A Phase 1, 2-Part, Multicenter, First-In-Human Dose-Escalation and Dose-Expansion Study of DS-1103a Combination Therapy in Subjects With Advanced Solid Tumors

Inclusion Criteria: * Sign and date the informed consent form (ICF), prior to the start of any study-specific qualification procedures * Adults ≥18 years of age at the time the ICF is signed (please follow local regulatory requirements if the legal age of consent for study participation is \>18 years old) * Pathologically documented HER2-expressing or HER2-mutated (activating mutation) solid tumor that is unresectable or metastatic * Is willing and able to provide tumor tissue * Presence of at least 1 measurable lesion based on computed tomography (CT) or magnetic resonance imaging (MRI) per…