For example, given that we are now aware of the existence of a small percentage of SCLC patients that carry wild-type copies of RB1, together with the fact that SCLC cells with a functional Rb protein may be amenable to CDK4/6 inhibition and more responsive to immune checkpoint inhibitors compared with SCLC tumors with mutated RB1, we can design clinical trials with SCLC patients stratified for wild-type RB1 and evaluate the administration of CDK4/6 inhibitors and immune checkpoint inhibitors individually or in combination with currently available approved drugs for SCLC [32,33]. Here, RB1 is linked to small cell lung carcinoma.