Phase 3 Study of Aztreonam for Inhalation Solution (AZLI) in a Continuous Alternating Therapy Regimen for the Treatment of Chronic Pseudomonas Aeruginosa Infection in Patients With CF

This study is to investigate whether using a continuous alternating therapy (CAT) regimen of
2 antibiotics of different classes and with different mechanisms of action may provide the
clinical benefits of reducing acute pulmonary exacerbations, maintaining lung function, and
controlling respiratory symptoms for cystic fibrosis (CF) patients while minimizing the risk
of emergence of antibiotic-resistant Pseudomonas aeruginosa (PA) strains.

After screening, eligible participants will be enrolled into the study and begin a 28-day
run in period of tobramycin inhalation solution (TIS) twice daily. After the run-in,
participants will return to the clinic and be randomized to either the Aztreonam for
Inhalation Solution (AZLI) arm or the placebo arm. The AZLI arm has 3 cycles of AZLI three
times daily for 28 days alternating with TIS twice daily for 28 days. The placebo arm has 3
cycles of placebo three times daily for 28 days alternating with 3 cycles of TIS twice daily
for 28 days. Participants will return to the clinic for evaluation after each cycle of
antibiotics for evaluation. There will be 9 scheduled study visits per participant.