Trilaciclib: A First-in-class Therapy to Reduce Chemotherapy-induced Myelosuppression

Oral cyclin-dependent kinase (CDK) 4/6 inhibitors are routinely used to treat metastatic hormone receptor-positive human epidermal growth factor receptor 2-negative breast cancer in combination with endocrine therapy; however, they have not been widely used for other tumour types. Trilaciclib is an intravenous CDK 4/6 inhibitor that causes reversible cell cycle arrest in the G1 phase and transient haematopoietic stem and progenitor cell arrest. Ultimately, this protects the bone marrow and immune system from the cytotoxic impact of chemotherapy. Trilaciclib has been evaluated in extensive-stage small cell lung cancer in combination with chemotherapy as a myeloprotective agent and was approved by the US Food and Drug Administration for this use in February 2021. In metastatic triple-negative breast cancer, trilaciclib plus chemotherapy had a survival benefit over chemotherapy alone. This is being further investigated in a phase III trial. This review outlines the mechanism of this novel agent and describes preclinical and clinical data, characterizing its use in extensive-stage small cell lung cancer and advanced triple-negative breast cancer.