This is an open-label, multicenter Phase 1 first-in-human trial of SYH2095, a selective KAT6A/B inhibitor. The trail contains two segments: Part 1A dose escalation and Part 2A cohort expansion. Part 1A uses the BOIN dose-escalation design, enrolling patients with advanced malignant tumors with no effective standard treatment. Its primary goals are to assess safety and tolerability, define dose-limiting toxicity (DLT) and maximum tolerated dose (MTD), and establish the recommended expansion dose (RDE). Part 2A is an expansion cohort using the RDE identified in Part 1A,. All participants receive oral SYH2095 once daily in 4-week treatment cycles. Safety evaluations, tumor imaging, pharmacokinetic (PK), pharmacodynamic (PD) and biomarker analyses will be performed at scheduled time points throughout treatment.