• Capable of giving signed informed consent

• Age 18 years or older

• Histologically confirmed diagnosis of DLBCL

• Tumor tissue for retrospective central pathology review must be provided as an adjunct to participation in this study.

• Patients must have:

‣ relapsed and/or refractory disease

⁃ at least one bidimensionally measurable, PET positive disease site (transverse diameter of ≥1.5 cm and perpendicular diameter of ≥1.0 cm at baseline)

⁃ received at least one, but no more than three previous systemic regimens for the treatment of DLBCL and one therapy line must have included a CD20-targeted therapy

⁃ Eastern Cooperative Oncology Group 0 to 2

• Patients not considered in the opinion of the investigator eligible to undergo intensive salvage therapy including ASCT

• Patients must meet the following laboratory criteria at screening:

‣ absolute neutrophil count ≥1.5 × 10\^9/L

⁃ platelet count ≥90 × 10\^9/L

⁃ total serum bilirubin ≤2.5 × ULN or ≤5 × ULN in cases of Glibert's Syndrome or liver involvement by lymphoma

⁃ alanine transaminase, aspartate aminotransferase and alkaline phosphatase ≤3 × ULN or \<5 × ULN in cases of liver involvement

⁃ serum creatinine clearance ≥ 60 mL/minute

• Patients who received previous CD19 targeted therapy (other than tafasitamab) must have CD19 positive lymphoma confirmed on a biopsy taken since completing the prior CD19 targeted therapy

• Patients with primary refractory disease who received at least one, but no more than three previous systemic regimens (including a CD20 targeted therapy)