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Programmed Death-ligand 1 Expression With Clone 22C3 in Non-small Cell Lung Cancer: A Single Institution Experience

Maiko Takeda1, Takahiko Kasai1, Maiko Naito2

  • 1Department of Laboratory Medicine and Pathology, National Hospital Organization Kinki-Chuo Chest Medical Center, Sakai, Japan.

Clinical Medicine Insights. Oncology
|January 24, 2019
PubMed
Abstract

Insights

Pembrolizumab (Keytruda) is approved for non-small cell lung cancer (NSCLC) based on PD-L1 expression. This study found PD-L1 expression rates consistent with prior reports, though older samples showed decreased expression.

Area of Science:

  • Oncology
  • Immunotherapy
  • Cancer Diagnostics

Background:

  • Pembrolizumab (Keytruda), an anti-programmed cell death 1 (PD-1) therapy, is approved for advanced non-small cell lung cancer (NSCLC).
  • Treatment efficacy is determined by programmed death-ligand 1 (PD-L1) expression levels, assessed via immunohistochemical assays.
  • This study evaluates 22C3-PD-L1 expression in NSCLC within a single institution.

Purpose of the Study:

  • To assess 22C3-PD-L1 expression in a cohort of NSCLC patients.
  • To compare PD-L1 expression with various clinicopathologic features.
  • To investigate the impact of sample age on PD-L1 expression detection.

Main Methods:

  • Analyzed 22C3-PD-L1 expression in 411 NSCLC patients using immunohistochemistry (IHC) with the 22C3 pharmDx kit.
  • Classified patients into three groups: <1% (no expression), 1%-49% (low expression), and ⩾50% (high expression) positive tumor cells.
  • Compared PD-L1 expression with clinicopathologic data and analyzed differences based on specimen age.

Main Results:

  • PD-L1 expression was observed in 67% of patients: 33% no expression, 38% low expression, and 29% high expression.
  • Archival samples, particularly those over 4 years old, exhibited significantly lower PD-L1 expression compared to recent samples.
  • PD-L1 positivity was associated with male sex, smoking history, higher tumor grade, squamous cell carcinoma, wild-type EGFR, and ALK rearrangement.

Conclusions:

  • The overall rate of 22C3-PD-L1 expression in NSCLC aligns with previous research findings.
  • The use of older paraffin-embedded blocks can lead to an underestimation of PD-L1 expression.
  • Accurate PD-L1 assessment is crucial for guiding immunotherapy decisions in NSCLC.
Keywords:
22C3EGFRNon-small lung cancerPD-L1 expression testingpembrolizumab

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