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Immune infiltrates and PD-L1 expression in treatment-naïve acinar prostatic adenocarcinoma: an exploratory analysis
  1. Elan Hahn1,2,
  2. Stanley K Liu3,
  3. Danny Vesprini3,
  4. Bin Xu1,2,
  5. Michelle R Downes1,2
  1. 1 Anatomic Pathology, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
  2. 2 Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
  3. 3 Radiation Oncology, Odette Cancer Centre, Sunnybrook Health Sciences Centre and University of Toronto, Toronto, Ontario, Canada
  1. Correspondence to Dr Michelle R Downes, Anatomic Pathology, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Toronto, ON M4N 3M5, Canada; michelle.downes{at}sunnybrook.ca

Abstract

Tumour-induced immunosuppression plays a role in the development and progression of cancer. Of interest is the interaction between programmed death-1 and programmed death ligand-1 (PD-L1) which can be targeted through immune checkpoint blockade; however, there are limited data surrounding the composition of the immune milieu in prostate cancer. We preliminarily assessed 21 radical prostatectomies in therapy-naïve patients for immune markers and PD-L1 expression. The immune infiltrates were higher in adenocarcinoma than benign prostate (lymphocytes p<0.001, macrophages p=0.010) with 5% of cases being PD-L1 high (≥5% expression). Increased peritumoural CD68 and CD163 expression correlated with lower grade group (GG) (p=0.024 and p=0.014, respectively) with a trend towards increased CD68 expression in lower stage cases (p=0.086). There was also increased CD45 expression in lower GGs (p=0.063). We found the immune infiltrate in acinar prostate cancer to be extremely heterogeneous with an overall immunophenotype unlikely to respond to immune checkpoint blockade.

  • prostate
  • PD-L1
  • immune checkpoint blockade

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Footnotes

  • Handling editor Runjan Chetty.

  • Contributors MRD: designed study, acquired data, drafted and approved manuscript. EH, SKL, DV: acquired data, drafted and approved manuscript. BX: statistical analysis, drafted and approved manuscript.

  • Competing interests MRD has received compensation from Hoffman – La Roche and Astra Zeneca for participating on advisory boards and honoraria from Astra Zeneca. BX has received honoraria from Merck.

  • Patient consent Not required.

  • Ethics approval Approval for this research was obtained from the research ethics board of Sunnybrook Health Sciences Centre (REB 459–2016).

  • Provenance and peer review Not commissioned; externally peer reviewed.

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