Efficacy and Safety of Allogeneic Umbilical Cord Blood Mononuclear Cells in Children With Autism and Immune Dysregulation:

Major Points and Findings:

Among published studies of cell therapy in autism, this trial has the most rigorous design to date. It was randomized, double-blinded and placebo-controlled. Nearly every other trial in this field is open-label, so parents and assessors know who received treatment, and behavioural rating scales are sensitive to a parent’s expectation. For that reason this one carries more weight than its size would suggest.

Enrolment was restricted to children with a defined immune profile, and the result has to be read with that restriction in mind.

Aim:

To test whether four intravenous infusions of allogeneic umbilical cord blood mononuclear cells (UCB-MNCs) improve symptoms in children with autism who also have laboratory-confirmed peripheral immune dysregulation, against a saline placebo.

Methods:

The study was a single-centre, prospective, randomized, double-blind, placebo-controlled trial at the First Medical Center of the Chinese PLA General Hospital, Beijing. It was registered as ChiCTR2400082762.

Population: Fifty-five children were screened, 36 were randomized and 34 completed. To be eligible a child had to be aged 3 to 8, meet DSM-5 criteria for autism, and have at least one of IL-1, IL-2, IL-6, IL-8 or TNF-α measured above 1.5 times the upper limit of the normal range. Children were excluded if their autism was attributable to epilepsy, cerebrovascular disease or traumatic brain injury, or if they had tumours, immunodeficiency, active infection, or a history of severe allergy to blood products. Three of the sixteen who failed screening were rejected because they did not meet the immune dysregulation threshold.

The investigators selected this subgroup deliberately, because the proposed mechanism is immunomodulation. The result therefore applies to children with an inflammatory profile and cannot be extended to autism in general.

Intervention: The UCB-MNCs came from the Shandong Provincial Cord Blood Hematopoietic Stem Cell Bank. They were pooled from multiple donors, GMP-compliant, released only at ≥90% viability, negative for bacteria, fungi, mycoplasma and endotoxin, with CD34+ at ≥0.05%. Each child received 3 × 10⁸ cells intravenously, once a week for four weeks. The placebo group received an identical volume of saline. Infusions started at 20 to 30 drops per minute for ten minutes and, if no reaction occurred, were increased to 60 to 70 drops per minute to finish within half an hour, followed by two hours of observation. No prophylactic medication was given, so that any infusion reactions would not be masked. Both groups continued their existing behavioural intervention and rehabilitation throughout.

For blinding, randomization codes were generated in SPSS by an independent statistician outside the study team. Duplicate sealed schedules were held separately by the principal investigator and the supplier, and infusion bags were covered with light-shielding sleeves so that saline and cells could not be told apart.

The primary outcome was the Social Responsiveness Scale-2 total score. Secondary outcomes were Vineland-3, the Autism Behavior Checklist, CARS, SNAP-IV, and a parent anxiety scale. Data were analysed by mixed model for repeated measures at baseline, week 4 and week 13. Follow-up ran 13 weeks.

Results:

At final follow-up the treated group’s SRS-2 total score fell further than placebo, with a least-squares mean difference of −6.03 (95% CI −11.93 to −0.14; p = 0.045). The effect was largest in the Social Cognition domain, at −9.95 (95% CI −15.90 to −4.00; p = 0.002).

Two caveats apply to the total score. Its confidence interval very nearly touches zero, and the power calculation was set with a one-tailed significance level. Of the two results, the Social Cognition finding is statistically the stronger.

Safety: Adverse events were more common in the placebo group than in the treated group.

• Treated: 5 children affected, 7 events in total (10.3%). Four had transient excitement after infusion and one a transient low-grade fever.
• Placebo: 6 children affected, 9 events in total (13.2%). These were two cases of transient excitement, three of transient low-grade fever and one mild infiltration at the infusion site.

No child withdrew and no unmasking occurred. Events were mostly CTCAE Grade 1, mild and reversible.

Conclusions:

Multiple intravenous infusions of allogeneic UCB-MNCs showed good short-term safety and preliminary efficacy on specific aspects of symptoms (the SRS-2 total and Social Cognition scores) in children with autism and immune dysregulation. The authors keep to that wording throughout the paper, and it should be kept when the trial is cited.

The authors list the following limitations. The sample was small and exploratory and may miss small-to-moderate effects. Outcomes still rest on subjective rating scales despite the blinding. Follow-up was short and gives no information on durability. There was a single centre and a single dose regimen. No stratification by intellectual disability was possible, because most participants scored below 80 on the Wechsler scale at baseline, with only one child at 105.

Background Information:

Delivery route: The authors chose intravenous infusion and explain at some length why they prefer it to the intrathecal approach. They accept that intrathecal injection bypasses the blood-brain barrier and achieves high local concentrations in the central nervous system. Against this, it is invasive, has low acceptance among parents in paediatric practice, demands considerable technical skill, takes longer, and carries risks of spinal canal infection and meningeal irritation. In a population of young children with low tolerance for invasive procedures, they judge those risks more pronounced. They also note that no study has directly compared intravenous against intrathecal delivery in autism, so their preference is a reasoned one and has not been tested.

Intravenous delivery has drawbacks of its own. The cells are diluted in the circulation, home poorly to the target tissue and cross the blood-brain barrier badly, which is the standard argument for intrathecal delivery.

Elevated IL-6, IL-17, TNF-α and IL-1β have been reported repeatedly in autism, and one analysis of 75 case-control studies found significantly raised levels across several cytokines. This explains the entry criterion. The trial is the first to use that profile to select who gets treated, where earlier work only hypothesised the mechanism afterwards. No earlier randomized controlled trial had used allogeneic UCB-MNCs as the sole intervention.

The authors count seven prior clinical trials of mononuclear cells in autism (two with cord blood, five with bone marrow) plus four case reports. Every one of them was open-label. Several reported improvement. The authors argue that open-label designs and caregiver expectation make those improvements difficult to trust, and their trial was designed to address that weakness.