Idelalisib In Patients With Relapsed/Refractory Diffuse Large B-Cell Lymphoma: First Results From The Nordic Lymphoma Group Nlg-Lbc-07 (Iliad) Phase Ii Trial

Introduction: Patients with relapsed/refractory diffuse large B-cell lymphoma (r/r DLBCL) who are ineligible for intensive chemotherapy and autologous stem cell transplantation have limited therapeutic options and poor prognosis, and there is an unmet need for new therapeutic alternatives in this situation. Based on gene expression profiling, DLBCL can be divided into the germinal centre B-cell (GCB) and the activated B-cell (ABC) subtype. These subtypes are dependent on different oncogenic pathways and may differ in responsiveness to targeted therapies. Idelalisib is a small-molecule inhibitor of PI3Kδ, currently approved for treatment of follicular lymphoma and CLL. Based on the high response rate of idelalisib in heavily pretreated patients with indolent B-cell lymphomas, among whom many may have undetected transformed disease, we hypothesized that idelalisib may also be active in r/r DLBCL, particularly in the GCB subtype, due to frequent PTEN loss and unregulated activation of PI3K signaling in this subtype. Here, we evaluated the efficacy and safety of idelalisib as a single agent therapy in patients with r/r DLBCL in a multi-centre phase II non-randomized trial. To our knowledge, this is the first prospective study on the use of single agent idelalisib in patients with DLBCL.