Loncastuximab Tesirine for the Treatment of Relapsed or Refractory B-Cell Malignancies

This study tests a targeted antibody-drug treatment called loncastuximab tesirine in people with B-cell blood cancers (lymphomas) that have come back or stopped responding to prior therapies. The drug is designed to attach to a protein on cancer cells and deliver a cell-killing payload directly to them. **You may be eligible if...** - You have been diagnosed with a B-cell lymphoma (such as diffuse large B-cell lymphoma, follicular lymphoma, or mantle cell lymphoma) or post-transplant lymphoproliferative disorder - Your cancer has returned or stopped responding to prior treatments - You have received at least one prior therapy - You are 18 or older with measurable disease **You may NOT be eligible if...** - Your cancer has never been treated (newly diagnosed, untreated) - You have severe organ dysfunction (liver, kidneys, bone marrow) - You are pregnant or breastfeeding - You have active serious infections - Your general health is too poor to tolerate treatment Talk to your doctor to see if this trial is right for you.