• Histologically confirmed DLBCL, not otherwise specified (NOS)

• R/R disease, defined as: relapsed = disease that has recurred following a response that lasted \>/= 6 months after completion of the last line of therapy; refractory = disease that did not respond to or that progressed \< 6 months after completion of the last line of therapy

• At least one line of prior systemic therapy

• Participants who have failed only one prior line of therapy must not be a candidate for high-dose chemotherapy followed by autologous stem cell transplant (ASCT)

• At least one bi-dimensionally measurable (\> 1.5 cm) nodal lesion, or one bi-dimensionally measurable (\> 1 cm) extranodal lesion, as measured on CT scan

• Eastern Cooperative Oncology Group (ECOG) status of 0, 1, or 2

• Adequate hematologic and renal function