KMHH-03

Primary objectives: (1) To evaluate the safety and tolerability of KMHH-03 for injection in subjects with advanced breast cancer; (2) To determine the dose-limiting toxicity (DLT) and maximum tolerated dose (MTD) of a single dose of KMHH-03 for injection. Secondary objectives: (1) To evaluate the pharmacokinetic (PK) characteristics of KMHH-03 for injection in subjects with advanced breast cancer; (2) To evaluate the immunogenicity of KMHH-03 for injection in subjects with advanced breast cancer; (3) To observe the preliminary efficacy of KMHH-03 for injection in subjects with advanced breast cancer and provide a basis for the recommended dose and dosing regimen for subsequent clinical trials.