Treatment of idiopathic anaphylaxis with omalizumab

Pediatric idiopathic anaphylaxis: practical management from infants to adolescents

Idiopathic anaphylaxis (IA) remains a frustrating challenge for both patients and physicians. The aim of this paper is to focus on IA in pediatric ages and suggest possible diagnostic algorithms according to specific age ranges (infants, children, and adolescents). In fact, in a variable percentage of patients, despite extensive diagnostic tests, the cause of anaphylactic episodes cannot be identified. Moreover, the lack of a unanimous IA definition requires a careful and detailed diagnostic workup. Prompt recognition of signs and symptoms, especially in younger children, and an accurate clinical history often allow a choice of the most appropriate diagnostic tests and a correct differential diagnosis.

Idiopathic anaphylaxis: Diagnosis and management

Introduction: Idiopathic anaphylaxis (IA) is a diagnosis of exclusion and is based on the inability to identify a causal relationship between a trigger and an anaphylactic event, despite a detailed patient history and careful diagnostic assessment. The prevalence of IA among the subset of people who experienced anaphylaxis is challenging to estimate and varies widely, from 10 to 60%; most commonly noted is ∼20% in the adult anaphylactic population. Comorbid atopic conditions, such as food allergy, allergic rhinitis, and asthma, are present in up to 48% of patients with IA. Improved diagnostic technologies and an increased understanding of conditions that manifest with symptoms associated with anaphylaxis have improved the ability to determine a more accurate diagnosis for patients who may have been initially diagnosed with IA. Methods: Literature search was conducted on PubMed, Google Scholar and Embase. Results: Galactose-α-1,3-galactose (α-gal) allergy, mast cell disorders, and hereditary a-tryptasemia are a few differential diagnoses that should be considered in patients with IA. Unlike food allergy, when anaphylaxis occurs within minutes to 2 hours after allergen consumption, α-gal allergy is a 3-6-hour delayed immunoglobulin E-mediated anaphylactic reaction to a carbohydrate epitope found in red meat (e.g., beef, lamb, pork). The more recently described hereditary α-tryptasemia is an inherited autosomal dominant genetic trait caused by increased germline copies of tryptase human gene alpha-beta 1 (TPSAB1), which encodes α tryptase and is associated with elevated baseline serum tryptase. Acute management of IA consists of carrying an epinephrine autoinjector to be administered immediately at the first signs of anaphylaxis. Long-term management for IA with antihistamines and other agents aims to potentially reduce the frequency and severity of the anaphylactic reactions, although the evidence is limited. Biologics are potentially steroid-sparing for patients with IA; however, more research on IA therapies is needed. Conclusion: The lack of diagnostic criteria, finite treatment options, and intricacies of making a differential diagnosis make IA challenging for patients and clinicians to manage.

Omalizumab for prevention of anaphylactic episodes in a patient with severe mosquito allergy

Anaphylaxis after mosquito bite is rare, but life threatening. No approved preventive therapy is available to date, but omalizumab could be a promising therapeutic option for reducing risk and improving quality of life in these patients.

Idiopathic Anaphylaxis: A Diagnosis of Exclusion

We report the case of a 67-year-old female with hypertension and rheumatoid arthritis who had 5 unprovoked episodes of anaphylaxis in an 18-month period of time. We review idiopathic anaphylaxis, including its definition, diagnostic work-up, and differential diagnosis.

Use of omalizumab for management of idiopathic anaphylaxis: A systematic review and retrospective case series

BACKGROUND

Patients with idiopathic anaphylaxis (IA) may fail to respond to a combination of high-dose H₁ and H₂ antihistamines and mast cell stabilizers. Treatment options for these patients are currently limited.

OBJECTIVE

To describe the clinical experience of omalizumab use for the treatment of patients with IA with no evidence of underlying clonal mast cell disorders.

METHODS

We performed a retrospective review at 2 separate institutions of medical records of patients with a diagnosis of IA without evidence of mast cell clonality who had received treatment with omalizumab. We searched PubMed for studies describing omalizumab use in similar patients. Information on symptoms and omalizumab therapy was compiled, and response pattern of anaphylaxis was determined.

RESULTS

A total of 35 patients with IA and no evidence of mast cell clonality who received omalizumab were identified. The median age was 36 years at the start of omalizumab (range, 11-54 years; n = 29). The frequency of anaphylaxis episodes before omalizumab treatment varied from 2 total episodes to several episodes per month. The most often used initial omalizumab dose was 300 mg every 4 weeks (n = 16). Most patients ultimately achieved clinical response after starting omalizumab: complete response (63%, n = 22), partial response (28.5%, n = 10), with 3 nonresponders.

CONCLUSION

Omalizumab may be an effective treatment option for patients with IA who do not have evidence of mast cell clonality and fail to respond to antihistamines and mast cell stabilizers.

Successful prevention of severe allergic transfusion reactions with omalizumab

BACKGROUND

Allergic transfusion reactions (ATRs) are a common adverse reaction to transfusion therapy and can be potentially fatal. Washing blood products is the most effective strategy for preventing ATRs; however, washed products, especially platelets, are not available at many blood centers.

STUDY DESIGN AND METHODS

A 29-year-old female patient with an advanced myelodysplastic/myeloproliferative neoplasm, unclassifiable, developed severe ATRs after four platelet transfusions in a week. She showed no response to premedication with histamines and steroids and still had severe ATRs with the next three platelet transfusions. A laboratory workup revealed that her IgA level was slightly decreased, while her haptoglobin level was normal. Anti-IgA testing was not available. The patient decided to undergo allogeneic peripheral blood stem cell (PBSC) transplantation. As the onset of symptoms ATR, which were similar to Type 1 hypersensitivity reactions mediated by IgE antibodies, occurred immediately after transfusion and omalizumab is a humanized monoclonal anti-IgE, we elected to offer off-label use of omalizumab before administering the conditioning regimen.

RESULTS

Omalizumab was injected subcutaneously at a dose of 150 mg. Surprisingly, transfusion reactions fully resolved within 24 hours. No serious side effects were noticed. Another 150 mg of omalizumab was administered 1 day before PBSC infusion. The patient remained asymptomatic without any signs of ATRs throughout the whole period of transplantation. Seven months after transplantation, the patient was in complete remission without overt complications.

CONCLUSION

This case suggests that omalizumab is a promising new alternative treatment for the prevention of severe ATRs.