Validation of PD-L1 Immunohistochemical Testing on Formalin Fixed Paraffin Embedded (FFPE) Cell Block (CB) Preparations

Accurate identification of bovine Parainfluenza type 3 virus in bovine respiratory disease requires dependable, sensitive, and specific techniques for detection in affected animals. Immunohistochemical testing can be a rapid and reliable means of demonstration of virus in tissues from suspect cases; however, this procedure is dependent upon the quality of the antisera directed against the viral antigens. The production of rabbit polyclonal and murine monoclonal antibodies directed against bovine Parainfluenza type 3 virus and techniques for their use in fresh-frozen and formalin-fixed paraffin-embedded tissues in immunofluorescence and immunoperoxidase-based immunohistochemical tests are described.

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CellBlockistry: Chemistry and art of cell-block making – A detailed review of various historical options with recent advances

CytoJournal ◽

10.4103/cytojournal.cytojournal_20_19 ◽

2019 ◽

Vol 16 ◽

pp. 12 ◽

Cited By ~ 9

Author(s):

Vinod B Shidham

Keyword(s):

Ffpe Tissue ◽

Cell Block ◽

Molecular Tests ◽

Recent Advances ◽

Pattern Approach ◽

Formalin Fixed Paraffin ◽

Formalin Fixed Paraffin Embedded ◽

Technical Advances ◽

Ancillary Studies ◽

Formalin Fixed

Cell-blocks are paraffin-embedded versions of cytology specimens comparable to the formalin-fixed paraffin-embedded (FFPE) tissue from surgical pathology specimens. They allow various elective ancillary studies on a variety of specimens with enhanced cytopathologic interpretation, including opportunity to perform molecular tests. However, different dictionaries and internet search engines primarily project “cellblock” and “cell block” definition in relation to prisons. Most of the top searches lead to information related to “prison cells” followed by a few cytopathology-related searches. Due to this in the current review, it is recommended that the word for cytopathology purposes should be hyphenated and spelled as “cell-block.” Cell-blocks have been increasingly indicated on most cytology specimens. Its role is growing further with the ongoing addition of new immunohistochemistry (IHC) markers with technical advances including multicolor IHC and the SCIP (subtractive coordinate immunoreactivity pattern) approach. In addition, it is an important source of tissue for many ancillary studies even as archived material retrospectively at later stage of management if the cell-blocks are improved qualitatively and quantitatively. Because of this, the significance of cell-block is critical with the increasing number of molecular markers standardized predominantly on FFPE tissue. As compared to core biopsies, high-quality cell-blocks prepared with enhanced methodologies predominantly contain concentrated diagnostic tumor cells required for the molecular tests without significant stromal contamination. This review introduces the terminology of CellBlockistry as the science of studying chemistry and the art of achieving quantitatively and qualitatively improved cell-blocks from different types of specimens. The review addresses the cell-block making process as “cell-blocking” and discusses different historical limitations with emphasis on recent advances.

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Immunohistochemical staining for programmed cell-death ligand 1 (PD-L1) in malignant thymoma and thymic carcinoma.

Journal of Clinical Oncology ◽

10.1200/jco.2017.35.15_suppl.e20003 ◽

2017 ◽

Vol 35 (15_suppl) ◽

pp. e20003-e20003

Author(s):

Alexei Shimanovsky ◽

Richard Cartun ◽

Mary Fiel-Gan ◽

Daniza Mandich ◽

Jonathan Earle ◽

...

Keyword(s):

Thymic Carcinoma ◽

Tumor Grade ◽

Predictive Biomarker ◽

Moderate Intensity ◽

Malignant Thymoma ◽

Formalin Fixed Paraffin ◽

Formalin Fixed Paraffin Embedded ◽

Automated Platform ◽

Formalin Fixed ◽

Immunohistochemical Testing

e20003 Background: Recent development of anti-PD-1/L1 antibodies has demonstrated activity in various neoplasms. Thymic malignancies (TMS) are rare and treatment in advanced disease is limited. To evaluate the potential impact of anti-PD-1/L1 therapy in TMS, we examined the expression of PD-L1 in previously resected thymoma (TM) and thymic carcinoma (TC). Methods: We examined resected specimens from patients at Hartford Hospital with TM and TC between 2000 and 2014. Expression of PD-L1 was evaluated on formalin-fixed paraffin-embedded tissue. Immunohistochemical testing was done using four different clones of PD-L1 antibodies on the Leica Bond Max automated platform. The four clones include: E1L3N (Cell Signaling Technology), 28-8 (Epitomics) and SP142 (Spring Bioscience), and CAL10 (BioCare). PD-L1 expression was evaluated based on the percentage of tumor cells positive and their intensity graded as negative, weak (1+), moderate (2+), and strong (+3). The scoring was performed by three pathologists and was blinded for clinicopathologic data and antibody clones. Results: We evaluated a total of 29 patients, including 26 patients with TM and 3 with TC. Among the 29 available specimens, 12 had completed PD-L1 expression assessment at the time of submission. PD-L1 expression is present in 75-100% of the evaluated patients. All had positive PD-L1 staining by SP142 and CAL10. Three patients showed strong intensity by CAL10, and one by SP142. E1L3N and 28-8 had positive PD-L1 expression in 9 and 8 patients respectively with weak/moderate intensity. SP142 and CLA10 demonstrated the strongest concordance (R2 = 0.91) but there was significant variation between antibodies (R2 = 0.31-0.91). No correlation was detected between tumor grade and PD-L1 expression. There were focal areas that lacked expression in all of the evaluated specimens. Conclusions: There is increased expression of PD-L1 in TMS. The level of PD-L1 expression varies between the four PD-L1 antibodies. Increased PD-L1 expression provides evidence for the use of PD-L1 inhibitors in TMS. The variable staining highlights the heterogeneity of TMS and challenges in developing predictive biomarker in this cancer.

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