In February 2021, trilaciclib (COSELATM), an intravenous cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitor, was approved by the US Food and Drug Administration to decrease the incidence of chemotherapy-induced myelosuppression in adult patients when administered prior to a platinum/etoposide- or topotecan-containing regimen for extensive-stage small cell lung cancer (ES-SCLC) (47). The gene discussed is CDK4; the disease is small cell lung carcinoma.