When looking for interventions for the negative aspects of autism, few people would look to a hundred-year-old drug used to fight African parasites. Yet this is where Professor Robert Naviaux of the University of California, San Diego has ended up. His study so far is very small scale, and the benefits have been temporary. Nevertheless, for a while the changes were striking.
Suramin was developed in 1916 to treat trypanosomiasis, or sleeping sickness, a disease that still affects thousands of people a year, and until recently killed many more. It is also used against river blindness, another disease caused by an African parasite. Tests of suramin on mice that display behavior analogous to autism have shown a reversal of some symptoms, inspiring Naviaux to test on humans.
Suramin has been given to so many people over the years, its side effects are well known. In the large doses needed to treat sleeping sickness, these can be severe, ranging from nausea to kidney problems, but Naviaux used much smaller doses. Funding limitations forced Naviauz to start small, giving just five boys aged 5-14 a single intravenous infusion of the drug, while another five got a placebo.
In Annals of Clinical and Translational Neurology, Naviaux reports the boys who received the infusion all showed significant changes, developing better language and coping skills, with social behavior more similar to neurotypical children of the same age. The boys given the suramin were assessed as having a fall of 1.6 points on the Autism Diagnostic Observation Schedule test, where a child is classified as autistic with a score of 9 or above. The scores for the boys given the placebos did not change.
Some of the effects were remarkably rapid. The parents of a 14-year-old-boy who had not spoken a complete sentence in 12 years said in a statement: "Within an hour after the infusion, he started to make more eye contact with the doctor and nurses in the room....We saw our son advance almost three years in development in just six weeks."
Two previously non-verbal children given the suramin spoke their first sentences within a week. Naviaux stressed treatment is more than a matter of providing an infusion. Instead the suramin “removed the roadblocks,” allowing children to benefit from enrichment programs and speech therapy.
However, the effects did not last, and over weeks the participants largely returned to their previous behaviors.
Findings on such a small group need to be replicated with a larger sample, along with work to see whether repeated doses can produce a more lasting effect without inducing serious side-effects. Naviaux also emphasized that, given the great diversity in ASD symptoms, it can't be assumed that benefits to children with serious deficits mean the drug is suitable for those whose autism represents a different form of intelligence.
The study's implications go much further than the potential for suramin to assist development. Assuming suramin's effectiveness is confirmed in further trials, it may build support for Naviaux's theories on the causes of autism.
Naviaux thinks autism is partially caused by hardening of the cell membranes, known as cell danger response (CDR). "The purpose of CDR is to help protect the cell and jump-start the healing process," Naviaux said. Sometimes, however, CDR fails to turn off after danger has passed, and Naviaux suspects this affects communication between the brain, gut, and immune system.
When a combination of genetic and environmental factors trigger lasting CDR early in life, Naviaux claims, autism can result. Suramin damps down the signal that keeps CDR operating after it has served its purpose. If Naviaux's findings are confirmed, it would stimulate the search for ways to control CDR.
Suramin's status as a well-established drug is a double-edged sword, however. On the one hand, being out of patent makes it cheap – a monthly course for sleeping sickness costs $27. On the other, the difficulty in profiting from the drug makes it hard to gain funding for larger trials. Naviaux's team is philanthropically funded, and he claims to have gone $500,000 into debt just to see this small trial through.
This is not the first time a drug for trypanosomiasis has been found to have an unexpected additional use.
Where suramin is used in the first phase of the disease, eflornithine (often sold as Vaniqa) tackles the second. Eflornithine can also be used as a topical cream to prevent the growth of facial hair in women, which might seem a trivial application with so many lives at stake, but is, in fact, the only reason eflornithine production continues. The populations most vulnerable to trypanosomiasis cannot afford to pay for its manufacture, and the drug was discontinued until demand for the facial cream caused production to restart. Economies of scale allowed additional doses to be provided for free to aid organizations.
