The Adv Halt Trial

Inclusion Criteria:

1. Males and females ≥ 3 months and ≤ 75 years of age.

2. Subjects have received an allogeneic HSCT.

3. Positive serum AdV PCR (> 100 copies/mL) as measured by the central laboratory.

4. Subject or guardian(s) are willing to comply with the protocol.

5. Subject or guardian(s) are willing and able to understand the informed
consent/assent.

6. Females of child-bearing potential must have a negative pregnancy test (serum
beta-hCG) and sexually active females must use a reliable and medically approved
method of contraception throughout the study. Sexually active males of procreation
potential must be able and willing to use a reliable and medically approved
contraceptive method throughout the study. At least one barrier method of
contraception must be used, in subjects of procreation potential.

Exclusion Criteria:

1. Subject has possible, probable, or definitive AdV disease. See Appendix 2Error!
Reference source not found. for a definition and criteria outlining possible,
probable or definitive AdV disease.

2. Suspected gut graft versus host disease (GVHD) that is not biopsy-proven (subjects
with a biopsy performed may be included in the study).

3. Subject has an eGFR ≤ 30 mL/minute and is not currently on dialysis.

4. Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) > 10 times the
ULN, conjugated bilirubin > 5 times the upper limit of normal (ULN).

5. Subject has mucositis preventing ingestion of oral medication.

6. Subject is Human Immunodeficiency Virus (HIV) antibody positive, based upon available
medical records.

7. Subject has ocular hypotony, uveitis, or retinitis or any other intraocular pathology
that would predispose the subject to one of these conditions.

8. Subject has participated in any other investigational drug study or was exposed to an
investigational drug within 14 days of enrollment.

9. Is pregnant or breast-feeding or intending to conceive during the course of the
study, including the follow-up period after drug discontinuation.

10. Known immunologic hypersensitivity to CDV or CMX001 drug or any of its excipients.

11. History of illicit drug use or alcohol abuse within the previous 6 months.

12. Any medical condition that, in the opinion of the Investigator, might interfere with
the subject's participation in the study, poses an added risk for the subject, or
confounds the assessment of the subject (e.g. severe cardiovascular, central nervous
system (CNS) or pulmonary disease).

13. Subject has received CMX001, CDV, ribavirin, or leflunomide within the previous 14
days.