Formalin fixation for optimal concordance of programmed death-ligand 1 immunostaining between cytologic and histologic specimens from patients with non-small cell lung cancer.

Autor: Koomen BM; Department of Pathology, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands., van der Starre-Gaal J; Department of Pathology, Isala Hospitals, Zwolle, the Netherlands., Vonk JM; Department of Epidemiology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands., von der Thüsen JH; Department of Pathology, Erasmus Medical Center, Rotterdam, the Netherlands., van der Meij JJC; Pathologie Friesland, Leeuwarden, the Netherlands., Monkhorst K; Department of Pathology, Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Amsterdam, the Netherlands., Willems SM; Department of Pathology, University Medical Center Utrecht, Utrecht University, Utrecht, the Netherlands.; Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands., Timens W; Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands., 't Hart NA; Department of Pathology, Isala Hospitals, Zwolle, the Netherlands.; Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
Jazyk: angličtina
Zdroj: Cancer cytopathology [Cancer Cytopathol] 2021 Apr; Vol. 129 (4), pp. 304-317. Date of Electronic Publication: 2020 Oct 27.
DOI: 10.1002/cncy.22383
Abstrakt: Background: Immunohistochemical staining of programmed death-ligand 1 (PD-L1) is used to determine which patients with non-small cell lung cancer (NSCLC) may benefit most from immunotherapy. Therapeutic management of many patients with NSCLC is based on cytology instead of histology. In this study, concordance of PD-L1 immunostaining between cytology cell blocks and their histologic counterparts was analyzed. Furthermore, the effect of various fixatives and fixation times on PD-L1 immunoreactivity was studied.
Methods: Paired histologic and cytologic samples from 67 patients with NSCLC were collected by performing fine-needle aspiration on pneumonectomy/lobectomy specimens. Formalin-fixed, agar-based or CytoLyt/PreservCyt-fixed Cellient cell blocks were prepared. Sections from cell blocks and tissue blocks were stained with SP263 (standardized assay) and 22C3 (laboratory-developed test) antibodies. PD-L1 scores were compared between histology and cytology. In addition, immunostaining was compared between PD-L1-expressing human cell lines fixed in various fixatives at increasing increments in fixation duration.
Results: Agar cell blocks and tissue blocks showed substantial agreement (κ = 0.70 and κ = 0.67, respectively), whereas fair-to-moderate agreement was found between Cellient cell blocks and histology (κ = 0.28 and κ = 0.49, respectively). Cell lines fixed in various alcohol-based fixatives showed less PD-L1 immunoreactivity compared with those fixed in formalin. In contrast to SP263, additional formalin fixation after alcohol fixation resulted in preserved staining intensity using the 22C3 laboratory-developed test and the 22C3 pharmDx assay.
Conclusions: Performing PD-L1 staining on cytologic specimens fixed in alcohol-based fixatives could result in false-negative immunostaining results, whereas fixation in formalin leads to higher and more histology-concordant PD-L1 immunostaining. The deleterious effect of alcohol fixation could be reversed to some degree by postfixation in formalin.
(© 2020 The Authors. Cancer Cytopathology published by Wiley Periodicals LLC on behalf of American Cancer Society.)
Databáze: MEDLINE
Externí odkaz: