Advanced Malignant Solid Tumor of Digestive System

Subjects were Chinese patients with histologically or cytologically confirmed advanced malignant solid tumors (mainly focused on MSS type colon and rectal cancer) who had failed standard systemic therapy and were inoperable. The first stage was the dose escalation stage, which was divided into 4 dose groups according to the "3+3" dose escalation principle. One patient was enrolled in the first dose group, and 3-6 patients were enrolled in each of the latter three dose groups, with a total of 10-19 patients enrolled. The second stage is the security extension stage, which is selected by SMC 1-2 dose cohorts were expanded for safety and divided into three cohorts in total(IIA, IIB, IIC) to explore the safety of sequential or combined administration modes with immune targeted therapy. Each cohort included 6-12 subjects at different dose levels, and three cohorts could be carried out at the same time. The third stage is the dose expansion stage. According to the safety, PK and clinical data of the three cohorts in the second stage, 1-2 cohorts were selected by SMC for dose expansion. The sample size of each cohort was expanded to 20 cases on the original basis. The estimated ORR of the trial drug was 24%, and the ORR of the standard treatment was 5%. When the type I error was one-sided 0.025, and the power was 80%, the sample size was estimated by the normal approximation method. So each dose expansion phase A minimum of 20 subjects were required to be enrolled in the cohort.