Efficacy of omalizumab in a series of 23 patients suffering from mast cell activating disorders

Abstract

Omalizumab, an anti-IgE antibody, is an efficient treatment for chronic spontaneous urticaria (CSU) and asthma. Moreover, omalizumab has demonstrated efficacy in treating allergic rhinitis, atopic dermatitis and, more recently, in nasal polyps. So we could suppose that it could be efficient in other mast cell activating disorders (MCAD) as mast cell activation syndrome (MCAS), indolent systemic mastocytosis (ISM) and extracutaneous signs of CSU (CSU+). We report the evolution of extracutaneous symptoms in CSU+, MCAS and ISM patients treated with omalizumab. We retrospectively collected data from all ISM, MCAS or CSU+ patients treated with omalizumab and followed by the Department of clinical immunology of Grenoble-Alpes University Hospital, France. Since 2014, 23 patients were included in our study: 8 ISM, 2 MCAS and 13 CSU+. Oral consent from all patient was collected. The median age of our cohort was 48 years (17–81). The majority of the patients were women (65.2%). The median age of patients having their first symptoms was 33 years (range: 6–68) and when the diagnosis was made was 45 years (range: 13–77). Before omalizumab therapy, the major debilitating symptoms are angioedema (70%), urticaria (83%), gastro-intestinal (GI) symptoms (70%) and recurrent anaphylactic reaction (35%). All patients received concomitantly venom immunotherapy (IT), H1-antihistamines, H2-antihistamines, anti-leukotriene, Cromolyn sodium treatments. Among patients, 5 (23%) were treated with a median dose of 300 mg/3 weeks, 11 (50%) received a dose of 300 mg/month and 6 a dose of 300 mg/15 days (27%). The injections were mainly delivered at home (70%). The median age of patients on the first injection was 46 years (range: 14–77). For our available data, extracutaneous symptoms were improved for all patients except for one. The improvement appeared 3 months post-treatment (range 1–12). Patients also noticed an asthenia improvement (31%). The majority of patient with anaphylactic reactions did not present anaphylactic attack during venom immunotherapy or during follow-ups. One patient had an ISM with vesical-, GI-, skin-symptoms and postural orthostatic tachycardia syndrome (POTS). Skin symptoms (urticaria) improved but not the extracutaneous ones. Omalizumab was given during a median period of 17 months (range: 5–62) with no severe or serious adverse events. The most common drug side effects were local swelling at the site of injection (4%), transient asthenia (30%), fainting attack (13%), arthralgia (8%). Two patients noticed exacerbation after first injections (8%). One patient noticed a hair loss. Other than that, no long-term side effect was observed. In conclusion, MCAD are relatively rare and heterogeneous diseases with poor therapeutic option. Omalizumab, an anti-IgE Ab, seems to be safe and efficient in several symptoms. It also seems to be efficient in CSU+ extracutaneous symptoms.