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

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.