Adding the LAMA* tiotropium or the LABA** salmeterol to maintenance inhaled corticosteroids (ICS) reduces airflow obstruction in Asians with moderate symptomatic asthma regardless of allergic status, according to a subgroup analysis of the phase III double-blind MezzoTinA-asthma trials presented at the APSR 2017 Congress in Sydney, Australia.

“Tiotropium added on to ICS improves lung function regardless of allergic status as defined by clinician-judged atopy, IgE concentration, or eosinophil count,” said lead author Dr Shu Hashimoto of Nihon University School of Medicine in Tokyo, Japan.

The analysis involved 670 Asian adult patients from a total study population of 2,100 patients with an asthma history of at least 3 months. The patients were randomized 1:1:1:1 to salmeterol 50 µg twice daily, tiotropium 2.5 or 5 µg once daily in the evening, or placebo, in addition to their maintenance medium-dose ICS. [APSR 2017, abstract AP204]

Similar improvements in the coprimary endpoints of peak and trough FEV₁ were seen across the salmeterol and the tiotropium (both doses) arms. Compared with placebo, peak FEV₁ improved by 0.215–0.271 L with tiotropium 2.5 µg, 0.201–0.353 L with tiotropium 5 µg, and 0.215 –0.315 L with salmeterol; while trough FEV₁ improved by 0.169–0.258 L, 0.148–0.310 L, and 0.123–0.240 L, respectively.     

The improvements seen in the Asian subgroup were greater than the overall population, according to Hashimoto.

Stratified analysis showed that improvements in peak and trough FEV₁ occurred regardless of atopy at 24 weeks as judged by a clinician (p_interaction=0.7668 and 0.8166 for peak and trough FEV₁, respectively).

Peak and trough FEV₁ also improved with salmeterol or tiotropium independently of IgE levels (≤430 vs >430 µg/L) and eosinophil count (≤0.6x10⁹/L vs >0.6x10⁹/L; p_interaction>0.05 for all).

“[The findings suggest that LAMA/LABA + ICS] may be a viable treatment option for Asian patients with moderate symptomatic asthma,” said Hashimoto.