Targeting of embryonic annexin A2 expressed on ovarian and breast cancer by the novel monoclonal antibody 2448

Abstract

Monoclonal antibodies (mAbs) play an increasingly important role in cancer therapy. To address the wide heterogeneity of the disease, the identification of novel antigen targets and the development of mAbs against them are needed. Our lab previously generated a panel of mAbs against human embryonic stem cells (hESC) using a whole cell immunization approach in mice. These mAbs can potentially target oncofetal antigens and be repurposed for antibody or antibody drug conjugate (ADC) therapy. From this panel, the novel IgG1 2448 was found to bind surface antigens on hESC and multiple cancer cell lines. Here, we show 2448 targets a unique glycan epitope on annexin A2 (ANXA2) and can potentially monitor the Epithelial-Mesenchymal Transition (EMT) in ovarian and breast cancer. To evaluate 2448 as a potential drug, 2448 was engineered and expressed as a chimeric IgG1. Chimeric 2448 (ch2448) demonstrated efficient and specific killing when conjugated to cytotoxic payloads as an ADC. In addition, ch2448 elicited potent antibody-dependent cell-mediated cytotoxicity (ADCC) activity in vitro and in vivo. Further engineering of ch2448 to remove fucose in the Fc domain enhanced ADCC. Overall, these findings indicate that embryonic ANXA2 is an attractive target and suggest that ch2448 is a promising candidate for further therapeutic development.

In vivo surveillance and elimination of teratoma‐forming human embryonic stem cells with monoclonal antibody 2448 targeting annexin A2

“…Although one of the mice died midway through the experiment, the cause of death could not be determined. However, we do not attribute the cause of death to ch2448 as no adverse effect was observed in the mice by Cua et al (2018). However, further optimization of the ADC is required to increase the efficacy of this mAb as an ADC drug.…”

“…3.1 | ch2448 binds specifically to hESC and exhibits ADCC in vitro ch2488 was previously shown to bind to cancer and not to normal cells Cua et al (2018). The binding of ch2448 to the immunogen hESC (HES-3) was assessed via flow cytometry.…”

“…Hence, as a naked mAb, ch2448 does not affect the proliferation of hESCs in vitro. Cua et al (2018) demonstrated that ch2448 was able to engage effector cells and elicit ADCC activity on target cancer cells. We proceeded to determine if ch2448 was able to elicit ADCC on hESCs.…”

“…ADCC, antibody-dependent cell-mediated cytotoxicity; EB, embryoid body; hESC, human embryonic stem cell; mAb, monoclonal antibody using engineered Jurkat cells that expressed the human Fc-gamma IIIA receptor coupled to an ADCC NFAT signalling pathway as the readout. As a negative control, F(ab′) 2 fragments of ch2448, termed ch2448F(ab′) 2 , were generated to eliminate the Fc-mediated ADCC (Cua et al, 2018). The successful cleavage and generation of the F(ab ′) 2 fragments were confirmed on a SDS-PAGE gel and binding of the fragments to hESCs was retained ( Figure S1).…”

“…The mAb also elicited 2 MOAs to kill cancer cells, namely; ADCC and ADC. ch2448 also causes cancer tumour regression via ADCC in vivo via Fc‐Fc receptor engagement with effector cells in mice (Cua et al, ). Here, we show that ch2448 is also able to eliminate hESC via ADCC and ADC in vitro.…”