Severe intraventricular haemorrhage (IVH) and white matter injury (WMI) are major neurological complications in preterm infants, leading to long-term neurodevelopmental impairments. Despite advances in neonatal care, effective treatments are lacking. Umbilical cord blood cell (UCBC) therapy shows neuroprotective potential, with autologous sources ideal but often not feasible due to the unpredictability of preterm births. Allogeneic UCBCs offer an alternative, although immunogenicity and human leucocyte antigen (HLA) compatibility present challenges with knowledge gaps in their relevance in neonatal populations. This study aims to assess the feasibility and safety of partially HLA-matched allogeneic UCBC therapy in preterm infants with severe brain injury.

The ALLO trial is an open-label, phase I, single-arm feasibility and safety study conducted at Monash Children’s Hospital, Victoria, Australia. Preterm infants born before 28 weeks (ALLO-1) or between 28 weeks and 36+6 weeks (ALLO-2) gestational age with severe brain injury identified on neuroimaging will be enrolled. Severe brain injury is defined as grade 3 or 4 IVH or significant WMI. Exclusion criteria include major congenital anomalies or redirection to comfort care. Eligible infants will receive a single intravenous infusion of unrelated, allogeneic, partially HLA-matched (4/6 or 5/6 HLA match) UCBCs sourced from a public cord blood bank. The target dose is 50 million total nucleated cells per kilogram body weight. Infusion will occur within 2–3 weeks of confirmation of eligibility, contingent on clinical stability and absence of active sepsis. Primary outcome includes: (1) feasibility, defined as having more than 60% of enrolled infants with an eligible allogeneic partially matched cord blood unit available and (2) safety, defined as absence of severe adverse events within 48 hours of infusion or graft-versus-host disease within 3 months of infusion. Secondary outcomes include survival, neonatal morbidities, neurodevelopmental assessments and serum cytokine analysis.

Monash HREC has granted full ethics approval (RES-23-0000-297A) for the study, including the research use of allogeneic cord blood from compassionate donations by healthy donors, facilitated through the Bone Marrow Donor Institute Cord Blood Bank within the AusCord network. Findings will be disseminated through peer-reviewed publications and conference presentations, contributing to the development of novel neuroreparative therapies for preterm brain injury.

ACTRN12623001352695 (The Australian New Zealand Clinical Trials Registry).