Abstract 5687: CDC7 inhibitor-induced replication stress generates inflamed aneuploid cells to sensitize immune checkpoint inhibitors
Authors: Morita Tomoko Yamamori , Yu Jie , Kashima Yukie , Tanaka Kosuke , Minamide Tatsunori , Mashima Chiaki , Hakozaki Yumi , Kageyama Shun-ichiro , Nakamura Akito , Lightcap Eric , Niu Huifeng , Kannan Karuppiah , Ohashi Akihiro 
Published: June 2022

Abstract
Background: The serine/threonine kinase, cell division cycle 7 (CDC7), is critical for initiating DNA replication. A highly specific CDC7 inhibitor, TAK-931, was developed as a next-generation of replication stress (RS) inducer. This study preclinically investigated the novel aspects of TAK-931 on antitumor efficacy and immunity for evaluating the therapeutic potential of TAK-931 in combination with immune checkpoint inhibitors (ICIs).
Methods: TAK-931-treated cells were subjected to cell growth assay, senescence-associated galactosidase (SA-β-gal) activity assay, transcriptome analysis (RNA-seq), and single-cell RNA-seq (scRNA-seq). The flowcytometry (FCM)-based immune profiling panel studies in J558 allograft syngeneic mouse models were performed. In vivo efficacy studies in J558 allograft models in combination with anti-mPD-1, anti-mPD-L1, and anti-mCTLA-4 antibodies were performed.
Results: TAK-931 intensively induced RS, generating senescence-associated secretory phenotype (SASP) aneuploid cells, which highly expressed inflammatory cytokines and chemokines. In the transcriptome analyses, the inflammatory cytokine and chemokine hallmarks were significantly and intensively enriched in the TAK-931-induced aneuploid cells; five out of the top six enriched hallmarks were related to inflammation. Single-cell RNA sequencing analyses revealed the advanced aneuploidy to be closely associated with the activation of the inflammatory-related and SASP-associated pathways. Flow cytometry-based immune profiling panel studies demonstrated that the tumor-infiltrating immune cells, such as CD8+ T, CD4+ T, PD-1+CD8+ T, and PD-1+CD4+ T cells, were significantly accumulated in the TAK-931-treated J558 mouse allografts, while the number of immune suppressive CD45+ myeloid-derived suppressor cells was significantly decreased. The single-agent treatment with TAK-931 exhibited significant antitumor efficacy and immunity in the J558 syngeneic allografts, which was confirmed by tumor re-challenging studies. Finally, TAK-931 and ICIs (anti-mPD-1, anti-mPD-L1, and anti-mCTLA-4 antibodies), in combination, were found to enhance the antiproliferative activities in the preclinical syngeneic mouse models.
Conclusions: These preclinical findings suggest the therapeutic potential of TAK-931 in antitumor efficacy and immunity, which may improve clinical benefit of the currently-used immunotherapy by combination treatment.
Citation Format: Tomoko Yamamori Morita, Jie Yu, Yukie Kashima, Kosuke Tanaka, Tatsunori Minamide, Chiaki Mashima, Yumi Hakozaki, Shun-ichiro Kageyama, Akito Nakamura, Eric Lightcap, Huifeng Niu, Karuppiah Kannan, Akihiro Ohashi. CDC7 inhibitor-induced replication stress generates inflamed aneuploid cells to sensitize immune checkpoint inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5687.