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Meta-analysis showed an association between the frequency of clinician-administered assessments and magnitude of placebo response in generalized anxiety disorder (GAD) trials
Other clinical trial design factors explored included baseline Hamilton Anxiety Rating Scale (HAM-A) score, number of trial sites, and total patient number, with none showing strong correlation with placebo response
Findings reinforce Seaport’s previously presented research on clinical trial design factors impacting placebo response in major depressive disorder (MDD) trials
BOSTON, February 20, 2026 – Seaport Therapeutics (“Seaport” or the “Company”), a clinical-stage therapeutics company advancing novel neuropsychiatric medicines with a proven strategy and team, today announced the presentation of a new meta-analysis examining the impact of clinical trial design factors on the magnitude of placebo response in generalized anxiety disorder (GAD) clinical trials. The research was presented at the International Society for CNS Clinical Trials and Methodology (ISCTM) Conference held February 18-20, 2026, in Washington, D.C.
The meta-analysis showed that the frequency of clinician-administered assessments (CAAs), also known as rater-based efficacy assessments, had a strong positive association with the magnitude of placebo response in GAD clinical trials. Other factors explored in this analysis that could potentially impact placebo response included baseline Hamilton Anxiety Rating Scale (HAM-A) score, number of trial sites, and total patient number, with none ultimately showing strong correlation with placebo response. These findings align with Seaport’s previously presented meta-analysis in major depressive disorder (MDD) clinical trials, which also found that more frequent CAAs were associated with a heightened placebo response.
“This robust analysis highlights the persistent challenges in CNS drug development, where in order to demonstrate efficacy, a sponsor must carefully manage the potential for high placebo response,” said Tony Loebel, M.D., Chief Medical Officer and President of Clinical Development at Seaport. “As evidence continues to show that more frequent clinician-administered assessments may increase placebo response – now in both GAD and MDD trials – we are directly applying these and other insights at Seaport to inform more effective clinical trial design and execution. The goal of this research is to enable meaningful advancements toward bringing life-changing medicines to the millions of patients struggling with depression, anxiety, and other debilitating neuropsychiatric disorders.”
Despite the significant unmet need in neuropsychiatry, over 90 percent of neuropsychiatry product candidates fail, according to the Biotechnology Innovation Organization. [1] A major barrier to successful neuropsychiatric drug development is suboptimal clinical trial design and execution, and a key part of this challenge is the placebo effect, which may be impacted by the frequency of CAAs, as shown in meta-analyses of both GAD and MDD clinical trials.
The meta-analysis examined 22 industry-sponsored Phase 2-4, randomized, placebo-controlled GAD trials conducted in the past 20 years, all of which met strict inclusion criteria, including the use of HAM-A as the primary endpoint, enrollment of ≥100 total participants, and enrollment of ≥25 participants in the placebo arm.
The research sharpens understanding of the factors that may be driving placebo response in GAD clinical trials and underscores the importance of continued optimization of CNS clinical trial design.
About Seaport Therapeutics
Seaport Therapeutics is a clinical-stage therapeutics company advancing the development of novel neuropsychiatric medicines in areas of high unmet patient needs. The Company has a proven strategy of advancing clinically validated mechanisms previously held back by limitations that are overcome with its proprietary Glyph TM technology platform. All the therapeutic candidates in its pipeline of first and best-in-class medicines are based on the Glyph platform, which is uniquely designed to enable oral bioavailability, bypass first-pass metabolism and reduce liver enzyme elevations or hepatotoxicity and other side effects. Seaport is led by an experienced team that invented and advanced important neuropsychiatric medicines and is guided by an extensive network of renowned scientists, clinicians, and key opinion leaders. For more information, please visit www.seaporttx.com .