Omalizumab: Efficacy and Safety in Mast Cell Disorders

Abstract Background. Patients with mast cell diseases may suffer from various distressing symptoms, which can be insufficiently controlled with available therapies, severely affecting quality of life. There is thus a need for new and safe treatment options for these patients. Objectives. We aimed to evaluate safety and efficacy of omalizumab administration in patients with a systemic mast cell disorder. Methods. We included 56 patients with a systemic mast cell disorder who received omalizumab treatment between January 2015 and December 2017, after a pluridisciplinary review at the French National Reference Center for Mastocytosis (CEREMAST). Results. A complete response was achieved for 1 patient (1.8%), a major response for 30 patients (53.6%) and a partial response for 12 patients (21.4%), resulting in an overall response rate of 76.8% (43/56 patients). The response was persistent at least 3 months in 33 patients (58.9%). Median time to first response was 2 months and median time to best response was 6 months. Omalizumab was dramatically effective on all superficial and general vasomotor symptoms and on most gastrointestinal or urinary symptoms, and partially effective on most neuropsychiatric symptoms (Figure 1). Safety profile was acceptable, except for one severe adverse event (cervical edema and dyspnea after the first injection of omalizumab). Side effects were reported in 16 patients (28.6%), mainly of low to mild intensity, yet causing interruption of treatment in 6 patients (10.7%). Conclusion. Omalizumab is an effective treatment option in systemic mast cell disorders, and displays a favorable safety profile. Prospective studies remain necessary to confirm these encouraging results. Disclosures No relevant conflicts of interest to declare.