A First-in-human Study Using BDC-1001 as a Single Agent and in Combination With Nivolumab in Advanced HER2-Expressing Solid Tumors

Key Inclusion Criteria: * Patient must have an advanced solid tumor with documented HER2-protein expression or gene amplification for which approved therapies have been exhausted or are not clinically indicated. * Measurable disease as determined by RECIST v.1.1. * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. * Tumor tissue (archival or collected prior to the study start) available for exploratory biomarker evaluation. Key Exclusion Criteria: * History of severe hypersensitivity to any ingredient of the study drug(s), including trastuzumab or other monoclonal antibody. * Previous treatment with a TLR 7, TLR 8 or a TLR 7/8 agonist. * Impaired cardiac function or history of clinically significant cardiac disease * Human Immunodeficiency virus (HIV) infection, active hepatitis B infection, or hepatitis C infection. * Active SARS-CoV-2 infection * Untreated central nervous system (CNS), epidural tumor or metastasis, or brain metastasis. Other protocol defined inclusion/exclusion criteria may apply.