Annual Report 2023

Division of Developmental Therapeutics

Masahiro Yasunaga, Yoshikatsu Koga, Hiroki Takashima, Ryo Tsumura, Hirobumi Fuchigami, Boran Osman,
Chihiro Morizono, Hiroko Shinohara, Yayoi Shino, Shigehiro Koganemaru, Chikako Funasaka, Hideki Tanaka,
Yu Shibahara, Yusuke Abe, Shiqi Yang, Hao Shi, Jira Huma, Yuka Tada, Teppei Azuma, Sota Matsumoto, Mayu Oka,
Yu Takeda, Rikuto Nakamura, Yuri Nakamura, Kosuke Masago, Yuki Nitta, Mamiko Shimada, Hiroshi Tsugawa, Takahiro Anzai, Shinji Saijo, Shingo Hanaoka

Introduction

 We are developing next-generation therapeutic antibodies, such as antibody-drug conjugates (ADCs), radioimmunotherapy (RIT), and bispecific antibodies (BsAbs), utilizing drug delivery systems (DDS) and molecular imaging. Moreover, we have applied for patents for all monoclonal antibodies established by our division. In addition, we are developing methods to regulate T cells using molecular genetics and cell biology to enhance the efficacy of T cell-dependent bispecific antibodies. Developing antibody therapeutics with excellent brain delivery capabilities is also a significant challenge. The shark antibody IgNAR, with its anti-denaturation solid properties, intratumoral delivery, and active targeting, is considered promising as a next-generation antibody material. Furthermore, we are working on novel cancer diagnostics and treatments using proprietary mass spectrometry and bioinformatics technologies.

The Team and What We Do

• Development of antibody therapeutics and technology transfer to pharmaceutical companies.
• Research and development of immunoregulation methods related to next-generation antibody technologies.
• Conducting translational research utilizing mass spectrometry.

Research Activities

1.  Development of novel antibodies

 We are developing novel antibodies using drug delivery systems (DDS) and molecular imaging. We have applied for patents on original antibodies, such as anti-IL-7R antibodies. We also conducted functional analyses of target molecules for anti-TMEM180 antibodies, which are progressing to first-in-human (FIH) trials.

2.  Development of ADCs

 We developed anti-TF ADC-DXd/MMAE and confirmed its antitumor effects in pancreatic cancer CDX/PDX models. We also developed anti-IL-7R ADC, which showed strong antitumor effects in leukemia models when conjugated with anticancer drugs. When conjugated with molecular targeted agents, it induced anti-inflammatory effects and immune tolerance in type 1 diabetes models.

3.  Development of α-RIT

 We established a platform for the development of α-particle RITs using two isotopes, 211At and 225Ac, and confirmed their efficacy in animal models. We demonstrated that ascorbic acid is effective in suppressing protein damage caused by α-particles and can be used as an additive in RIT formulation and storage. We also developed anti-IL-7R RIT-211At and confirmed strong cytotoxic effects in vitro.

4.  Development of BsAbs and T cell regulation methods

 We demonstrated that anti-EGFR/CD3 BsAbs effectively activate T cells and show efficacy in colorectal cancer models, regardless of the presence of BRAF mutations. We established MOAs for BsAbs: 1) immunological synapse-dependent cytotoxicity, 2) cytokine-dependent cytotoxicity, and 3) enhanced T cell migration. We explored candidate molecules involved in T cell exhaustion, a resistance factor to BsAb therapy, and confirmed that introducing these genes could induce anti-exhaustion effects in T cells, restoring the efficacy of BsAbs.

5.  Research and development of brain antibody delivery

 We performed a functional analysis of the blood-brain barrier (BBB) in antibody delivery to the brain and identified Claudin5 and ZO1 as key regulatory factors.

6.  Application of shark antibody IgNAR to antibody therapeutics

 We established a platform for producing shark antibodies (IgNAR).

7.  Development of advanced mass spectrometry methods

 We established a method for measuring in situ drug distribution within tumor tissues, demonstrating the bystander effect of ADCs. We also confirmed reduced drug delivery in hypoxic regions within tumor tissues. Additionally, we developed a method for measuring cancer antigen-binding antibodies in tissues, enabling the distinction between passive and active targeting and allowing for the quantification of antibody concentration. A platform for breath biopsy (exhaled breath mass spectrometry) was also established.

Education

1)  Doctoral students

 Graduate School of Frontier Sciences, the University of Tokyo: three students

 Juntendo University: two students

2)  Masters students

 Graduate School of Frontier Sciences, The University of Tokyo: nine students

3)  Undergraduate students

 College of Industrial Technology, Nihon University: one student

Future Prospects

 In addition to DDS and molecular imaging, we aim to create novel antibody therapeutics with enhanced delivery efficiency by applying protein engineering, amino acid modification techniques, and other approaches. For ADCs, we will quickly obtain non-clinical proof of concept (POC) and aim for early clinical application. Regarding α-particle RIT, we will improve the precision of critical technologies such as antibody carriers and linkers to accelerate clinical development, with blood cancers as the initial target. Furthermore, alongside developing original bispecific and trispecific antibodies, we will conduct a comprehensive analysis of anti-exhaustion factors in T cells to enhance the efficacy of T-BsAbs. For brain delivery, we will elucidate the role of the blood-brain barrier in T-cell migration, in addition to antibodies. We will also evaluate the characteristics of the shark immune system and the properties and functionality of shark antibody IgNAR. Lastly, we will initiate clinical research on breath biopsy using mass spectrometry.

List of papers published in 2023

Journal

1. Tsumura R, Haruta M, Kuwano M, Yasunaga M. Expansion of mixed immune cells using CD3/CD161 co-stimulation for the treatment of cancer . Scientific reports, 13:6803 , 2023

2. Hiranyakorn M, Iwamoto S, Hoshinoo A, Tsumura R, Takashima H, Yasunaga M, Manabe S. Chromatographic Analysis of the N-Glycan Profile on Therapeutic Antibodies Using FcγRIIIa Affinity Column Chromatography . ACS omega, 8:16513-16518 , 2023

3. Fujii T, Ito K, Takahashi K, Aoki T, Takasugi R, Seki T, Iwai Y, Watanabe T, Hirama R, Tsumura R, Fuchigami H, Yasunaga M, Matsuda Y. Bispecific Antibodies Produced via Chemical Site-Specific Conjugation Technology: AJICAP Second-Generation . ACS medicinal chemistry letters, 14:1767-1773 , 2023

Book

1. Yasunaga M. Development of Next-Generation Antibody Therapeutics Using DDS and Molecular Imaging . In: Rezaei N (ed), Handbook of Cancer and Immunology, Cham , Springer Nature, pp 1–31 , 2023