Inclusion Criteria:
* Willingly sign the informed consent form.
* Age ≥ 18 years, any gender.
* Histologically confirmed as B-cell non-Hodgkin lymphoma, including:
* Diffuse large B-cell lymphoma (DLBCL) not otherwise specified (DLBCL-NOS)
* Transformed follicular lymphoma (tFL)
* High-grade B-cell lymphoma (HGBL) with MYC, BCL2, and/or BCL6 rearrangements
* High-grade B-cell lymphoma not otherwise specified (HGBL-NOS)
* Primary mediastinal large B-cell lymphoma (PMBL)
* Follicular lymphoma grade 3b (FL3b)
* Patients must have experienced at least one line of treatment for relapsed or refractory disease, meeting the following definitions:
* Refractory: At least partial response (PR) after the last chemotherapy or relapse within 12 months after autologous transplantation.
* Relapsed: Complete response (CR) after the last chemotherapy, followed by relapse before enrollment, or relapse or progression 12 months or longer after autologous transplantation.
* Maximum tumor diameter (long axis) \> 4 cm.
* Evaluator determines that the patient does not meet HDCT/ASCT criteria and meets at least one of the following:
* Age ≥ 60 years
* ECOG score = 2
* FEV1% or DLCO% ≤ 60%
* LVEF \< 50%
* Creatinine clearance \< 60 mL/min
* ALT or AST \> 2× upper limit of normal (ULN)
* Patient unwilling to receive high-dose chemotherapy and autologous stem cell transplantation.
* Measurable target lesions: lymph nodes ≥ 15 mm in longest diameter, or extranodal lesions \> 10 mm.
* Expected survival ≥ 12 weeks.
* Laboratory tests must meet the following requirements at screening:
* Lymphocyte count ≥ 0.1 × 10\^9/L
* Hemoglobin ≥ 80 g/L
* Platelets ≥ 50 × 10\^9/L
* ALT/AST ≤ 5 × ULN and total bilirubin \< 2 × ULN
* Creatinine clearance ≥ 30 mL/min
* Lung function: ≤ CTCAE grade 1 dyspnea, and oxygen saturation (SpO2) ≥ 92% in room air.
* LVEF ≥ 40%
* Patients with primary central nervous system lymphoma are allowed (secondary CNS lymphoma is not allowed).
* Sufficient venous access for apheresis, and no other contraindications for blood cell separation; female participants of childbearing potential must have a negative pregnancy test at screening.
Exclusion Criteria:
* History of allergy to any component of the cellular product or study treatment.
* History of allogeneic hematopoietic stem cell transplantation.
* History of organ transplantation.
* Patients with active viral hepatitis requiring treatment, including:
* Chronic HBV carriers with HBV DNA ≥ 500 IU/mL.
* Positive HCV RNA in patients with positive HCV antibodies.
* Positive HIV antibodies (HIV-Ab).
* Positive Treponema pallidum antibodies (TP-Ab).
* Elevated CMV DNA or EBV DNA above normal limits.
* Clinical significance of CNS diseases
* Presence of active primary central nervous system lymphoma.
* Prior treatment with other genetically modified T-cell therapies or CAR-T therapies.
* Severe genetic diseases or autoimmune diseases (e.g., systemic lupus erythematosus).
* Thromboembolic events (e.g., myocardial infarction, pulmonary embolism, deep vein thrombosis) within 6 months prior to screening.
* History of malignancies other than the indication for this trial within the last 5 years, except for in situ cancers (e.g., cervical, bladder, breast) or non-melanoma skin cancer.
* Active infections requiring systemic treatment or uncontrolled infections.
* Received lenalidomide, calcineurin inhibitors, chemotherapy (e.g., methotrexate, cyclophosphamide, ifosfamide, nitrogen mustard, or melphalan), mycophenolate, thalidomide, immunosuppressive antibodies (e.g., anti-TNF, anti-IL6, or anti-IL6R), radiation therapy, or any drug that binds FKBP12 (e.g., rapamycin, tacrolimus, everolimus) within 4 weeks prior to PBMC collection.
* Pregnant or breastfeeding women, or men or women of childbearing potential unwilling to use contraception during the trial and for 2 years after RJ CAR-T 002 cell infusion.
* Participation in other drug clinical trials (e.g., new drug trials, registrational studies, investigator-initiated trials) within 4 weeks prior to PBMC collection.
* Researcher's judgment that the patient is unsuitable for the trial (e.g., poor compliance, drug abuse).
* Vaccination with live or attenuated vaccines within 3 months prior to PBMC collection, or expected vaccination during the trial.
