Immunohistochemistry of immune checkpoint markers PD-1 and PD-L1 in prostate cancer.

Publication/Presentation Date

9-1-2019

Abstract

Recent availability of immune checkpoint inhibitors has facilitated research involving programmed cell death protein 1 (PD-1) and its ligand, programmed death-ligand 1 (PD-L1). However, the incidence and clinical implication of PD-1 and PD-L1 expression in prostate cancer remain poorly understood. The current study aimed to determine the status of PD-1/PD-L1 expression in prostate cancer specimens and its prognostic significance.We immunohistochemically stained for PD-1 and PD-L1 in our tissue microarray (TMA) consisting of radical prostatectomy specimens. The expression of PD-1/PD-L1 was designated as positive when moderate to strong staining or weak staining was seen in at least 1% or 10%, respectively, of tumor cells and/or associated immune cells. We then evaluated the relationship between the expression of each protein and clinicopathological features available for our patient cohort.PD-1 and PD-L1 were positive in 3 (1.5%) and 1 (0.5%) of 201 non-neoplastic prostate tissues, and also in 17 (7.7%) and 29 (13.2%) of 220 prostate cancers, respectively. PD-1 and PD-L1 were also expressed in tumor-infiltrating lymphocytes/macrophages in 172 (78.2%) and 33 (15.0%) cases, respectively. PD-L1 expression in tumor cells was more often seen in high pT stage (pT2: 10.8% vs pT3/4: 20.4%; P = .072; pT2/3a: 11.4% vs pT3b/4: 31.6%; P = .013) or lymph node-positive (pN0: 10.1% vs pN1: 27.3%; P = .086) cases, whereas PD-1 expression in tumor cells was not significantly associated with pT/pN stage. In addition, there were no statistically significant associations between PD-1/PD-L1 expression in tumor cells or tumor-infiltrating lymphocytes/macrophages versus patient age, preoperative prostate-specific antigen level, or Gleason score. Kaplan-Meier analysis coupled with log-rank test further revealed no significant associations between PD-1/PD-L1 expression in tumor cells (P = .619/P = .315), tumor-infiltrating lymphocytes/macrophages (P = .954/P = .155), or either or both of them (P = .964/P = .767) versus disease recurrence after radical prostatectomy.PD-1/PD-L1 expression was detected in a subset of prostate cancers. In particular, PD-L1 expression was considerably up-regulated in nonorgan-confined tumors. However, PD-1/PD-L1 expression in our TMA was found to be not very helpful in predicting tumor recurrence in prostate cancer patients who underwent radical prostatectomy.

Volume

98

Issue

38

First Page

17257

Last Page

17257

ISSN

1536-5964

Disciplines

Medicine and Health Sciences

PubMedID

31567999

Department(s)

Department of Pathology and Laboratory Medicine

Document Type

Article

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