A Study of INCB050465 in Subjects With Relapsed or Refractory Marginal Zone Lymphoma (CITADEL-204)

Inclusion Criteria: * Men and women, aged 18 or older (except in South Korea, aged 19 or older). * Histologically confirmed marginal zone lymphoma, including extranodal, nodal, and splenic subtypes. * Radiographically measurable lymphadenopathy or extranodal lymphoid malignancy (defined as the presence of ≥ 1 lesion that measures \> 1.5 cm in the longest transverse diameter and ≥ 1.0 cm in the longest perpendicular diameter. * Participants with splenic MZL who do not meet the radiographically measurable disease criteria described herein are eligible for participation provided that bone marrow infiltration of MZL is histologically confirmed. * Participants must be willing to undergo an incisional or excisional lymph node or tissue biopsy or provide a lymph node or tissue biopsy from the most recent available archival tissue. * Eastern Cooperative Oncology Group performance status 0 to 2. Exclusion Criteria: * Evidence of diffuse large B-cell transformation. * History of central nervous system lymphoma (either primary or metastatic) or leptomeningeal disease. * Prior treatment with idelalisib, other selective PI3Kδ inhibitors, or a pan-PI3K inhibitor. * Allogeneic stem cell transplant within the last 6 months, or autologous stem cell transplant within the last 3 months before the date of the first dose of study treatment. * Active graft versus host disease. * Subjects positive for hepatitis B surface antigen or hepatitis B core antibody will be eligible if they are negative …