CD274 and cancer: Responses were seen regardless of PD-L1 status (ORR of 12% in PD-L1-positive vs 17% in PD-L1-negative), but HPV-positive HNC had significantly higher response rate (ORR of 33% in HPV-positive versus 5% in HPV-negative), perhaps due to the more enriched pre-existing immune response in these viral-driven cancers (65).