A Clinical Study of 9MW2821 (and PD-1 Inhibitor) in Locally Advanced or Metastatic Triple-Negative Breast Cancer

Inclusion Criteria:

1. Competent to comprehend, sign, and date an independent ethicscommittee/institutional review board/research ethics board (IEC/IRB/REB) approvedinformed 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 locally advanced or metastatic triple negative breastcancer. Not suitable for radical therapy.

5. Subjects who have failed standard treatment or naive to systemic antitumor therapyin advanced setting.

6. Subjects must submit tumor tissues for test.

7. Life expectancy of ≥ 12 weeks.

8. Subjects must have measurable disease according to RECIST (version 1.1).

9. Adequate organ functions.

10. Sexually active fertile subjects, and their partners, must agree to use methods ofcontraception during the study and at least 6 months after termination of studytherapy.

11. Subjects are willing to follow study procedures

Exclusion Criteria:

1. Preexisting treatment related toxicity Grade ≥ 2 and Grade ≥ 3 immune relatedadverse reactions

2. Preexisting peripheral neuropathy Grade ≥ 2.

3. Hemoglobin A1C (HbA1c) ≥ 8%.

4. Has ocular conditions that may increase the risk of corneal epithelium damage.

5. History of ILD or pneumotitis, other severe or uncontrolled disease or centralnervous system metastases.

6. Chemotherapy or radiotherapy within 21 days prior to the first dose of study drug (Cohort A). Received immune checkpoint inhibitor or systemic immunosuppressivetherapy was administered within 14 days prior to the first study (Cohort B and C).traditional Chinese medicine with anticancer indication within 14 days prior to thefirst dose of study drug, use of any investigational drug or device within 28 daysprior to the first dose of study drug, received treatment of nectin-4 targeted ADCwith MMAE payload, any P-glycoprotein (P-gp) inducers/inhibitors or strong CYP3A4inducers/inhibitors within 14 days prior to the first dose of study drug, majorsurgery within 28 days prior to first dose of study drug or any live vaccines within 28 days before first dose of study drug or during the study..

7. History of allogeneic hematopoietic stem cell transplantation or solid organtransplantation;

8. Known sensitivity to any of the ingredients of the investigational product; Historyof drug abuse or mental illness.

9. Documented history of pulmonary embolism or clinically significant cardiac orcerebrovascular diseases within 6 months prior to the first dose of study drug

10. Active autoimmune disease requiring systemic treatment within 2 years before thesubject's first study medication.

11. History of another malignancy within 3 years before the first dose of study drug.

12. Not suitable to receive study treatment for other conditions as per investigator.