Development of Highly Sensitive and Specific Monoclonal Antibodies Against Glypican-1 Using the Cell-Based Immunization and Screening Technology

Background/Objectives: Glypican-1 (GPC1) is a heparan sulfate proteoglycan that plays a critical role in regulating various signaling pathways and tumor development. Overexpression of GPC1 promotes tumor cell proliferation and invasiveness, and is associated with poor clinical outcomes. Therefore, anti-GPC1 monoclonal antibodies (mAbs) have been developed in various modalities for tumor therapy. Methods: We developed novel anti-GPC1 mAbs using a flow cytometry-based high-throughput screening approach, the Cell-Based Immunization and Screening (CBIS) method. Results: A clone G1Mab-28 (IgG1, κ) reacted with GPC1-overexpressed Chinese hamster ovary-K1 (CHO/GPC1), but not parental CHO-K1, in flow cytometry. Furthermore, G1Mab-28 recognizes the endogenous GPC1-expressing human esophageal squamous cell carcinoma KYSE770 cell line. Furthermore, G1Mab-28 specifically recognized only CHO/GPC1, but not the other GPC family-overexpressed CHO-K1. The dissociation constant values of G1Mab-28 for CHO/GPC1 and KYSE770 were determined to be 3.3 × 10−8 M and 4.6 × 10−9 M, respectively. Moreover, G1Mab-28 is suitable for Western blotting and immunohistochemistry. Conclusions: G1Mab-28, established by the CBIS method, is versatile for basic research and is expected to contribute to antibody-based tumor therapy.