Neoadjuvant Study of DV in Combination Toripalimab or Sequence Chemotherapy in HR-negative, HER2 Low-expressing Breast Cancer

2.0mg/kg, intravenous infusion，D1, every 2 weeks, Every 6 weeks is a treatment cycle. A total of 3 cycles (18 weeks) of treatment are performed.

3.0 mg/kg, intravenous infusion, D1, every 2 weeks

AUC 3 Q2W or AUC1.5 QW intravenous infusion

2.0mg/kg, intravenous infusion，D1, every 2 weeks, Every 6 weeks is a treatment cycle. A total of 2 cycles (12 weeks) of treatment are performed.

According to body surface area, 90mg/m2, intravenous infusion, D1, every 3 weeks, A total of 12 weeks of treatment are performed.

According to body surface area,600mg/m2, intravenous infusion, D1, every 3 weeks, A total of 12 weeks of treatment are performed.

3.0 mg/kg, intravenous infusion, D1, every 2 weeks, A total of 2 cycles (12 weeks) of treatment are performed. Sequential therapy 3.0 mg/kg, intravenous infusion, D1, every 2 weeks, A total of 2 cycles (12 weeks) of treatment are performed.