Small bowel adenocarcinomas (SBAs) are often associated with poor prognosis and have limited therapeutic options. Programmed cell death protein-1 (PD-1)/programmed cell death ligand 1 (PD-L1) pathway blockade is an effective treatment in many microsatellite instability-high (MSI-H) solid tumors. We aimed at investigating PD-L1 and PD-1 expression in non-hereditary, non-ampullary SBAs, associated with celiac disease (CeD), Crohn’s disease (CrD), or sporadic, recruited through the Small Bowel Cancer Italian Consortium. We assessed PD-L1 and PD-1 by immunohistochemistry in a series of 121 surgically resected SBAs, including 34 CeD-SBAs, 49 CrD-SBAs, and 38 sporadic SBAs. PD-L1 and PD-1 expression was correlated with several clinico-pathological features, such as the etiology, microsatellite instability status, and tumor-infiltrating lymphocyte (TIL) density. The prevalence of PD-L1 positivity according to combined positive score (CPS) was 26% in the whole cohort of SBAs, with significantly (p = 0.001) higher percentage (35%) in both CeD-SBAs and CrD-SBAs in comparison with sporadic SBAs (5%). CPS ≥ 1 SBAs were significantly (p = 0.013) more frequent in MSI-H cases (41%) than in non-MSI-H ones (18%); however, 15 CPS ≥ 1 microsatellite stable SBAs were also identified. CPS ≥ 1 SBAs showed higher TIL and PD-1+ immune cell density, more frequently medullary histotype, as well as a better outcome in comparison with CPS < 1 cases. This study demonstrates an increased proportion of PD-L1+ cases in both CeD-SBAs and CrD-SBAs in comparison with sporadic SBAs. In addition, the identification of a subset of PD-L1+ microsatellite stable SBAs supports the need to ascertain additional biomarkers of response to immune checkpoint inhibitors along with MSI-H. © 2020, The Author(s), under exclusive licence to United States & Canadian Academy of Pathology.
Original languageEnglish
Pages (from-to)1398-1409
Number of pages12
JournalMod. Pathol.
Issue number7
Publication statusPublished - 2020


  • antineoplastic metal complex
  • fluorouracil
  • programmed death 1 ligand 1
  • programmed death 1 receptor
  • adenocarcinoma
  • adult
  • Article
  • cancer combination chemotherapy
  • cancer surgery
  • celiac disease
  • cell density
  • clinical feature
  • cohort analysis
  • controlled study
  • Crohn disease
  • disease association
  • female
  • human
  • human cell
  • human tissue
  • immunohistochemistry
  • longitudinal study
  • major clinical study
  • male
  • microsatellite instability
  • middle aged
  • prevalence
  • priority journal
  • protein expression
  • retrospective study
  • small intestine carcinoma
  • tumor associated leukocyte


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