A Study of Surufatinib in Combination With Gemcitabine in Pediatric, Adolescent, and Young Adult Patients With Recurrent or Refractory Solid Tumors

The purpose of this study is to evaluate the safety and tolerability of surufatinib, thereby identifying the Maximum Tolerated Dose (MTD) and/or Recommended Phase 2 Dose (RP2D) of surufatinib administered in combination with gemcitabine in pediatric patients with recurrent or refractory solid tumors or lymphoma. The study will be conducted in 2 parts: Part 1 - evaluation of tolerability and safety of surufatinib administered in combination with gemcitabine, and confirmation of the recommended clinical dose of surufatinib in pediatric patients with recurrent or refractory solid tumors or lymphoma. Part 2 - evaluation of anti-tumor activity and confirmation of tolerability of surufatinib administered in combination with gemcitabine in pediatric patients with recurrent or refractory osteosarcoma, Ewing sarcoma, RMS, and non-rhabdomyosarcoma soft tissue sarcoma (NRSTS). Part 1 will enroll 2 to 6 patients per dose level cohort (up to 4 cohorts) with recurrent or refractory solid tumors. During cycle 1, surufatinib will be administered, orally, once daily (QD), as a single agent for 14 days followed by surufatinib daily in combination with gemcitabine intravenously on days 15 and 22 (cycle 1 duration=35 days) and days 1 and 8 of all subsequent cycles (cycle duration=21 days). Assessment based on dose limiting toxicity (DLT) criteria will be performed in the first 35-day cycle (DLT Evaluation Period). This study will utilize a rolling 6 design for part 1, with 3 dose escalation levels and 1 de escalation level, if needed. Part 2 of the study will use a Simon 2-stage design with a maximum of 18 patients per cohort (osteosarcoma, Ewing sarcoma, RMS, and non-rhabdomyosarcoma soft tissue sarcoma (NRSTS)). Surufatinib will be administered orally at identified MTD/RP2D daily in combination with gemcitabine (1000 mg/m2 weekly × 2 doses) intravenously on days 1 and 8. In both parts 1 and 2, patients can remain on treatment until completing cycle 17, or until progressive disease, unacceptable toxicity, or death; whichever comes first.