Background: In the phase 3 SANET-p trial (NCT02589821), surufatinib significantly increased progression-free survival (PFS) compared with placebo in patients with progressive, well-differentiated (grade 1 or 2), advanced pancreatic neuroendocrine tumors (NETs). Here we report the relationship of Ki-67 and baseline Chromogranin A (CgA) on efficacy outcomes. Methods: A total of 172 patients with advanced pancreatic NETs were randomized to surufatinib or placebo in a 2:1 ratio. Investigator-assessed PFS and objective response rate (ORR) per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 were used for the analysis. The post-hoc subgroup analyses were performed on Ki-67 subcategory: < 5% (n = 40 vs 21), 5-10% (n = 57 vs 31), > 10% (n = 16 vs 7), and baseline CgA subcategory: ≤ 2 times of upper limit of normal (ULN) (n = 59 vs 31), > 2 × ULN (n = 44 vs 24). Results: In the intent-to-treat population, surufatinib was superior to placebo, median PFS (mPFS) of 10.9 vs 3.7 months (mo) (p = 0.0011), with a stratified hazard ratio (HR) of 0.491 (95% confidence interval [CI]: 0.319, 0.755). mPFS was statistically significantly longer in the surufatinib arm versus that in the placebo arm in subgroups of Ki-67 5-10% (11.0 vs 3.7 mo, HR = 0.33, p= 0.0002), Ki-67 > 10% (11.1 vs 2.8 mo, HR = 0.04, p = 0.0003) and CgA > 2 × ULN (11.0 vs 3.7 mo, HR = 0.36, p = 0.0036). There was numerical PFS improvement with surufatinib compared to placebo in subgroup of Ki-67 < 5% (9.3 vs 5.6 mo, HR = 0.91, p = 0.8015) and CgA ≤ 2 × ULN (9.4 vs 3.7 mo, HR = 0.61, p = 0.0809). ORRs in the subgroups of Ki-67 < 5%, 5-10%, and > 10% with surufatinib were 15.8%, 24.0% and 12.5% respectively. There was only one partial response in the placebo arm (with Ki-67 < 5%). ORRs in the subgroups of CgA ≤ 2 × ULN and > 2 × ULN with surufatinib were 18.9% and 21.4%, while also only one partial response in the placebo arm with CgA ≤ 2 × ULN. Conclusions: Surufatinib showed statistically significant and clinically meaningful improvement in PFS compared to placebo in patients with advanced, progressive, well-differentiated pancreatic NETs. From this exploratory analysis, surufatinib demonstrated benefit irrespective of Ki-67 expression levels or baseline CgA. Clinical trial information: NCT02589821