Abstract 2182
Background
Immune checkpoint inhibitors mediated by PD-1 and PD-L1 are promising treatments for various tumors. The PD-L1 expression in tumor cells was found to be correlated with the likelihood of a response to PD-1- or PD-L1-targeted therapy in non-small cell lung cancer (NSCLC). For PD-L1 immunohistochemistry (IHC), 22C3 pharmDx is the only companion diagnostic assay that can identify NSCLC patients suitable for pembrolizumab treatment. Specimens are scored and divided into 3 categories (<1%, 1-49%, ≥50%) based on the tumor proportion score (TPS). The PD-L1 prevalence in NSCLC patients screened for the KEYNOTE-024 trial was 31% with TPS <1%, 39% with TPS 1-49%, and 30% with TPS ≥50%. While specimens used for the IHC 22C3 assay are recommended to be formalin-fixed for 12-72 h, the specimens were fixed in 10% neutral-buffered formalin for less than 6 h in our institution. Thus, we retrospectively assessed the PD-L1 prevalence in NSCLC patients to determine whether the PD-L1 TPS differs according to the duration of formalin fixation.
Methods
We screened consecutive NSCLC patients who underwent tumor biopsy by bronchoscopy between January 2017 and June 2018 at National Hospital Organization Fukuokahigashi Medical Center. In the present study, we only included 70 patients whose tumors were formalin-fixed for less than 6 h and whose PD-L1 expression had been evaluated by IHC with antibodies to human PD-L1 (22C3 pharmDx).
Results
The PD-L1 prevalence in patients with NSCLC in our hospital was 26 (37%) with TPS<1%, 23 (33%) with TPS 1-49%, and 21 (30%) with TPS ≥50%, suggesting that small biopsy samples obtained by bronchoscopy that were formalin-fixed for <6 h are suitable for PD-L1 IHC. We also performed analyzed in 35 surgically-resected NSCLC specimens that had been formalin-fixed for 1-7 days by PD-L1 IHC. The PD-L1 prevalence was 20 (57%) for TPS < 1%, 9 (26%) for TPS 1-49%, and 6 (17%) for TPS ≥50%.
Conclusions
The PD-L1 prevalence in specimens with short-duration formalin fixation was consistent with the results of the KEYNOTE-024 trial. We will present our conclusion regarding these results, including the characteristics of patients and the PD-L1 prevalence in specimens fixed for 12-72 h in our institution, from July 2018 onward.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
National Hospital Organization Fukuokahigashi Medical Center.
Funding
JSPS KAKENHI JP18K15927.
Disclosure
All authors have declared no conflicts of interest.
Resources from the same session
4925 - Prognostic role of CD73 in metastatic Non Small Cell Lung Cancer according to the presence of driver alterations
Presenter: Giulia Galli
Session: Poster Display session 1
Resources:
Abstract
785 - JAK-STAT inhibitor overcomes interferon γ-reduced, NK cell-mediated cytotoxicity in non-small-cell lung cancer cells
Presenter: Riki Okita
Session: Poster Display session 1
Resources:
Abstract
2326 - Low LATS2 expression is associated with poor prognosis in non small cell lung cancer
Presenter: Si-hyong Jang
Session: Poster Display session 1
Resources:
Abstract
5960 - Application of ESCAT and OncoKB scales in Liquid biopsy (LB) in Advanced NSCLC patients (pts): Is it feasible and reliable?
Presenter: Michael McCusker
Session: Poster Display session 1
Resources:
Abstract
4855 - IDH1R132H mutation induces a less aggressive phenotype of glioma cells and affects the radiosensitivity by interacting with Wnt/β-catenin signaling
Presenter: Xuetao Han
Session: Poster Display session 1
Resources:
Abstract
2641 - Impact of Angiopoietin-2 on glioblastoma response to combined chemo-radiotherapy
Presenter: Charly Helaine
Session: Poster Display session 1
Resources:
Abstract
5743 - The Discovery of RNA-aptamers That Selectively Bind and Inhibit Glioblastoma Stem Cells by targeting EphA2
Presenter: Alessandra Affinito
Session: Poster Display session 1
Resources:
Abstract
4160 - Impact of tumor reoxygenation by nanoparticles on Tumor Associated Macrophages (TAMs)
Presenter: Aurélie Ferré
Session: Poster Display session 1
Resources:
Abstract
2474 - Prognostic significance of c-Rel/p50 heterodimer in the tumor microenvironment of uveal melanoma
Presenter: Seema Kashyap
Session: Poster Display session 1
Resources:
Abstract
1769 - Synergistic role of BAP1 and DNA damage response pathway in uveal melanoma and its prognostic significance.
Presenter: JAYANTI JHA
Session: Poster Display session 1
Resources:
Abstract