CD274 and neoplasm: Up to 18 (85%) and 20 (95%) of 21 pre-S2 mutant-positive patients had high densities of PD-L1-expressing cells and Tregs in tumor tissues but only two (10%) and none of 19 pre-S2 mutant-negative patients had high densities of PD-L1-expressing cells and Tregs, respectively (Table 2).