What is the key question?

• In an era when PD-L1 expression influences the use of immunotherapy and where immunotherapy clinical trials were based on histology as to opposed to cytology specimens, what is the performance of EBUS-TBNA specimens for PDL-1 immunohistochemical staining in comparison to resected lung specimens

What is the bottom line?

• PD-L1 has emerged as a biomarker for immunotherapy.
• Pembrolizumab is approved as a first line therapy in patients who have PD-L1 expression ≥ 50% in absence of targetable mutation and second line for any PD-L1 activity traditionally based on histological specimens.
• With EBUS-TBNA sampling (n=61), a PD-L1 IHC cutoff of ≥ 1% on EBUS-TBNA has a strong concordance with historical resected tumor specimens ( for the sensitivity, specificity, PPV, and NPV were 72%, 100%, 100%, and 80%, respectively. The concordance rate was 87% (53/61).
• At a PD-L1 IHC cutoff of ≥ 50% (15/61 patients), the sensitivity, specificity, PPV, and NPV were 47%, 93%, 70%, and 84%, respectively. The concordance rate was 82% (50/61)
• Potential reasons for discordance and false negatives reported by authors included low cell counts in EBUS samples (<5000 tumor cells) and discordance of expression in histology samples.

Why read on?

• The authors discuss potential methods of improving performance of EBUS-TNBA for PD-L1 IHC and the importance of recognizing the limitations of EBUS-TBNA currently when making decisions as regards therapy