Abstract CT084: Prediction of surufatinib treatment outcome in advanced grade 3 neuroendocrine tumors (NET G3) patients

Abstract Background: Prognosis of NET G3 patients is usually poor and there is currently no standard treatment. Preliminary studies have suggested antiangiogenic TKIs could improve PFS for these patients. This study aims to evaluate the efficacy of surufatinib in advanced NET G3 via Cox regression analysis and identify predictive factors. Methods: A national multi-center study was carried in advanced NET G3 patients who were treated with surufatinib. PFS was the primary endpoint. Logistic regression and Cox proportional-hazards models were used to assess the predictive factors of PFS. The following variables were entered into analysis, including gender (male vs. female), age (<54 years vs. ≥54 years), ki-67 (<30% vs. ≥30%), primary site (gastrointestinal vs. pancreatic vs. thoracic), number of metastatic sites (1 vs. ≥2), bone metastasis (yes vs. no), liver metastasis burden (<25% vs. ≥25%), functional status (functional vs. non-functional), line of treatment (1 vs. ≥2), prior therapies including chemotherapy (yes vs. no), somatostatin analogs (SSA, yes vs. no), targeted therapy (yes vs. no), immunotherapy (yes vs. no), interventional therapy (yes vs. no), and administration strategy (monotherapy vs. combination therapy). Results: Among the 77 NET G3 patients with evaluable efficacy, the overall PFS was 9.4 months (95% CI: 8.5, 13.0), with PFS for p-NET and ep-NET being 9.7 months (95% CI: 8.8, 13.3) and 8.6 months (95% CI: 7.0, 16.0), respectively. The ORR across all patients was 22.2%, with p-NET and ep-NET patients showing an ORR of 28.6% and 10.7%, respectively. Univariate Cox regression analysis revealed that none of the investigated factors had significant impact on PFS. Patients with ki-67 < 30% had a trend of longer PFS than those with ki-67 ≥ 30% (13.1 months vs. 9.0 months), so did patients with low liver metastasis burden < 25% than ≥25% (11.8 months vs. 8.6 months). Multivariate Cox regression analysis confirmed that ki-67 level was an independent predictor of prognosis (p=0.032). Most ki-67≥55% patients were within the p-NET subgroup, patients with ki-67<55% were shown a better PFS in p-NET (11.8 months vs. 9.0 months). Conclusion: This study revealed that NET G3 patients with a ki-67 index <30% derived greater benefit of surufatinib in terms of PFS. Future researches are still warranted to confirm this finding and explore surufatinib combinations to improve NET G3 patients outcome. Citation Format: Jian Wang, Ning Zhang, Yun Liang, Jiang Long, Yihebali Chi, Suzheng Zhang, Chunmei Bai, Yu Wang, Yinying Wu, Hanguang Hu, Weiyu Hu, Li Huang, Ying Liu, Huifang LV, Shanai Song, Aili Suo, Xiangling Wang, Lin Zhang, Liming Zhu, Jie Chen, Jing Hao. Prediction of surufatinib treatment outcome in advanced grade 3 neuroendocrine tumors (NET G3) patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr CT084.