Effect of Allopurinol for Hypoxic-ischemic Brain Injury on Neurocognitive Outcome

Overview

Neonatal hypoxic-ischemic encephalopathy (HIE) is a major cause of death or long-term disability in infants born at term in the western world, affecting about 1-4 per 1.000 life births and consequently about 5-20.000 infants per year in Europe. Hypothermic treatment became the only established therapy to improve outcome after perinatal hypoxic-ischemic insults. Despite hypothermia and neonatal intensive care, 45-50% of affected children die or suffer from long-term neurodevelopmental impairment. Additional neuroprotective interventions, beside hypothermia, are warranted to further improve their outcome. Allopurinol is a xanthine oxidase inhibitor and reduces the production of oxygen radicals and brain damage in experimental, animal, and early human studies of ischemia and reperfusion. This project aims to evaluate the efficacy and safety of allopurinol administered immediately after birth to near-term infants with HIE in addition to hypothermic treatment.

During labour and childbirth various events (such as placental abruption, uterine rupture, umbilical cord complications etc.) may result in impaired oxygenation and/or perfusion of the newborn brain which may result in brain injury termed "hypoxic-ischemic encephalopathy" (HIE). HIE is associated with development of long-term motor, cognitive, and neurosensory and memory disability and is one of the fundamental problems in perinatal medicine affecting about 5,000-20,000 infants/year in Europe (or 1-4/1000 live births in western societies) and approximately 1 million infants/year worldwide. In term infants with perinatal asphyxia and postnatal HIE, brain injury predominantly originates in the immediate perinatal period (in contrast to a more distant prenatally acquired brain injury) as indicated by the lack of already established brain injury on early postnatal MRI. Consequently, brain injury in this population may potentially be ameliorated by postnatal pharmacological interventions. The most common motor disability resulting from HIE is "cerebral palsy", the other major adverse outcome is cognitive disability, which prevents affected patients to lead their lives independently (without assistance and/or financial support). The single major cause of HIE is a perinatal hypoxic/ischemic event (perinatal asphyxia). This hypoxic insult can cause immediate (necrosis) and delayed death (apoptosis) of (especially neuronal) cells, the latter responsible for a substantial amount of HIE-associated permanent brain damage. Whereas no intervention is known to prevent necrosis, the delayed cell death by apoptosis can be reduced by therapeutic interventions: Apoptosis is in part caused by secondary energy failure which can be reduced by hypothermic treatment. Apoptosis is also caused by xanthine oxidase-mediated production of cytotoxic oxygen radicals during reperfusion, and there is evidence that allopurinol, a xanthine-oxidase inhibitor, reduces delayed cell death in animal models of perinatal asphyxia and ischemia/reperfusion. Allopurinol prevents adenosine degradation, oxygen radical formation, preserves NMDA receptor integrity, and consequently may reduce brain injury in HIE by several mechanisms of action which are independent from the proven beneficial effect of hypothermic treatment on cellular energy metabolism. An additional beneficial (or even synergistic?) effect of allopurinol in addition to hypothermia can therefore be expected. As no safety concerns were known at the start of this study regarding administration of even high doses of Allopurinol to neonates a phase III study was planned instead of a pilot study or an adaptive design. Close follow-up of MR-imaging along with reporting of all safety relevant data to a Data Monitoring Committee (which includes experts for brain imaging not otherwise involved in the study) ensures patients' safety. Primary objective of this study is to evaluate whether newborns with asphyxia and early clinical signs of hypoxic ischemic encephalopathy will benefit from early administered Allopurinol compared to placebo, both in addition to standard of care, regarding long-term follow-up such as severe neurodevelopmental impairment or death at two years.