Overcoming severe adverse reactions to venom immunotherapy using anti-IgE antibodies in combination with a high maintenance dose.

BACKGROUND: An omalizumab treatment and a high maintenance venom dose may both help to prevent recurrent systemic allergic reactions (SAR) to venom immunotherapy (VIT). The effectiveness of this combination therapy, however, is unclear. OBJECTIVE: We wanted to explore the possibility whether a temporary treatment with the anti-IgE antibody omalizumab combined with a VIT using an elevated maintenance dose of >100 µg venom may establish a permanent tolerance of maintenance VIT. METHODS: For this retrospective case series, we scoured our institutional data base for patients who had had an insect venom allergy, and in whom it had not been possible to continue VIT because of repeated unstoppable SAR during maintenance VIT. Patients were divided into those who had received the combination therapy (omalizumab group) and those who had not received omalizumab because its costs could not be covered (controls). Guided by the total IgE level and by body weight, omalizumab had been given subcutaneously 5, 3 and 1 weeks before VIT had been restarted. Three to 6 months after an elevated maintenance dose (200-300 µg venom) had been reached, omalizumab had been stopped. RESULTS: Between 2006 and 2011, 15 patients had qualified for an off-label use of omalizumab: 10 patients had received the combination therapy, and 5 patients had remained without such a therapy. The combination therapy leads to a durable tolerance of VIT in all patients even after omalizumab had been discontinued (median of follow-up time 5.8 years, IQR 2.7-8.6 years). Sting challenge tests were tolerated by all of the re-stung omalizumab patients (n = 8). In all controls, VIT had to be stopped permanently due to repeated SARs (P < .001 vs omalizumab group). CONCLUSIONS AND CLINICAL RELEVANCE: Combining a temporary omalizumab therapy with an elevated maintenance dose seems a promising approach to achieve a tolerance of treatment in patients with a recurrent SAR to VIT.

Predictors of clinical effectiveness of Hymenoptera venom immunotherapy.

BACKGROUND: Treatment failure during venom immunotherapy (VIT) may be associated with a variety of risk factors, of which the relative importance is unknown. OBJECTIVE: Our aim was to evaluate the association of baseline serum tryptase concentration (BTC), mastocytosis in the skin (MIS) and of other parameters with the frequency of objective systemic reactions during in-hospital sting challenge (SC). METHODS: In this observational retrospective study, we enrolled 1532 patients (1609 cases due to double SC) with established honeybee or vespid venom allergy who had undergone VIT and a subsequent SC. Data were collected on various putative risk factors. Adult-onset MIS and/or a BTC > 20.0 µg/L was defined as clinical indicators of systemic mastocytosis. Relative rates were calculated with logistic regression models. RESULTS: Ninety-eight patients (6.4%) presented with MIS and/or BTC > 20.0 µg/L. 104 cases (6.5%) developed objective generalized symptoms during SC. In the absence of MIS, a BTC ≤ 20 µg/L did not increase the risk for VIT failure. The most important factors associated with a worse outcome were ACE inhibitor medication (OR 5.24, 95% CI 1.83-13.00, P < 0.001), honeybee venom allergy (OR 5.09, 95% CI 3.17-8.15, P < 0.001), systemic allergic reaction during VIT (OR 3.07, 95% CI 1.79-5.14, P < 0.001), and a substantial likelihood to suffer from SM (OR 2.74, 95% CI 1.37-5.22, P = 0.003), whereas a double VIT (OR 0.51, 95% CI 0.27-0.90, P = 0.027) and a longer duration of therapy (OR 0.68 per treatment month, 95% CI 0.50-0.93, P = 0.017) reduced the failure rate. CONCLUSION: The magnitude of therapeutic success correlates with type of venom, duration of therapy, and venom dose. Adult-onset MIS and/or a BTC > 20 µg/L is a significant, albeit not the strongest determinant for VIT failure. According to its odds ratio, ACE inhibitor therapy appears to be associated with the highest risk for VIT failure.