Low dose suramin and autism: a small RCT with potentially big results

'Low dose' has been a feature of my autism research reading this week; first starting with the results from Dan Quintana and colleagues [1] talking about some important effects following intranasal delivery of low dose oxytocin and then moving on to the primary reason for this entry with results from Robert Naviaux and colleagues [2] (open-access) continuing a research theme looking at suramin and autism (see here for some background).

For those interested in the oxytocin-autism research base, I can recommend following Dr Quintana on Twitter (find him here).

In relation to the Naviaux findings  - the "Suramin Autism Treatment-1 (SAT-1) trial" - well, they are open-access but I want to provide some overview and then a little bit of discussion. I might add that this research team are making research waves in several areas of medical science as per their research foray into chronic fatigue syndrome (CFS) recently (see here). Such 'metabolomic' research is pertinent to their autism research too.

This time around as on previous research occasions, the focus was on suramin - the "century-old sleeping sickness drug" - and, as far as I can see, the first time said drug has been tested experimentally with children diagnosed with an autism spectrum disorder (ASD). The accompanying ClinicalTrials.gov trial entry is here.

As per the title to this blog entry, this was a small trial including only 10 participants, all male, aged between 5-14 years old. This was a randomised-controlled trial (RCT) with a placebo element to it too, so half of the participants got suramin - "a single, intravenous infusion of suramin (20 mg/kg)" - and half got saline as a control. Alongside looking at behaviour and functioning, researchers also took blood and urine samples "for safety and toxicity monitoring at 5 times throughout the study." This was accompanied by quite a bit of effort to look at the possibility of adverse events related to suramin or placebo administration.

Results: "A single intravenous dose of suramin was associated with improved scores for language, social interaction, and decreased restricted or repetitive behaviors measured by ADOS, ABC, ATEC, and CGI scores. None of these improvements occurred in the five children who received placebo." The authors also do the right thing by stating: "The generalizability of these findings is unknown." I'm particularly impressed that the ATEC gets a showing given the rise and rise of this autism research tool (see here) in various placebo-controlled contexts (see here).

In relation to the safety aspect to suramin, well, it seemed to do alright. We are told that: "Extensive monitoring revealed no serious toxicities" so one can assume that the 'first, do no harm' tenet was upheld in this trial. But there was one important side-effect noted: "Five children who received suramin developed a self-limited, evanescent, asymptomatic, fine macular, patchy, morbilliform rash over 1–20% of their body." The rash was short-lived and did not require specific attention/intervention but it's worthwhile noting it especially when nothing similar was reported in the placebo group.

Going back to the mention of this research group delving into CFS with metabolomics in mind, so similar results are reported on the basis of examination of plasma samples from participants. Various biological pathways seemed to be affected by the infusion of suramin, not least "the importance of the cell danger response (CDR) [3]... and purinergic signaling." Interestingly, authors also noted effects in relation to "1-carbon, folate, methionine, and cysteine metabolism" too, potentially linked to other findings independently reported in relation to autism (see here for example).

Reiterating again that this was a small study (albeit using the gold-standard in scientific methodologies) these results are rather interesting and potentially quite important. They most definitely point to the requirement for further large-scale studies to look at any effects in a larger participant group and to 'zoom in' on potential best-responders to this type of intervention. I end with an important conclusion from the authors who again, have not over-stated their findings:

"Suramin is not approved for the treatment of autism. Like many intravenous drugs, when administered improperly by untrained personnel, at the wrong dose and schedule, without careful measurement of drug levels and monitoring for toxicity, suramin can cause harm. Careful clinical trials will be needed over several years at several sites to learn how to use low-dose suramin safely in autism, and to identify drug–drug interactions and rare side effects that cannot currently be predicted. We strongly caution against the unauthorized use of suramin."

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[1] Quintana DS. et al. Dose-dependent social-cognitive effects of intranasal oxytocin delivered with novel Breath Powered device in adults with autism spectrum disorder: a randomized placebo-controlled double-blind crossover trial. Transl Psychiatry. 2017 May 23;7(5):e1136.

[2] Naviaux RK. et al. Low-dose suramin in autism spectrum disorder: a small, phase I/II, randomized clinical trial. Annals of Clinical & Translational Neurology. 2017. 26 May.

[3] Naviaux RK. Metabolic features of the cell danger response. Mitochondrion. 2014; 16: 7-17.

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Naviaux, R., Curtis, B., Li, K., Naviaux, J., Bright, A., Reiner, G., Westerfield, M., Goh, S., Alaynick, W., Wang, L., Capparelli, E., Adams, C., Sun, J., Jain, S., He, F., Arellano, D., Mash, L., Chukoskie, L., Lincoln, A., & Townsend, J. (2017). Low-dose suramin in autism spectrum disorder: a small, phase I/II, randomized clinical trial Annals of Clinical and Translational Neurology DOI: 10.1002/acn3.424