The study will follow a 3+3 dose-escalation scheme enrolling cohorts of at least 3 subjects sequentially at escalating doses. During study treatment, subjects will receive HX009 treatment via intravenous infusion once every 2 weeks. Dose escalation will continue until identification of an MTD or the maximum dose is reached. Dose-limiting toxicities (DLTs) will be assessed from the first dose of study treatment until 28 days .~The study is divided into a screening period (28 days before first dose), treatment period , and survival follow-up period. Safety will be evaluated throughout the study up until at least 28 days after the last dose of study treatment. Blood samples will be collected at regular intervals for pharmacokinetics (PK) and immunogenicity evaluation. Tumor evaluation (assessed by the Investigator in accordance with Response Evaluation Criteria in Solid Tumors Version 1.1 [RECIST 1.1] and immune RECIST [iRECIST]) to assess efficacy will start from the first dose and occur every 8 weeks in the first 24 weeks and every 12 weeks thereafter.
This is an open, multi-dose administration dose exploratory clinical phase I study to evaluate the safety, tolerability, and PK characteristics of HX009 injection in patients with advanced solid tumors and to initially measure its antitumor efficacy.