Single Treatment With MM120 (Lysergide) in Generalized Anxiety Disorder

Importance Effective and well-tolerated pharmacotherapies for generalized anxiety disorder (GAD), which is one of the most common psychiatric disorders, are needed. Objective To determine the dose-response relationship of MM120 (lysergide D-tartrate) in adults with moderate to severe GAD. Design, Settings, and Participants This phase 2b, multicenter, randomized, double-blind, placebo-controlled study enrolled 198 adults aged 18 to 74 years with a primary GAD diagnosis who presented with moderate to severe symptoms (defined by a Hamilton Anxiety Rating Scale [HAM-A] score ≥20) and was conducted at 22 outpatient psychiatric research sites in the US from August 2022 to August 2023. The anxiety and depression end point assessments were conducted by independent central raters who were blinded to the trial protocol, treatment allocation, and study visit date. The last date of follow-up was November 27, 2023. Interventions Participants were randomized to receive a single (freebase equivalent) treatment dose with 25 µg (n = 39), 50 µg (n = 40), 100 µg (n = 40), or 200 µg (n = 40) of MM120 or placebo (n = 39). Main Outcome and Measures The primary outcome was a dose-response relationship assessed using the multiple comparison procedure modeling (MCP-Mod) method for change in HAM-A score at 4 weeks (score range, 0-56; higher scores indicate greater severity; ≤7 indicates no or minimal anxiety; 8-14, mild; 15-23, moderate; and ≥24, severe). The minimal clinically important difference was 2.5 points. Results Of the 198 participants randomized, 194 were included in the full analysis set (mean age, 41.3 [SD, 13.6] years; 56.7% were female; and 3.6% were Asian, 7.7% were Black or African American, and 83.0% were White). The dose-response relationship assessed using the MCP-Mod method for change in HAM-A score at week 4 was statistically significant for the 100-µg and the 200-µg dose groups vs placebo (least-squares mean difference, −5.0 points [95% CI, −9.6 to −0.4 points] with 100 µg of MM120 and −6.0 points [95% CI, −9.8 to −2.0 points] with 200 µg of MM120) but the 25-µg and 50-µg dose groups did not reach significance vs placebo (least-squares mean difference, −1.2 points [95% CI, −6.0 to 3.5 points] with 25 µg of MM120 and −1.8 points [95% CI, −7.6 to 4.0 points] with 50 µg of MM120). The adverse events were consistent with the expected effects of MM120. The most common adverse events were visual perceptual changes (illusion, pseudo-hallucination, and visual hallucination), which occurred in 46.2% of participants who received 25 µg of MM120, in 75.0% who received 50 µg, in 92.5% who received 100 µg, in 100% who received 200 µg, and in 10.3% who received placebo; nausea occurred in 7.7%, 27.5%, 40.0%, 60.0%, and 7.7%, respectively; and headache occurred in 12.8%, 22.5%, 35.0%, 27.5%, and 23.1%. Conclusions and Relevance In participants with moderate to severe GAD, a single dose of MM120 produced a dose-dependent reduction in anxiety. These results support the dose-dependent efficacy of MM120 and inform the dose selection for phase 3 pivotal trials. Trial Registration ClinicalTrials.gov Identifier: NCT05407064