Inclusion Criteria:
* Signed informed consent;
* 18 Years and older;
* Female;
* Breast cancer confirmed by pathological histology, ER-negative (\<1% positive), PR-negative (\<1% positive), and HER2-negative (IHC: HER2 (0), HER2 (1+), or HER2 (2+) and FISH non-amplification;
* Patients must receive full course of neoadjuvant chemotherapy before surgery and did not achieve pathological complete response (i. e., pathologically confirmed residual lesion, maximum diameter of 1cm) or / lymph node positive (ypN+);
* Previous neoadjuvant chemotherapy regimen included anthracycline, taxane, or a combination of both.
* Patients who clinically require radiotherapy of the affected breast or chest wall and regional lymph node area should receive radiotherapy before or after study medication;
* All toxicities related to previous antitumor therapy must return to Grade 1 (CTCAE v5.0), except alopecia;
* Within 1 week before enrollment, the blood routine examination was basically normal (taking the normal value of each study center as the standard): 1) Blood routine: hemoglobin (Hb) \> 90g / L, White blood cell count (WBC) \> 3.5\*10\^9 / L, Number of neutrophils (ANC) \* 1.5\*10\^9 / L, Platelet count (PLT)\* 100\*10\^9 / L; 2) Renal function: upper limit of normal serum creatinine value; 3) Liver function: for patients without liver metastasis: glutamulate aminotransferase (AST), glutamate aminotransferase (ALT), alkaline phosphatase (ALP) are less than 2.5 times of the upper limit of normal value, and totle bilirubin is less than 1.25 times of the upper limit of normal value; for patients with liver metastasis, AST, ALT, ALP, ALT, ALP, are less than 5 times of the upper limit of normal value, and totle bilirubin is less than 1.25 times of the upper limit of normal value;
* The ECOG physical status score for patients must be 0 or 1;
Exclusion Criteria:
* Metastatic breast cancer at diagnosis;
* Breast cancer patients who did not completed surgery;
* History of other malignancies within 5 years prior to randomization, but patients with the following tumors may participate in the study: carcinoma of the cervix in situ, colon in situ, melanoma in situ and basal cell carcinoma of the skin and squamous cell carcinoma;
* Any other non-malignant systemic disease (cardiovascular, renal, liver, etc.) that hinders the implementation or follow-up of the treatment program;
* Symptomatic congestive heart failure (New York Heart Association Grade II-IV), symptomatic or poorly controlled arrhythmia, history of congenital long QT syndrome or corrected QTc\> 500ms at screening, history of uncontrolled hypertension or hypertensive crisis or hypertensive encephalopathy;
* History of interstitial pneumonia, Need for steroids or evidence of active pneumonia;
* Suffering from an active autoimmune disease, and required systemic treatment in the past 2 years (i. e., use of disease regulators, corticosteroids, or immunosuppressive drugs);
* Patients with a known infection with human immunodeficiency virus (HIV);
* Patients with active infections requiring systemic treatment;
* Any hormonal medication (such as raloxifene, tamoxifen, or other selective oestrogen receptor modulators) for osteoporosis or breast cancer prophylaxis (only patients who have discontinued these drugs before randomization may participate in the study);
* The patient received either capecitabine or utiderone before surgery;
* Pregnant or lactating women;
* Known or suspected allergy to any study drug or excipients;
* Prohibition of corticosteroids;
* Any other condition the investigator considers inappropriate to participate in the trial.
