Therapeutic effect of fully human anti-Nrp-1 antibody on non-small cell lung cancer in vivo and in vitro.

Although immune checkpoint inhibitors have changed the treatment paradigm for non-small cell lung cancer (NSCLC), not all patients benefit from them. Therefore, there is an urgent need to explore novel immune checkpoint inhibitors. Neuropilin-1 (Nrp-1) is a unique immune checkpoint capable of exerting antitumor effects through CD8(+) T cells. It is also a T-cell memory checkpoint that regulates long-term antitumor immunity. However, its role in NSCLC remains unclear. The aim of this study was to develop a fully human anti-Nrp-1 antibody with therapeutic effects against NSCLC in vitro and in vivo. We screened and constructed of a high-affinity anti-Nrp-1 IgG antibody from a constructed high-capacity fully human single-chain fragment variable (scFv) phage library. This novel anti-Nrp-1 IgG antibody partially restored the killing function of exhausted CD8(+) T cells in malignant pleural fluid in vitro. Co-culture of peripheral blood mononuclear cells (PBMC) with A549 and the addition of anti-Nrp1-IgG enhanced the killing of A549 target cells, leading to an increase in late-stage apoptosis of target cells. Importantly, anti-Nrp1-IgG treatment significantly reduced tumor volume in a mouse model of lung cancer with humanized immune system. These findings suggest that 53-IgG has a promising application as a potent Nrp-1-targeting agent in NSCLC immunotherapy.