Treatment with Idelalisib in Patients with Relapsed or Refractory Follicular Lymphoma: The Observational Italian Multicenter FolIdela Study

Simple Summary Idelalisib, the first-in-class phosphatidylinositol 3-kinase inhibitor, approved by the Italian Medicines Agency for the treatment of relapsed/refractory follicular lymphoma patients, showed high antitumor activity with an acceptable safety profile in a phase II registration trial. A 6-year follow-up of the same trial did not reveal any new safety concerns, confirming the role of idelalisib as an effective option for indolent non-Hodgkin lymphoma, refractory to previous therapies. The aim of this multicenter study is to point out the role of idelalisib in a real-life context, since data from everyday clinical practices are scarce. We report the effective and manageable safety profile of idelalisib in the treatment of 72 relapsed/refractory follicular lymphoma patients, bringing further demonstrations of its role in this setting. Follicular lymphoma (FL) is an indolent hematological disease, often responsive to the first line of treatment, but characterized by repeated relapses. The therapeutic algorithm for relapsed/refractory FL patients comprises phosphatidylinositol 3-kinase inhibitors. Idelalisib showed anticancer activity, while inducing a significant rate of toxicities. Since the evidence in the literature on its use in normal clinical practice is scarce, a retrospective multicenter study was conducted to evaluate effectiveness and tolerability in a real-life context. Seventy-two patients with a median age at diagnosis of 57.2 years-mostly with an advanced stage (88.9%) and relapsed to the most recent therapy (79.1%)-were enrolled. The median number of prior therapies was three (20.8% refractory to the last therapy before idelalisib). With a median number of 4 months of treatment, the overall response rate was 41.7% (20.8% complete responses). Median disease-free survival and overall survival were achieved at 8.4 months and at 4 years, respectively. Forty-four percent of patients experienced at least one drug-related toxicity: 6.9% hematological ones and 43% non-hematological. The study confirmed that idelalisib has anticancer effectiveness and an acceptable safety profile in relapsed/refractory FL with unfavorable prognostic characteristics, even in the context of normal clinical practice.