This multicenter, randomized, double-blind study aims to assess the safety and efficacy of AK112 in combination with Nab-Paclitaxel, compared to a placebo plus Nab-Paclitaxel, as a first-line treatment for inoperable locally advanced or metastatic triple-negative breast cancer (TNBC).

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.