Ibudilast improved cognition and behavior in men with fragile X syndrome in a small clinical trial. The use of the other drug in STP1, bumetanide, in autistic people is cloudier. A 2020 clinical trial found that only some of the children who received bumetanide for three months showed reduced repetitive behaviors, though studies over the past two years have suggested that patterns of electrical activity in the brain or levels of specific immune molecules in the blood can predict a person’s response to the drug. Last year, however, phase 3 studies of bumetanide were ended after researchers found no benefit to treatment.
“Bumetanide is an excellent drug for autism, provided you select specific subpopulations of young people,” says Yehezkel Ben-Ari, president and co-founder of French biotech company Neurochlore, which owns the patent for bumetanide as an autism treatment. Adults, he adds, may not respond as well. The 2020 trial found that younger children showed more improvement in social communication and responsiveness than did older ones.
“Many people have hoped for precision medicine, but generally, the field of autism has moved away to some degree.” Catherine Lord
Beyond the questions around bumetanide, others doubt that personalized therapy can be applied to autism at all. “Many people have hoped for precision medicine, but generally, the field of autism has moved away to some degree,” says Catherine Lord, distinguished professor of psychiatry at the University of California, Los Angeles. That’s because, she says, for something as complex and heterogeneous as autism, there’s no clear link between known genetic factors and autism traits. Researchers have not yet had success in finding biomarkers for diagnosis of the condition, let alone predicting who is most likely to respond to treatment, she says.
“Understanding the more convergent mechanisms of autism, and what is common about people with autism rather than what’s different about them, is a more important approach to understanding what’s treatable or preventable in the condition,” says John Constantino, professor of psychiatry and pediatrics at Washington University in St. Louis, Missouri.
A molecular footprint found only in a subgroup of people with autism may have nothing to do with the condition and instead be related to other factors, such as depression or anxiety, Constantino says. So far, he adds, researchers haven’t even been able to reliably differentiate people with autism from those without the condition by looking at biological traits. Identifying a biological profile for different autism subtypes would be a significant advance in the field, he says, if Stalicla has actually done it.