Fadraciclib

Fadraciclib (CYC065) is a second-generation, orally available ATP-competitive inhibitor of CDK2/CDK9 kinases^[1] with IC₅₀s of 5 and 26 nM, respectively^[2]. IC50 & Target: CDK2/CDK 9^[1] In Vitro: Fadraciclib blocks cells in the G1 phase of the cell cycle and inhibits cell growth specifically in cyclin E1 (CCNE1)-overexpressing uterine serous carcinomas (USCs). USC cell lines expressing high CCNE1 mRNA and protein levels to be significantly more sensitive to treatment with Fadraciclib in vitro when compared with low CCNE1-expressing cell lines (IC₅₀: mean±s.d.=124.1±57.8 nM in CCNE1-overexpressing USC cell lines vs 415±117.5 nM in CCNE1 low expressors, respectively; P=0.0003). Importantly, low concentrations of Fadraciclib (i.e., 100 nM) causes an arrest in the G1 phase of the cell cycle only in the CCNE1-overexpressing USC cell lines (i.e., USC-ARK-2, USC-ARK-7) ^[1]. In Vivo: To evaluate the therapeutic potential of Fadraciclib as a single agent, USC-ARK-2-derived xenografts are treated daily with Fadraciclib (22.5 mg/kg) for a 3-week period. Tumor size and mouse weight are recorded two times a week. The daily administration of Fadraciclib results in a significant reduction of tumor growth compared with the vehicle-treated mice (P=0.012 starting at day 9 of the treatment). No significant weight loss is reported during the entire treatment period^[1].