A Feasibility Trial of Tazemetostat Plus CAR T Cell Therapy in B-cell Lymphomas

Participants will take 800 mg of tazemetostat twice a day starting 7 days before apheresis and continue to take tazemetostat until lymphodepletion, which is chemotherapy given prior to receiving the CAR T cells. Participants will stop taking tazemetostat after lymphodepletion until after CAR T cell infusion. Once lymphocyte counts increase, tazemetostat will be resumed and tazemetostat will be taken for 6 - 12 months, depending on participant response.