A Study of D3L-001 as Monotherapy in Subjects With HER2-Positive Advanced Solid Tumors

Inclusion Criteria: * Subject must have documented HER2 positivity (determined by immunohistochemistry \[IHC\], in situ hybridization \[ISH\], Next Generation Sequencing \[NGS\] or other analysis techniques as appropriate). * Subject must have Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. * Subject must have left ventricular ejection fraction (LVEF) ≥50% by either echocardiography (ECHO) or multiple-gated acquisition (MUGA) within the screening period. * Subject must have adequate organ and marrow function within the screening period. Exclusion Criteria: * Subject has any prior treatment with anti-CD47 or SIRPα agent. * Subject has major surgery or radiotherapy, immunostimulatory agents, investigational agents, or any other anticancer treatment including chemotherapy, targeted therapy, biologics that is not completed 28 days before first dose of study medication. * Subject has immunosuppressive medication that is not completed 14 days before the first dose of study medication. * Subject has uncontrolled intercurrent illness that would limit compliance with study requirements, substantially increase risk of incurring AEs, or compromise the ability of the subject to give written informed consent. * Subject has unresolved treatment-related toxicities from previous anticancer therapy of NCI CTCAE Grade ≥2 (with exception of vitiligo or alopecia). * Judgment by the Investigator that the subject should not participate in the study if the subject is unlikely to comply with study procedures, restrictions, and requirements.