November 30, 2020

The Niche

Knoepfler lab stem cell blog

Cord blood for cerebral palsy: mostly discouraging new trial data

umbilical cord blood
Cropped Flickr image labeled for reuse of cord blood unit

Some notable newly published Phase II data from the Duke cord blood for cerebral palsy trial unfortunately doesn’t give much reason for optimism that this approach is going to have a substantial positive effect for these kids.

The double-blinded, placebo-controlled study did not find a meaningful benefit overall from infusions of autologous cord blood (ACB) for children with cerebral palsy. It didn’t meet its primary endpoint. The study was published in Stem Cells Translational Medicine and was entitled, “Effect of Autologous Cord Blood Infusion on Motor Function and Brain Connectivity in Young Children with Cerebral Palsy: A Randomized, Placebo-Controlled Trial.”

This finding is discouraging overall. I can’t say I’m too surprised as to me at least there is no obvious mechanism by which this would work. Yes, investigational therapies based on non-obvious hypothesized mechanisms can rarely give surprisingly good outcomes anyway, but with the publication of the new data in this case that future possibility seems pretty remote at this point.

cord blood cerebral palsy
Figure 2A, Sun, et al. Stem Cells Translational Medicine

Some hold onto a bit of hope from specific aspects of the new study data because the higher dose (>=20 million ACB/kg) produced some moderate significantly different (better) outcomes than either lower dose or placebo. I feel mostly skeptical about that. I’m no expert on ACB or on cerebral palsy, but I’m looking at the data as a stem cell scientist just based on common sense.

I also found it discouraging that for some key measures the lower dose of ACB may have made patients slightly worse off than placebo, although I’m not sure that change downward was meaningful (see Figure 2A at right, potential low-dose worsening more evident in panels 2B-D). I don’t see significant safety issues based on that and overall this kind of therapy when provided by a proper clinical trial appears safe. Longer term follow up is needed as well.

The authors, including senior author Joanne Kurtzberg and first-author Jessica Sun, focused on the hopeful dosing effect, but more data would be needed to make clear meaning of that. The phase II trial had some limitations too pointed out by the authors that may have impacted the findings including patient family socioeconomic factors and in turn patients receive other kinds of therapies concurrently.

Overall, there just isn’t much evidence to date that stem cells or related cellular therapies can benefit specific pediatric brain conditions examined so far such as cerebral palsy and autism (see recent post on autism including regarding another ACB Duke trial).

I find the mostly discouraging data to be frustrating as pediatric regenerative medicine is an area of research interest for me more broadly and was hoping for better news. There is still reason for hope in general. Cord blood won’t solve everything, but it remains a very promising, powerful resource. We just need to learn where and how it can be best used beyond current indications. Along the way there are going to be both successes and not so great outcomes too, which is a natural progression with clinical science even if it can be discouraging at times.

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