At a glance
| Clinical context | Rett syndrome |
|---|---|
| U.S. age range | Two years and older |
| Historical name | NNZ-2566 |
| Pivotal evidence | LAVENDER randomized phase 3 study |
| Major limitation | Diarrhea, vomiting, and weight loss |
Overview
Trofinetide was developed from glycine-proline-glutamate, a small fragment associated with insulin-like growth factor 1. NNZ-2566 was an earlier development name for the active ingredient now known as trofinetide; its predecessor studies form part of the same clinical history. Rett syndrome is a complex neurodevelopmental condition, and the medicine is used within broader clinical support. The pivotal evidence concerns Rett-related symptoms and caregiver or clinician ratings. It does not establish a treatment for normal aging, routine cognitive enhancement, or every condition that has been explored during development.
How it works
Trofinetide is a modified analog of glycine-proline-glutamate, designed to have different pharmacologic properties from the native fragment. Preclinical work explored effects on inflammatory signaling and synaptic function. However, the FDA label states that the mechanism producing the therapeutic effect in Rett syndrome is unknown. A proposed biological explanation should therefore be presented as a hypothesis, not as a demonstrated correction of the underlying genetic disorder.
What LAVENDER measured
The 12-week LAVENDER trial randomized 187 females with Rett syndrome. Trofinetide improved the Rett Syndrome Behaviour Questionnaire and clinician global-improvement measure relative to placebo, with modest standardized effect sizes. These group-level changes support symptom benefit. They do not show complete recovery, and a short trial cannot alone establish every long-term developmental outcome.
Supporting sources [2]
Gastrointestinal effects matter
Diarrhea was reported by about 81% of trofinetide participants versus 19% receiving placebo in LAVENDER. The prescribing information also emphasizes vomiting and weight loss. Hydration, nutrition, body weight, and concomitant medicines require attention. These are substantive treatment burdens in a population that may already have feeding or gastrointestinal difficulties.
How predecessor research fits
Earlier studies helped establish the program that led to the Rett indication. Their existence does not create a separate approved compound or support all earlier investigational uses. Earlier findings remain relevant only to the disease, study design, and formulation actually investigated; they do not extend the current approval to other conditions.
Reading this profile
Jurisdiction: United States; status and indications may differ elsewhere. Molecular class: Synthetic analog of the tripeptide glycine-proline-glutamate.
This profile was written with AI-assisted research and checked against the linked sources. It has not been represented as a clinician’s review. Evidence summaries describe the cited studies and products; they do not establish that a separately purchased preparation is equivalent.
Sources & references
Follow the original material. Product labels define specific formulations and uses; trial registration describes a study and does not by itself establish benefit.
- FDA prescribing information: Daybue (trofinetide) ↗Regulatory source · Checked 2026-10-27
- Trofinetide for Rett syndrome: randomized phase 3 LAVENDER study ↗Clinical trial source · Checked 2026-10-27