The regulatory role of CDK4/6 inhibitors in tumor immunity and the potential value of tumor immunotherapy (Review).

Cyclin‑dependent kinase (CDK)4/6 inhibitors regulate the cell cycle by binding to CDK4/6, thus exerting an inhibitory effect, and they have a notable impact on tumor immunity. CDK4/6 inhibitors have been demonstrated to modulate the immune microenvironment by affecting immune cells and immune escape phenomena in the tumor microenvironment. T cells, natural killer cells and macrophages are all regulated by CDK4/6 inhibitors, thereby acting on cancer cells. In addition, these inhibitors modulate immune checkpoints, enhancing antitumor immune responses when combined with immune checkpoint inhibitors, such as programmed death‑ligand 1 and programmed death‑1. However, these inhibitors are not without limitations, as they can enhance tumor immune evasion. Therefore, combination therapies to improve efficacy are being investigated, including immunotherapy, targeted therapy, chemotherapy and radiation therapy. In addition, challenges associated with the widespread use of CDK4/6 inhibitors, such as the emergence of tumor resistance, underscore the necessity for further research to enhance the clinical applicability of these inhibitors.