Inclusion Criteria:

          -  Signed informed consent.

          -  Male or female patients aged ≥ 18 years

          -  histologically or cytologically confirmed HER2 positive advanced breast cancer which
             failed prior therapies

          -  Predicted life expectancy ≥ 12 weeks.

          -  ECOG performance status 0 to 1 for patients without LM, and 0 to 2 for patients with
             LM at the time of signing ICF

          -  Adequate bone marrow reserve and organ system functions

          -  For patients without CNS metastases, patients must have at least one measurable lesion
             according to RECIST (version 1.1)

          -  For patients with Brain metastasis: Patient must have at least one measurable
             intracranial lesion according to modified RECIST 1.1

        Exclusion Criteria:

          -  Intervention with any of the following: Any investigational agents or study drugs from
             a previous clinical study within 4 weeks of the first dose of study treatment； Any
             cytotoxic chemotherapy or other anticancer drugs for the treatment of metastatic
             breast cancer from a previous treatment regimen within 4 weeks of the first dose of
             study treatment； Any intrathecal chemotherapy within 2 weeks of the first dose of
             study treatment；Major surgery procedure (excluding placement of vascular access), or
             significant traumatic injury within 4 weeks of the first dose of study treatment, or
             have an anticipated need for major surgery during the study； Radiotherapy with a wide
             field of radiation within 4 weeks or radiotherapy with a limited field of radiation
             for palliation within 1 week of the first dose of study treatment;

          -  CNS complications that require urgent neurosurgical intervention

          -  Any evidence of severe or uncontrolled systemic diseases

          -  Another malignancy within 5 years prior to enrolment with the exception of adequately
             treated in-situ carcinoma of the cervix, uterus, basal or squamous cell carcinoma or
             non-melanomatous skin cancer.

          -  Live vaccines within 4 weeks prior to first dose.

          -  Active infections including:Tuberculosis (clinical evaluation that includes clinical
             history, physical examination and radiographic findings, and tuberculosis testing in
             line with local practice)；Positive Hepatitis B surface antigen (HBsAg) or positive HCV
             antibodies or confirmed positive HIV test result.

          -  Refractory nausea and vomiting if not controlled by supportive therapy, chronic
             gastrointestinal diseases, inability to swallow the formulated product or previous
             significant bowel resection that would preclude adequate absorption of DZD1516

          -  Involvement in the planning and conduct of the study (applies to Sponsor staff or
             staff at the study site).

          -  Judgment by the investigator that the patient should not participate in the study if
             the patient is unlikely to comply with study procedures, restrictions and
             requirements.