CD19/20 Bispecific Nanobody-derived CAR-T Cells in B Cell Lymphoma

Inclusion Criteria: * expected lifetime\>3 months * CD19/CD20 positive relapsed/refractory B cell lymphoma * KPS\>70 * at least one measurable lesion according to RECIST 1.1 * enough function of hear, liver, kidney and bone marrow * no history of severe allergies * no other history of malignancy * no other diseases that conflict with this regimen * no serious mental illness * patient or family member sign informed consent Exclusion Criteria: * Pregnant or lactating women * Severe infectious or viral disease * Active B or C viral hepatitis * Patients who have used large amounts of glucocorticoids or other immunosuppressive agents during the last 4 weeks * participated in other clinical studies in the last 3 months, or have been treated with other gene products * Others not appropriate to participate in this study examined by the investigators