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. ABSTRACT: 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.