Fully human antagonistic antibodies targeting FPR2 through dual extracellular-loop engagement for gastric cancer therapy

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Background Gastric cancer (GC) remains a major cause of cancer mortality worldwide, particularly in metastatic stages. N-formyl peptide receptor 2 (FPR2), a class A G protein-coupled receptor activated by the Helicobacter pylori–derived peptide Hp(2–20), promotes GC progression by stimulating oncogenic signaling pathways. However, no clinically applicable agents selectively targeting FPR2 have been developed. Methods We generated fully human antagonistic antibodies targeting FPR2 using a two-step discovery strategy. A CDR-H3–focused synthetic single-chain variable fragment library was screened against an extracellular loop 3 (ECL3) peptide, followed by light-chain engineering to confer dual engagement of extracellular loop 2 (ECL2). Results The engineered antibody exhibited dose-dependent binding to both ECL2 and ECL3 peptides, selectively recognized FPR2 over other FPR family members, and showed nanomolar binding to FPR2-expressing cancer cells. The antibody inhibited Hp(2–20)–induced calcium mobilization and suppressed migration and invasion of Adenocarcinoma Gastric (AGS) gastric cancer cells. Structural modeling indicated a lid-like binding mode occluding the orthosteric pocket. Conclusions We developed a fully human antagonistic antibody that selectively binds and inhibits FPR2 through dual extracellular-loop engagement. The antibody potentially suppresses FPR2-driven signaling and invasive behaviors in gastric cancer cells, supporting its development for therapeutic application. Further assessment of its efficacy in vivo is warranted.