A novel anti-FGFR1 monoclonal antibody OM-RCA-01 exhibits potent antitumor activity and enhances the efficacy of immune checkpoint inhibitors in lung cancer models

Background: Fibroblast growth factor receptor 1 (FGFR1) plays a crucial role in carcinogenesis. Exploring the combination of the novel humanized monoclonal anti-FGFR1 antibody OM-RCA-01 and immunotherapy was intriguing due to involvement of FGFR1 in mechanisms of resistance to checkpoint inhibitors. Materials and methods: Lung cancer A549, exhibiting distinct levels of FGFR1 expression, were cultured in basic FGF medium with OM-RCA-01 supplementation. The efficacy of antibody monotherapy was validated in a lung cancer xenograft study. To investigate whether OM-RCA-01 could enhance the efficacy of immunotherapy in vitro and in vivo, mixed lymphocyte reaction/Staphylococcal enterotoxin B assays and FGFR1/programmed death-ligand 1-positive patient-derived xenograft model were established. Results: The antibody effectively suppressed receptor phosphorylation, resulting in inhibited cell proliferation. OM-RCA-01 led to a substantial delay in tumor growth compared to non-specific immunoglobulin G in a xenograft study. The median tumor volume was 1048.5 mm³ and 2174 mm³ in the study and vehicle groups, respectively, representing a twofold difference in favor of the anti-FGFR1 antibody. In vitro, the combination of nivolumab and OM-RCA-01 resulted in higher levels of interferon gamma and interleukin-2 release compared with nivolumab alone. In vivo, pembrolizumab in combination with OM-RCA-01 produced a greater inhibitory effect on tumor growth compared with vehicle and pembrolizumab alone. The curve plateaued, indicating minimal tumor growth from day 16 onwards in the combination group. The OM-RCA-01 demonstrated no toxicity, even at therapeutic doses or higher doses. Conclusions: Our preclinical studies demonstrate that OM-RCA-01 exhibits robust activity with minimal toxicity. Combining an anti-FGFR1 antibody with a checkpoint inhibitor may enhance the efficacy of both drugs. However, further studies are needed to elucidate the mechanism of this interaction.