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.
- immune checkpoint blockade
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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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