Presented at:
61st Annual Meeting of the American Academy of Allergy, Asthma and Immunology
San Antonio, TX, March 18-22, 2004
Omalizumab Pretreatment Prevents Allergic Reactions Due to Rush Immunotherapy (RIT)
TB Casale, WB Busse, J Kline, Z Ballas, M Mokhtarani, V Seyfert-Margolis, K Bateman, M Plaut.
Creighton University, Omaha, NE; University of Wisconsin, Madison, WI; Univ. of Iowa, Iowa City, IA; Immune Tolerance Network, San Francisco, CA; PPD Development, Wilmington, NC; NIAID, NIH, Bethesda, MD.
Rationale: To examine whether omalizumab given 9 weeks prior to RIT makes RIT safer.
Methods: Adult patients with a positive history and skin test for ragweed sensitivity were enrolled in a double-blinded, parallel-group, 3-center, placebo-controlled trial. Patients received either 9 weeks of omalizumab (0.016 mg/kg/IgE [IU/mL]/mo) or placebo, followed by 1 day RIT (1.2 to 4.0 mcg ambA1 maximum dose) or placebo over 3 to 5 hours. RIT placebo contained increasing amounts of histamine, 6 to 62.5 mcg, to aid in the blinding process. Patients received 180mg fexofenadine the day before and morning of RIT.
Results : One hundred fifty-nine patients were randomized: 150 received all omalizumab or placebo pretreatments and 149 received at least 1 dose of RIT. IgE levels decreased > 90% in the omalizumab treated patients. The percentage of patients with adverse events in the omalizumab plus RIT versus placebo plus RIT groups, respectively, were: wheezing, 0 versus 7.7; flushing, 13.9 versus 41.0; urticaria, 8.3 versus 28.2; angioedema, 2.8 versus 7.7; drops in BP>15mm, 11.1 versus 7.7; lightheadedness, 5.6 versus 17.9; itching 13.9 versus 30.8. Overall, the reaction rates during RIT for the 4 groups were: 33.3% omalizumab plus RIT; 29.7% omalizumab plus placebo RIT; 56.4% placebo omalizumab plus RIT and 34.9% placebo plus placebo. Over twice as many patients required epinephrine and/or prednisone in the placebo plus RIT arm versus the omalizumab plus RIT arm.
Conclusion : Omalizumab pretreatment may be an effective strategy to permit more rapid and higher doses of allergen IT.