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 any prior treatment without adequate washout periods as defined in the protocol. * 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.