CAR T CELL THERAPY achieved high response rates at ultralow doses in adults with relapsed or refractory diffuse large B cell lymphoma, according to findings from a phase one clinical trial. Phase One Trial Assessed Ultralow Dose TherapyThe nonrandomised phase one trial enrolled patients at a single centre between November 2023 and April 2025. Patients received one of three ultralow dose levels of 2×10³, 5×103, and 2×10⁴ CAR T cells per kilogram. Complete remission was achieved in 11 patients: 84.6%, while one patient achieved partial remission: 7.7%. Cytokine release syndrome occurred in 12 patients and was predominantly low grade, including grade 1 events in eight patients and grade 2 events in three patients.