Lebrikizumab, an experimental asthma drug from Roche , showed encouraging results in a mid-stage clinical trial when given on top of standard inhaled treatments, researchers said on Wednesday. The Swiss drugmaker gained rights to the medicine following the acquisition of Tanox by its U.S. biotech unit Genentech in 2007, and Roche CEO Severin Schwan last year highlighted the product as one with particularly promising prospects. Lebrikizumab works by inhibiting a substance called interleukin-13 that is thought to play a central role in asthma.