Study of Disitamab Vedotin and Anlotinib in Patients With HR-Negative, HER2-Low-Expressing Metastatic Breast Cancer

Inclusion Criteria:

• 1)At the time of signing the informed consent form, the age is ≥ 18 years old,regardless of gender;
• 2)Patients with pathohistologically proven, locally advanced or metastatic breastcancer have progressed through second-line standard treatment;
• 3)The immunohistochemical (IHC) test results of archived tissue (within 6 months) orfresh biopsy lesions were negative for ER and PR, while patients with low HER-2expression were HR -, HER2IHC1+, or HER2IHC2+and ISH negative;
• 4)ECOGPS: 0-1 points;
• 5)Expected survival time>12 weeks;
• 6)Adequate organ function: bone marrow function: hemoglobin ≥ 9g/dL; Absoluteneutrophil count ≥ 1.5 × 109/L; White blood cell count ≥ 3.0 × 109/L; Platelets ≥ 100 × 109/L; Liver function: serum total bilirubin ≤ 1.5 times the upper limit of normalvalue (ULN); Aspartic acid Transaminase (AST) and alanine Transaminase (ALT) ≤ 3.0 ×ULN (or ≤ 5.0 in the presence of liver metastasis) × ULN) Renal function: bloodcreatinine ≤ 1.5 × The creatinine clearance rate (CrCl) calculated by ULN or CockcroftFault formula method is ≥ 60mL/min; Cardiac function: New York Heart Association (NYHA) grading<3; Left ventricular Ejection fraction ≥ 50%;
• 7)At least one measurable lesion defined in RECIST version 1.1;
• 8)Women of childbearing age must have taken reliable contraceptive measures orconducted a Pregnancy test (serum or urine) within 7 days before enrollment, and theresult is negative, and are willing to use appropriate methods of contraception duringthe test and 8 weeks after the last administration of the test drug. For males, it isnecessary to agree to use appropriate methods of contraception or undergo surgicalsterilization during the trial period and 8 weeks after the last administration of theinvestigational drug;
• 9)The subjects voluntarily joined this study and signed an informed consent form, withgood compliance and cooperation in follow-up.

Exclusion Criteria:

• 1)The second-line treatment within 3 months is paclitaxel drug therapy;
• 2)Received antitumor therapy or radiation therapy for any malignancy within theprevious five years, excluding cured cervical carcinoma in situ, skin basal cellcarcinoma, or squamous cell carcinoma;
• 3)had a major non-breast cancer related surgery in the 4 weeks prior to enrollment, orhad not fully recovered from such surgery;
• 4)Previously received ADC drugs, anti-angiogenesis drugs, anti-HER2 and othertreatments;
• 5)Serious cardiovascular and cerebrovascular disease or discomfort, including but notlimited to the following diseases: - History of confirmed heart failure or systolicdysfunction (LVEF<50%) - high-risk uncontrolled arrhythmias - angina, acute myocardialinfarction - clinically significant valvular heart disease - poorly controlledhypertension (systolic blood pressure >180mmHg and/or diastolic blood pressure >100mmHg)
• 6)known allergic history of the drug components of this protocol;
• 7)A history of immunodeficiency, including HIV testing positive, or other acquired orcongenital immunodeficiency diseases, or a history of organ transplantation;
• 8)symptomatic brain metastases or brain metastases (excluding prophylactic cranialirradiation) within 4 weeks prior to initiation of treatment; 9) Pregnant andlactating women, fertile women who tested positive for baseline pregnancy tests, orpatients of childbearing age who were unwilling to take effective contraceptionthroughout the trial period;
• 9)Have a serious concomitant condition or other comorbid condition that interfereswith planned treatment, or any other condition in which the investigator deems thepatient unsuitable for participation in the study.