Yasuhiro Aga

UR-3216: A New Generation Oral Platelet GPIIb / IIIa Antagonist

Various oral platelet GPIIb/IIIa receptor antagonists have undergone clinical investigations, but to date without success. Various factors have been proposed to explain their failure such as low affinity for the receptor, large peak/trough ratio, low bioavailability, partial agonist activity and pro-aggregatory effect. Efforts to discover a truly effective, safe, oral antagonist led to the discovery of UR-3216 (Fig. 1). The active form of UR-3216, UR-2922, possessed a high affinity for the human platelet receptor (K(d) <1 nM) with a slow dissociation rate (k(off)= 90 min) in vitro. UR-2922 induced no ligand-induced binding sites (LIBS) expression or prothrombotic activity in human platelets, distinctly different from orbofiban and other small molecule antagonists. To date, UR-2922 is the only high affinity GPIIb/IIIa antagonist without LIBS expression. In vivo characteristics of UR-3216 showed prolonged duration of efficacy (>24 h) with its favorable pharmacokinetic profile, superior to all the other oral GPIIb/IIIa antagonists. UR-3216 showed high bioavailability, rapid bioconversion to the active form and biliary excretion. UR-3216 is a novel, orally active GPIIb/IIIa antagonist of a new generation, which has substantially improved the crucial compounding factors and will be useful for the treatment of cardiovascular diseases.

Abstract LB-297:In vivoanti-tumor efficacy of UD-017, a novel highly selective & orally available CDK7 inhibitor, in colorectal cancer cells xenograft models

Background: Cyclin dependent kinase 7 (CDK7) is an attractive target for cancer drugs due to its dual roles, cell cycle regulation & gene transcription/RNA procession. Recent studies show that transcription of some oncogene is highly sensitive to inhibition of transcription such as inhibition by CDK7. The dependence of cancer cells on transcription can be therefore advantageous to CDK7 inhibitors as effective anti-cancer drugs. We synthesized a novel small molecule highly selective reversible CDK7 inhibitor, UD-017. In this study, we evaluated anti-cancer activity of UD-017 in the colorectal cancer cells, HCT-116, xenograft models in mice & investigated the rationale for CDK7 inhibition as anti-cancer drugs. Experimental procedures: We first examined the pharmacokinetics profile of UD-017 after an oral administration in mice. We then evaluated the anti-tumor efficacy of UD-017 in HCT-116 xenograft models in mice. We further investigated the pharmacodynamics of UD-017 by detecting the phosphorylation levels of the retinoblastoma (cell cycle) & RNA polymerase II (transcription) & expression levels of c-myc in the tumor tissues in the same model after oral administration of UD-017. Results: UD-017 was identified as an orally available inhibitor of CDK7. The bioavailability was approximately 50% in BALB/c mice. In the HCT-116 xenograft model in mice, UD-017 inhibited the cancer growth by 33%, 64% & 88% at 25, 50 & 100 mg/kg, respectively, with clear dose-dependence by once daily administration for 14 days. Throughout the experiment, UD-017 was well tolerated with no reduction in body weights & no myelosuppression. In order to evaluate the effect of UD-017 in combination with chemotherapeutics, UD-017 was administrated with 5-fluorouracil (5-FU) to HCT-116 xenografted mice with either 50 mg/kg of UD-017 alone, or 15 mg/kg ip of 5-FU alone, or in combination of UD-017 plus 5-FU. UD-017 showed clear combination effect with 5-FU without further affecting the side effects of 5-FU. Phosphorylation of the retinoblastoma was inhibited after oral administration of UD-017 time-dependently in the tumor tissues. Phosphorylation of RNA polymerase II COOH-terminal domain (CTD) was also inhibited & expression of c-myc was decreased. PPAP cleavage was subsequently induced, causing apoptotic death of the cancer cells. Conclusion: We propose UD-017 as a novel type of anti-cancer drug that shows favorable oral pharmacokinetics profile & complete anti-tumor responses in xenograft models of colorectal cancer cells, & also shows in vivo synergy in combination with chemotherapy. These data support the rationale for further advancing towards clinical development. IND-enabling studies are in progress. Citation Format: Yasuhiro Aga, Sayaka Ogi, Yasunori Tokunaga, Ayumi Ogawa, Kazuhiro Onuma, Takashi Matsushita, Hidetoshi Sunamoto, Toru Hasegawa, Shigeru Ushiyama. In vivo anti-tumor efficacy of UD-017, a novel highly selective & orally available CDK7 inhibitor, in colorectal cancer cells xenograft models [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 LB-297. doi:10.1158/1538-7445.AM2017-LB-297

