Patients with systemic mastocytosis (SM) who rely on venom immunotherapy (VIT) to prevent life-threatening allergic reactions can safely extend their maintenance treatment intervals to 12 weeks after completing five years of therapy, suggests results from a new study published recently in The Journal of Allergy and Clinical Immunology: In Practice.
Patients with indolent SM, particularly those with the bone marrow mastocytosis subtype, face a significantly elevated risk of anaphylaxis, especially from stings by insects such as bees and wasps.
Historically, VIT has provided life-saving protection in patients with insect venom allergies, with protection rates up to 96% in wasp venom-treated patients. However, patients with SM are typically advised to continue VIT for life because they remain vulnerable to severe, even fatal, systemic reactions if therapy is discontinued. Until now, whether patients with SM could safely reduce the frequency of their VIT injections without losing protection was unclear.
“Our findings indicate, for the first time, that extending the VIT maintenance interval up to 12 weeks, after five years of VIT, is safe and effective also in patients with SM,” explained the authors of this study.
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This multicenter study followed 191 adults with insect venom allergies, including patients with SM, and compared standard four- to five-week maintenance VIT intervals with extended 12-week intervals that began after five years of treatment. After an average follow-up of more than 10 years, researchers analyzed reactions to real-life stings. Among the 80 participants who experienced field re-stings, those on the 12-week schedule actually had fewer serious allergic reactions (3.9%) compared to those on the standard interval (20.7%), a statistically significant difference.
Importantly, no serious side effects occurred from extending the injection intervals, and patients on medications such as ACE inhibitors also tolerated the treatment well. While gender was the only variable significantly associated with allergic reactions, with females experiencing higher rates, the extended interval remained effective regardless of sex.
For patients with SM, these results provide new reassurance that a less frequent treatment schedule can be both safe and effective. This could improve long-term quality of life by reducing the burden of frequent injections, while still offering vital protection against dangerous stings. Further studies may refine these results, but for now, the evidence supports longer maintenance intervals in patients with SM already on stable long-term VIT.
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