Emerging asthma treatments which offer the convenience of once-daily dosing will generate more than $2 billion in sales in the world's leading markets by 2019, according to new forecasts.

Driving these sales - which will be at the expense of current market-leading drugs that are dosed twice-daily - will be the uptake of emerging once-daily long-acting beta2 antagonist (LABA)/inhaled corticosteroid (ICS) combinations such as GlaxoSmithKline/Theravence's Relovair (fluticasone furoate/vilanterol trifenatate), Novartis' indacaterol/momentasone and Chiesi's carmoterol/budesonide), according to the study, published by research firm Decision Resources.

Relovair will emerge as the market leader among once-daily LABA/ICS combinations, as GSK wages an aggressive campaign to switch patients off Advair (fluticasone and salmeterol), Seretide (salmeterol xinafoate/fluticasone propionate) and Adoair (salmeterol xinafoate/fluticasone propionate ester dry powder inhaler/aerosol) prior to branded-generic entry in the US and generic and branded-generic entry in Europe, according to the study.

As the only once-daily LABA/ICS combination product expected to launch in the US and as a result of its high price, Relovair will garner nearly one-third of sales within the LABA/ICS drug class by 2019 in the US, France, Germany, Italy, Spain, the UK and Japan, the firm forecasts.

"Although emerging therapies with novel mechanisms of action aim to offer new treatment options for patients with severe corticosteroid-refractory asthma, we expect only interleukin inhibitors to launch and provide a treatment option for this subgroup of patients before 2019," comments Amanda Puffer, an analyst at Decision Resources.

The company is also forecasting that although Genentech/Novartis' Xolair (omalizumab) will be joined by the launch of emerging interleukin inhibitors as treatment options for patients with severe asthma before 2019, the use of novel interleukin inhibitors is expected to be restricted to patients with high eosinophils. Use of emerging therapies with novel mechanisms of action, such as chemokine receptor antagonists, are also likely to be restricted to a distinct subgroup of asthma patients, it adds.