ST205

Primary Objective: To evaluate the safety and tolerability of a fixed-dose ST114 combined with ST205 in patients with recurrent or metastatic solid tumors who have failed standard therapy, and to determine the maximum tolerated dose (MTD) of ST205 and/or recommended dosing regimens and doses (RDEs) for subsequent clinical trials. Secondary Objectives: 1. To evaluate the pharmacokinetic characteristics of ST114 combined with ST205 in patients with recurrent or metastatic solid tumors who have failed standard therapy; 2. To preliminarily assess the antitumor efficacy of ST114 combined with ST205 in patients with recurrent or metastatic solid tumors who have failed standard therapy; to explore the correlation between steady-state plasma drug concentrations (ST205, metabolite MMAE) and efficacy and safety. Exploratory Objective: To evaluate the pharmacodynamic significance of ST114 combined with ST205 as a biomarker in the treatment of advanced solid tumors.