Seaport Therapeutics Presents New GAD Findings
Seaport Therapeutics presented new data on placebo response in generalized anxiety disorder (GAD) trials. The findings were shared at the International Society for CNS Clinical Trials and Methodology Conference 2026, held February 18–20, 2026, in Washington, D.C.
The meta-analysis examined how clinical trial design factors influence GAD placebo response. Importantly, the results highlight opportunities to improve CNS trial design.
Frequent Assessments Increase GAD Placebo Response
The study found that more frequent clinician-administered assessments (CAAs) were strongly linked to higher GAD placebo response. In other words, repeated rater-based evaluations may unintentionally amplify placebo effects.
In contrast, several other factors showed no strong correlation. These included:
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Baseline Hamilton Anxiety Rating Scale (HAM-A) score
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Number of trial sites
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Total patient enrollment
Similarly, Seaport’s earlier research in major depressive disorder (MDD) trials reported comparable findings. Therefore, the pattern appears consistent across multiple neuropsychiatric indications.
Why Placebo Response Matters in CNS Trials
Placebo response remains a major challenge in CNS drug development. High placebo rates can reduce the ability to detect true drug efficacy. As a result, promising therapies may fail in late-stage studies.
According to the Biotechnology Innovation Organization, more than 90% of neuropsychiatry product candidates fail. Consequently, optimizing clinical trial design is critical.
Tony Loebel, M.D., Chief Medical Officer and President of Clinical Development at Seaport Therapeutics, emphasized that sponsors must carefully manage placebo response. Moreover, insights from meta-analyses can directly inform better study execution.
Study Scope and Methodology
The analysis reviewed 22 industry-sponsored Phase 2–4 randomized, placebo-controlled GAD trials conducted over 20 years. All studies met strict inclusion criteria.
Specifically, each trial:
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Used HAM-A as the primary endpoint
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Enrolled at least 100 total participants
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Included at least 25 participants in the placebo arm
As a result, the dataset ensured consistency and comparability across trials.
Toward Better GAD Clinical Trial Design
Overall, the findings sharpen understanding of GAD placebo response drivers. More importantly, they support data-driven improvements in CNS trial methodology.
Going forward, Seaport plans to apply these insights to future GAD and MDD studies. Ultimately, improved trial design could help accelerate the development of effective treatments for patients with anxiety and related disorders.
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