Inclusion Criteria:

          -  Adults ≥18 years old. Other age restrictions may apply as per local regulations.

          -  Unresectable and/or metastatic solid tumors with pre-specified HER2 mutations locally
             determined by NGS, who have progressed following prior treatment or who have no
             satisfactory alternative treatment options.

          -  Prior HER2 targeted therapy is permitted.

          -  All patients must provide an FFPE tumor sample for retrospective central HER2 testing.

          -  LVEF ≥50%

          -  ECOG 0-1

        Exclusion Criteria:

          -  HER2 overexpressing (IHC3+ or IHC2+/ISH+) breast, gastric or gastroesophageal junction
             adenocarcinoma.

          -  HER2 mutant NSCLC.

          -  History of non-infectious pneumonitis/ILD, current ILD, or where suspected ILD cannot
             be ruled out by imaging at screening

          -  Lung-specific intercurrent clinically significant severe illnesses.

          -  History of active primary immunodeficiency, known HIV, active HBV or HCV infection

          -  Uncontrolled infection requiring intravenous (IV) antibiotics, antivirals, or
             antifungals

          -  Pleural effusion, ascites or pericardial effusion that requires drainage, peritoneal
             shunt, or Cell-free and Concentrated Ascites Reinfusion Therapy (CART).

          -  Has spinal cord compression or clinically active central nervous system metastases.