A novel anti-HER2 antibody GB235 reverses Trastuzumab resistance in HER2-expressing tumor cells in vitro and in vivo

Abstract

HER2 overexpression is frequently associated with tumor metastasis and poor prognosis of breast cancer. More evidence indicates that HER3 is involved in HER2-resistant therapies. Combination treatments with two or more different monoclonal antibodies are a promising strategy to overcome resistance to HER2 therapies. We presented a novel fully human HER2-targeted monoclonal antibody, GB235, screened from a phage-display library against the HER2 antigen. GB235 in combination with Trastuzumab overcomes resistance in HER2-positive tumors and results in more sustained inhibition of tumor growth over time. The competition binding assay showed that the epitopes of GB235 do not overlap with those of Pertuzumab and Trastuzumab on HER2. Further HER2 mutagenesis results revealed that the binding epitopes of GB235 were located in the domain III of HER2. The mechanism of action of GB235 in blocking HER2-driven tumors is different from the mechanisms of Trastuzumab or Pertuzumab. GB235 does not affect the heterodimerization of HER2 and HER3, whereas the GB235 combined treatment with Trastuzumab significantly inhibited heregulin-induced HER3 phosphorylation and downstream signaling. Moreover, GB235 in combination with Trastuzumab reversed the resistance to heregulin-induced proliferation in HER2-overexpressing cancer cell lines. GB235 combined with Trastuzumab treatment in xenograft models resulted in improved antitumor activity. Complete tumor suppression was observed in the HER2-positive NCI-N87 xenograft model treated with the combination treatment with GB235 and Trastuzumab. In a Trastuzumab-resistant patient-derived tumor xenograft model GA0060, GB235 plus Trastuzumab reversed the resistance to Trastuzumab monotherapy. Because GB235 showed a different working mechanism with Pertuzumab and Trastuzumab, these agents can be considered complementary therapy against HER2 overexpression tumors.www.nature.com/scientificreports www.nature.com/scientificreports/ to HER2 ECD proteins of three different species. GB235 specifically bound to human and rat HER2 ECD, but did not cross-react with the mouse HER2 ECD in the ELISA (Fig. 6C). Moreover, it was observed that 362D, 374Q, 395D, 456 H are phylogenetically conserved in human and rat HER2 ECD d III , but not in mouse HER2 ECD d III . The residues are conserved in the human and rat HER2 but not in the mouse HER2, thus explaining the lack of cross-reaction with mouse HER2. The binding of the full-length human HER2 ECD d I-IV to GB235 was abolished in site-directed mutants of human HER2 (D362N, Q374H and H456N) (Fig. 6D). The residues 362D, 374Q and 456 H in the human HER2 ECD d III were found to be critical for the binding of GB235.

Photodynamic Therapy for the Treatment and Diagnosis of Cancer–A Review of the Current Clinical Status

“…Such a difference in receptor expression underlies an active targeting strategy, which takes advantage of the combination of PDT with trastuzumab. Indeed, trastuzumab, which is a humanized anti-HER2 antibody, is the first HER2-targeted therapeutic monoclonal antibody approved by the FDA in 1998 for the therapy of metastatic HER2 + breast cancer ( Rossi et al, 2016 ; Shu et al, 2020 ). In addition to targeting receptors with specific monoclonal antibodies, conjugation of PSs with specific ligands that bind to the receptors is also a promising approach.…”

Case Report: Herceptin as a Potentially Valuable Adjuvant Therapy for a Patient With Human Epidermal Growth Factor Receptor 2-Positive Advanced Esophageal Squamous Cell Carcinoma

“…Mengjun et al. found the GB235 anti-HER2 antibody can be considered a complementary therapy for HER2-positive breast cancer ( 23 ). Therefore, it is necessary to formulate complementary therapy for HER2-positive patients.…”

“…MyPathway, a phase IIa multiple basket study, indicated that 38% of patients with colorectal cancer with HER2 amplification achieved PR after treatment with patuzumab combined with the HER2 inhibitor trastuzumab (22). Mengjun et al found the GB235 anti-HER2 antibody can be considered a complementary therapy for HER2positive breast cancer (23). Therefore, it is necessary to formulate complementary therapy for HER2-positive patients.…”

Fully human recombinant antibodies against EphA2 from a multi-tumor patient immune library suitable for tumor-targeted therapy

“…The screened EphA2-scFv with good binding activity and specificity was ligated with a pcDNA3.1/SP-Fc (human IgG1-Fc) recombinant vector constructed in our laboratory and recombined to form a bivalent EphA2-scFv-Fc in accordance with the experimental methods in [ 51 ]. The full-length IgG1 antibody was constructed as previously described [ 52 ]. VH and VL were amplified by PCR using EphA2-scFv as template, and VH was homologously recombined into the pcDNA3.1/SP-CH vector constructed in our laboratory.…”