Potential Revolutionary Therapy Shows Promise in Autism Treatment

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A new study has found that a medicine called L1-79 may help improve social skills in teens and young adults with autism spectrum disorder (ASD). The results were shared at the 2025 International Society for Autism Research (INSAR) annual meeting, held in Seattle from April 30 to May 3.

“These results are extremely encouraging for the autism community,” J. Thomas Megerian, M.D., Ph.D., chief medical officer at Yamo Pharmaceuticals, said in a statement. “Seeing nearly an 8-point jump in the [Vineland-3 Socialization Standard Score (VSSS)] is remarkable. To our knowledge, this is one of the largest positive effects observed to date on an adaptive-behavior measure in ASD for any medication. More importantly, it represents a clinically meaningful change — essentially moving patients to a higher level of social functioning. For families and clinicians, that could translate to noticeable gains in real-life social engagement and independence.”

ASD is a condition that affects how a person communicates and interacts with others. People with ASD may also have restricted or repetitive behaviors and interests. Symptoms usually appear in early childhood and continue into adulthood. According to the Centers for Disease Control and Prevention (CDC), about one in 31 children in the U.S. has ASD, with boys being diagnosed about four times more often than girls.

Currently, there are no U.S. Food and Drug Administration (FDA)-approved medicines that treat the core symptoms of autism, like social communication challenges. Some medicines, such as risperidone and aripiprazole, are approved to treat irritability but do not improve social skills — and they can have side effects.

That is why investigators are excited about L1-79. This medicine works differently than other treatments. It targets a brain chemical called tyrosine hydroxylase, which helps make dopamine and norepinephrine. These chemicals are important for brain signaling, but too much activity in these pathways may make it harder for people with ASD to connect socially. By lowering this activity, L1-79 may help balance brain signals related to social interaction.

The Phase 2 study included 58 people with ASD aged 12 to 21 years. Participants received either L1-79 or a placebo for 12 weeks. Then, after a short break, they switched to the other treatment.

Investigators measured changes in social skills using a test called the VSSS — a trusted tool for measuring real-world social skills.

The Findings:

• Social improvement: Teens and young adults taking L1-79 had an average improvement of 7.94 points on the VSSS compared with placebo. This improvement was nearly double what experts say is a meaningful change.
• Better overall symptoms: Investigators rated participants’ autism symptoms as less severe while taking L1-79, using a scale called the Clinical Global Impression of Severity (CGI-S).
• Caregiver feedback: Parents and caregivers reported noticeable improvements in the three most bothersome symptoms their loved ones experienced.
• Safe and well tolerated: No serious side effects were reported, and no participants had to stop taking L1-79 due to side effects.

Megerian, one of the co-lead investigators, said it was exciting to see both doctors and caregivers notice improvements. “Rather than chasing downstream symptoms, we’re modulating a core neural pathway,” he said.

What’s Next?

The results are promising, but more research is needed before L1-79 could be approved by the FDA. Right now, there are no approved medicines for improving social communication in autism. L1-79 may be one of the first treatments designed to help with this core symptom.

The company plans to continue studying L1-79 in more patients to confirm these findings.

For families and individuals affected by autism, this research brings hope for new treatment options that target the root causes of social challenges, not just the behaviors.

“With these compelling Phase 2 data, we are moving full speed into Phase 3 planning and FDA discussions,” Chuck Bramlage, chief executive officer of Yamo Pharmaceuticals, said in a statement. “Our mission is clear: bring the first medicine that meaningfully improves social functioning in autism to patients as quickly and responsibly as possible.”