A Clinical Study of 9MW2821 in Advanced Malignant Solid Tumors

Inclusion Criteria:

* Competent to comprehend, sign, and date an independent ethics committee/institutional review board/research ethics board (IEC/IRB/REB) approved informed consent form.
* Male or female subjects aged 18 to 80 years (including 18 and 80 years).
* Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1.
* Phase Ia：Histologically or cytologically confirmed advanced malignant solid tumors (except sarcoma). Phase Ib：Only local advanced or metastatic UC tumors.
* Subjects must have received ICIs or GC/GP therapies in the previous treatment.
* Subjects must submit tumor tissues for test.
* Life expectancy of ≥ 3 months.
* Subjects must have measurable disease according to RECIST (version 1.1).
* Adequate organ functions.
* Sexually active fertile subjects, and their partners, must agree to use methods of contraception during the study and at least 6 months after termination of study therapy.
* Subjects are willing to follow study procedures.

Exclusion Criteria:

* Chemotherapy、radiotherapy or immunotherpy within 14 days prior to the first dose of study drug.
* Preexisting treatment related toxicity Grade ≥ 2 (except alopecia).
* Major surgery within 28 days prior to first dose of study drug.
* History of uncontrolled diabetes mellitus.
* Preexisting peripheral neuropathy Grade ≥ 2.
* Received treatment of ADCs with MMAE payload.
* Any live vaccines within 4 weeks before first dose of study drug or during the study.
* Documented history of clinically significant cardiac or cerebrovascular diseases within 6 months prior to the first dose of study drug.
* Other severe or uncontrolled disease, i.e. severe respiratory system disease, thromboembolic events, active bleeding or active infection.
* Uncontrolled central nervous system metastases.
* History of another malignancy within 3 years before the first dose of study drug. Subjects with curable malignancies are allowed.
* History of autoimmune disease requiring systemic treatment within 2 years before the first dose of study drug.
* Has ocular conditions that may increase the risk of corneal epithelium damage.
* Known sensitivity to any of the ingredients of the investigational product; History of drug abuse or mental illness.
* Any P-glycoprotein (P-gp) inducers/inhibitors or CYP3A4 inducers/inhibitors for high and medium effect within 14 days prior to the first dose of study drug.
* Use of any investigational drug or device within 30 days prior to the first dose of study drug.
* Conditions or situations which may put the subject at significant risk.