A Phase 1, Open-Label, Dose-Finding Study of INCB050465 in Combination With Investigator Choice of Rituximab, Bendamustine and Rituximab,or Ibrutinib in Participants With Previously Treated B-Cell Lymphoma (CITADEL-112)

Inclusion Criteria:

• Men and women, aged 18 years or older on the day of signing the Informed Consent Form (ICF).

• Histologically confirmed indolent/aggressive DLBCL, FL, MZL, or MCL.

• Participants with DLBCL, MZL or MCL must have received at least 1 prior line of systemic therapy with documented progression or documented failure to achieve CR or PR after the most recent systemic treatment regimen.

• Participants with FL must have received at least 2 prior lines of systemic therapy with documented progression or documented failure to achieve CR or PR after the most recent systemic treatment regimen.

• Ineligible for stem cell transplant.

• Participants with DLBCL must have failed or refused stem cell transplantation or failed first-line salvage therapy if ineligible for transplantation.

• Must be willing to undergo an incisional or excisional lymph node or tissue biopsy or to provide a lymph node or tissue biopsy from the most recent available archival tissue.

• Life expectancy of > 3 months.

• Eastern Cooperative Oncology Group (ECOG) performance status score of 0 to 2.

• Adequate hematologic, hepatic, and renal function.

• Willingness to avoid pregnancy or fathering a child.

• Ability to comprehend and willingness to sign an ICF

Exclusion Criteria:**

• Evidence of transformed non-Hodgkin lymphoma histologies (with the exception of FL).

• Histologically confirmed rare non-Hodgkin B-cell subtypes.

• History of or central nervous system lymphoma (either primary or metastatic) or leptomeningeal disease.

• Prior treatment with idelalisib, other selective PI3Kδ inhibitors, or a pan-PI3K inhibitor.

• For participants to be treated with bendamustine (Treatment B), prior treatment with bendamustine (within 12 months of the start of study treatment). Participants with prior bendamustine treatment (> 12 months before the start of study treatment) are eligible if they meet the following criteria:

• Did not discontinue because of tolerability concerns.

• Achieved either partial response (PR) or complete response (CR) to the bendamustine regimen of at least 12 months in duration before relapse/progression.

• Experienced progression following a regimen containing an alkylating agent.

• For participants to be treated with ibrutinib (Treatment C), prior treatment with a Bruton's tyrosine kinase (BTK) 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 following allogeneic transplant.

• Hepatitis B virus (HBV) or hepatitis C virus (HCV) infection.