A Phase 2 Safety and Efficacy Study of INCB050465 in Subjects With Relapsed or Refractory Diffuse Large B-Cell Lymphoma (CITADEL-202)

Inclusion Criteria: * Eligible 19 years and older in South Korea * Relapsed or refractory DLBCL, which has been histologically documented, defined as having received at least 2 but no more than 5 prior treatment regimens and ineligible for high-dose chemotherapy supported by autologous stem cell transplant. * Must have ≥ 1 measurable lesion (≥2 cm in longest dimension) or ≥ 1 measurable extranodal lesion (≥1 cm in longest dimension) on computed tomography (CT) scan or magnetic resonance imaging (MRI). * Subjects must be willing to undergo an incisional or excisional lymph node biopsy of accessible adenopathy or provide the most recent, available archived tumor biopsy. * Eastern Cooperative Oncology Group performance status 0 to 2. Exclusion Criteria: * Primary mediastinal (thymic) large B-cell lymphoma. * Known brain or central nervous system metastases or history of uncontrolled seizures. * Allogeneic stem cell transplant within the last 6 months, or active graft versus host disease following allogeneic transplant, or autologous stem cell transplant within the last 3 months. * Use or expected use during the study of any prohibited medications, including potent cytochrome P450 3A4 inhibitors or inducers within 14 days or 5 half lives (whichever is longer) before the first dose of study drug. * Prior treatment with the following: * Group A: Prior treatment with a selective phosphatidylinositol 3-kinase (PI3K) δ inhibitor (eg, idelalisib), a pan-PI3K inhibitor, or a BTK inhibitor (eg, ibrutinib). * Group B: Prior treatment with a selective PI3Kδ inhibitor (eg, idelalisib) or a pan PI3K inhibitor.