This study aims to evaluate the efficacy and safety of tafasitamab combined with lenalidomide plus standard immunochemotherapy, followed by sequential autologous stem cell transplantation (ASCT), in patients with relapsed/refractory diffuse large B-cell lymphoma (DLBCL).

Inclusion Criteria

Age ≥18 years;

Pathologically confirmed diagnosis of relapsed or refractory DLBCL;

Patients must meet the following criteria:

1. Definition of relapsed or refractory: Refractory: Patients who did not achieve remission (≥PR) with the most recent systemic therapy; Relapsed/progressive: Patients who developed new lesions or experienced a ≥50% increase in existing lesions (based on the Lugano 2014 classification for non-Hodgkin lymphoma) following the most recent systemic therapy;
2. At least one bidimensionally measurable lesion, defined as a lesion with the longest dimension >1.5 cm and perpendicular diameter >1.0 cm on contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI), confirmed as positive by PET-CT;
3. For DLBCL, prior receipt of at least one line but no more than four lines of systemic therapy, which must include CD20-targeted therapy;
4. ECOG performance status score of 0-2.

Meet the criteria for autologous hematopoietic stem cell transplantation (ASCT) and be willing to undergo ASCT;

Adequate major organ function:

1. Liver function: ALT/AST <3× upper limit of normal (ULN) and total bilirubin ≤34.2 μmol/L;
2. Renal function: Creatinine <220 μmol/L;
3. Pulmonary function: Oxygen saturation ≥95% without supplemental oxygen;
4. Cardiac function: Left ventricular ejection fraction (LVEF) ≥40%;
5. Transplant comorbidity index score ≤3.

As judged by the investigator, patients must:

1. Be willing to receive adequate prophylaxis and/or treatment for thromboembolic events;
2. Be able to understand and sign informed consent, and comply with all study-related procedures, medication use, and evaluations;
3. Have no history of non-adherence to medical prescriptions or be deemed by the investigator to have no potential for non-adherence;
4. Be able to understand and comply with pregnancy prevention requirements and reasons, the pregnancy prevention risk management plan, and provide written confirmation.

Exclusion Criteria

Pregnant (positive urine/serum pregnancy test) or lactating women;

Men or women with plans for conception within 1 year;

Inability to guarantee effective contraceptive measures (e.g., condoms, contraceptives) within 1 year after enrollment;

Uncontrolled infectious disease within 4 weeks prior to enrollment;

Active hepatitis B or C virus infection;

Severe autoimmune disease or immunodeficiency disorder;

History of allergy to macromolecular biologic drugs such as antibodies or cytokines;

Participation in another clinical trial within 6 weeks prior to enrollment;

Systemic use of corticosteroids within 4 weeks prior to enrollment (excluding patients using inhaled corticosteroids);

Psychiatric illness;

Substance abuse/dependence;

Any other condition that, in the investigator's judgment, makes the patient unsuitable for enrollment.