Omalizumab Therapy for Mast Cell-Mediator Symptoms in Patients with ISM, CM, MMAS, and MCAS.

Background: Patients with mast cell diseases may suffer from various distressing symptoms, which can be insufficiently controlled with available therapies, severely affecting their quality of life. There is 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 symptomatic mast cell disorder.

Methods: We included 55 patients with a mast cell disorder associated with debilitating symptoms who received omalizumab treatment between January 2015 and December 2017, after a multidisciplinary team meeting at the French National Reference Center for Mastocytosis.

Results: A complete response was achieved for 1 patient (1.8%), a major response for 30 patients (54.5%), and a partial response for 12 patients (21.8%), resulting in an overall best response rate of 78.2% (43 of 55 patients). The response was persistent at least 3 months in 33 of 43 responding patients (76.7%). At the last follow-up, the final overall response rate was 58.2% (32 of 55 patients). 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. Safety profile was acceptable, except for one severe adverse event (edema of the larynx and dyspnea after the first injection of omalizumab). Side effects were reported in 16 patients (29%), mainly of low to mild intensity, yet causing interruption of treatment in 5 patients (9%).

Conclusion: Omalizumab seems to be a useful therapeutic option to control mast cell-mediator symptoms and displays a favorable safety profile.