Life science
Medicine / Healthcare, Tumor immunity

Regulation of endogenous chemokines for activating anti-tumor immunity and its
therapeutic potential in intrahepatic cholangiocarcinoma
Department of Gastroenterological Surgery, Graduate School of Medicine
Clinical Fellow Yasunari Fukuda

Researchmap https://researchmap.jp/yfukuda.hbp

Professor Hidetoshi Eguchi

Researchmap https://researchmap.jp/abcdabcdabcd

Life science

Abstract
Intrahepatic cholangiocarcinoma (iCCA) is a refractory neoplasm
with a dismal outcome. It has become increasingly important toregulate the interplay between tumor and tumor microenvironment
to overcome this malignancy. CXCL9, an IFN-γ inducible chemokine, is involved in tumor immunity by acting as a chemoattractant
to direct the migration of activated immune cells. Here, we sought
to determine the impact of endogenous CXCL9 on tumor immune
microenvironment in iCCA.

can augment anti–tumor immune surveillance and boost the effects
of chemotherapies or immune checkpoint inhibitors via the regulation of endogenous chemokines.

▍ Background & Results
Chemokines, released by either tumor cells or surrounding cells,
greatly contribute to the recruitment of immune cells to tumor microenvironment. We previously reported that intra-graft CXCL9was a most sensitive biomarker of acute cellular rejection after livertransplantation. This indicates CXCL9 is a key modulator of liver
cellular immunity and would play a central role in the regulation oftumor immunity in iCCA. We, therefore, aimed to clarify the significance of endogenous CXCL9 on tumor immunity in iCCA. First, endogenous CXCL9 expression and the number of tumor-infiltrating
lymphocytes were immunohistochemically assessed using resection specimens. High CXCL9 expression in tumor was closely associated with prolonged postoperative survival and a large numberof NCR1+ tumor-infiltrating natural killer (NK) cells. Next, we validated this fact in mice treated by silencing CXCL9 with short hairpin(sh) RNA. CXCL9-defficient cells were more tumorigenic in the liverthan CXCL9-sufficient cells. Flow cytometry analyses revealed thatthe trafficking of total, tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) expressing, and CXCR3 expressing NK cells
into tumors was significantly lessened in tumors with CXCL9-defficient cells compared to those with CXCL9-sufficient cells. Lastly,
we showed that the depletion of NK cells using the PK136 antibody
eliminated the volume differences between CXCL9-deficient andCXCL9-sufficient tumors. Taken together, our findings suggest that
endogenous CXCL9 drives tumor-infiltrating NK cells, which in turn
determines the growth of iCCA.

▍ Significance of the research and Future perspectiveFig. 1: Significance of endogenous CXCL9 in intrahepatic cholangiocarcinoma

Fig. 2: Boosting the effects of chemotherapies and immune checkpoint inhibitors
by the regulation of endogenous chemokines

The advent of immune checkpoint inhibitors reaffirms us theimportance of tumor immunity. However, only a small subset ofpatients has gained the survival benefits from these drugs so far
and the development of effective drugs that can favorably alter tumor immune microenvironment remains challenging. In the current
study, we clarified that endogenous CXCL9 in tumor contributed to
the recruitment of NK cells into tumor and affected patient prognosis in iCCA. These results indicate that the regulation of endogenous chemokines may offer a new therapeutic approach in various
types of cancer. High-throughput screening of compound libraries
in future studies would help us identify new drug candidates which

P a t e n t
Tr e a t i s e

Fukuda, Yasunari; Asaoka, Tadafumi; Eguchi, Hidetoshi et al. Endogenous CXCL9 affects prognosis by regulating tumor-infiltrating natural killer cells inintrahepatic cholangiocarcinoma. Cancer Sci. 2020; 111(2): 323-333. doi: 10.1111/cas.14267. Epub 2020 Jan 23.

URLK e y w o r d intrahepatic cholangiocarcinoma, CXCL9, natural killer cell, chemokine, tumor-infiltrating lymphocyte