Omalizumab prevents anaphylaxis and improves symptoms in systemic mastocytosis; efficacy and safety observations

Abstract

Background

Patients with systemic mastocytosis (SM) may suffer from mast cell (MC) mediator-related symptoms insufficiently controlled by conventional therapy. Omalizumab is an established treatment in other MC-driven diseases, but experiences in SM are limited.

Objective

To assess the efficacy and safety of omalizumab in SM.

Methods

In our patient cohort we evaluated all SM patients treated with omalizumab. A physician global assessment of type and severity of symptoms was performed at baseline, at 3 and 6 months and at latest follow-up. Quality-of-life was assessed by visual analogue scale. S-tryptase and KIT D816V allele burden were monitored.

Results

A total of 14 adult SM patients (10 ISM, 2 BMM, 1 SSM and 1 ASM-AHN) received omalizumab with a median duration of 17 months (range: 1-73 months). One patient was excluded due to concomitant cytoreductive therapy. In the remaining 13 patients we observed a significant reduction of symptoms, with complete symptom control in five (38.5%), major response in three (23.1%) and a partial response in three (23.1%) patients, whereas two patients (15.4%) withdrew due to subjective side-effects at first dose. The treatment was most effective for recurrent anaphylaxis and skin symptoms, less for gastrointestinal, musculoskeletal and neuropsychiatric symptoms. Patient-reported quality-of-life showed significant improvement. No significant changes in s-tryptase/KIT D816V allele burden were observed. No severe adverse events were recorded.

Conclusions

Omalizumab appears to be a promising treatment option in SM, effectively preventing anaphylaxis and improving chronic MC mediator-related symptoms, insufficiently controlled by conventional therapy. Controlled studies are needed to substantiate findings.

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