The goal of this clinical trial is to learn if investigational drug called SYS6043 works in adults with advanced or metastatic solid tumors that have spread or cannot be treated with standard therapies. The main goals of the study are to understand how safe SYS6043 is, what side effects it may cause, and what dose can be given safely. Researchers will also study how the drug moves through the body and whether the immune system reacts to it. In addition, the study will look for early signs that SYS6043 may help slow or shrink tumors and explore whether the amount of a tumor protein called B7-H3 is related to how well the treatment works.
Participants will:
* Provide written informed consent * Undergo screening tests to ensure they are eligible for study treatment * Attend all required study visits and receive SYS6043 by intravenous infusion once every 3 weeks (Q3W), with 21 days as one treatment cycle until the study doctor determines that study treatment should be stopped based on how well a participant is doing on treatment. * Have safety follow-up (SFU), and long-term follow-up. * Be followed until progression.
Aged ≥18 years old (on the date of signing the ICF).
Advanced/unresectable or metastatic solid tumors confirmed by histology or cytology, disease recurrence or progression during or after systemic standard of care, and should be intolerant of or have no available standard of care therapy.
Have at least one measurable lesion, according to the Response Evaluation Criteria in Solid Tumors (RECIST V1.1). Participants with metastatic castration-resistant prostate cancer (mCRPC) who have only metastases to bone will be evaluated through discussion with the sponsor's medical monitor, before determining whether they can be enrolled.
Expected life expectancy of ≥ 3 months.
Prior B7-H3 targeted therapy.
Previously received drug therapy with topoisomerase inhibitor antibody-drug conjugate (e.g., trastuzumab deruxtecan).
Symptomatic congestive heart failure (CHF) (New York Heart Association [NYHA] Class II-IV) or a history of severe arrhythmia requiring treatment.
History of myocardial infarction or unstable angina within 6 months prior to enrollment.