Abstract DPOC-002: A NOVEL CELL LINE BASED IMMUNOHISTOCHEMICAL TP53 EXPRESSION PATTERN CONTROL PANEL

BACKGROUND:TP53 gene mutation status is known to be manifested through distinct p53 immunohistochemical staining patterns; diffuse, “wild-type” and null. This stratified staining pattern is commonly utilized in subtyping ovarian and endometrial cancer subtypes as well as distinguishing between ovarian low- and high-grade serous carcinoma. EXPERIMENTAL PROCEDURES: Three ovarian cancer cell lines consistently demonstrating either diffuse, wild-type or null p53 staining were utilized in the construction of an immunohistochemical control panel slide that highlights each TP53 expression pattern. Cell lines were expanded, harvested and resuspended in agarose gel and subsequently sectioned onto a microscope slide (Figure 1A). Procured tissue specimens were submitted along with either standard control tissue or the TP53 cell line control panel to three pathologists of varying experience. RESULTS: Interobserver variability was demonstrated to be similar with the use of the TP53 expression panel (Fleiss kappa= 0.79 vs 0.76) and there was a net decrease in categorization errors. The TP53 cell line expression pattern control panel sections demonstrated consistent clean and easily interpretable diffuse, wild-type and null p53 staining (Figure 1B). CONCLUSIONS: We developed a novel cell line-based TP53 expression pattern control panel with refined quality assurance potential that would act, as a minimum, a model for antibody optimization. This study suggests the addition of a cell line TP53 control panel could potentially increase the accuracy of identification for ovarian and endometrial cancer subtypes as well as ovarian low grade versus high-grade serous carcinoma distinction. This control panel has the potential to be utilized in other disease states where TP53 expression pattern assists in diagnosis. Citation Format: Viqar Syed PhD, Imran Hussain, BSc, Jeptha Johnson MD, Patrick Malafronte MD, Justin Wells MD, Yaling Zhou PhD, Deyin Xing MD PhD, John D. Andersen DO. A NOVEL CELL LINE BASED IMMUNOHISTOCHEMICAL TP53 EXPRESSION PATTERN CONTROL PANEL [abstract]. In: Proceedings of the 11th Biennial Ovarian Cancer Research Symposium; Sep 12-13, 2016; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(11 Suppl):Abstract nr DPOC-002.