Abstract 2726: A novel trispecific antibody HC010 targeting PD-1/CTLA-4/VEGF for the potential treatment in anti-PD-1 antibody resistant NSCLC patients

Abstract Background and Aim: Immune checkpoint inhibitors (anti-PD-1/CTLA-4 antibody) have been approved and widely used for the first line treatment of non-small cell lung cancer (NSCLC). However, most patients are experiencing resistant to PD-1 blockade. In recent clinical trials, anti-VEGF antibody has shown to improve the clinical outcomes of anti-PD-1 antibodies and overcome resistance to checkpoint blockade. We developed a PD-1/CTLA-4/VEGF trispecific antibody (HC010) by site-specifically fusing anti-PD-1 scFv and anti-CTLA-4 nanobody to the defined site of anti-VEGF antibody. The aim of this study was to evaluate the potential use of HC010 for treatment of anti-PD-1 antibody resistant NSCLC patients. Method: Humanized mice were established in NCG mice by reconstituting human PBMC before inoculating the PDX tissue, which was derived from a NSCLC patient treated with two cycles of an anti-PD-1 antibody sintilimab. When tumors were approx. 170mm3, mice were dosed with HC010 twice weekly for 3 weeks. Pembrolizumab, sintilimab and a Standard of Care (SoC) agent docetaxel were included as reference. For IHC analysis, tumor samples were harvested 24h post final dose and fixed with 10% NFB overnight and subsequently stained with CD31 and CD8 to explore the change in tumor microenvironment after HC010 treatment. For preclinical toxicity assessment, HC010 was intravenously administered once weekly for four weeks in naïve cynomolgus monkeys and immunogenicity/local tolerance/clinical pathology were evaluated during the dosing and recovery phase. Results: HC010 showed a significant tumor inhibition (TGI=81%) when compared with the vehicle control. Pembrolizumab and sintilimab alone exhibited limited anti-tumor effect. Docetaxel only showed a partial response during the dosing phase. By analyzing tumor samples, there was a significant increase in CD8+ positive T cells in HC010 treated tumors in contrast to the vehicle group and pembrolizumab/sintilimab treated groups, suggesting that HC010 can significantly improve CD8+ T cell infiltration. Expression of CD31 as an angiogenic and vasculogenic marker, was significantly reduced in HC010 treated tumors. In the toxicity study, HC010 at selected doses showed no obvious toxicity in cynomolgus monkeys. Conclusion: Our trispecific antibody HC010 targeting PD-1/CTLA-4/VEGF showed a superior anti-tumor effect in a sintilimab resistant PDX animal model when compared with pembrolizumab and sintilimab as well as SoC. By analyzing tumor microenvironment, HC010 overcame acquired resistance by modulating tumor microenvironment such as increase in intra-tumoral cytotoxic T cell infiltration and normalization of blood vessels. Together with preclinical efficacy and safety data, HC010 showed potential benefits in treatment of anti-PD-1 antibody resistant NSCLC patients. Citation Format: Diandong Jiang, Yue Xi, Chen Xu, Xingding Wang, Qiaoshan Yin, Zhaohui Li, Teddy Yang. A novel trispecific antibody HC010 targeting PD-1/CTLA-4/VEGF for the potential treatment in anti-PD-1 antibody resistant NSCLC patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2726.