CDK7 and head and neck squamous cell carcinoma: Research evidence indicates that heterogeneity develops through time as tumor-initiating stem cells, also known as CSCs.43 Hence, complete eradication of tumors requires therapies able to effectively eliminate the CSC subpopulations responsible for treatment resistance, relapse and metastasis.44,45 On this basis, it is a relevant finding that both YKL-5-124 and samuraciclib effectively reduced the viability of CSC-enriched tumorspheres as well as HNSCC PDOs, thereby suggesting that selective CDK7 targeting could also be an efficacious strategy to target and eradicate the CSC niche in HNSCC.