Abstract LB-111:In vitroanti-cancer activity of UD-017, a novel potent & highly selective CDK7 reversible inhibitor

Background: Cyclin dependent kinase 7 (CDK7) is a member of the CDK family, & has a dual function relating to the cell cycle progression & gene transcription/ RNA processing. Recently CDK7 has been emerged as an attractive target for anticancer drugs due to its dual role. We synthesized UD-017, a small molecule, highly selective CDK7 inhibitor with a novel chemotype. In this study, we characterized in vitro antiproliferative profile of UD-017 & elucidated underlying mechanism how CDK7 inhibition contributes to the antiproliferation of cancer cells. Experimental procedures: We conducted a large panel of 9 CDKs & 313 other kinases assay of UD-017 to determine its selectivity & analyzed kinetics for CDK7 enzyme inhibition. We evaluated the antiproliferative activity of UD-017 in over 100 multiple types of cancer cell lines. We then investigated the mechanism of antiproliferative activity of UD-017 using human colorectal cancer cell line, HCT-116, & human multiple myeloma cell line, NCI-H929. We also explored biomarker candidates mainly using colorectal cancer cell lines. Results: UD-017 inhibited CDK7 enzyme with an IC50 value of 16 nM, which is at least 300-fold more selective against other CDKs, CDK1 through CDK9. Inhibition of UD-017 was reversible & ATP-competitive. In a panel of 313 kinases assay, the compound inhibited CDK7 almost mono-specifically. In antiproliferative panel assays using over 100 cancer cell lines, UD-017 broadly inhibited a wide range of cancer cells from colon, breast, lung, kidney, blood, pancreas & urinary bladder cancers. Specifically, it inhibited the growth of HCT-116 & NCI-H929 with GI50 values of 29 nM and 6.8 nM, respectively. In the mechanism study of the antiproliferative activity, UD-017 inhibited phosphorylation of CDK1, CDK2 & the retinoblastoma (RB) & arrested the cell-cycle. Phosphorylation of RNA polymerase II c-terminal domain was also inhibited & expression levels of c-Myc and XIAP decreased & the cleavage of PARP increased, which were followed by significant induction of apoptosis. UD-017 showed both cell cycle arrest & induction of apoptosis. In the biomarker study, c-Myc & cyclin H showed good correlation with antiproliferative activities in 6 colorectal cancer cell lines and will be candidate biomarkers of UD-017. Conclusion: UD-017 is a potent & highly selective CDK7 inhibitor, & significantly inhibits the proliferation of human cancer cells with concomitant cell cycle arrest & induction of apoptosis. In vivo anti-tumor efficacy for UD-017 is warranted. Citation Format: Takashi Matsushita, Kazuhiro Onuma, Hidetoshi Sunamoto, Ayumi Ogawa, Sayaka Ogi, Toru Hasegawa, Shigeyuki Kono, Noriaki Iwase, Yasuhiro Aga, Shigeru Ushiyama. In vitro anti-cancer activity of UD-017, a novel potent & highly selective CDK7 reversible inhibitor [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 LB-111. doi:10.1158/1538-7445.AM2017-LB-111