Headlines tout it as a “new hope” drug for autism, but suramin, a 100-year-old drug used for African sleeping sickness, isn’t new and any hope associated with it requires some tempering.
In the small clinical trial that is generating the huge buzz, 10 autistic boys were randomized to receive either one intravenous infusion of suramin or a placebo infusion. The boys, ages 5 to 14 years, were matched by age, IQ, and autism intensity. The study was published in the Annals of Clinical and Translational Neurology.
Following the treatments, Robert Naviaux at the University of California, San Diego, and his team monitored suramin blood levels and autism-related traits for six weeks. At one week after the infusion, scores on a battery of autism tests had improved for the five boys in the treatment group but not the five boys in the placebo group. A few weeks later, those improvements faded.
Suramin hit autism research radars after Naviaux announced a few years ago that it decreased certain behaviors in mice. The drug blocks proteins that, so goes the idea, overreact to infection. Serious infections during certain periods of pregnancy have been associated with having an autistic child, so the hypothesis with suramin is perhaps that these overreacting proteins are involved and suramin can stop them.
From that premise, a few years ago, researchers induced a mock infection in pregnant mice and found that their pups show problems with motor skills and some other behaviors that some scientists like to equate to autism. Obvious caveat: Mice aren’t people, of course, as Naviaux himself has noted.
When Naviaux’s team gave these mouse pups one dose of suramin, the animals’ motor deficits and other signs diminished somewhat. The researchers tried it in adult mice born to these mouse mothers and found some decrease in signs related to mouse social behaviors. Naturally, the next step was to try it on autistic children.
The catch is that suramin has already been used in people for a long time. Thus, its serious side effects are already known and can include neuropathy, anemia, and adrenal insufficiency. Those effects usually come with higher doses of the drug and longer-term treatments than used in this latest trial.
All of the boys receiving suramin developed a rash within a day or two of the infusion, but the rash resolved spontaneously within four days. The investigators identified no serious adverse events.
Some reports have called these results “dramatic,” but the annals of human therapeutic breakthroughs are littered with dramatic results that became less so with more research and time to fully understand side effects. Naviaux himself has said as much, noting in a university press release that “new trials could prove suramin is not an effective (autism) treatment…. Its benefits may prove too limited over the long term…or an unacceptable safety issue might arise.”
In addition, this study was supposed to be blinded so that no one knew who was getting the suramin infused, but the rash was likely a dead giveaway about which children got the drug. The study authors note that “Five children who received suramin developed a self-limited, evanescent, asymptomatic, fine macular, patchy, morbilliform rash over 1–20% of their body.”
The risk of influence from such hints and high expectations is a real one. One parent in the study is quoted in the UC San Diego press release as seeing improvement within one hour of infusion of the drug, saying that their son began to make more eye contact with the clinicians in the room just following the treatment. In the same release, researchers describe children who said their first words in a decade within a week of receiving the drug.
Concerned that reports like this could lead parents to seek out suramin without sufficient evidence of effectiveness–or worse, inspire less ethical practitioners to prey on vulnerable parents–the authors have appended the following note to the university media materials announcing 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.”