Potent anti-tumor activity of a macrocycle-quinoxalinone class pan-Cdk inhibitor in vitro and in vivo

• Published in: Investigational new drugs Vol. 29; no. 4; pp. 534 - 543
• Main Authors: Hirai, Hiroshi, Takahashi-Suziki, Ikuko, Shimomura, Toshiyasu, Fukasawa, Kazuhiro, Machida, Takumitsu, Takaki, Toru, Kobayashi, Makiko, Eguchi, Tomohiro, Oki, Hiroko, Arai, Tsuyoshi, Ichikawa, Koji, Hasako, Shinichi, Kodera, Tsutomu, Kawanishi, Nobuhiko, Nakatsuru, Yoko, Kotani, Hidehito, Iwasawa, Yoshikazu
• Format: Journal Article
• Language: English
• Published: Boston Springer US 01.08.2011; Springer Nature B.V
• Subjects: Animals; Antineoplastic Agents - adverse effects; Antineoplastic Agents - chemistry; Antineoplastic Agents - pharmacology; Apoptosis; Binding sites; Bromodeoxyuridine - metabolism; Cancer; Cancer therapies; Cell cycle; Cell Cycle - drug effects; Cell death; Cell Death - drug effects; Cell growth; Cell Proliferation - drug effects; Cyclin-dependent kinases; Cyclin-Dependent Kinases - antagonists & inhibitors; Cyclin-Dependent Kinases - metabolism; Dose-Response Relationship, Drug; Drug dosages; Female; HCT116 Cells; Humans; Inhibitor drugs; Kinases; Laboratories; Leukocyte Count; Macrocyclic Compounds - adverse effects; Macrocyclic Compounds - chemistry; Macrocyclic Compounds - pharmacology; Medicine; Medicine & Public Health; Oncology; Pharmaceutical industry; Pharmacology; Pharmacology/Toxicology; Phosphorylation; Preclinical Studies; Quinoxalines - adverse effects; Quinoxalines - chemistry; Quinoxalines - pharmacology; Rats; Rats, Nude; Research centers; RNA polymerase; Studies; Substrate Specificity - drug effects; Tumors; Xenograft Model Antitumor Assays; Japan; Anti-tumor efficacy; Cdk; Pan-Cdk inhibitor; Small molecule inhibitor
• ISSN: 0167-6997; 1573-0646
• DOI: 10.1007/s10637-009-9384-8

Summary Deregulation of cell-cycle control is a hallmark of cancer. Thus, cyclin-dependent kinases (Cdks) are an attractive target for the development of anti-cancer drugs. Here, we report the biological characterization of a highly potent pan-Cdk inhibitor with a macrocycle-quinoxalinone structure. Compound M inhibited Cdk1, 2, 4, 5, 6, and 9 with equal potency in the nM range and was selective against kinases other than Cdks. This compound inhibited multiple events in the cell cycle in vitro, including retinoblastoma protein (pRb) phosphorylation, E2F-dependent transcription, DNA replication (determined by bromodeoxyuridine incorporation), and mitosis completion (assayed by flow cytometry) in the 10 nM range. Moreover, this compound induced cell death, as determined by induction of the subG1 fraction, activated caspase-3, and anexin V. In vivo, Compound M showed anti-tumor efficacy at a tolerated dose. In a nude rat xenograft tumor model, an 8-h constant infusion of Compound M inhibited pRb phosphorylation and induced apoptosis in tumor cells at ∼30 nM, which led to the inhibition of tumor growth. Immunosuppression was the only liability observed at this dose, but immune function returned to normal after 10 days. Suppression of pRb phosphorylation in tumor cells was clearly correlated with tumor cell growth inhibition and cell death in vitro and in vivo. In vivo, Compound M inhibited pRb phosphorylation in both tumor and gut crypt cells. Rb phosphorylation may be a suitable pharmacodynamic biomarker in both tumors and normal tissues for monitoring target engagement and predicting the efficacy of Compound M.