A First-in-human Study to Assess OT-C001 (Amplified/Activated Allogenic Natural Killer Cells) in Patients With Relapsed/Refractory Diffuse Large B Cell Lymphoma

The goal of this clinical trial is to learn the safety of OT-C001 and decide a good dose in treating relapsed or refractory diffuse large B-cell lymphoma patients. It will also learn about the preliminary activity of OT-C001. Participants will: Receive a short course of chemotherapy before OT-C001 treatment. During the study treatment, participants will recieve weekly dose of OT-C001 for 3 or 6 weeks. During the study period, participants will also receive another two drugs, rituximab and IL-2, to support OT-C001 treatment. Participants need to visit the clinic or may be hospitalized according to the study plan.