We then stratified the 36 HNSCC patients treated with nivolumab into the same G1-G5 immunotypes as a validation cohort. At baseline, the G2 group had higher OR rates than other groups (p=0.02; figure 2). Baseline primary tumors showed OR correlated with PD-L1 and PD-L2 expression, interferon responsive genes, T-cell trafficking, and MHC class I pathway (higher values in Responders versus Non-responders, p<0.05; figure 3).