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Outcome of PD-L1 Testing in Endobronchial Ultrasound Guided Transbronchial Needle Aspiration (EBUS-TBNA)

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A6147 - Outcome of PD-L1 Testing in Endobronchial Ultrasound Guided Transbronchial Needle Aspiration (EBUS-TBNA)
Author Block: N. Al Nasrallah1, K. J. Diab2; 1Pulmonary, Critical Care, Indiana University School of Medicine, Indianapolis, IN, United States, 2Pulmonary and Critical Care Medicine, Indiana Univ School Of Med, Indianapolis, IN, United States.
Introduction:
New therapies for non-small-cell lung cancer (NSCLC) continue to be developed. Recently, several immune checkpoint inhibitors have been used. Programmed death receptor 1 (PD-1) and its ligand, programmed death ligand 1 (PD-L1), has been the target of several therapies. The most important step in checking for PD-L1 is to obtain sufficient lung cancer tissue for examination. EBUS-TBNA remains the preferable way to diagnose and stage lung cancer and initial studies suggest that EBUS-TBNA is also a promising method to evaluate PD-L1 expression in lung cancer.
Objectives: In this study we will evaluate the adequacy of specimens from EBUS-TBNA for assessment of PD-L1 status.
Method: We conducted a retrospective cohort analysis of patients that underwent EBUS-TBNA for suspected lung cancer at a university teaching hospital from 9/1/2016 through 10/1/2017. Only adult patients with a confirmed diagnosis of non-small-cell lung cancer were included. PD-L1 testing was done using clone PD-L1 IHC 22C3 pharmDx on formalin-fixed, paraffin-embedded tissues sections. Our lung pathologist interpreted those tests.
Results:
Thirty-nine patients were eventually diagnosed with NSCLC. Thirty-seven of them were diagnosed by EBUS while the other two were found to have NSCLC by transbronchial biopsy or endoscopic ultrasound. Most patients had 8 samples collected for cellblocks. Most of these samples were collected using 22-gauge needles (Expect or Olympus). PD-L1 testing was attempted on 32 of the TBNA specimens that were positive for NSCLC. Twenty-eight specimens (87.5%) had enough cells to perform PD-L1 staining on them. Sixteen specimens (57%) of patients were considered to be PD-L1 positive and 12 patients (43%) were negative. Four cases (12.5%) did not have enough cells to perform staining even though some other molecular testing could be done.
Conclusion: EBUS-TBNA is a promising diagnostic tool for the testing of PD-L1 tumor expression. It has a high diagnostic yield and obtains a sufficient amount of tissue for testing. Prospective randomized studies are needed to confirm these findings.
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