A Study of Duvelisib Versus Gemcitabine or Bendamustine in Participants With Relapsed/Refractory Nodal T Cell Lymphoma With T Follicular Helper (TFH) Phenotype

Key Inclusion Criteria: * Pathologically confirmed nodal T cell lymphoma with TFH phenotype according to the criteria of the World Health Organization classification (Swerdlow 2017, Alaggio 2022) including any one of Angioimmunoblastic T cell lymphoma (AITL), follicular T cell lymphoma, and other nodal peripheral T cell lymphoma (PTCL) with a TFH phenotype. * Relapsed or refractory to at least 1 prior systemic, cytotoxic therapy for T cell lymphoma. * Measurable disease as defined by Lugano 2014 criteria (Cheson 2014) for T cell lymphoma. Key Exclusion Criteria: * Cutaneous-only disease. * Received prior allogeneic transplant any time in the past or received autologous transplant within 60 days prior to the first dose of study drug. * Received prior treatment with a phosphoinositide-3-kinase (PI3K) inhibitor. * Prior exposure to planned study treatment investigator's choice therapy (gemcitabine or bendamustine) within 60 days prior to the first dose of study drug. Other protocol-defined criteria apply.