Intervention: FZ-AD004, an investigational antibody–drug conjugate (ADC) administered intravenously. Mechanism/type: Targeted cytotoxic therapy, a monoclonal antibody binds a tumor-associated surface antigen, is internalized, and releases a linked cytotoxic payload inside the cancer cell to induce cell death. This is classified as immunotherapy/targeted therapy. Cells/pathways targeted: Antigen-expressing tumor cells (advanced solid tumors). The precise antigen and payload are not disclosed in the listing, thus, the ADC is expected to act via antigen-mediated endocytosis with intracellular payload activity (e.g., DNA or microtubule damage depending on payload). Trial context: First-in-human Phase 1 dose escalation/expansion to determine safety, MTD/RP2D, PK, and preliminary efficacy.