Background: Surufatinib is a novel small-molecule inhibitor targeting vascular endothelial growth factor receptors 1, 2 and 3, fibroblast growth factor receptor 1 and colony stimulating factor 1 receptor. Toripalimab (JS001) is a monoclonal humanized IgG4 PD-1 antibody. The potential synergistic antitumor activity of surufatinib and anti-PD-L1 combination regimen had been demonstrated in preclinical study (presented at 2017 AACR). Here, we report the safety and preliminary efficacy results from a phase I trial of surufatinib plus toripalimab in patients with advanced solid tumor (NCT03879057). Methods: This study is an open-label, dose escalation and expansion study in solid tumor patients who had failed standard therapies or had no effective treatment. In dose escalation stage, 3 dose levels of surufatinib (200, 300 and 250 mg once daily) were evaluated in combination with a fixed dose of toripalimab 240 mg every 3 weeks until the maximum tolerated dose (MTD) or recommended phase II dose (RP2D) was reached, which ever occurred first. Additional patients were enrolled at dose expansion phase to further assess the efficacy, safety and pharmacokinetic (PK) profile. Results: As of 2020-1-20, a total of 30 patients were enrolled. Tumor types include neuroendocrine tumor (NET) Grade (G) 1/2 (4), NET G3 (4), neuroendocrine carcinoma (NEC) (13), colorectal carcinoma (CRC) (4), gastric adenocarcinoma (GC) (2), esophageal squamous cell carcinoma (ESCC) (2) and metastatic squamous cell carcinoma with unknown primary (1). The RP2D was determined at surufatinib 250 mg daily plus toripalimab. One patient at 300 mg experienced dose-limiting toxicity, grade 3 hyperthyroidism. The most common grade 3/4 treatment emergent adverse events (TEAE, ≥5%) were transaminase elevation, bilirubin elevation, fatigue, hyponatremia, and vomit, with higher frequencies in the 300 mg cohort compared with lower dose cohorts. There was no treatment-related fatal serious adverse event. Preliminary PK analysis showed surufatinib exposure at steady state increased dose-proportionally. Individual PK profiles was comparable to those of surufatinib or toripalimab from previous monotherapy trials. By 2020-1-10, 25/30 patients across 3 cohorts were evaluable for tumor response: 1 complete response, 6 partial response (ORR=28%); in NET G1/2 (3), NEC (2), ESCC (1), and CRC (1). Twelve patients experienced stable disease for at least 6 weeks (DCR=76%). Most patients with negative or low PD-L1 expression achieved PR or CR. Of 21 evaluable neuroendocrine neoplasms (NENs) patients, the ORR and DCR were 23.8% and 81.0%, respectively. Four of 8 evaluable patients at RP2D achieved PR, and the ORR and DCR were 50% and 100%, respectively. Conclusions: Surufatinib plus toripalimab were well tolerated with no unexpected safety signals observed, and showed encouraging antitumor activity in patients with advanced solid tumor, especially in NENs patients. The phase II trial (NCT04169672) has been initiated.

Citation Format: Ming Lu, Yanshuo Cao, Jifang Gong, Yu Sun, Jie Li, Lin Shen. A phase I trial of surufatinib plus toripalimab in patients with advanced solid tumor [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr CT142.