Abstract 2129: Efficacy and underlying mechanisms of surufatinib combined with PD-1 monoclonal antibody and chemotherapy in pancreatic cancer

Abstract Background: A phase 1b/2 study (NCT05218889) of surufatinib combined with camrelizumab, nab-paclitaxel, and S-1 (NASCA) as first-line therapy for metastatic pancreatic adenocarcinoma has shown promising results, potentially overcoming the limitations of current pancreatic immunotherapies. Animal studies are underway to further explore the synergistic effects and mechanisms of this combined therapeutic approach. Methods: Genetically engineered KPC mouse cells were used to establish a subcutaneous transplantation tumor model in female mice, which were then divided into control group, AG group (nab-paclitaxel + gemcitabine), and NASCA group. Tumor metrics were recorded until euthanasia after 21 days. Blood and tumor samples were analyzed using Flow Cytometry. Results: Compared with the control group, the NASCA and AG groups demonstrated tumor volume reductions of 14.7% (p=0.172) and -0.4% (p=0.972) on day 7, respectively. At day 14, the reductions were 48.8% and 29.9% (p<0.001*, p=0.002*). At day 21, the reductions were 37.4% and 21.5% (p=0.001*, p=0.144). The tumor growth inhibitions (TGIs) for NASCA and AG group were 56.7% (p<0.001*) and 21.2% (p=0.36), respectively. Compare to AG group, the tumor volume reduction in NASCA group were 15.1% (p=0.050*), 26.9% (p=0.001*) and 20.3% (p=0.116), respectively. And the TGIs for NASCA group compare AG group was 45.0% (p=0.020*). Distinguishingly, the NASCA group, when compared to the AG group, had a heightened proportion of M1 macrophages (28.5% vs. 15.5%, p=0.019*), mCD68+ Macrophages (99.7% vs. 99.1%, p=0,014*) and mPD-1+/mCD8+ T cells (24.8% vs. 9.8%, p=0.03*). Furthermore, T-regulatory cells (T-regs) in peripheral blood demonstrated uniformity across the groups, were no statistically. RNA-seq analysis revealed that the NASCA significantly suppressed multiple anti-angiogenic pathways while enhancing the cytokine pathway (p=0.005*), indicating potential immune system activation. Conclusion: The NASCA group outperformed the AG group in controlling tumor growth and early tumor shrinkage, potentially due to macrophage polarization regulation. Further research is vital to understand the benefits of integrating targeted therapy, immunotherapy, and chemotherapy for pancreatic cancer. Citation Format: Nan Zhang, Ru Jia, Guanghai Dai. Efficacy and underlying mechanisms of surufatinib combined with PD-1 monoclonal antibody and chemotherapy in pancreatic cancer [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 2129.