Voruciclib hydrochloride is an orally active and selective CDK inhibitor with Ki values of 0.626 nM-9.1 nM. Voruciclib hydrochloride potently blocks CDK9, the transcriptional regulator of MCL-1. Voruciclib hydrochloride represses expression of MCL-1 in multiple models of diffuse large B-cell lymphoma (DLBCL). In Vitro: Voruciclib hydrochloride (0.5-5 µM; 6 hours) shows targeted downregulation of MCL-1 in both ABC and GCB subtypes. Ki values for each target such as CDK9/cyc T2, CDK9/cyc T1, CDK6/cyc D1, CDK4/cyc D1, CDK1/cyc B, and CDK1/cyc A for Voruciclib hydrochloride are 0.626 nM, 1.68 nM, 2.92 nM, 3.96 nM, 5.4 nM, 9.1 nM, respectively. In Vivo: Combination of Voruciclib hydrochloride (200 mpk; Oral gavage) and Venetoclax (10 mpk, 1 mpk, 50 mpk, 25 mpk in U2932, RIVA, SU-DHL-4 and NU-DHL-1, respectively) leads to enhance tumor growth inhibition compared to either drug alone in U2932, RIVA, SU-DHL-4 (six days per week for 4 weeks), and NU-DHL-1 models (five days per week for 3 weeks) of DLBCL.