G1T38 is a selective cyclin-dependent kinase 4 (CDK4) inhibitor developed for the treatment of cancer, particularly in tumors driven by dysregulation of the CDK4/6 pathway. It is being investigated for its ability to halt the progression of the cell cycle in cancer cells, specifically by blocking the G1 to S phase transition, which suppresses tumor cell proliferation. It has shown promising activity in preclinical models of various solid tumors, including those with Rb protein expression and intact cell cycle regulation. G1T38 is designed to offer improved selectivity and pharmacokinetic properties over earlier CDK4/6 inhibitors, potentially reducing off-target effects and enhancing efficacy. In combination with other anticancer agents, such as hormone therapies or targeted drugs, G1T38 is being explored to overcome resistance mechanisms and improve patient outcomes. Its development focuses on advancing personalized cancer treatment strategies, especially in breast cancer and other malignancies dependent on CDK4 signaling.