Trofinetide

Does Trofinetide work?

Yes, in large controlled trials. The main trial had 187 people.

Approval rests on LAVENDER, a 187-patient randomized placebo-controlled phase 3 trial that met both co-primary endpoints, preceded by two randomized phase 2 trials in 56 adolescents and adults and 82 children. The approved use matches the studied use, so it grades A, with the caveat that the endpoints are rating scales and the effect size is modest. ²³⁵⁶

LAVENDER randomized 187 girls and women aged 5 to 20 with Rett syndrome. They got trofinetide or placebo for 12 weeks. Caregivers rated symptoms on the Rett Syndrome Behaviour Questionnaire. Scores improved by 4.9 points on trofinetide versus 1.7 on placebo. Clinicians rated change on the Clinical Global Impression-Improvement scale. Mean scores were 3.5 versus 3.8 (lower is better). That gap reached significance. A secondary measure of communication also favored trofinetide. ²

Two phase 2 trials came first. One was published in 2017 and included 56 adolescent and adult females with Rett syndrome. Trofinetide was well tolerated. The higher of two doses met prespecified criteria for whether it works. The other was published in 2019 and included 82 girls aged 5 to 15. The highest dose beat placebo on the Rett Syndrome Behaviour Questionnaire, a clinician-rated symptom scale and the Clinical Global Impression-Improvement score. A separate phase 2 trial in 72 adolescent and adult males with fragile X syndrome found the drug well tolerated. It showed a signal that it works at the higher dose. Long-term open-label studies have followed patients for safety. ⁵⁶¹³

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Reference information only, not medical advice. Drawn from the Trofinetide article, fact-checked against the cited sources. No dosing anywhere on this site.