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ABSTRACT: Introduction
Programmed death ligand 1 (PD-L1) testing of non-small cell lung cancer (NSCLC) specimens helps select patients most likely to respond to immune checkpoint inhibitors. PD-L1 immunohistochemical testing is approved for formalin-fixed, paraffin-embedded (FFPE) surgical pathology specimens; however, the testing performance on FFPE cytology cell block specimens is unknown.Materials and methods
The study is a retrospective cohort analysis of advanced stage NSCLC patients treated at our institution where tumor PD-L1 expression using the clone 22C3 pharmDx kit on the Dako Automated Link 48 platform was performed on either cytology cell block or surgical pathology specimens. Concomitant tumor mutation biomarkers were also collected, as well as tumor clinicopathologic characteristics and clinical outcome data following pembrolizumab treatment.Results
232 patient tumor specimens were tested for PD-L1 expression (94 on cytology cell block and 138 on surgical pathology specimens). No significant differences in PD-L1 tumor proportion score (TPS) were observed between cytology and surgical pathology groups, with both patient cohorts containing ~35% of tumors showing TPS ≥50%. Although few in number, patients with PD-L1 TPS ≥50% based on cytology vs. surgical pathology who received treatment with pembrolizumab demonstrated similar response and disease control rates.Conclusions
In this cohort of advanced NSCLC patients with standard of care PD-L1 testing performed on either FFPE cytology cell blocks or FFPE surgical pathology specimens, similar patterns were observed in population tumor PD-L1 expression patterns, concomitant driver mutations, and clinical response to palliative pembrolizumab in selected patients with TPS ≥50%.
SUBMITTER: Torous VF
PROVIDER: S-EPMC5919255 | biostudies-literature | 2018 May-Jun
REPOSITORIES: biostudies-literature
Journal of the American Society of Cytopathology 20180216 3
<h4>Introduction</h4>Programmed death ligand 1 (PD-L1) testing of non-small cell lung cancer (NSCLC) specimens helps select patients most likely to respond to immune checkpoint inhibitors. PD-L1 immunohistochemical testing is approved for formalin-fixed, paraffin-embedded (FFPE) surgical pathology specimens; however, the testing performance on FFPE cytology cell block specimens is unknown.<h4>Materials and methods</h4>The study is a retrospective cohort analysis of advanced stage NSCLC patients ...[more]