Antitumor Activities against Breast Cancers by an Afucosylated Anti-HER2 Monoclonal Antibody H₂Mab-77-mG_2a-f

Abstract

Breast cancer patients with high levels of HER2 (human epidermal growth factor receptor 2) expression had worse clinical outcomes. Anti-HER2 monoclonal antibody (mAb) is the most important therapeutic modality for HER2-positive breast cancer. We previously immunized mice with the ectodomain of HER2 to create the anti-HER2 mAb, H2Mab-77 (mouse IgG1, kappa). This was then altered to produce H2Mab-77-mG2a-f, an afucosylated mouse IgG2a. In the present work, we examined the reactivity of H2Mab-77-mG2a-f and antitumor effects against breast cancers in vitro and in vivo. BT-474, an endogenously HER2-expressed breast cancer cell line, was identified by H2Mab-77-mG2a-f with a strong binding affinity [a dissociation constant (KD): 5.0 × 10-9 M]. H2Mab-77-mG2a-f could stain HER2 of breast cancer tissues in immunohistochemistry and detect HER2 protein in western blot analysis. Furthermore, H2Mab-77-mG2a-f demonstrated strong antibody-dependent cellular cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) for BT-474 cells. MDA-MB-468, a HER2-negative breast cancer cell line, was unaffected by H2Mab-77-mG2a-f. Additionally, in the BT-474-bearing tumor xenograft model, H2Mab-77-mG2a-f substantially suppressed tumor development when compared to the control mouse IgG2a mAb. In contrast, the HER2-negative MDA-MB-468-bearing tumor xenograft model showed no response to H2Mab-77-mG2a-f. These findings point to the possibility of H2Mab-77-mG2a-f as a treatment regimen by showing that it has antitumor effects on HER2-positive breast tumors.

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

“…We previously established several anti-HER2 mAbs, such as H2Mab-19 (IgG2b, kappa) [13], H2Mab-41 (IgG2b, kappa) [14], H2Mab-77 (IgG1, kappa) [15], H2Mab-119 (IgG1, kappa) [16], H2Mab-139 (IgG1, kappa) [17], and H2Mab-181 (IgG1, kappa) [18] by the immunization of HER2 ectodomain (HER2ec). We further engineered the mAbs into the mouse IgG2a type (H2Mab-77-mG2a, H2Mab-119-mG2a, and H2Mab-139-mG2a, respectively), and produced the core fucose-deficient types (H2Mab-77-mG2a-f, H2Mab-119-mG2a-f, and H2Mab-139-mG2a-f, respectively) to potentiate the antibodydependent cellular cytotoxicity (ADCC) and antitumor effect in vivo [19][20][21]. In this study, we developed and characterized a novel HER2 mAb, named H2Mab-250/H2CasMab-2.…”

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

“…We previously established several anti-HER2 mAbs, such as H2Mab-19 (IgG2b, kappa) [13], H2Mab-41 (IgG2b, kappa) [14], H2Mab-77 (IgG1, kappa) [15], H2Mab-119 (IgG1, kappa) [16], H2Mab-139 (IgG1, kappa) [17], H2Mab-181 (IgG1, kappa) [18], H2Mab-193 (IgG1, kappa), and H2Mab-215 (IgG1, kappa) by the immunization of HER2 ectodomain (HER2ec). We further engineered the mAbs into the mouse IgG2a type (H2Mab-77-mG2a, H2Mab-119-mG2a, and H2Mab-139-mG2a, respectively), and produced the core fucose-deficient types (H2Mab-77-mG2a-f, H2Mab-119-mG2a-f, and H2Mab-139-mG2a-f, respectively) to potentiate the antibody-dependent cellular cytotoxicity (ADCC) and antitumor effect in vivo [19][20][21]. In this study, we developed and characterized a novel HER2 mAb, named H2Mab-250/H2CasMab-2.…”

A Cancer-Specific Monoclonal Antibody against HER2 for Breast Cancers

“…We previously established anti-HER2 mAbs, H2Mab-77 (IgG1, kappa) [13], H2Mab-119 (IgG1, kappa) [14], and H2Mab-139 (IgG1, kappa) [15] by the immunization of HER2 ectodomain produced by cancer cells. We further engineered the mAbs into the mouse IgG2a type (H2Mab-77-mG 2a , H2Mab-119-mG 2a , and H2Mab-139-mG 2a , respectively), and produced the core fucose-deficient types (H2Mab-77-mG 2a -f, H2Mab-119-mG 2a -f, and H2Mab-139-mG 2a -f, respectively) to potentiate the antibodydependent cellular cytotoxicity (ADCC) and antitumor effect in vivo [16][17][18]. During the development, we have established a variety of anti-HER2 mAbs.…”