PDCD1 and neoplasm: While CDK4/6 inhibition has been shown to enhance the efficacy of anti-PD-1/PD-L1 therapies leading to complete tumor regression in a substantial proportion of animals48,49, our data suggest that the immune modulatory effects of tumor-intrinsic RB activation on the TME may not be as potent as those induced by CDK4/6 inhibition.