treated as a single entity. We aimed to examine the diversity in histology, phenotype and tumour vasculature of MF-iCCAs. Methods and results: Based on morphology and immunophenotype, we classified MF-iCCAs into small bile duct (SBD), cholangiolocarcinoma (CLC), ductal plate malformation (DPM) and hepatocellular carcinoma (HCC)-like subtypes. Genetic correlations among the histological subtypes were examined by multi-region tumour sequencing. Vasculatures and other clinicopathological features were compared among tumour groups with various proportions of the histological subtypes in 62 MF-iCCAs. Cases of pure SBD, CLC, DPM and HCC-like subtypes numbered 18 (29%), seven (11.3%), none (0%) and two (3%), respectively; the remaining 35 (56.4%) cases comprised several components. Genetic alterations, isocitrate dehydrogenase (IDH)1/2, KRAS, TP53, polybromo-1 (PBRM1) and BRCA1-associated protein 1 (BAP1), were shared among SBD, CLC, DPM and hepatoid components within a tumour. We uncovered distinct vascularisation mechanisms among SBD, CLC and DPM subtypes with a prominent vessel cooption in CLC tumours. iCCA with a DPM pattern had the highest vascular densities (mean microvascular density,140/mm 2 ; arterial vessel density, 18.3/ mm 2 ). Increased CLC component was correlated with longer overall survival time (r = 0.44, P = 0.006). Pure SBD tumours had a lower 5-year overall survival rate compared with MF-iCCA with CLC pattern (30.5 versus 72.4%, P = 0.011). Conclusions: MF-iCCAs comprise four histological subtypes. Given their sharing some driver gene alterations, indicating they can have a common cell origin, SBD, CLC and DPM subtypes, however, differ in cell differentiation, histology, phenotype or tumour vasculature.

Background and Aims Synthetic cyclin‐dependent kinase (CDK) 4/6 inhibitors exert antitumor effects by forcing RB1 in unphosphorylated status, causing not only cell cycle arrest but also cellular senescence, apoptosis, and increased immunogenicity. These agents currently have an indication in advanced breast cancers and are in clinical trials for many other solid tumors. HCC is one of promising targets of CDK4/6 inhibitors. RB family dysfunction is often associated with the initiation of HCC; however, this is revivable, as RB family members are not frequently mutated or deleted in this malignancy. Approach and Results Loss of all Rb family members in transformation related protein 53 (Trp53)−/− mouse liver resulted in liver tumor reminiscent of human HCC, and re‐expression of RB1 sensitized these tumors to a CDK4/6 inhibitor, palbociclib. Introduction of an unphosphorylatable form of RB1 (RB7LP) into multiple liver tumor cell lines induced effects similar to palbociclib. By screening for compounds that enhance the efficacy of RB7LP, we identified an I kappa B kinase (IKK)β inhibitor Bay 11‐7082. Consistently, RB7LP expression and treatment with palbociclib enhanced IKKα/β phosphorylation and NF‐κB activation. Combination therapy using palbociclib with Bay 11‐7082 was significantly more effective in hepatoblastoma and HCC treatment than single administration. Moreover, blockade of IKK–NF‐κB or AKT pathway enhanced effects of palbociclib on RB1‐intact KRAS Kirsten rat sarcoma viral oncogene homolog mutated lung and colon cancers. Conclusions In conclusion, CDK4/6 inhibitors have a potential to treat a wide variety of RB1‐intact cancers including HCC when combined with an appropriate kinase inhibitor.

Occupational cholangiocarcinoma (CCA) was first described in patients who were working in an offset color proof-printing department at a printing company in Osaka, Japan 1,2. By November 2019, a total of 20 patients were regarded as occupational CCA at the printing company. The exposure to organic solvents, such as 1,2-dichloropropane (DCP) and dichloromethane (DCM), was assumed to be responsible for the development of occupational CCA. In 2014, the International

Cholangiocarcinoma is an aggressive malignancy with high mortality, and effective therapeutic agents for this cancer are limited. Cyclin-dependent kinase (CDK) pathways are therapeutic targets for various types of cancers; however, their involvement in cholangiocarcinoma remains unclear. The present study examined the biological significance of CDK pathways in cholangiocarcinoma. An immunohistochemical analysis of cholangiocarcinoma tissue sections revealed the upregulated expression of phosphorylated cyclin-dependent kinase 1 (p-CDK1), p-CDK2, cyclin B1, and cyclin E1 in carcinoma cells. The nuclear expression of p-CDK1 and cyclin B1 was positively correlated with the presence of lymph node metastasis and the clinical stage, and p-CDK1 expression was also associated with poor patient survival. The treatment of human cholangiocarcinoma cell lines (CCKS-1, TFK-1 and HUCCT-1) with the multi-CDK inhibitor roscovitine decreased p-CDK1 expression, inhibited cell proliferation, arrested the cell cycle at the G1 or G2/M phase, and significantly inhibited carcinoma cell invasion. In vivo studies using a murine xenograft model revealed that an intraperitoneal injection of roscovitine significantly inhibited cholangiocarcinoma cell growth. Roscovitine induced apoptosis in cholangiocarcinoma cells in vitro and in vivo. These results demonstrated the potential of the CDK pathway involving CDK1 as a therapeutic target for cholangiocarcinoma. Furthermore, the immunohistochemical expression of p-CDK1 may be a useful prognostic marker of cholangiocarcinoma.