A Study of BGB-B455 in Adults With Advanced or Metastatic Solid Tumors

Claudin proteins are cell proteins that can play an important role in how cancer starts and progresses. Because of its preferential expression in tumors compared to normal tissues, CLDN6 is an ideal tumor antigen to target for treatment. BGB-B455 is a bispecific antibody (BsAbs) that targets CLDN6 on tumor cells and the CD3 receptor on T cells, which may provide a CLDN6-dependent antitumor immune response in a more tolerable manner without undue systemic toxicity. This new study will check how safe and helpful this potential anticancer drug is. In addition, this study will explore the recommended dosing level for BGB-B455. This drug will be tested by itself or in combination with investigator-selected chemotherapy in participants with selected solid tumors expressing the CLDN6 protein. This study is an open label study, meaning that both you and your study doctor will know what study drug/treatment you are given. This study has two parts: * Phase 1a consists of a dose escalation part where increasing amounts of the study treatment are given to different dose cohorts, and a safety expansion part that will enroll additional participants at selected doses for further assessments. * Phase 1b (dose expansion) will enroll participants at the best dose found in Phase 1a to see if it helps people with certain solid tumors. Our company, previously known as BeiGene, is now officially BeOne Medicines. Because some of our older studies were sponsored under the name BeiGene, you may see both names used for this study on this website.