• ≥ 80 years of age at the time of screening, or

• ≥ 65 to 79 years of age at the time of screening and considered ineligible for chemoimmunotherapy

• Histologically documented DLBCL

• No prior treatment for DLBCL

• Stage II, III, or IV disease by the Ann Arbor Classification .

• Eastern Cooperative Oncology Group performance status of 0, 1, or 2 with no deterioration over the previous 2 weeks prior to baseline or day of the first dosing except when due to underlying lymphoma.

• At least 1 lesion that can be accurately measured at baseline as ≥ 10 mm in the longest diameter with computed tomography or magnetic resonance imaging and is suitable for accurate repeated measurements.

• Adequate organ and marrow function independent of growth factor or transfusion support within 1 week of Screening.