CDK7 and cancer: We selected two distinct compounds: YKL-5-124, a selective covalent CDK7 inhibitor,35 and samuraciclib (CT7001, ICEC0942), an orally bioavailable, ATP-competitive inhibitor36 currently undergoing Phase I/II clinical trials in cancer patients.33 We first analyzed the effects of selective CDK7 inhibitors on the viability of a panel of five HNSCC cell lines.