Impact of Omalizumab Withdrawal After a 3 Year Duration Treatment in Well Controlled Severe Allergic Asthma : a Multicentric Randomized Controlled Trial

Omalizumab (OMA) is a monoclonal anti IgE antibody, developed for severe uncontrolled allergic asthma. Efficacy of OMA in this indication is well documented in randomized trials as well as in real life studies, reducing the number of severe exacerbations by about 50% and improving asthma control score .

However, despite commercialized since 2006 in France, the optimal duration of the treatment remains unclear when asthma is well controlled. In particular, there is no guideline to apply the "step down theory" to biologics in well controlled patients.

It seems clear that a treatment given for less than one year is associated with an early relapse of the disease. However, in a randomized controlled study including 176 patients, stopping the treatment after 5 years induced a small, but acceptable loss of control (average decrease of asthma control test (ACT) by 2.88 and 1.16 point, p= 0.18), but some patients had uncontrolled asthma when the treatment was stopped. In a smaller cohort of 49 patients in Spain who voluntarily accepted to discontinue OMA treatment after 6 years of therapy, asthma deterioration (defined by one or more exacerbation and any Asthma Control Test change during the 1st year) was observed in 24% of patients during the first year following discontinuation , with a maximal rate of 2 exacerbations/yr. After 4 years of discontinuation, 60% of patients still take advantage of the 6 yrs of treatment with OMA. A retrospective study in France found that 14/26 patients treated for at least 3 years kept the same level of control after discontinuation. All these data suggest that a large part of patients with well controlled asthma can discontinue OMA therapy without any asthma control deterioration or with an acceptable decrease in asthma control.

Inducing long term asthma remissions, rather than complete cure, is one potential goal of biologics. OMA is supposed to have disease modifying effects , explaining why there is a hope for a good asthma control being maintained after discontinuation. For this reason, French experts propose that omalizumab can be given for "3 to 5 yrs if asthma remains well controlled" . After an asthma relapse, OMA can be prescribed again theoretically, but no data regarding clinical response after a "second line" of treatment with the same biologic are available. The question of optimal treatment duration is also questioned with other biologics.

The costs related to OMA are high (estimated to 12 k€/year/patient). Frequent injections (1 subcutaneous injection every 4 weeks for the lowest dose to 4 injections every 2 weeks for the highest dose) represent severe constraints for patients, especially for the youngest ones. For all these reasons, evaluating whether shortening duration of OMA therapy is feasible while maintaining acceptable asthma control is a critical point. The main objective is to demonstrate the non-inferiority (i.e. no more exacerbations at 12 months) of OMA withdrawal attempt compared to OMA continuation in asthma-controlled patients treated for at least 33 months with OMA. Secondary objectives are to compare OMA withdrawal attempt versus OMA continuation in asthma-controlled patients treated for at least 33 months with OMA on other asthma control features at 6 and 12 months.