**Study Overview:** This study explores how a new drug, ABBV-253, affects advanced solid tumors in adults. Solid tumors are abnormal masses of tissue, and ABBV-253 is a drug still being tested. Researchers want to understand how safe it is (adverse events), how it changes the disease, and how it moves through the body (pharmacokinetics). **Study Details:** The study has two parts. First, participants with any of the eligible cancer types, like lung or ovarian cancer, will receive different doses of ABBV-253 in Part 1. In Part 2, only participants with a specific type of lung cancer (NSCLC) will receive one of three doses. The study will enroll about 130 people across 11 global locations. Participants will get ABBV-253 through an intravenous (IV) infusion, which means the drug is given directly into a vein. **Key Points:** - **Duration & Visits:** The study lasts up to 4 years with regular hospital or clinic visits. - **Treatment Burden:** Participants may have more procedures than usual care. - **Monitoring:** Regular assessments, blood tests, and questionnaires will track effects and side effects. Participants must meet specific health criteria to join, and some conditions might exclude them.