Antibodies blocking PlGF or VEGF interactions with the NRP1 receptormediate anti-proliferative effects

Blackman, S. A.; Qerqez, A. N.; Lee, A. G.; Johnson, N. V.; Owens, J. M.; Lai, G. S.; Aldrich, E. C.; Sprenger, K. G.; Lee, J.; Verrier, S.; Stoddart, M. J.; Nguyen, A. W.; Maynard, J. A.

doi:10.1101/2025.10.25.684565

bioRxiv · 10.1101/2025.10.25.684565

Antibodies blocking PlGF or VEGF interactions with the NRP1 receptormediate anti-proliferative effects

Blackman, S. A.·Qerqez, A. N.·Lee, A. G.·Johnson, N. V.·Owens, J. M.·Lai, G. S.·Aldrich, E. C.·Sprenger, K. G.·Lee, J.·Verrier, S.·Stoddart, M. J.·Nguyen, A. W.·Maynard, J. A.

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Abstract

Antibodies blocking the function of vascular endothelial growth factor A (VEGFA) remain a promising therapeutic strategy, especially when combined with check-point inhibitors, but their efficacy is limited by tumor resistance. This can occur via multiple mechanisms, including upregulation of placental growth factor 2 (PlGF-2), an alternative ligand for VEGF receptor 1 (VEGFR1) and neuropilin receptor 1 (NRP1). Activity of both growth factors is mediated by interactions with multiple receptors and extra-cellular matrix components, which complicates efforts to understand their contributions to cancer progression. To complement existing antibodies, we discovered those blocking interactions between PlGF-2 or VEGFA and their shared NRP1 receptor in the presence of heparin. Limiting angiogenesis to promote vascular normalization is one mechanism of anti-VEGF protection; here, anti-VEGFA antibodies blocking interactions with VEGFR1 and NRP1 reduced HUVEC tube formation in a physiological angiogenesis model. By contrast, antibodies binding PlGF-2 or VEGFA to block NRP1 significantly reduced proliferation of Caki-I kidney carcinoma cells in vitro, indicating this receptor mediates additional effects. Interestingly, one antibody exhibited dual-reactive binding to VEGFA and PlGF-2, suggesting a novel therapeutic strategy to prevent PlGF-driven VEGF-resistance. Overall, these antibodies define new mechanisms to disrupt PlGF activity and support a role for NRP1 in cell proliferation. Key ResultsO_LINew antibodies binding VEGFA or PlGF selectively block NRP1-receptor interactions. C_LIO_LIAntibody blockade of VEGFA binding to NRP1 reduced HUVEC angiogenesis. C_LIO_LIBlocking growth factor interactions with NRP1 reduced Caki-I renal carcinoma proliferation. C_LIO_LIIdentified an antibody with dual-reactive binding to VEGFA and PlGF. C_LI

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Blackman, S. A., Qerqez, A. N., Lee, A. G., Johnson, N. V., Owens, J. M., Lai, G. S., Aldrich, E. C., Sprenger, K. G., Lee, J., Verrier, S., Stoddart, M. J., Nguyen, A. W., Maynard, J. A.. 2025-10-26. Antibodies blocking PlGF or VEGF interactions with the NRP1 receptormediate anti-proliferative effects. https://doi.org/10.1101/2025.10.25.684565

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