Analytical and clinical performance of progesterone receptor antibodies in breast cancer

Publication date: Available online 27 February 2018
Source:Annals of Diagnostic Pathology
Author(s): Benjamin C. Calhoun, Brian Mosteller, Daniel Warren, Margie Smith, J. Jordi Rowe, Christopher P. Lanigan, Karen C. Mrazeck, Espen Walker, Amy Hanlon Newell, Raymond Jones
ObjectiveComparison of analytical and immunohistochemical performance of progesterone receptor (PR) antibodies with correlation to recurrence of invasive breast cancer treated with endocrine therapy.MethodsThe binding-affinity kinetics of PR clones 1E2, 1A6, 16 and 636 were compared using synthetic peptides derived from identified epitopes on a Biacore T200. A cohort of 351 cases (Hormone Receptor (HR)+/HER2−) were stained for PR expression with immunohistochemistry (IHC) and scored according to ASCO/CAP criteria.ResultsThe stability of the antigen/antibody complex was greater for the 1E2 clone compared to 1A6, 16 and 636 clones. PR IHC on archival tissue resulted in 94.3% (299/317) concordance with clones.ConclusionClones evaluated in this study had a high level of concordance with IHC despite PR (1E2) demonstrating higher analytical binding properties than other clones. In a minority of cases (1.3% for 1E2 and 2.5% for 636) IHC results could convert estrogen receptor (ER)−/PR− to ER−/PR+ tumors, making these patients potentially eligible for endocrine therapy.



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