Safety and clinical efficacy of sintilimab (anti-PD-1) in pediatric patients with advanced or recurrent malignancies in a phase I study

The aim of this phase I study is to evaluate, for the first time, the safety and efficacy of sintilimab in pediatric patients diagnosed with advanced or recurrent malignancies. During the dose escalation phase, patients received a single intravenous infusion of sintilimab at varying doses of 1, 3, and 10 mg/kg. The primary endpoints included the identification of dose-limiting toxicities (DLTs) as well as the evaluation of safety and tolerance. Secondary endpoints focused on assessing objective response rate (ORR), progression-free survival (PFS), and overall survival (OS). A total of 29 patients were enrolled, including 10 individuals diagnosed with Hodgkin lymphoma (HL) and 19 patients with various other tumor categories. Notably, diverse pathological types such as thymoma, choroid plexus carcinoma, and NK/T-cell lymphoma were also included in the study cohort. By the safety data cutoff, most adverse events were grade 1 or 2, with grade 3 or higher treatment-related adverse events (TRAE) occurring in 10% of patients. Among the 27 evaluated subjects, four achieved confirmed complete response (CR) while seven patients exhibited confirmed partial response (PR). Additionally, seven patients maintained disease (SD) during the study period. Notably, sintilimab demonstrated remarkable tolerability without DLTs and exhibited promising anti-tumor effects in pediatric HL. Whole-exome sequencing (WES) was conducted in 15 patients to assess the mutational landscape and copy number variation (CNV) status. The completion of this phase I study establishes the foundation for potential combination regimens involving sintilimab in childhood cancer treatment. The trial is registered on ClinicalTrials.gov with the identifier NCT04400851.