A Phase II, Randomized, Double-blind, Placebo-controlled Study to Examine the Effects of DAS181 in Immunocompromised Subjects With Lower Respiratory Tract Parainfluenza Infection on Supplemental Oxygen

Inclusion Criteria:

- Age ≥12 years

- Able to provide informed consent, child assent with parental consent or surrogate
consent when applicable

- Currently on invasive mechanical ventilation or noninvasive positive pressure
ventilation (CPAP or bilevel positive airway pressure) or requiring > 2LPM
supplemental oxygen therapy to maintain O2 saturation > 90% due to hypoxemia

- Immunocompromised, as defined by one of the following: Autologous or Allogeneic
hematopoietic cell transplantation (HSCT); Lung or lung-heart transplantation;
Subjects treated with chemotherapy for hematologic malignancies; Subjects treated with
chemotherapy for solid tumor malignancies

- Confirmed parainfluenza at screening by one of the following methods using any sample
type: Respiratory Virus Panel, Direct fluorescent antibody (DFA),
Qualitative/quantitative RT-PCR test for parainfluenza virus performed at the local
laboratory (a confirmatory PCR test will be done at the central lab but is not
required to start the patient on study).

- Confirmed PIV lower tract disease for subjects on mechanical ventilation will be
defined as PIV detection in bronchoalveolar lavage (BAL) or biopsy within last 7 days
of screening

- Confirmed PIV lower tract disease for subjects on non-invasive positive pressure
ventilation or supplemental oxygen will be defined as all of the following within the
last 7 days of screening: New pulmonary infiltrate on chest imaging and at least one
PIV sign and/or symptom as defined in section 10.3.6

- Female subjects of child-bearing potential who are capable of conception must be
post-menopausal (one year or greater without menses), surgically incapable of
childbearing, or practicing two effective methods of birth control. Acceptable methods
include abstinence, intrauterine device, spermicide, barrier, male partner surgical
sterilization and hormonal contraception. A female subject ≥18 years of age and of
child bearing potential must agree to practice two acceptable methods of birth control
during the study period. All reproductive female subjects must have a negative serum
pregnancy test during the screening visit.

- Male subjects must agree to use medically accepted form of contraception during the
study period. Abstinence is an acceptable method of contraception.

Exclusion Criteria:

- Psychiatric or cognitive illness or recreational drug/alcohol use that, in the opinion
of the principal investigator, would affect patient safety and/or compliance.

- Any significant finding in the patient's medical history or physical examination that,
in the opinion of the investigator, would affect patient safety or compliance with the
dosing schedule.

- In the opinion of the Investigator, subjects with a low chance of survival during the
first 5 days of treatment.

- Subjects treated with oral, aerosolized or intravenous (IV) ribavirin for the
treatment of PIV. A forty-eight hour (48 hr) wash out period prior to randomization is
allowed.

- Subjects with a history of RSV or MPV

- Subjects taking any other investigational drug used to research or treat PIV.

- Subjects with a history of allergic reactions to lactose.

- Subjects with a history of documented Pseudomonas aeruginosa pneumonia confirmed
radiographically and by culture from BAL.