Successful desensitization in a boy with severe cow's milk allergy by a combination therapy using omalizumab and rush oral immunotherapy

Background: Rush oral immunotherapy (OIT) combined with omalizumab (OMB) has been reported to be an effective and safe treatment for severe milk allergies. However, no report has described long-term follow-up observations after OMB discontinuation. The purpose of this case report was to evaluate the safety and efficacy of rush OIT in combination with OMB during a long period of treatment. Case presentation: A 5-year-old boy presented with a past history of two severe episodes of anaphylaxis (at the age of 2 and 3 years) after consuming small amounts of cow's milk (CM). Before the OIT, the total immunoglobulin E (IgE) level was 654 IU/mL, and specific-IgE (sIgE) levels for CM, casein, and beta-lactoglobulin were 77.0 kUA/L, 86.2 kUA/L and 12.0 kUA/L, respectively. The skin prick test (SPT) for CM showed a wheal (diameter, 20 mm) and erythema (diameter, 50 mm). In the open food challenge, he reacted to a 0.2 mL ingestion of CM and presented with dyspnea and laryngospasms, and he was then administrated 150 mg OMB every 2 weeks for 8 weeks. In the 9th week, he was admitted to hospital for the rush phase of the OIT. Once he was able ingest a dose of 200 mL CM without having an adverse reaction, he was discharged and allowed to continue a daily dose of 200 mL CM at home. During this phase, the sIgE levels were elevated, but the end-point titration values from the SPT gradually decreased, and the SPT was negative after 1 year of OMB treatment. Five months after discontinuation of OMB, the daily CM ingestion was ceased for a 2-week period, followed by an oral food challenge (OFC) that was negative. The patient experienced only five mild adverse events during the course of rush OIT, even after the discontinuation of OMB and his quality of life improved dramatically afterwards. Conclusions: The combination therapy of rush OIT and OMB successfully maintained desensitization to CM in a boy with severe allergies. We propose that a negative SPT may be useful to guide discontinuation of OMB in such patients.