Long-Term Safety and Efficacy of Xanomeline and Trospium Chloride in Schizophrenia: A 52-Week Open-Label Extension Trial

OBJECTIVE: Xanomeline and trospium chloride (X/T) reduced symptoms and was generally well tolerated in two phase 3, 5-week, randomized, double-blind, placebo-controlled trials in adults with schizophrenia. The authors evaluated the long-term safety, tolerability, and efficacy of X/T in an open-label extension of the two phase 3 trials. METHODS: EMERGENT-4 was a 52-week open-label extension trial of participants who completed the EMERGENT-2 and EMERGENT-3 acute trials. Between February 2021 and October 2023, 152 participants initiated twice-daily oral doses of xanomeline 50 mg/trospium 20 mg and titrated to a maximum dosage of twice-daily oral xanomeline 125 mg/trospium 30 mg. The primary endpoint was the proportion of participants reporting a treatment-emergent adverse event (TEAE). Efficacy measures included Positive and Negative Syndrome Scale (PANSS) and Clinical Global Impressions severity scale (CGI-S). RESULTS: A total of 156 (42.6%) of the 366 participants who completed EMERGENT-2 or EMERGENT-3 enrolled in EMERGENT-4; of these 34 (21.8%) enrolled participants completed the 52-week treatment period. Overall, 81 (53.3%) of 152 treated participants experienced at least one TEAE. Consistent with the acute trials, the most common treatment-related adverse events were gastrointestinal disorders (e.g., nausea, vomiting, dyspepsia, dry mouth) that were mild or moderate in intensity and resolved with continued treatment. No new safety or tolerability issues were observed. X/T was not associated with clinically meaningful motor symptoms, hyperprolactinemia, weight gain, or adverse effects on metabolic parameters. X/T was associated with continued symptom improvement over the trial duration. Mean changes in PANSS total score from acute trial baseline to week 52 were -33.8 and -31.3 in the treatment groups receiving X/T and placebo, respectively, in the acute trials. Similar patterns of continued improvement were observed for scores on the CGI-S, PANSS positive subscale, and PANSS negative subscale. CONCLUSIONS: Long-term treatment with X/T over 52 weeks was safe, generally well tolerated, and associated with durable symptom improvement in people with schizophrenia.