• Cohort 1:

‣ Patients with pathologically confirmed DLBCL who have not received prior anti-lymphoma therapy.

⁃ Disease stage II to IV by Ann Arbor Classification.

⁃ Life expectancy ≥ 12 months.

• Cohort 2, 3:

‣ Pathologically confirmed DLBCL patients who have received adequate first-line treatment containing CD20 monoclonal antibody and anthracyclines (such as R-CHOP-like regimen).

⁃ Relapsed or refractory to first-line R-CHOP-like regimen.

⁃ For patients who have received only one line of therapy, if the patient has not received autologous stem cell transplantation, the investigator needs to assess as unsuitable or the patient refuses intensive chemotherapy and hematopoietic stem cell transplantation.

⁃ Life expectancy ≥ 6 months.

• Patients must also meet all of the following criteria to be included in this study:

‣ All patients must provide a signed and dated written informed consent prior to any study-specific procedure, sampling, and analysis.

⁃ Patients must be ≥ 18 years of age at the time of informed consent.

⁃ ECOG status score of 0 to 2.

⁃ Presence of at least one radiologically measurable lesion in 2 perpendicular directions as assessed by CT or MRI and a positive lesion on PET/CT scan consistent with a tumor site identified by CT or MRI.

⁃ Adequate bone marrow hematopoietic reserve and organ function.

⁃ No uncontrolled medical complications.

⁃ Patients should be able to follow the relevant requirements of this study for medication and follow-up.

⁃ Willing to comply with contraceptive restrictions.