JSKN003 Versus Treatment Of Physician'S Choice For HER2-low, Unresectable and/or Metastatic Breast Cancer Subjects

Prior treatment

• 1\. Untreated, or unstable brain parenchymal metastases, spinal cord metastases or compression, cancerous meningitis.
  • 2\. Patients with only skin lesions as target lesions. 3. Those with a history of other primary malignant tumors within 5 years before administration.
  • 4\. Selection of the control drug by the investigator who is not suitable for the protocol prescribed.
  • 5\. Previous use of antibody conjugates containing topoisomerase I inhibitors. 6. There is a third gap fluid that cannot be controlled by drainage, etc. 7. Previous or current interstitial pneumonia/lung disease requiring systemic hormone therapy.
  • 8\. Inability to swallow, chronic diarrhea, intestinal obstruction, or other factors that affect oral administration and absorption of the drug.
  • 9\. Previous or current autoimmune disease. 10. Have uncontrolled comorbidities. 11. The toxicity of previous antitumor therapy has not been restored to grade ≤1 (NCI-CTCAE v5.0).
  • 12\. History of previous immunodeficiency. 13. History of life-threatening allergic reactions or known ≥ grade 3 allergy to any component or excipient in the investigational pharmaceutical formulation.
  • 14\. Other conditions that the investigators believe will affect the safety or adherence to drug treatment in this study, including but not limited to psychiatric disorders, alcohol or drug abuse.

• 1\. The subject is able to understand the informed consent form, voluntarily participate and sign the informed consent form.
  • 2\. The subject ≥ 18 years old on the day of signing the informed consent form, male or female.
  • 3\. Unresectable locally recurrent or metastatic breast cancer, previous histopathological reports of HER2 IHC 1+ or 2+ and ISH-, previous histopathological reports have not been diagnosed as HER2 IHC 3+ or 2+ and ISH+.
  • 4\. Have received at least 1 to 2 lines of chemotherapy regimens for breast cancer in the relapse/metastatic stage.
  • 5\. Willing to provide sufficient archived tumor pathology specimens for central laboratory detection of HER2 status.
  • 6\. Documented radiographic disease progression (during or after the most recent treatment).
  • 7\. At least one extracranial measurable lesion at baseline according to RECIST 1.1 criteria.
  • 8\. Expected survival ≥ 3 months. 9. ECOG score of 0 or 1 within 14 days prior to administration. 10. Female subjects of childbearing potential or male subjects of fertile partner consent to use highly effective contraception from the signing of informed consent.
  • 11\. Laboratory tests within 14 days before administration and cardiac function tests within 28 days meet the criteria.
  • 12\. Have sufficient elution of previous treatment before administration.