Prospective Multiomic Analysis in Small-Cell Lung Cancer

This is an observational study to collects blood samples and tumor tissue from adults with relapsed small-cell lung cancer (SCLC) receicing standard of care commercial DLL3 T cell engager. The goal of the study is to understand the changes in tumor markers over time and examine whether these changes are associated with clinical outcomes. Participants will provide blood samples and, when clinically feasible, tumor tissue during routine care visits, treatment, and imaging assessments. The study does not assign cancer treatment.

Inclusion Criteria: 1. 18 years of age or older 2. Confirmed pathologic diagnosis of active SCLC or neuroendocrine cancer. 3. Relapsed small cell lung cancer (SCLC) planning to receive commercial DLL3 bispecific T cell engager. 4. Willing to provide informed consent. 5. Willing to provide blood samples and undergo tissue biopsy at various time points throughout the study, collected in concurrence with treatment cycles and/or imaging visits 6. Patients with multiple primary malignancies, recurrent lung cancer, or mixed histology are not excluded. 7. Patients who have contraindications or are unable to receive immunotherapy will be eligible for the study, and their samples will be used for comparison and control. Exclusion Criteria: 1. Prisoners or incarcerated patients 2. Those with cognitive impairments lacking decision-making capacity are excluded. 3. There will be no specific restrictions with respect to performance status, organ function, or prior/concurrent modes of therapy other than that the patient must be able to tolerate venipuncture and any planned interventional radiology or surgical procedures deemed necessary by their treating physicians.