The goal of this clinical trial is to learn if Axicabtagene Ciloleucel (axi-cel) works for consolidation after first-line treatment of high-risk Large B-cell Lymphoma (LBCL). It will also learn about the safety of axi-cel treatment. The main questions it aims to answer are:

• Does axi-cel treatment result in prolonged clinical benefit to patients with high-risk LBCL after first-line treatment?
• What medical problems do participants have when receiving axi-cel treatment?

In this investigator-initiated, single-arm clinical trial, participants will:

• Receive atezolizumab treatment at 2.0×10^6 cells/Kg as a one-time therapy.
• Visit the clinic as instructed for checkups and tests.

Inclusion Criteria:

1. Understand and voluntarily sign the informed consent form;
2. 18-70 years of age (inclusive);
3. Previously untreated CD19-positive large B-cell lymphoma;
4. Anticipated survival ≥12 weeks;
5. Adequate bone marrow reserve prior to apheresis
6. Appropriate organ function:
7. Eastern Cooperative Oncology Group (ECOG) Physical Status Score of 0 or 1; 8. Absence of CNS lymphoma;

9. Negative blood/urine pregnancy test in women of childbearing age.

Exclusion Criteria:

1. History of allergy to any of the components of the cell product;
2. History of stem cell transplantation;
3. History of organ transplantation;
4. Presence of active infections;
5. Current or history of central nervous system disorders;
6. Previous treatment with other modified T-cell therapy;
7. Previous treatment with anti-CD19/CD3 or other anti-CD19 therapies;
8. Malignancies other than those indicated for this trial;
9. History of any prior systemic immune checkpoint therapy;
10. History of short-acting cell growth factors or haematopoietic agonists/stimulants ;
11. History of a live vaccine within 3 months prior to screening;.