Autism spectrum disorders affects about 1 out of every 54 children in the U.S. But while there are drugs available for some of the symptoms patients experience, there are no approved treatments for the underlying condition.

Neurochlore had hoped that bumenatide, a diuretic commonly used to treat fluid retention, would offer a way forward because it affects a chemical messenger in the brain that some researchers think may play a role in autism. Parents said children involved in earlier research appeared “more present,” Ben-Ari said in 2017, according to the autism research-focused publication Spectrum.

But even as researchers expressed early optimism, experts suggested the 2017 trial results may have reflected a placebo effect, Spectrum reported at the time. As bumenatide is a strong diuretic that causes a need to urinate frequently, some parents probably figured out their child was getting the active medicine instead of a placebo.

In the companies’ statement, Servier’s head of R&D Claude Bertrand emphasized the “extremely rigorous” standards of its two Phase 3 trials and expressed disappointment in the study results. The two trials enrolled 422 children and adolescents between the ages of two and 17.

According to the companies, none of the effectiveness criteria of the studies were reached after six months of treatment. That was true for both younger children as well as adolescents, they said.

Servier has been expanding its research reach, especially in the U.S., where it opened a Boston headquarters in 2019. Late last year, the company agreed to pay Agios Pharmaceuticals $1.8 billion for a portfolio of cancer medicines and extended job offers to about a third of the Massachusetts-based biotech’s staff.