一种新型anti-PD-1×CTLA-4×VEGF三特异性抗体实现肿瘤选择性免疫检查点阻断并具有强效抗肿瘤活性

Combination strategies integrating immune checkpoint blockade and anti-angiogenic therapy by co-targeting PD-1 and VEGF pathways have demonstrated meaningful clinical benefit across multiple tumor types. However, the incorporation of CTLA-4 blockade remains limited by systemic immune-related toxicities. To address these challenges, we engineered a novel tri-specific antibody designed to concurrently inhibit PD-1, CTLA-4, and VEGF while enabling tumor-selective, PD1-dependent CTLA-4 engagement. This tri-specific antibody demonstrated high-affinity PD-1 binding and checkpoint blockade activity comparable to pembrolizumab, along with potent VEGF neutralization consistent with clinically validated anti-VEGF antibodies. Importantly, CTLA-4 blockade by the tri-specific antibody was minimal in CTLA-4 single-positive reporter systems, but was markedly enhanced in PD-1/CTLA-4 dual-expressing cells. This avidity-dependent mechanism preferentially enables CTLA-4 inhibition in activated T cells within the tumor microenvironment, thereby providing a potential strategy to improve the therapeutic index relative to conventional systemic CTLA-4 blockade. In ex vivo primary human immune cell assays, the tri-specific antibody induced strong IL2 release, supporting enhanced functional immune modulation. In vivo efficacy was further evaluated across complementary tumor models. In the MC38 syngeneic mouse model, the tri-specific antibody produced superior tumor growth inhibition relative to pembrolizumab or ipilimumab monotherapy, indicating cooperative immune checkpoint engagement. In the COLO205 xenograft model, anti-tumor activity was comparable to bevacizumab, confirming preserved VEGF pathway blockade and anti-angiogenic function. Moreover, non-human primate studies demonstrated favorable tolerability, pharmacokinetic behavior, and developability characteristics of the tri-specific antibodies, with no unexpected safety findings, supporting further translational development. In summary, this novel PD-1 × CTLA-4 × VEGF tri-specific antibody integrates immune checkpoint inhibition with angiogenesis blockade through a rationally designed, avidity-based mechanism that conditionally enhances CTLA-4 engagement in tumor-relevant immune contexts. These preclinical findings support its potential as a next-generation immuno-oncology therapy with improved balance between efficacy and safety, warranting further clinical investigation.