• Overall survival (OS) [ Time Frame: Up to 24 months ]
  OS indicates the length of time from enrollment to death from any cause.When no information on death is collected in the clinical database, the last date when the patient is still known to have survived is used as the cut-off point.
• Disease control rate (DCR) [ Time Frame: Up to 24 months ]
  DCR indicates the percentage of patients with CR, partial remission, and disease stabilization; and maintenance over 4 weeks, accounts for all the subjects with evaluable efficacy.
• Overall remission rate (ORR) [ Time Frame: Up to 24 months ]
  ORR is the proportion of patients who achieve a complete or partial response ((CR+PR)/total number of cases x 100%), as assessed by the RECIST v1.1.
• Adverse events at levels 3 and 4 [ Time Frame: every 6 weeks (two cycles) and 4 weeks after treatment discontinuation ]
  Patients with adverse events at levels 3 and 4 will be assessed according to the National Cancer Institute Common Toxicity Criteria (NCI-CTC) Version 4.0.

• Drug: Vinorelbine + placebo
  Combined administration of vinorelbine and placebo. Based on oral administration of vinorelbine, the patients will be given oral placebo (starch as an ingredient). The placebo appearance, including shape, size, color and weight, taste, labeling and packing are the same with those of apatinib mesylate tablets.
  Other Name: AiTan+ placebo
• Drug: Vinorelbine + Apatinib
  Combined administration of vinorelbine and apatinib. Vinorelbine tartrate soft capsule (also named Navelbine; registration No. H20140657; Pierre Fabre Medicament, Boulogne, France) 40 mg once orally, taken in the morning (at least 1 hour before or at least 1 hour after meals), three times a week (Mondays, Wednesdays, and Fridays), for a continuous 21-day cycle. Apatinib mesylate tablets (also named Aitan, State Medical Permission No. H20140103; Jiangsu Hengrui Pharmaceutical Co., Ltd., China), 500 mg orally, taken once a day for a continuous 21-day cycle.
  Other Name: Navelbine+AiTan

• Active Comparator: Vinorelbine + placebo group
  92 enrolled patients will be assigned to receive oral vinorelbine plus placebo until disease progression or other criteria for administration termination.
  Intervention: Drug: Vinorelbine + placebo
• Experimental: Vinorelbine + Apatinib group
  92 enrolled patients will be assigned to receive oral patatinib mesylate in combination with vinorelbine until disease progression or other criteria for administration termination.
  Intervention: Drug: Vinorelbine + Apatinib

Inclusion Criteria:

• Female patients with recurrent or metastatic TNBC, as confirmed by histological or cytological examination
• Age 18-70 years old
• According to the Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1, there is at least one measurable lesion.
• The Eastern Cooperative Oncology Group (ECOG) scores 0-2
• Expected survival ≥ 12 weeks
• Negative for ER/PR
• All patients will be tested for bone marrow capacity, liver and renal functions within 7 days prior to enrollment
• Previous use of anthracyclines and/or taxanes
• The medication history of vinorelbine
• Female patients of childbearing age must take adequate contraception; otherwise the patients must be proven to be infertile
• No history of serious heart, lung, liver, and kidney diseases
• Provision of written informed consent

Exclusion Criteria:

• Patients who receive chemotherapy, radiation therapy, targeted drugs, or hormone therapy within 3 weeks of administration
• Patients using corticosteroids for untreated brain or subdural metastatic lesions, need to have stopped it, at least for 4 weeks or until there are no signs of brain metastasis and/or symptoms must have stabilized for at least 4 weeks, if local treatment has been completed. Enhanced computed tomography (CT) or magnetic resonance imaging (MRI) images during screening are compared with those performed at least 4 weeks earlier to determine radiological stability.
• Patients with severe vascular diseases, including unstable angina, myocardial infarction, or severe arrhythmia in the past 6 months
• History of HIV infection or active chronic hepatitis B or C
• Patients with other serious infectious diseases
• Patients positive for ER/PR/HER-2 positive
• Patients with allogeneic organ transplants requiring immunosuppressive therapy
• History of other malignant tumors within 5 years, except for cured cervical carcinoma in situ or basal cell carcinoma of the skin
• Other destabilizing factors that may interfere with patients or have an impact on the trial results
• Allergic to target drugs or allergic to related drugs applied in the trial
• Pregnant or lactating women