Toripalimab in Combination With Nab-Paclitaxel For Patients With Metastatic or Recurrent Triple-Negative Breast Cancer (TNBC) With or Without Systemic Treatment

Inclusion Criteria: Metastatic or recurrent triple negative breast cancer (TNBC); * Histologically confirmed diagnosis of TNBC characterized by estrogen-receptor negative (ER-), progesterone receptor negative (PR-) and human epidermal growth factor-2 receptor negative (HER2-); * Eligible for taxane monotherapy; * No more than one line of chemotherapy in metastatic setting; * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1; * Life expectancy of 12 weeks or more; * At least one measurable lesion per RECIST v1.1; * Demonstrate adequate hematologic and organ functions as defined in the protocol Exclusion Criteria: Prior treatment with taxane as first line treatment; * Prior treatment with PD-1 antibody, PD-L1 antibody, PD-L2 antibody, or CTLA4 antibody (or any other antibody acting on T cell co-stimulation or checkpoint pathway) * MRI assessment during screening or previous imaging studies confirmed active or untreated brain metastases. Patients previously treated with local treatment of brain metastases has been stable for ≥ 1 month, and have stopped systemic hormonal therapy (\>10 mg/d prednisone or equivalent) \> 4 weeks before randomization can participate in the study; * Meningeal carcinomatosis; * Pregnancy or lactation; * Active hepatitis B or hepatitis C.