Implicações clínicas de um anticorpo recombinante (Fab) construído e selecionado por Phage display e avaliação do papel das citoqueratinas no câncer de mama

Abstract

Background Currently there are no biomarkers capable of predicting the outcome or avoiding unnecessary treatment in breast cancer (BC), and diagnostic markers have variable behavior, suggesting a higher complexity and heterogeneity of existing BC subtypes. We have characterized the biological target of a new Fab antibody in BC tissues and assessed its clinical relevance in diagnostics, disease staging and prognosis. Methods A Fab antibody combinatorial library was constructed by mixing transcripts from twenty patients with invasive ductal carcinoma. Phage Display selections against BC tissues from all stages led to the breast specific FabC-4 antibody, which was thoroughly investigated by immunohistochemistry (IHC) in a tissue microarray generated by a cohort of 232 BC patients. The FabC-4 ligand was determined by mass spectrometry. Results The FabC-4 was selected based on its high reactivity to all BC stages and discrimination power from benign diseases and healthy controls, with significant sensitivity and specificity (70% and 62% respectively). Its higher tissue expression was associated with aggressive BCs; i.e., younger age, lack of progesterone receptor, higher histological grades and non-luminal phenotypes, and it also identified a subset of good prognostic triple-negative BCs. Its biological target, identified through mass spectrometry, is a conformational epitope of Cytokeratin- 10 (CK10). Conclusion A CK10-epitope specific antibody is the first bi-functional highly specific tissue biomarker for BC diagnosis and histopathological classification, which was also shown to be associated with aggressive BCs. In addition, the antibody identified a subset of triple negative BCs with good prognosis. Its role in BCs should be addressed in future studies.