Aztreonam lysine for inhalation, an antibiotic for cystic fibrosis patients infected with pulmonary Pseudomonas aeruginosa, met its primary efficacy endpoint of change in respiratory symptoms from baseline at day 28 in the second of three planned Phase III trials, Gilead announced May 29.

Gilead, in Foster City, Calif., gained the inhalation antibiotic, then known as Cayston , with its acquisition of Corus Pharma last year (¹ Also see "Gilead Acquisition Of Corus Adds Respiratory Disease Candidate" - Pink Sheet, 21 July, 2006.).

The trial, AIR-CF1, is the first Phase III trial in CF to use a patient-reported outcome tool - the Cystic Fibrosis Questionnaire-Revised - as its primary endpoint, the company said. Gilead said it plans to submit an NDA for aztreonam lysine for inhalation for treatment of CF patients with pulmonary P. aeruginosa in the second half of 2007.

Data from the 164-patient, double-blind, randomized study demonstrated "significant improvement" in the CFQ-R, with a treatment difference in mean change from baseline of 9.7 points on a scale of 100 in the respiratory domain compared with placebo, following a 28-day treatment course with 75 mg aztreonam lysine or volume-matched placebo administered three times a day via nebulizer, the company said.

Patients in the treatment group also experienced significant improvements at day 28 in respiratory function, as measured by relative improvement on the FEV1 lung function test, with a treatment difference in mean change from baseline of 10.3 percent versus placebo.

Gilead reported positive results from the AIR-CF2 trial in April. The randomized, double-blind, placebo-controlled study assessed the safety and efficacy of a 28-day course of 75 mg aztreonam lysine for inhalation administered either twice or three times a day following 28 days of treatment with tobramycin (Novartis' Tobi ) inhalation solution in CF patients with P. aeruginosa.

Patients were followed for an overall study period of 126 days, with 56 days of observation after receiving aztreonam lysine for inhalation or placebo.

AIR-CF3 is an ongoing open-label, multi-center follow-up study of patients who participated in AIR-CF1 or AIR-CF2 to evaluate the safety of repeated exposure to aztreonam lysine for inhalation in persons with CF. Patients will participate for 18 months, receiving treatment with 75 mg aztreonam lysine for inhalation with the same regimen they received in AIR-CF1 or AIR-CF2.

Aztreonam is a potent antibiotic against Gram-negative bacteria, including P. aeruginosa. It is FDA approved in formulation with arginine for intravenous administration. Gilead does not own the IV therapy.

- Shirley Haley (s.haley@elsevier.com)

Gilead Inhalation Antibiotic For Cystic Fibrosis Successful In Second Pivotal Trial

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