PD-L1 and Emerging Biomarkers in Immune Checkpoint Blockade Therapy

Tricia R. Cottrell, Janis M. Taube

Research output: Contribution to journalReview articlepeer-review


PD-L1 checkpoint blockade is revolutionizing cancer therapy, and biomarkers capable of predicting which patients are most likely to respond are highly desired. The detection of PD-L1 protein expression by immunohistochemistry can enrich for response to anti-PD-(L)1 blockade in a variety of tumor types, but is not absolute. Limitations of current commercial PD-L1 immunohistochemical (IHC) assays and improvements anticipated in next-generation PD-L1 testing are reviewed. Assessment of tumor-infiltrating lymphocytes in conjunction with PD-L1 testing could improve specificity by distinguishing adaptive (interferon γ driven and cytotoxic T-lymphocyte associated) from constitutive (non-immune mediated) expression. The presence of a high tumor mutational burden also enriches for response to therapy, and early data indicate that this may provide additive predictive value beyond PD-L1 IHC alone. As candidate biomarkers continue to emerge, the pathologist's assessment of the tumor microenvironment on hematoxylin-eosin stain combined with PD-L1 IHC remains a rapid and robust way to evaluate the tumor-immune dynamic.

Original languageEnglish (US)
Pages (from-to)41-46
Number of pages6
JournalCancer Journal (United States)
Issue number1
StatePublished - Jan 1 2018


  • PD-(L)1
  • PD-(L)1 checkpoint blockade
  • PD-L1 testing

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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