Trilaciclib is used in the treatment of small cell lung cancer (SCLC) to reduce chemotherapy-induced myelosuppression. It works by temporarily inhibiting cyclin-dependent kinase 4/6 (CDK4/6), protecting bone marrow cells from damage during chemotherapy. This helps maintain healthier blood cell counts, reducing the need for interventions like transfusions or growth factor support. It is administered intravenously prior to chemotherapy sessions, enhancing patient tolerance to treatment and improving overall quality of life during cancer therapy.