This study is one single group of participants with advanced solid tumors. It is the first time the drug has been used in humans. There will be two parts including Dose Escalation and Dose Expansion to evaluate the safety, tolerability, pharmacokinetics, and clinical activity of FZ-AD004.

This is a first-in-human (FIH), Phase 1, open-label, dose escalation and dose expansion study to evaluate the safety, tolerability, pharmacokinetics and preliminary efficacy of FZ-AD004 in patients with advanced/metastatic solid tumors. FZ-AD004 is administered via intravenous infusion using an accelerated titration method followed by a conventional 3 + 3 study design to identify the maximum tolerated dose (MTD) and dose-limiting toxicities（DLT）during cycle 1. In addition, the maximum-tolerated dose and recommended Phase II dose for FZ-AD004 will be determined.

Inclusion Criteria:

1. Patients able to give written informed consent;
2. Age ≥ 18 and ≤ 75 years old, male or female;
3. Patients have histological or cytological diagnosis with advanced solid tumors.
4. Have measurable lesions defined in RECIST v. 1.1;
5. Expected survival ≥ 12 weeks;
6. Eastern Cancer Cooperative Group (ECOG) performance status 0-1;
7. Patients of child bearing potential must agree to take contraception during the study and for 6 months after the last day of treatment.

Exclusion Criteria:

1. Have had other malignant tumors in the past 5 years;
2. Have CNS (central nervous system) metastasis with clinical symptoms;
3. Had undergone major surgery or severe trauma within 4 weeks prior to the first dose;
4. Had undergone systemic high-dose steroids within 2 weeks of initiation of study treatment;
5. Have history of psychotropic drug abuse, alcohol or drug abuse；
6. Women who are pregnant or lactating；
7. Other circumstances that is deemed not appropriate for the study.