Trofinetide — Complete Research Guide (2026)

Last updated 2026-06-30

What is Trofinetide?

Trofinetide (brand name Daybue) is a synthetic analog of the naturally occurring glycine-proline-glutamate (GPE) tripeptide derived from insulin-like growth factor-1 (IGF-1). It was approved by the US FDA in March 2023 as the first drug indicated specifically for Rett syndrome, in adults and pediatric patients aged 2 years and older.

The evidence base is strong for this indication: approval rested on a randomized, double-blind, placebo-controlled phase 3 trial (LAVENDER) plus an open-label extension (LILAC), so the human efficacy and safety data are pivotal-trial grade rather than preclinical.

How does Trofinetide work?

Trofinetide is thought to reduce neuroinflammation and support synaptic function by modulating glial (astrocyte and microglial) activity and normalizing IGF-1 pathway signaling in the brain.

Its exact mechanism of action in Rett syndrome has not been fully established.

What does the research say about Trofinetide?

• In the pivotal 12-week phase 3 LAVENDER trial, trofinetide produced statistically significant improvements over placebo on both co-primary endpoints (caregiver-rated Rett Syndrome Behaviour Questionnaire and clinician-rated Clinical Global Impression-Improvement) in girls and women with Rett syndrome. ^[1]
• An earlier phase 2 randomized, placebo-controlled study in pediatric Rett syndrome supported an efficacy signal and informed dose selection for the later phase 3 program. ^[4]
• In the open-label LILAC extension, improvements observed in the controlled trial were generally maintained with continued treatment, though gastrointestinal adverse events remained the leading reason for discontinuation. ^[2]

Clinical research & studies

The references below are the primary sources cited throughout this guide. Each links directly to PubMed or the regulator. Where evidence is preclinical (animal or in-vitro), that is stated rather than implied.

• [1] Trofinetide for the treatment of Rett syndrome: a randomized phase 3 study — Neul JL et al., Nature Medicine 2023. (Randomized double-blind placebo-controlled phase 3 trial (LAVENDER))
• [2] Trofinetide for the treatment of Rett syndrome: Results from the open-label extension LILAC study — Percy AK et al., Med 2024. (Open-label extension study)
• [3] Trofinetide for the treatment of Rett syndrome: Long-term safety and efficacy results of the 32-month, open-label LILAC-2 study — Percy AK et al., Med 2024. (Long-term open-label extension study)
• [4] Double-blind, randomized, placebo-controlled study of trofinetide in pediatric Rett syndrome — Glaze DG et al., Neurology 2019. (Randomized double-blind placebo-controlled phase 2 trial)
• [5] Design and outcome measures of LAVENDER, a phase 3 study of trofinetide for Rett syndrome — Neul JL et al., Contemporary Clinical Trials 2022. (Trial design/methodology paper)
• [6] Managing Gastrointestinal Symptoms Resulting from Treatment with Trofinetide for Rett Syndrome: Caregiver and Healthcare Provider Perspectives — Moore R et al., Advances in Therapy 2024. (Qualitative survey/perspectives study)

Dosing context

Trofinetide is an oral solution dosed by body-weight bands, typically taken twice daily, and can be given by mouth or via gastrostomy tube.

This is context only and not a dosing recommendation; actual dosing must be individualized and directed by the treating physician per the approved label.

Side effects & safety profile

The most common adverse effects are diarrhea and vomiting, which can be frequent and severe enough to cause dehydration, weight loss, and treatment discontinuation; prescribing information advises monitoring for diarrhea and managing it (for example stopping laxatives, using anti-diarrheal treatment, and ensuring hydration).

Weight loss was also observed.

Trofinetide should be used under specialist supervision, and caregivers should be counseled on recognizing and managing gastrointestinal symptoms and dehydration.

Stacking & combinations

There is no research supporting combining trofinetide with unapproved peptides or supplements; it is a prescription drug used within a physician-managed Rett syndrome treatment plan.

Finding Trofinetide vendors

User reviews

Frequently asked questions

References

1. [1] Trofinetide for the treatment of Rett syndrome: a randomized phase 3 study — Neul JL et al., Nature Medicine 2023. PMID: 37291210. View sourceStudy: Randomized double-blind placebo-controlled phase 3 trial (LAVENDER)Trofinetide significantly improved both co-primary endpoints (RSBQ and CGI-I) versus placebo over 12 weeks, with diarrhea and vomiting the most common adverse events.
2. [2] Trofinetide for the treatment of Rett syndrome: Results from the open-label extension LILAC study — Percy AK et al., Med 2024. PMID: 38917793. View sourceStudy: Open-label extension studyEfficacy improvements were generally sustained during open-label treatment, with gastrointestinal events (notably diarrhea) the leading cause of discontinuation.
3. [3] Trofinetide for the treatment of Rett syndrome: Long-term safety and efficacy results of the 32-month, open-label LILAC-2 study — Percy AK et al., Med 2024. PMID: 39025065. View sourceStudy: Long-term open-label extension studyLonger-term open-label data showed a consistent safety profile and continued clinical benefit over up to 32 months of treatment.
4. [4] Double-blind, randomized, placebo-controlled study of trofinetide in pediatric Rett syndrome — Glaze DG et al., Neurology 2019. PMID: 30918097. View sourceStudy: Randomized double-blind placebo-controlled phase 2 trialThe phase 2 study demonstrated an efficacy signal and acceptable tolerability, supporting dose selection for the phase 3 program.
5. [5] Design and outcome measures of LAVENDER, a phase 3 study of trofinetide for Rett syndrome — Neul JL et al., Contemporary Clinical Trials 2022. PMID: 35149233. View sourceStudy: Trial design/methodology paperThis paper describes the design, endpoints, and outcome measures of the pivotal LAVENDER phase 3 trial.
6. [6] Managing Gastrointestinal Symptoms Resulting from Treatment with Trofinetide for Rett Syndrome: Caregiver and Healthcare Provider Perspectives — Moore R et al., Advances in Therapy 2024. PMID: 38378975. View sourceStudy: Qualitative survey/perspectives studyCaregivers and clinicians reported practical strategies for managing trofinetide-associated diarrhea and other GI symptoms, which are the main tolerability challenge.