EFFICACY OF CONCURRENT TREATMENT WITH OMALIZUMAB IN A PATIENT WITH ANAPHYLAXIS TO VENOM IMMUNOTHERAPY

Abstract

<h3>Introduction</h3> Anaphylaxis is a life-threatening IgE mediated systemic reaction. Hymenoptera stings induced reactions are estimated 3.3% in the United States. Venom immunotherapy (VIT) is a well-established treatment modality with ≥ 98% protection rate. We describe a case of anaphylaxis with profound hypotension on standard maintenance dosing of VIT, successfully treated with a higher dosing of VIT concurrently with omalizumab. <h3>Case Description</h3> 55-year-old male with history of asthma who presented due to hymenoptera sting anaphylaxis, which resulted in severe hypotension. Venom skin testing revealed positive yellow Jacket, honeybee and wasp. Baseline tryptase level was normal. Patient was started on VIT to mixed vespid, honeybee, and wasp with standard maintenance dose (100 microgram). Several weeks after achieving maintenance VIT dose, he developed anaphylactic reaction with facial flushing, severe hypotension & tachycardia. Standardized treatment for anaphylaxis was administered with improvement. Later, screening for occult mastocytosis with c-KIT mutation was negative. VIT build was restarted concurrently with omalizumab, and higher recommended maintenance dose of 200 microgram was achieved. On six months follow-up, he continued to tolerate the VIT. <h3>Discussion</h3> This case illustrates a promising treatment for patients at risk for hymenoptera VIT anaphylaxis. Our patient did not confer protection at recommended maintenance VIT dose of 100 microgram. Concurrent treatment with omalizumab and VIT was effective in preventing further anaphylaxis and achieving higher recommended maintenance VIT dosage in our patient. This treatment strategy may mitigate the risk of recurrent anaphylaxis during VIT, however long-term effectiveness and duration is yet to be determined.