AK112 or Placebo Plus Nab-Paclitaxel as First-line Treatment in Inoperable Locally Advanced/ Metastatic Triple-negative Breast Cancer

Inclusion Criteria: 1. Voluntarily sign a written informed consent form. 2. Age at enrollment is ≥ 18 and ≤ 75 years, both males and females are eligible. 3. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. 4. Life expectancy of ≥ 3 months. 5. Histologically confirmed unresectable locally advanced or metastatic breast cancer with negative status for ER, PR, and HER-2. 6. Subjects who have not received prior systemic treatment for advanced breast cancer are eligible for the study. 7. Suitable for monotherapy with taxane-based agents. 8. At least one measurable lesion per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1. 9. Adequate organ function. Exclusion Criteria: 1. Patients with locally recurrent disease who are eligible for surgery or radiotherapy. 2. History of other malignancies within the past 5 years. 3. Active autoimmune disease requiring systemic treatment within the past 2 years. 4. Pregnant or breastfeeding women. 5. Concurrent participation in another clinical trial, unless it is an observational or non-interventional study or in the follow-up phase of an interventional study. 6. Participants with clinically symptomatic pleural effusion, pericardial effusion, or ascites that require repeated drainage. 7. Participants with a history of immune deficiency; those who test positive for HIV antibodies; those currently using systemic corticosteroids or other immunosuppressive agents on a long-term basis. 8. Individuals with known active tuberculosis (TB), or those suspected of having active TB (who must undergo clinical evaluation for exclusion), and those with known active syphilis infection.