Raising an Antibody Specific to Breast Cancer Subpopulations Using Phage Display on Tissue Sections

Background/Aim: Primary tumors display a great level of intra-tumor heterogeneity in breast cancer. The current lack of prognostic and predictive biomarkers limits accurate stratification and the ability to predict response to therapy. The aim of the present study was to select recombinant antibody fragments specific against breast cancer subpopulations, aiding the discovery of novel biomarkers. Materials and Methods: Recombinant antibody fragments were selected by phage display. A novel shadowstick technology enabled the direct selection using tissue sections of antibody fragments specific against small subpopulations of breast cancer cells. Selections were performed against a subpopulation of breast cancer cells expressing CD271 + , as these previously have been indicated to be potential breast cancer stem cells. The selected antibody fragments were screened by phage ELISA on both breast cancer and myoepithelial cells. The antibody fragments were validated and evaluated by immunohistochemistry experiments. Results: Our study revealed an antibody fragment, LH8, specific for breast cancer cells. Immuno - histochemistry results indicate that this particular antibody fragment binds an antigen that exhibits differential expression in different breast cancer subpopulations. Conclusion: Further studies characterizing this antibody fragment, the subpopulation it binds and the cognate antigen may unearth novel biomarkers of clinical relevance. Today it is widely recognized that breast cancer is a disease that exhibits a large degree of heterogeneity, between and within patients. The heterogeneity between patients is characterized as belonging to one of several histological subtypes. Within any given patient, heterogeneity exists between the primary lesion and metastasis. Even within individual primary tumors different subpopulations of cancer cells co-exist, each displaying diverse sets of properties. This well-documented intra-tumor heterogeneity greatly affects