HHLA2 and familial pancreatic carcinoma: Briefly, the overall phenotypes could be categorized according to the three negative conditions: (a) without differential expression between pancreatic cancer and the normal samples (eg, PD‐L1 and CD80); (b) upregulated in pancreatic cancer but without any significant relevance to the OS and DFS of pancreatic cancer patients (eg, PD‐L2 and CD86); and (c) upregulated in pancreatic cancer, significantly related to the OS and DFS of pancreatic cancer patients (favorable or unfavorable), but with both stimulatory and inhibitory potential on immune system (eg, HHLA2 and PVR).