PDCD1 and metastatic neoplasm: Here, we demonstrated that 9p24.1 genetic dosage significantly contributed to an immune-cold or -hot phenotype (when genes are lost or gained, respectively) in HPV– HNSC, in WES and WTS analyses of three independent cohorts, which in turn predicted resistance and sensitivity to standard anti-PD-1 ICT in a fourth real-world patient cohort with recurrent/metastatic disease.