This study aims to evaluate the efficacy and safety of Relma-cel in the treatment of central nervous system lymphoma (CNSL), as well as its pharmacokinetic characteristics. Enrolled patients with relapsed/refractory (R/R) CNSL will receive Relma-cel infusion, followed by Tislelizumab treatment (200mg, IV, q4w, for 12 months) starting on day 35 after infusion. Bruton's tyrosine kinase (BTK) inhibitors will be used in combination as needed. The follow-up period will last for 4 years, monitoring drug safety, disease status, survival, and the pharmacokinetic characteristics of Relma-cel.

Inclusion Criteria:

1. Age greater than or equal to 18 years old, male or female;

2. Relapsed or refractory CNS-involved large b-cell lymphoma after at least first-line therapy, with an efficacy assessment of CR or PR after salvage therapy, and current stable efficacy status;

3. Eastern Cooperative Oncology Group (ECOG) score of 0-2;

4. Have a life expectancy of ≥ 12 weeks

5. Use contraception

6. Have adequate bone marrow and organ function:

   1. Neutrophil count (anc) ≥1.0 x 109/L;
   2. Hemoglobin ≥ 8.0 g/dl;
   3. Platelet count ≥ 50 x 109/L;
   4. Total bilirubin ≤ 1.5 × upper limit of normal (ULN)
   5. Alanine aminotransferase/aspartate aminotransferase (ALT/AST) ≤ 2.5 x ULN or ≤ 5 x ULN (in the presence of hepatic invasion);
   6. Creatinine clearance ≥40mL/min
   7. Lipase ≤ 1.5 x ULN

Exclusion Criteria:

1. Severe active central nervous system symptoms
2. Prior chimeric antigen receptor cellular immunotherapy targeting cd19
3. Known human immunodeficiency virus (hiv) infection or positive immunoassay;
4. Live vaccination within 30 days prior to study drug administration;
5. Active autoimmune disease requiring systemic therapy in the last 12 months
6. Allergy to the study drug or history of severe allergic reactions
7. Potential risk of malignant cardiac arrhythmia
8. History of stroke or intracranial hemorrhage within 3 months prior to the date of administration of study medication
9. Other malignant tumors presently or within 3 years prior to enrollment
10. Conditions that, in the judgment of the investigator, would interfere with full participation in the study; pose a significant risk to the subject; or interfere with the interpretation of the study data
11. Pregnant or lactating patients;