A Multicenter Study Evaluating the Safety, Efficacy, and Pharmacokinetics of IDE849 in Patients with DLL3 Expressing Tumors Including Small Cell Lung Cancer

This is a research study that includes studying IDE849 in small cell lung cancer (SCLC) that has progressed or recurred (returned) after previous standard treatment. The purpose of this study is to determine the highest dose of IDE849 that can be safely given to participants. The study drug used in this study is called IDE849. The study drug will be given through an intravenous (IV - into the vein) infusion on a slow drip. Study drug will be given once every 3 weeks in 21-day cycles. IDE849 is an experimental drug that is not approved by the Food and Drug Administration (FDA). This research study has 2 parts: the first part (Dose Escalation) will test different dose levels of IDE849 in participants; the second part (Dose Optimization/Expansion) will further test dose levels of IDE849 in additional subjects.

Are you Eligible? (Inclusion Criteria)

• years or older - Must be diagnosed with small cell lung cancer (SCLC) - Be willing to provide blood and tumor tissue samples - Cannot be pregnant or trying to become pregnant