PRF1 and neoplasm: Moreover, in line with our OS observations of these patients, CD8A/B, HLA-A, and PRF1 expressions were higher in resistant patient tumor samples from cluster1 than for those from cluster2 (P = 9.0e-6, P = 2.0e-6, P = 0.038, and P = 0.0008 respectively; Fig. 4f-i).