• Age: 18-75 years old; Eastern Cooperative Oncology Group Performance Status (ECOG PS) score: 0\

∙ 1; The expected survival is over 3 months.

• Phase Ib

‣ Advanced malignancies confirmed by cytology / histopathology, priority given to subjects with HER2 expression or amplification;

⁃ Subjects with malignant tumors who have failed standard treatment or lack effective treatment;

⁃ Confirmed presence of at least one evaluable lesion according to RECIST 1.1 criteria

• Phase II

‣ Hormone receptor (HR)-negative, HER2-positive breast cancer confirmed by cytology / histopathology, with evidence of local recurrence or distant metastasis, unsuitable for surgery or radiotherapy for curative purposes:

⁃ Have not received systemic antitumor therapy for metastatic stage; Systemic use of endocrine therapy is permitted, but not exceed 2 lines;

⁃ at least one measurable lesion that meets the RECIST 1.1 criteria.

• Major organs are functioning normally.

• Female subjects of reproductive age should agree to use contraceptive methods during the study period and until 6 months after the end of the study; Negative serum pregnancy / urine pregnancy test within 7 days prior to study enrollment and must be non-lactating subjects; Male subjects should agree to use contraception during the study and until six months after the end of the study.