FDA asks Gilead for another clinical study of aztreonam

Shares in Gilead Sciences fell 2.7% to $48.50 on September 16, after the US drugmaker received a complete response letter from the Food and Drug Administration for aztreonam lysine for inhalation, saying that the investigational therapy for cystic fibrosis with Pseudomonas aeruginosa cannot be approved in its current form and an additional clinical study will be required. Gilead says it will continue its dialog with the FDA to determine whether further analyses of existing data could lead to approval, or whether the firm will need to conduct the additional study as stated in the letter. John Martin, chief executive of Gilead, noted that the FDA "has not raised any significant concerns regarding the safety profile of aztreonam lysine." The firm plans to continue its expanded access program for the drug.