Study to Evaluate the Effect of KB001-A on Time-to-Need for Antibiotic Treatment

Inclusion Criteria:

   - Individuals with CF who are older than 50 years of age may participate if treated with
   2 or more courses of antibiotics (IV and/or oral) for respiratory sign and symptoms
   (CF exacerbation) in the 12 months before the Screening Visit

   - Confirmed diagnosis of CF

   - At least 2 respiratory tract cultures in the previous 12 months, with Pa present. The
   most recent positive Pa culture must be within 12 weeks before the Screening Visit (or
   obtain a positive culture at screening)

   - FEV1 % levels within acceptable ranges (per the study protocol)

   - Received inhaled ABX for equivalent of 8 weeks or greater in the 26 weeks before the
   Day 0 Visit

Exclusion Criteria:

   - Treatment with antibiotics for acute illness within the 4 weeks before the Day 0 Visit

   - Use of systemic corticosteroids within the 4 weeks before the Day 0 Visit

   - Any change in regimen of CF maintenance therapies within the 4 weeks before the Day 0
   Visit

   - History of sputum cultures positive for B. cepacia complex in the 2 years before the
   Screening Visit

   - History of organ transplantation

   - Current smoker (tobacco, marijuana, or any other material). Use of smokeless
   inhalers/vaporizers for these materials is also prohibited

   - History of drug addiction or alcohol abuse in the 12 months before the Screening Visit

   - History of hepatic disease (clinical cirrhosis or portal hypertension), renal
   dysfunction

   - Breast-feeding or pregnancy as evidenced by a positive blood pregnancy test

   - Receiving any investigational drug in the 16 weeks (or 5 half lives) before the Day 0
   Visit, whichever is longer