Can Suramin Emerge as a Treatment for Autism Spectrum Disorders (ASD)?

The drug suramin, used for the treatment of African sleeping sickness, could soon find its way into the treatment armamentarium of autism spectrum disorders (ASD) in children. A study evaluating suramin for this new possibility was published in the Annals of Clinical and Translational Neurology. Medicine has evolved in a big way over the decades. New molecules have evolved into drugs, while some of the older, toxic and relatively inefficient drugs have fallen into disuse. An almost reverse trend also exists, where traditional and older medications are explored for use once again, either for the same, or for a different condition. One such drug is suramin,which has been used for the treatment of African sleeping sickness for around a century, and is now being evaluated for its possible benefits in autism patients.

Sleeping sickness or African trypanosomiasis is a parasitic infection spread by the tsetse flies. It causes neurological symptoms like behavioral problems, confusion and alterations in sleep cycles. With extreme measures to control the spread of flies, the disease burden has been reduced to a large extent, with health authorities setting goals to eliminate the infection by 2020. Suramin is one of the drugs used to treat sleeping sickness. It is associated with a number of side effects including nausea, diarrhea, low blood pressure and kidney problems.

A small trial, the Suramin Autism Treatment-1 (SAT-1) trial, on 10 boys aged between 5 and 14 years evaluated the use of low-dose suramin for autism (ASD). ASD include a group of disorders in children characterized by problems in communication, language and socialization, and repetitive behaviors. The condition arises due to genetic and environmental factors that affect the development of the child. The researchers found clues of the possible benefits of suramin for ASD based on studies on mice.

Five out of the ten boys included in the study received an intravenous infusion of low-dose suramin, while the other five received only saline, which acted as a placebo. Based on observations and standardized interviews, the researchers found that:

• The boys who received suramin improved with respect to speech and language, social behavior and communication, focus, calmness, repetitive behaviors and coping skills at the end of 6 weeks following treatment. This improvement was not observed in those administered the placebo. The positive changes caused by suramin were obvious and noted by the parents as well.
• The children who received suramin also experienced enhanced benefits from their other treatments like speech therapy, occupational therapy and applied behavioral analysis
• The benefits of suramin faded after several weeks. This indicates that the effects of the single dose are temporary and multiple doses may be required
• The side effects of suramin were minimal in the study and included the development of rash. Again, it must be remembered that only a single low dose of suramin was used in the study

How can a drug used for the treatment of a parasitic infection be effective in a developmental brain disorder? Researchers believe that they have an answer to this as well. They believe that the cell danger response plays a role in the development of autism, along with genetic factors and exposure to environmental toxins. The cell danger response (CDR) is a protective mechanism by cells in response to stress or injury. It prevents interaction of the cell with other cells so that it does not get damaged. At times, however, the response continues even after the stressful condition or injury resolves. This can do more harm than good, which makes it necessary to stop it with drugs like suramin. The oxidative stress caused by the CDR may also impact nerve cells and circuits, thereby contributing to ASD. Suramin appears to block the effect of adenosine triphosphate (ATP), which is released from cells and takes part in the CDR. It thereby, pauses the CDR and protects the nerve cells from its damaging effects.

It would now be necessary to demonstrate whether suramin can produce its benefits in a large number of ASD children. The dose required to maintain a sustained response with minimal adverse effects will also need to be estimated. If suramin does not stand the test, a similar molecule with a beneficial effect, at the same time, with minimal side effects, could see the light of the day.

Reference:

1. Naviaux RK et al. 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
2. Parasites - African Trypanosomiasis (also known as Sleeping Sickness) - (https://www.cdc.gov/parasites/sleepingsickness/health_professionals/index.html#tx)

Advertisement

Source-Medindia