Hannah Koepsell

After two relapses of acute lymphoblastic leukemia, Hannah Koepsell received CAR-T cell therapy. A pediatric oncologist explains why leukemia can return after treatment and how researchers are working to make CAR-T responses last longer.

Hannah was 11 when she was diagnosed with acute lymphoblastic leukemia (ALL). Four years, two relapses and a 53-day hospital stay later, she is back in school.