It is normal for red blood cells to die, even in newborn babies. The waste from that is called bilirubin. The liver clears bilirubin out of the body.

Some babies are born with illness that makes red blood cells die too fast, so the liver is not strong enough to keep up with it.

The yellowish color in eyes or skin means there is too much bilirubin in the body. It can be dangerous if a baby's bilirubin gets too high.

Special lights are put on jaundiced babies (called phototherapy) to help the liver get rid of bilirubin.

This study tests an experimental drug to see if it can help the liver even more, by safely cutting down the amount of bilirubin the body is making in the first place.

Participants randomized (1:1:1) to treatment groups will be term or near-term infants with isoimmune hemolytic disease or glucose-6-phosphate dehydrogenase (G6PD) deficiency.

Inclusion Criteria:

1. Term and near term infants ≥35 and ≤ 43 weeks gestational age (GA), age 0-48 hours with antibody (ABO) or rhesus factor (Rh) incompatibility (anti C, c, D, E or e) who are Coombs positive, or age 0-72 hours with G6PD deficiency
2. Parental or guardian consent
3. Birth weight ≥ 2500 grams
4. At or above the age-specific threshold for initiating phototherapy (PT) per the American Academy of Pediatrics (AAP) guidelines based on measurement of total serum bilirubin (TSB)
5. Parents agree to observe light precautions for 10 days post treatment

Exclusion Criteria:

1. Elevated direct bilirubin ≥2 mg/dL, OR > 20% of the total serum bilirubin
2. Alanine aminotransferase (ALT) > 2 times the upper limit of normal (ULN) and/or aspartate aminotransferase (AST) > 3 times ULN
3. Abnormal renal function defined as creatinine and/or blood urea nitrogen >2 times the ULN
4. Any other clinically significant abnormalities on screening laboratory evaluation [including electrocardiogram (ECG)] that in the opinion of the investigator makes the patient unsuitable for the clinical trial
5. Apgar score ≤6 at age 5 minutes
6. An unexplained existing rash or skin erythema
7. Prior exposure to PT
8. Clinical suggestion of neonatal thyroid disease or current uncontrolled thyroid disease in the mother (maternal Hashimoto's disease is not exclusionary)
9. Cardio-respiratory distress, defined as a respiratory rate >60 breaths per minute at time of enrollment
10. Any abnormal auditory or ophthalmologic findings on screening physical exam
11. Treatment or need for treatment in the neonate with medications that are photoreactive or may prolong the QT interval (erythromycin ointment for eye prophylaxis is permitted), or family history of Long QT syndrome
12. Known porphyrias or risk factors for porphyrias, including family history
13. A maternal history of systemic lupus erythematosus
14. Maternal use of phenobarbital 30 days before, or after delivery, if breast-feeding
15. Maternal current drug or alcohol abuse, or maternal history of drug or alcohol abuse that, in the opinion of the Investigator, would not make the patient a suitable candidate for participation in the clinical trial
16. Significant congenital anomalies or infections
17. Risk of requiring surgery or exposure to operating room (OR) lights in the first 2 weeks of life
18. Persistent hypoglycemia (blood glucose <40 mg/dL)
19. Temperature instability defined as temperature consistently (3 consecutive times) <36 degrees centigrade (ºC) and/or >37.5 degrees centigrade (ºC) axillary
20. Use of intravenous immunoglobulin (IVIg) or albumin prior to study drug administration
21. Post-delivery treatment with medications that are known or suspected to displace bilirubin from albumin (e.g., ceftriaxone or sulfa-based antibiotics)
22. Use of photosensitizing drugs or agents
23. Unwillingness of parents/guardians to adhere to recommendations regarding light precautions
24. Exposure to any investigational medications or devices after delivery, or participation in another clinical trial while participating in this trial
25. Any other concurrent medical condition, which in the opinion of the Investigator, makes the patient unsuitable for the clinical trial