CDK4 and small cell lung carcinoma: The addition of CDK4/6 inhibitor to chemotherapy/ICI regimens in murine syngeneic tumor models enhanced antitumor response and overall survival compared with chemotherapy, and ICI combinations alone and transient exposure of CDK4/6 inhibition in patients with SCLC during chemotherapy treatment enhanced immune system function by preserving peripheral lymphocyte counts and enhancing T-cell activation (17).