Epcoritamab Compared to Observation for Treating B-cell Lymphoma Patients Not in Complete Remission After CD19-directed CAR-T Therapy

This study is testing whether giving a drug called epcoritamab after CAR-T cell therapy can help patients with a type of blood cancer called B-cell lymphoma (specifically diffuse large B-cell lymphoma) who did not achieve a complete response from CAR-T treatment. CAR-T therapy reprograms your own immune cells to fight cancer, but some patients only achieve a partial response — this trial aims to improve outcomes for those patients. **You may be eligible if...** - You are 18 or older - You have been diagnosed with diffuse large B-cell lymphoma or a related B-cell lymphoma with CD20 positivity - You received one of three approved CAR-T therapies (axi-cel, tisa-cel, or liso-cel) - Your PET scan at day 30 after CAR-T showed only a partial response (not full remission) - You have measurable disease remaining - Your general health status is good (ECOG 0, 1, or 2) - Your blood counts meet the required levels **You may NOT be eligible if...** - You achieved a complete response from CAR-T therapy - You have disease that is not measurable - You have poor organ function or very low blood counts Talk to your doctor to see if this trial is right for you.