LAUSR

Cell division cycle 7 (CDC7) is a serine/threonine kinase, which plays important roles in initiation of DNA replication by phosphorylating MCM2. Kinase activity of CDC7 is controlled by its binding protein DBF4 in a cell-cycle dependent manner. Here we developed a potent CDC7 inhibitor TAK-931 (IC50 120-fold selectivity of TAK-931 for CDC7 kinase inhibition compared to other kinase inhibitions. Treatment with TAK-931 suppressed the cellular MCM2 phosphorylation at Ser40, resulting in a delayed S phase progression, checkpoint activation, apoptosis, and potent growth suppression in various cancer cell lines. Furthermore, oral administration of TAK-931 as a single agent caused a significant antitumor activity in multiple xenograft models which include both cell line-based xenografts and patient-derived xenograft (PDX) models. These results demonstrate that TAK-931 is a highly potent and selective inhibitor of CDC7 kinase, and causes a potent antiproliferation both in vitro and in vivo studies using various cancer cells. Next, to identify potential predictive biomarkers to guide patient-selection strategies, in vitro cell panel screening of TAK-931 using was tested for its ability to antiproliferation in 246 cell lines, which includes both solid and hematological cancer cells. TAK-931 inhibited proliferation of multiple cancer cell lines, with mean concentration producing a half-maximal response (EC50) values ranging from 29.1 nM to > 30 μM (median = 554.5 nM). While the wide range of TAK-931 antiproliferative spectrum was observed, neither doubling speed nor CDC7 expression profile did predict tTAK-931 sensitivity in cancer cell lines. A correlative study of the tumor genetic mutations in relation to antiproliferative activity that KRAS mutant cancer cells were more sensitive to TAK-931 compared to KRAS non-mutant cell lines (p 60% TGI. Our findings suggest that the KRAS-mutant pancreatic tumors could be the potential candidate for the TAK-931 target indication. Citation Format: Kenichi Iwai, Tadahiro Nambu, Osamu Kurasawa, Noriko Uchiyama, Ryo Dairiki, Yukiko Yamamoto, Satoru Nishizawa, Mengkun Zhang, Yuko Ishii, Huifeng Niu, Akihiro Ohashi. Potential predictive biomarkers of clinical responses for a novel CDC7-selective inhibitor TAK-931 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3073. doi:10.1158/1538-7445.AM2017-3073