Omalizumab: new drug. Asthma: too many unknowns for an anti-IgE

(1) Long-term therapy for severe asthma (stage 4) currently consists of a high-dose inhaled steroid plus a long-acting beta-2 agonist. (2) Omalizumab is a recombinant anti-IgE antibody marketed for the treatment of severe allergic asthma associated with high circulating IgE levels, as an adjunct to inadequate ongoing treatment. Omalizumab is administered subcutaneously every 2 to 4 weeks. (3) Omalizumab has been evaluated in many clinical trials but only one, a double-blind randomised placebo-controlled trial lasting 28 weeks and involving 419 patients, corresponded to the approved indications. Omalizumab adjunction to ongoing treatment prevented one emergency department admission for asthma every 2.5 years on average, but this trial provided weak evidence as it suffered from several biases. In particular, the two groups were not identical at baseline in terms of prior frequency of asthma exacerbations. These were more frequent in the omalizumab group. In addition, many analyses were retrospective, few events occurred, and the protocol was modified 4 times. (4) A combined analysis of this and 4 other trials involving slightly different patients suggests that omalizumab prevents one asthma emergency approximately every 3 patient-years. (5) During comparative trials, the main adverse effects were anaphylaxis and local injection site reactions. Omalizumab may increase the risk of parasitic infections. Cases of laryngeal oedema and angioedema have been reported. (6) The possibility of an increased risk of cancer is to be examined in a post-marketing cohort study. (7) Treatment can cost more than 1700 euros a month. (8) In practice, in view of the potentially severe adverse effects of omalizumab, the evidence supporting its efficacy is too weak. It is better to carefully tailor existing treatments to the individual patient.