BACKGROUND:
Mastocytosis is associated with mast cell (MC) mediator-related symptoms for which limited
therapies are available. OBJECTIVE: Our aim was to assess the efficacy and safety of
omalizumab in the treatment of MC mediator-related symptoms in adult patients with
mastocytosis. RESULTS: We identified one multi-centre retrospective cohort study (39 patients), one retrospective cohort study (13 patients), 4 case series and 10 case reports. No published controlled randomized study was identified. We included 69 patients (13 patients with
cutaneous mastocytosis and 56 with
systemic mastocytosis). The mean age was 48 years.
Omalizumab maintenance dose was 300 mg for the majority of patients. The mean
duration of treatment was 17 months. Treatment led to a tolerability of venom immunotherapy and to a complete resolution of severe reactions in all patients with post-honeybee
sting anaphylaxis. Complete resolution of idiopathic
anaphylaxis episodes was noted in 84% of the patients. Complete resolution of palpitations, gastrointestinal, cutaneous, neuropsychiatric, respiratory and musculoskeletal symptoms was observed at a rate of 43%, 29%, 27%, 11%, 9% and 0%, respectively. Efficacy was maintained for the entire duration of the treatment in all but four responders. Adverse events were reported for 13 patients. CONCLUSIONS AND CLINICAL RELEVANCE:
Omalizumab appears to prevent some life-threatening reactions associated with
mastocytosis and may be a good option to treat the associated symptoms. However, the evidence relied upon is observational, uncontrolled and from a small number of patients. A randomized controlled trial is needed to better understand the place of
omalizumab in
mastocytosis treatment.