Riviciclib

Riviciclib (P276-00 free base) is a potent cyclin-dependent kinase (CDK) inhibitor, which inhibits CDK9-cyclinT1, CDK4-cyclin D1, and CDK1-cyclinB with IC₅₀s of 20 nM, 63 nM, and 79 nM, respectively^[1][2]. Riviciclib shows antitumor activity on cisplatin-resistant cells^[3]. IC50 & Target: IC₅₀: 0.020 μM (Cdk9-T1), 0.063 μM (Cdk4-D1), 0.079 μM (Cdk1-B)^[1] In Vitro: Riviciclib (1.5-5 μM; 72 hours) shows no detectable cells in G1 and G2 in promyelocytic leukemia cells and arrest of cells in G1 in synchronized human non-small cell lung carcinoma (H-460) and human normal lung fibroblast (WI-38) cells^[3].
Riviciclib (3-24 hours; 1.5 μM) reduces cyclin D1, Cdk4, and Rb levels in H-460 cells. Rb (retinoblastoma) phosphorylation at Ser⁷⁸⁰ decrease at 3 h^[2].
Riviciclib shows activity in human cancer cell lines, such as colon carcinoma, osteosarcomal, cervical carcinoma, and bladder carcinoma cells^[2]. In Vivo: Riviciclib (administered i.p.; 35 kg/mg daily for 10 days, in human xenograft mode with severe combined immunodeficient mice) shows significant inhibition in the growth of human colon carcinoma HCT-116 xenograft^[3].
Riviciclib (administered via i.p.; 50 mg/kg once daily; 30 mg/kg twice daily for 18 treatments, in human xenograft mode with severe combined immunodeficient mice) significantly inhibits growth^[3].