GA201 (RG7160): A Novel, Humanized, Glycoengineered Anti-EGFR Antibody with Enhanced ADCC and Superior In Vivo Efficacy Compared with Cetuximab

Abstract

Purpose: Anti-EGF receptor (EGFR) antibodies and small-molecule tyrosine kinase inhibitors have shown activity in epithelial tumors; however, agents that work by blocking the EGFR growth signal are ineffective when the oncogenic stimulus arises downstream, such as in tumors with KRAS mutations. Antibodies of the IgG 1 subclass can also kill tumor cells directly through antibody-dependent cell-mediated cytotoxicity (ADCC), and the efficacy of this is determined by the interaction of the Fc portion of the target cell-bound antibody and Fc receptors present on immune effector cells.Experimental Design: We report the development of GA201, a novel anti-EGFR monoclonal antibody with enhanced ADCC properties. GA201 was derived by humanization of the rat ICR62 antibody. The Fc region of GA201 was glycoengineered to contain bisected, afucosylated carbohydrates for enhanced binding to FcgRIIIA.Results: In vitro binding of GA201 to EGFR inhibited EGF ligand binding, EGFR/HER2 heterodimerization, downstream signaling, and cell proliferation to a similar extent as cetuximab. However, GA201 exhibited superior binding to both the low-and high-affinity variants of FcgRIIIA. This resulted in significantly enhanced induction of ADCC compared with cetuximab against both KRAS-wild-type and -mutant tumor cells lines. This enhanced ADCC translated into superior in vivo efficacy in a series of mouse xenograft models. Efficacy of GA201 was further increased when administered in combination with chemotherapy (irinotecan).Conclusions: These data suggest that GA201 may be more effective than cetuximab in patients with EGFR-positive solid tumors and may also represent a first-in-class treatment of patients with KRAS-mutated tumors.

The “less-is-more” in therapeutic antibodies: Afucosylated anti-cancer antibodies with enhanced antibody-dependent cellular cytotoxicity

“… 103 Human IgG1   Enhanced B-cell depletion over fucosylated counterpart in cynomolgus monkeys Imgatuzumab /GA201/ RG7160EGFRReduced (∼15%)Coexpression with GnT III and α-ManII in CHO cells (GlycoMAb Technology)Enhanced survival rate over fucosylated counterpart in mouse xenograft models displaying murine FcγRIV and over commercial Cetuximab in mouse xenograft models displaying murine FcγRIV and/or human FcγRIIIA.Gerdes et al. 108 Humanized IgG1     ARGX-111c-METafucosylatedFUT8 −/− CHO cells (Potelligent® Technology)Potent inhibition of c-Met-amplified tumor growth in MKN-45 xenograft mice(a)Human IgG1     XGFRIGF-1R and EGFRReducedCoexpression with GnT III and α-ManII in CHO cells (GlycoMAb Technology)Improved survival rate of mice treated with XGFR over its fucosylated counterpart in intrasplenic colon carcinoma model in SCID beige miceSchanzer et al. 110 Bispecific antibody with EGFR (GA201) and IGF-1R (R1507) specificities     XGFR*IGF-1R and EGFRReducedCoexpression with GnT III and α-ManII in CHO cells (GlycoMAb Technology)Enhanced tumor inhibition over fucosylated bispecific orthotopic Mia-PaCa2 pancreatic cancer xenograft model in SCID miceSchanzer et al.…”

“…Antibodies with reduced fucosylation against receptors like EGFR, insulin-like growth factor 1 receptor and c-Met have been generated and tested in murine models. 108-110 In addition to the anti-EGFR antibody imgatuzumab (GA201 or RG7160), bi-specific glycoengineered formats against two different receptors have also been developed 109 110 In xenograft SCID mouse models, these afucosylated antibodies demonstrated enhanced tumor inhibition in vivo , which is probably dependent on their enhanced binding to FcγRIII on various effector cells.…”

Glycoengineering of Therapeutic Antibodies Enhances Monocyte/Macrophage-Mediated Phagocytosis and Cytotoxicity

“…Despite the overall similarity in protein structure, individual FcgRs have unique binding patterns. In the case of the CD16a-IgG Fc interaction, the carbohydrate attached to CD16a at its Fc binding interface, a structural element unique to CD16a among FcgRs, is required for the increased binding affinity to afucosylated, GE Abs (10,(15)(16)(17).…”

Isolation and 111In–Oxine Labeling of Murine NK Cells for Assessment of Cell Trafficking in Orthotopic Lung Tumor Model

“…These mice express human FcgRIIIA (CD16) positive NK cells as effectors (about 80% of murine NK cells express human CD16), allowing a more accurate representation of efficacy via antibody-dependent cell-mediated cytotoxicity. 10 5 CB17/Icr-Prkdc scid /IcrlcoCrl mice (Charles River Laboratories Inc.) were used for biodistribution experiments. These mice have T and B-lymphocyte deficiency, but normal NK cell activity and radiation sensitivity, providing an appropriate in-vivo microenvironment for NK cell trafficking and irradiation experiments.…”