Prevention of S. Aureus Pneumonia Study in Mechanically Ventilated Subjects Who Are Heavily Colonized With S. Aureus.

This is a double-blind, randomized, single-dose, placebo-controlled study of ASN100 for the
prevention of S. aureus pneumonia in mechanically ventilated subjects who are heavily
colonized with S. aureus. This will be a global study conducted at approximately 65 sites to
assess the safety, tolerability, and efficacy of ASN100.

Eligible subjects who meet all of the inclusion criteria and none of the exclusion criteria
will be screened by semi-quantitative culture of an endotracheal aspirate (ETA) to identify
those who are heavily colonized with S. aureus (3+ to 4+). Upon determination of eligibility,
subjects will be randomized in a 1:1 ratio to 1 of 2 treatment groups, ASN100 or placebo.

Inclusion Criteria:

- Subject is currently hospitalized and is mechanically ventilated endotracheally (i.e.,
orotracheal or nasotracheal) and, in the Investigator's opinion, will require ongoing
ventilator support for at least 48 hours;

Exclusion Criteria:

- Subject has a chest X-ray or thoracic computed tomography (CT) scan that is definitive
for a diagnosis of pneumonia

- Subject has a known and documented ETA culture showing heavy colonization with a
-Gram-negative organism at enrollment or at any time during the Screening period;

- Significant Neutropenia

- Severe non-pulmonary source of infection.

- Subjects with a known history or current (suspected) diagnosis of cytokine release
syndrome associated with the administration of peptides, proteins, and/or antibodies.