A Study of Runimotamab in Participants With Locally Advanced or Metastatic HER2-Expressing Cancers

Inclusion Criteria * Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1 * Life expectancy of at least 12 weeks * Adequate hematologic and end-organ function * Acute, clinically significant treatment-related toxicity from prior therapy must have resolved to Grade \</=1 prior to study entry * Left Ventricular Ejection Fraction (LVEF) \>/=50% HER2-Expressing Breast Cancer-Specific Inclusion Criteria * Locally tested, Human Epidermal Growth Factor Receptor 2 (HER2)-expressing BC * Locally advanced or metastatic BC that has relapsed or is refractory to established therapies HER2-Expressing Gastric/Gastroesophageal (GEJ) Cancer-Specific Inclusion Criteria * Adenocarcinoma of the stomach or GEJ with inoperable locally advanced or recurrent and/or metastatic disease, not amenable to curative therapy * HER2-expressing tumor (primary tumor or metastasis) as assessed by local lab testing * HER2-positive gastric/GEJ cancer must have received prior trastuzumab, cisplatin (or carboplatin or oxaliplatin or investigational platinum agent) and 5-fluorouracil (5-FU)/capecitabine HER2-Positive Solid Tumor Specific Inclusion Criteria * HER2-positive tumor (primary tumor or metastasis) as assessed by local (non-central) laboratory testing * Locally advanced, recurrent, or metastatic incurable malignancy that has progressed after at least one available standard therapy; or for whom standard therapy has proven to be ineffective or intolerable, or is considered inappropria…