This study checks the effectiveness and safety of a medicine called Ifinatamab Deruxtecan (I-DXd) for different types of recurring or spreading solid tumors. Solid tumors are lumps of abnormal cells that grow in the body. This study is divided into three parts to test different things. Participants will need to give a tumor sample for testing before starting the study. They must be 18 years or older and have a tumor that can be measured using special scans like CT or MRI. Some include specific criteria for different cancer types, such as endometrial, head and neck, and pancreatic cancer. Participants should not have had certain treatments before and need to meet other health requirements.

• The study has three stages, and participants might be in more than one stage depending on results.
• Participants should not have had previous treatments with similar medicines.
• Participants must provide a tumor sample for study purposes.