Cohort selection for this trial was based on immune responsiveness, with HCC and SCCHN being moderately immune-responsive to anti-PD-1/PD-L1 monotherapy, and GBM and EOC being immune-resistant cancers for which PD-1/PD-L1 axis blockade alone has not been shown to be effective. Here, PDCD1 is linked to head and neck squamous cell carcinoma.