Basic Study
Copyright ©The Author(s) 2018. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Dec 28, 2018; 24(48): 5491-5504
Published online Dec 28, 2018. doi: 10.3748/wjg.v24.i48.5491
Near-infrared photoimmunotherapy of pancreatic cancer using an indocyanine green-labeled anti-tissue factor antibody
Winn Aung, Atsushi B Tsuji, Aya Sugyo, Hiroki Takashima, Masahiro Yasunaga, Yasuhiro Matsumura, Tatsuya Higashi
Winn Aung, Atsushi B Tsuji, Aya Sugyo, Tatsuya Higashi, Department of Molecular Imaging and Theranostics, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology (QST-NIRS), Chiba 263-8555, Japan
Hiroki Takashima, Masahiro Yasunaga, Yasuhiro Matsumura, Division of Developmental Therapeutics, Exploratory Oncology Research and Clinical Trial Center, National Cancer Center, Chiba 277-8577, Japan
Author contributions: Aung W designed the research, performed the majority of experiments and analyzed the data; Takashima H, Yasunaga M and Matsumura Y provided the anti-TF antibody; Sugyo A participated in the animal experiments; Tsuji AB and Higashi T coordinated the research and helped for the manuscript preparation; Aung W wrote the manuscript; All authors revised and endorsed the final draft.
Supported by a Grant-in-Aid for Scientific Research (C) from the Ministry of Education, Culture, Sports, Science, and Technology, Japan, No. 17K10460 (to Aung W).
Institutional review board statement: This study was reviewed and approved by the Institutional review board of National Institute of Radiological Sciences. No patients and patient derived samples were involved in this study.
Institutional animal care and use committee statement: All procedures involving animals were reviewed and approved by the Institutional Animal Care and Use Committee of National Institute of Radiological Sciences. (Protocol No: 13-1022-6).
Conflict-of-interest statement: The authors declare no potential conflicts of interest relevant to this article.
Data sharing statement: All relevant data were presented in the manuscript. Further information is available from the corresponding author at winn.aung@qst.go.jp.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Winn Aung, MBBS, PhD, Senior Researcher, Department of Molecular Imaging and Theranostics, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan. winn.aung@qst.go.jp
Telephone: +81-43-3823706 Fax: +81-43-2060818
Received: October 2, 2018
Peer-review started: October 2, 2018
First decision: November 1, 2018
Revised: November 7, 2018
Accepted: November 16, 2018
Article in press: November 16, 2018
Published online: December 28, 2018
ARTICLE HIGHLIGHTS
Research background

Pancreatic cancer is still one of major life-threatening diseases. Therefore, there is an urgent need to explore early diagnostic and new therapeutic options. Near infrared photoimmunotherapy (NIR-PIT) is a highly selective tumor treatment that utilizes antibody-photosensitizer conjugate systemic administration, accompanied by subsequent NIR light exposure. Tissue factor (TF) is a transmembrane protein and its overexpression is associated with increased tumor growth, tumor angiogenesis and metastatic potential in many malignancies, including pancreatic cancer.

Research motivation

Previously, we suggested that TF may be a promising target for cancer diagnostic imaging probe and have already reported the usefulness of anti-TF monoclonal antibody (anti-TF mAb) in cancer imaging and therapy. However, NIR-PIT using anti-TF mAb has not been attempted.

Research objectives

In this study, we aim to investigate the photoimmunotherapeutic effect induced by a rat IgG2b anti-TF monoclonal antibody 1849 (anti-TF 1849), conjugated to the NIR photosensitizer, indocyanine green (ICG), in a TF-expressing BxPC-3 pancreatic cancer model.

Research methods

An ICG-labeled antibody conjugate (1849-ICG) was generated by labeling an anti-TF 1849 with ICG. The expression levels of TF in two human pancreatic cancer cell lines were examined by western blotting. Specific binding of the 1849-ICG to BxPC-3 cells was examined by fluorescence microscopy. NIR-PIT-induced cell death was determined by cell viability imaging assay. In vivo longitudinal fluorescence imaging was used to explore the accumulation of 1849-ICG conjugate in xenograft tumors. To determine the effect of NIR-PIT, tumor-bearing mice were divided into 5 groups: (1) 100 μg of 1849-ICG i.v. administration followed by NIR light exposure (50 J/cm2) on two consecutive days (Days 1 and 2); (2) NIR light exposure (50 J/cm2) only on two consecutive days (Days 1 and 2); (3) 100 μg of 1849-ICG i.v. administration; (4) 100 μg of unlabeled anti-TF 1849 i.v. administration; and (5) the untreated control. Semiweekly tumor volume measurements, accompanied with histological and immunohistochemical (IHC) analyses of tumors, were performed 3 d after the 2nd irradiation with NIR light to monitor the effect of treatments.

Research results

High TF expression in BxPC-3 cells was observed via western blot analysis, concordant with the observed preferential binding with intracellular localization of 1849-ICG via fluorescence microscopy. NIR-PIT-induced cell death was observed by performing cell viability imaging assay. In contrast to the other test groups, tumor growth was significantly inhibited by NIR-PIT with a statistically significant difference in relative tumor volumes (P < 0.05). Tumors that received NIR-PIT showed evidence of necrotic cell death-associated features upon hematoxylin-eosin staining accompanied by a decrease in Ki-67-positive cells (a cell proliferation marker) by IHC examination.

Research conclusions

The TF-targeted NIR-PIT with the 1849-ICG conjugate can potentially open a new platform for treatment of TF-expressing pancreatic cancer.

Research perspectives

Because TF-targeted NIR-PIT is a promising new treatment modality with a useful contemporaneous diagnostic utility, we will approach to apply it in clinical use. In addition, the association of PIT and immune response is an interesting topic and we will explore it in the future study.