Study to Assess the Safety, Tolerability, and Preliminary Efficacy of ST266 in Infants With Necrotizing Enterocolitis

Inclusion Criteria:

1. Infants born from ≥26 weeks gestational age to 40 weeks gestational age; up to 40weeks postmenstrual gestational age (gestational age plus chronological age in termsof weeks) with current weight at diagnosis of NEC between ≥800g and ≤3000g as aresult of prematurity and/or IUGR. Parent(s)/legal medical representative(s)voluntarily provides written consent prior to study enrollment.

2. Minimum Bell stage IIA NEC diagnosis by radiologic confirmed pneumatosisintestinalis and may include intestinal dilation and ileus.

Exclusion Criteria:

1. Infants with abdominal perforation at less than 10 days of life

2. Not expected to survive ≥2 weeks or born with a lethal condition requiring hospiceor palliative care (e.g., disease has progressed to NEC totalis, or patient hasmulti-organ system failure).

3. Born with major congenital anomalies such as cardiac defects (e.g., Tetralogy ofFallot) or chromosomal disorders/anomalies (e.g., neural tube defect).

4. Mother's receipt of any investigational product during pregnancy.

5. Infants with malignancies (e.g., neoplastic cell growth as a solid tumor or a bloodneoplasm, such as congenital leukemia).

6. Infants with hypercoagulability disorders (any active thrombosis, diagnosis ofdisseminated intravascular coagulation or other acquired/inherited disorders (i.e.,hemophilia) of coagulation.

7. Infants with a known immunodeficiency (such as galactosemia or agranulocytosis).

8. Infants with anatomic defects that require surgical intervention.

9. Infants with persistent pulmonary hypertension of newborn.

10. Infants with any congenital or acquired gastrointestinal pathology that precludefeeds within 7 days after birth (e.g., duodenal atresia).

11. Infants who have hypoxic ischemic injury (perinatal asphyxia).

12. Infants with polycythemia (at time of treatment) (>22 g/dL).

13. Positive maternal human immunodeficiency virus status.

14. History of maternal drug abuse (such as amphetamines, opiates, cocaine). This doesnot include marijuana, or prescription medications for treatment of drug abuse.

15. Considered by the Investigator, for any reason, to be an unsuitable candidate forthe study.

16. Infants diagnosed with NEC who will require immediate surgical intervention.