MapLight Therapeutics autism drug shows mixed potential in adolescents
MapLight Therapeutics Inc. announced mixed results from the Phase 2 IRIS study of ML-004 for autism spectrum disorder, missing the primary social communication endpoint but achieving clinically meaningful improvements in irritability for adolescents with moderate to severe baseline symptoms. The drug was generally well-tolerated with a favorable safety profile, showing no serious adverse events in the treatment group.
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MapLight Therapeutics Inc. (NASDAQ: MPLT) reported mixed topline results from its Phase 2 IRIS study of ML-004 in patients with autism spectrum disorder. The trial missed the primary endpoint while demonstrating clinically meaningful improvements in irritability among a subgroup of adolescents. The findings could support further development of the drug in a more targeted patient population, reinforcing views that ML-004 may still hold commercial potential.
Primary Endpoint Missed In Broad Autism Population
The IRIS study enrolled 161 participants, including 102 adolescents and 59 adults, and was designed as an exploratory Phase 2 trial to assess multiple clinical outcomes. The study failed to achieve its primary endpoint, which measured changes from baseline through week 12 in caregiver-reported social communication scores using the Autism Behavioral Inventory Social Communication Domain. MapLight noted that social communication remains an area without approved pharmacological treatments and that validated measures capable of detecting treatment-related changes continue to be actively studied.
Adolescent Subgroup Demonstrates Strong Irritability Benefit
Despite the primary endpoint miss, ML-004 produced encouraging results in a prespecified subgroup of adolescents ages 12 to 17 who entered the study with moderate or greater irritability. Among these participants, ML-004 generated clinically meaningful improvements versus placebo on the Aberrant Behavior Checklist-Irritability subscale, with a least squares mean difference of -9.58 and an effect size of 1.33. The company also reported favorable results on the Clinician Global Impression-Improvement irritability domain, where adolescents receiving ML-004 showed greater improvement than those receiving a placebo. Treatment benefits appeared strongest among adolescents with the highest baseline irritability levels. In the broader population of participants with elevated irritability scores, ML-004 achieved an effect size of 0.64 on a key secondary endpoint, although the result did not reach nominal statistical significance.
Safety Profile Remains Favorable
MapLight said ML-004 was generally well tolerated, with all treatment-emergent adverse events classified as mild to moderate. No serious or severe adverse events occurred among participants receiving ML-004. By comparison, placebo-treated participants experienced two severe treatment-emergent adverse events and one serious adverse event. Investigators observed no extrapyramidal adverse events in patients receiving ML-004, while average weight gain during the study was lower in the treatment arm than in the placebo group.
| Metric | ML-004 | Placebo |
|---|---|---|
| Adolescent TEAEs | 62.7% | 41.2% |
| Adult TEAEs | 86.7% | 72.4% |
| Headache (Adolescents) | 13.7% | 3.9% |
| Somnolence (Adolescents) | 11.8% | 0% |
| Nausea (Adolescents) | 9.8% | 0% |
| Vomiting (Adolescents) | 5.9% | 0% |
| Discontinuations (Adolescents) | 3.9% | 0% |
How will MapLight adjust the design of future trials to focus specifically on the adolescent subgroup with high irritability?
What regulatory pathways might MapLight pursue given the failure to meet the primary endpoint but success in a secondary measure?
How will investors and partners react to the mixed results, and what impact could this have on MapLight's funding and collaborations?
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