ACE1702 in Subjects With Advanced or Metastatic HER2-expressing Solid Tumors

Inclusion Criteria: * Signed informed consent * Subjects must be ≥ 18 years of age ( ≥ 20 years of age for Taiwan site) * Subject with advanced or metastatic solid tumors that is not amenable to surgical resection and is not eligible or has refused other approved therapeutic options that have demonstrated clinical benefit. * Histologically confirmed HER2 expression. * Eastern Cooperative Oncology Group (ECOG) Performance Status ≤ 1 * Measurable or non-measurable evaluable disease according to RECIST 1.1 * Adequate hematologic and end-organ function at baseline * Oxygen saturation via pulse oxygenation ≥ 90% at rest on room air Exclusion Criteria: * Untreated central nervous system (CNS) metastases * Multiple primary malignancies * Clinically significant cardiovascular disease such as New York Heart Association (NYHA) cardiac disease (class III or greater) * Pregnant or lactating female * Serious, uncontrolled medical disorder that, in the opinion of the Investigator, would impair the ability of the subject to receive study treatment * History of autoimmune or immune mediated symptomatic disease * Any anti-cancer chemotherapy or targeted small molecule therapy, or experimental therapy/device within 4 weeks or 5 half-lives of the drug prior to planned start of the study