Psychiatry · Clinical trials
Autism Spectrum Disorder Clinical Trials
Approved therapies, the pivotal-trial endpoints they were judged on, the magnitude of benefit — and the drugs that failed their endpoints, and why.
Indication overview
About autism spectrum disorder — and why its trials are hard
Autism Spectrum Disorder (ASD) is a neurodevelopmental condition defined by differences in social communication and restricted, repetitive behaviors. Importantly, no medication is FDA-approved to treat the core symptoms of autism. The only two FDA-approved drugs — risperidone (2006) and aripiprazole (2009) — are indicated for irritability associated with autism (aggression, self-injury, tantrums) in children and adolescents, NOT for social-communication deficits or repetitive behaviors. Both are antipsychotics with meaningful metabolic and sedative side effects. Efforts to target core symptoms have repeatedly failed. Balovaptan, a vasopressin V1a receptor antagonist, failed its trials (pediatric aV1ation and the adult V1aduct phase 3 program was terminated) without improving socialization or communication. Intranasal oxytocin showed no benefit in the large NIH SOARS-B trial (Sikich et al., NEJM 2021). Bumetanide phase 3 studies were terminated in 2021 for lack of efficacy, and arbaclofen (STX209) did not meet primary endpoints. These failures underscore autism's heterogeneity and the difficulty of defining sensitive, agreed-upon core-symptom endpoints for regulatory trials.
Approved therapies & pivotal evidence
What's been approved — and by how much it moved the endpoint
| Drug (brand) | Approved | Setting | Pivotal trial | Primary endpoint | Magnitude of benefit |
|---|---|---|---|---|---|
| Risperidone (Risperdal) | 2006 | Irritability associated with autistic disorder in children/adolescents (aggression, self-injury) — NOT core symptoms | RUPP Autism Network (McCracken et al., NEJM 2002) | Aberrant Behavior Checklist (ABC) Irritability subscale | ~57% reduction in irritability score vs ~14% for placebo; ~69% responder rate vs ~12% |
| Aripiprazole (Abilify) | 2009 | Irritability associated with autistic disorder in children/adolescents — NOT core symptoms | Owen et al. (2009) and Marcus et al. (2009) pediatric RCTs | ABC Irritability subscale | Significant reduction in irritability vs placebo (e.g., ~-12.4 vs -5.0 points); effect on core social-communication deficits not established |
Where trials have failed
Drugs that missed their endpoint — and what contributed
The most instructive lessons in autism spectrum disorder development come from programmes that failed the endpoint that mattered.
| Drug / trial | Endpoint outcome | What contributed |
|---|---|---|
| Balovaptan (vasopressin V1a antagonist) — aV1ation (pediatric, JAMA Psychiatry 2022); V1aduct phase 3 (adults) — program terminated 2020 | Failed — no improvement in socialization/communication; core-symptom efficacy not demonstrated | No separation from placebo on Vineland/SRS-based endpoints; highlights difficulty targeting core social deficits and measuring them reliably |
| Intranasal oxytocin — SOARS-B (Sikich et al., NEJM 2021) | Failed — no benefit over placebo on social/communication outcomes in children/adolescents | Large placebo response, heterogeneity of ASD, and lack of a predictive biomarker to select responders |
| Bumetanide — Phase 3 program (Servier/Neurochlore), terminated 2021 | Failed — did not meet efficacy endpoints; development halted | No efficacy signal on core symptoms; diuretic tolerability issues; heterogeneity limited detectable effect |
Choosing the right endpoint
Primary endpoints that matter in autism spectrum disorder trials
- ABC Irritability subscale — Basis for both approved drugs; measures behavioral irritability, not core autism features
- Social Responsiveness Scale (SRS) — Core social-communication measure; caregiver-rated, prone to placebo effects in trials
- Vineland Adaptive Behavior Scales — Used in balovaptan program for socialization/communication; failed to show drug benefit
- CGI-I (Clinical Global Impression-Improvement) — Global clinician-rated change; commonly a secondary endpoint in ASD trials
How iNGENū runs autism spectrum disorder trials
Physician-led design, built for FDA submission
Endpoint & biomarker strategy
Board-certified specialists design endpoints and patient selection aligned to current FDA guidance for this indication.
FDA-ready data
Built to ICH-GCP and 21 CFR 312.120, with direct FDA submission — data accepted by the FDA, EMA and MHRA.
Faster, lower-cost delivery
~4-week ethics via the TGA CTN scheme, up to 43.5% R&D rebate, and 80–90% below US CRO cost.
Request a fixed-milestone proposal and a tailored endpoint & feasibility summary for this indication.
Frequently asked questions
Autism Spectrum Disorder clinical trials — FAQs
Is there a drug that treats core autism symptoms?
What do risperidone and aripiprazole actually treat?
Why did drugs like balovaptan and oxytocin fail?
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