CEACAM1 is a member of the CEA family expressed in cell membranes of T cells and NK cells as well as tumor cells. CEACAM1 overexpressed in tumor cells interacts with CEACAM1 expressed in tumor infiltrating lymphocytes (TIL) and suppresses TIL activity by sending an inhibitory signal to immune cells, which is an immune escape mechanism in cancer. Therefore, we developed MG1124, a monoclonal antibody that specifically binds to CEACAM1 but not to other CEA family members, thereby blocking tumor growth by triggering immune response.
CEACAM1 specific binding of MG1124 was tested in CEACAM1 or other CEA family over-expressing cells. MG1124 was examined by in vitro tumor cell lysis assays using NK92, a human NK cell line. The anti-tumor efficacy of MG1124 alone or in combination with a PD-1 inhibitor was studied in a humanized mouse model engrafted with non-small cell lung cancer (NSCLC) patient-derived tumor xenografts (NSCLC hu-PDX models).
An anti-CEACAM1 antibody, MG1124 binds to CEACAM1 overexpressing Jurkat cells but not to other CEA family members and blocks ligands interaction in a dose-dependent manner. MG1124 increased NK92-mediated tumor cell lysis against cancer cells with strong CEACAM1 expression, but not to those with no or weak CEACAM1 expression. In a single mouse trial, MG1124 (tumor growth inhibition (TGI) 55%) was efficacious in the high CEACAM1 expressing NSCLC hu-PDX model as monotherapy. In addition, the combination therapy (TGI 42%) with a PD-1 inhibitor displayed enhanced antitumor activity than the anti-CEACAM1 monotherapy (TGI 17%) in a CEACAM1-low expression model as well as in a CEACAM1-high expression model (combination therapy TGI 63% vs monotherapy TGI 46%). Moreover, tumor tissues (n = 150) of NSCLC patients showed extensive expression of CEACAM1, suggesting a potential therapeutic use of MG1124 in NSCLC patients.
In this study, the anti-CEACAM1 antibody MG1124 showed antitumor efficacy in human CEACAM1-expressing cancer cell lines and NSCLC hu-PDX xenograft models, and demonstrated potential as a targeted therapy for NSCLC, both as a single agent and in combination with a PD-1 inhibitor.
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All authors have declared no conflicts of interest.