This is an open-label, two-part study to evaluate the safety, tolerability, pharmacokinetics and immunogenicity of SHR-A1811 and preliminary anti-tumor efficacy in HER2 expressing or mutated advanced malignant solid tumor subjects.

Inclusion Criteria:

• Advanced/unresectable or metastatic solid tumor with HER2 expression or mutation that is refractory to or intolerable with standard treatment, or for which no standard treatment is available
• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
• LVEF ≥ 50% by either ECHO or MUGA
• Has adequate renal and hepatic function
• Female subjects agree not to be pregnant or lactating from beginning of the study screening until 6 months after receiving the last treatment

Exclusion Criteria:

• History of clinically significant lung diseases (e.g., interstitial pneumonia, pneumonitis, pulmonary fibrosis, and severe radiation pneumonitis) or suspected to have these diseases by imaging at screening period
• Known hereditary or acquired bleeding and thrombotic tendency