Eligible patients (≥18 years) with advanced solid tumors after prior therapy provide informed consent, have measurable disease (RECIST 1.1), ECOG 0-1, and adequate organ function (ANC ≥1.5x10⁹/L, platelets ≥100x10⁹/L, hemoglobin ≥9.0g/dL, CrCl ≥45mL/min, LVEF ≥50%). Exclusion criteria: prior TOP1-ADC treatment, active brain metastases, unresolved Grade >1 toxicities, recent systemic therapy/radiation/surgery, significant cardiac/liver disease, infections (HIV/HBV/HCV under control allowed), pregnancy, or concurrent clinical trials.

Phase 1a and 1b evaluate the safety and tolerability of CUSP06 over 36 months, recording adverse events (AEs), serious adverse events (SAEs), dose interruptions, and reductions per NCI CTCAE v5.0, while Phase 1a determines the recommended dose for expansion (RDE) within 15 months. In Phase 1b, preliminary efficacy is assessed via RECIST 1.1, measuring the overall response rate (ORR) over 16 months, defined as confirmed partial (PR) or complete responses (CR).

CUSP06's pharmacokinetics (PK) are evaluated, including maximum concentration (Cmax), time to Cmax (Tmax), area under the curve (AUC), and terminal half-life (t1/2) over 36 months. Efficacy metrics include RECIST 1.1-defined ORR (18 months), disease control rate (DCR), clinical benefit rate (CBR), duration of response (DoR), time to progression (TTP), progression-free survival (PFS), overall survival (OS), and PRROC patients' CA-125 reduction ≥50% (36 months). Immunogenicity is also assessed via antidrug antibodies (ADAs).