XKH-002

Main objectives: 1. Determine the maximum tolerated dose (MTD) or maximum dose (MAD) of XKH002 for the treatment of patients with solid tumors, and confirm the recommended dose (RDE) for the extension phase; 2. Evaluate the safety and tolerability of XKH002 in patients with solid tumors. Secondary objectives: 1. Evaluate the pharmacokinetic (PK) characteristics of XKH002; 2. Evaluate the anti-tumor efficacy of XKH002; 3. Evaluate the immunogenicity of XKH002. Exploratory objectives: 1. Evaluate the relationship between the content of soluble B7-H4 and other tumor immune-related factors such as TNF-α, IFN-γ, IL-6, IL-8 and the efficacy before XKH002 treatment, as well as the changes in serum content before and after treatment; 2. Evaluate the correlation between the expression levels of B7-H4, PD-L1 and CD8 and the efficacy.