This study is a Phase Ib/ll, open-label, multicenter study designed to evaluate the safety and efficacy of 9MW2821 monotherapy or combined with other anticancer therapy in advanced solid tumors.

Inclusion Criteria:

1. Competent to comprehend, sign, and date an independent ethics committee/institutional review board/research ethics board (IEC/IRB/REB) approved informed consent form.
2. Male or female subjects aged 18 to 75 years (including 18 and 75 years).
3. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
4. Histopathological diagnosed of recurrent or locally advanced or metastatic solid tumors.
5. Adequate tumor tissues submitted for test.
6. Life expectancy of ≥ 12 weeks.
7. Subjects must have measurable disease according to RECIST (version 1.1).
8. Adequate organ functions.
9. Sexually active fertile subjects, and their partners, must agree to use contraception during the study and at least 6 months after termination of study therapy.
10. Subjects are willing to follow study procedures.

Exclusion Criteria:

1. History of another malignancy within 3 years before the first dose of study drug.
2. Ongoing clinically significant toxicities related to prior treatment.
3. Grade ≥ 2 peripheral neuropathy.
4. Severe or uncontrolled gastrointestinal diseases.
5. Other severe or uncontrolled diseases, including severe respiratory diseases, cardiovascular and cerebrovascular diseases of clinical significance.
6. Experienced clinically significant bleeding or had a clear bleeding tendency.
7. Central nervous system (CNS) metastasis and/or malignant meningitis.
8. Clinically significant pleural, abdominal, or pericardial effusion.
9. Chemotherapy or radiotherapy within 21 days prior to the first dose of study drug;
10. Known sensitivity to any of the ingredients of the investigational product; History of drug abuse or mental illness.
11. Pregnant and lactating women.
12. Other conditions that, in the Investigator's opinion, may not be suitable for the subject to be enrolled.