An independent clinical trial has identified GlaxoSmithKline's Advair as the best drug for kids with asthma when 'first-line' therapy fails, prompting Panmure Gordon to repeat its 'buy' stance.The medical journal New England Journal of Medicine (NEJM) says a component of Advair represents the most likely add-on therapy for children whose asthma is not controlled by inhaled corticosteroids (ICS).Panmure recommends snapping up stock ahead of a Food & Drug Administration (FDA) advisory committee meeting on the use of asthma drugs on 10 March."GSK has undergone the majority of its patent expiries and emerged strongly, and can now focus on growth. It has a strong pipeline of products, led by Benlysta for lupus and which could reach the market in 2010 and provide a significant source of upside," says the broker. "We believe that most of the risks are adequately reflected in the price," it added, keeping its £14 target price.