title: Clinical significance and therapeutic potential of the programmed death-1 ligand/programmed death-1 pathway in human pancreatic cancer.
abstract: OBJECTIVE
  The programmed death-1 ligand/programmed death-1 (PD-L/PD-1) pathway has been recently suggested to play a pivotal role in the immune evasion of tumors from host immune system. In this study, we tried to reveal the clinical importance and therapeutic potential of the PD-L/PD-1 pathway in pancreatic cancer, which is one of the most aggressive and intractable malignant tumors.
  
  
  METHODS
  We used immunohistochemistry to investigate PD-L expression in 51 patients with pancreatic cancer who underwent surgery and explored the therapeutic efficacy of blocking the PD-L1/PD-1 pathway in murine pancreatic cancer in vivo.
  
  
  RESULTS
  PD-L1-positive patients had a significantly poorer prognosis than the PD-L1-negative patients, whereas there was no significant correlation of tumor PD-L2 expression with patient survival. PD-L1 expression was inversely correlated with tumor-infiltrating T lymphocytes, particularly CD8(+) T cells. These clinical data have suggested that the PD-L1/PD-1 pathway may be a critical regulator in human pancreatic cancer. Monoclonal antibodies against PD-L1 or PD-1 induced a substantial antitumor effect on murine pancreatic cancer in vivo. PD-L1 blockade promoted CD8(+) T-cell infiltration into the tumor and induced local immune activation. Furthermore, the combination of anti-PD-L1 monoclonal antibody and gemcitabine exhibited a significant synergistic effect on murine pancreatic cancer and resulted in complete response without overt toxicity.
  
  
  CONCLUSIONS
  Our data suggest for the first time that PD-L1 status may be a new predictor of prognosis for patients with pancreatic cancer and provide the rationale for developing a novel therapy of targeting the PD-L/PD-1 pathway against this fatal disease.
authors.affiliation: Department of Surgery, Second Department of Internal Medicine, First Department of Internal Medicine, Nara Medical University, Nara, Japan.
authors.forename: Takeo
authors.initials: T
authors.lastname: Nomi
authors.forename: Masayuki
authors.initials: M
authors.lastname: Sho
authors.forename: Takahiro
authors.initials: T
authors.lastname: Akahori
authors.forename: Kaoru
authors.initials: K
authors.lastname: Hamada
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kubo
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Kanehiro
authors.forename: Shinji
authors.initials: S
authors.lastname: Nakamura
authors.forename: Koji
authors.initials: K
authors.lastname: Enomoto
authors.forename: Hideo
authors.initials: H
authors.lastname: Yagita
authors.forename: Miyuki
authors.initials: M
authors.lastname: Azuma
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Nakajima
mesh_terms: D000230:Adenocarcinoma / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D000368:Aged; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D015703:Antigens, CD / Q000187:drug effects / Q000378:metabolism*; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology; D060890:B7-H1 Antigen; D014408:Biomarkers, Tumor / Q000032:analysis*; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D003841:Deoxycytidine / Q000031:analogs & derivatives / Q000494:pharmacology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D016246:Lymphocytes, Tumor-Infiltrating / Q000187:drug effects / Q000276:immunology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008875:Middle Aged; D010190:Pancreatic Neoplasms / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D010455:Peptides / Q000378:metabolism; D011379:Prognosis; D061027:Programmed Cell Death 1 Ligand 2 Protein; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000093542:Gemcitabine
chemical_list: D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D060890:B7-H1 Antigen; D014408:Biomarkers, Tumor; C423236:CD274 protein, human; C556977:PDCD1LG2 protein, human; C556978:Pdcd1lg2 protein, mouse; D010455:Peptides; D061027:Programmed Cell Death 1 Ligand 2 Protein; D003841:Deoxycytidine; D000093542:Gemcitabine