Establishment of a Novel Cancer-Specific Anti-HER2 Monoclonal Antibody H₂Mab-250/H₂CasMab-2 for Breast Cancers

Abstract

Overexpression of human epidermal growth factor receptor 2 (HER2) in breast and gastric cancers is an important target for monoclonal antibody (mAb) therapy. All therapeutic mAbs, including anti-HER2 mAbs, exhibit adverse effects probably due to the recognition of antigens expressed in normal cells. Therefore, tumor-selective or specific mAbs can be beneficial in reducing the adverse effects. In this study, we established a novel cancer-specific anti-HER2 antibody, named H2Mab-250/H2CasMab-2 (IgG1, kappa). H2Mab-250 reacted with HER2-positive breast cancer BT-474 and SK-BR-3 cells. Importantly, H2Mab-250 did not react with non-transformed normal epithelial cells (HaCaT and MCF 10A) and immortalized normal epithelial cells in flow cytometry. In contrast, most anti-HER2 mAbs, such as H2Mab-119 and trastuzumab reacted with both cancer and normal epithelial cells. Immunohistochemical analysis demonstrated that H2Mab-250 possesses much higher reactivity to the HER2-positive breast cancer tissues compared to H2Mab-119, and did not react with normal tissues, including heart, breast, stomach, lung, colon, kidney, and esophagus. The epitope mapping demonstrated that the Trp614 of HER2 domain IV mainly contributes to the recognition by H2Mab-250. H2Mab-250 could contribute to the development of chimeric antigen receptor-T or antibody-drug conjugates without adverse effects for breast cancer therapy.

Establishment of a Highly-sensitive Anti-EphB2 Monoclonal Antibody Eb2Mab-3 for Flow Cytometry

“…We have developed cancer-specific mAbs (CasMabs) against HER2 (H2Mab-214 and H2Mab-250) [34,35], podocalyxin (PcMab-6 and PcMab-60) [36,37], and podoplanin (LpMab-2 and LpMab-23) [38,39] and revealed that these mAbs react with cancer cells, but not normal cells in flow cytometry. The strategy used in this study is also applicable to select anti-EphB2 CasMabs from Eb2Mabs (Supplementary Table S1) or clones from remaining positive wells.…”