What is DAYBUE?

Kate, age 9, with her dad and brother

An opportunity to add more of her sparkle to the world around us

By sparking meaningful improvements in the signs and symptoms of Rett syndrome, DAYBUE™ (trofinetide) can help illuminate more of the girl you’ve always known was inside. See the results from the clinical trial below.

DAYBUE is a prescription medicine used to treat Rett syndrome in adults and children 2 years of age and older. It is not known if DAYBUE is safe and effective in children under 2 years of age.

DAYBUE is not a cure for Rett syndrome.

DAYBUE: The first and only FDA-approved treatment for Rett syndrome

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Proven effective

By 12 weeks, treatment with DAYBUE demonstrated improvements in signs and symptoms of Rett syndrome, as measured by both caregivers and doctors

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Twice-daily dosing

DAYBUE is a strawberry flavored oral medication taken twice a day by mouth, gastrostomy (G) tube, or G-port of gastrojejunal (GJ) tube

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Common side effects

Diarrhea and vomiting are the most common side effects with DAYBUE. Your doctor can provide tips and strategies to help manage side effects

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Dedicated patient support

Once your child is prescribed DAYBUE, Acadia Connect is here to provide you with dedicated support and resources throughout the treatment journey

How was DAYBUE studied?

The effectiveness and safety of DAYBUE were evaluated in the 12-week LAVENDER™ clinical trial of 187 female patients aged 5 to 20 with Rett syndrome.


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12-week clinical trial

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187 patients

During the trial, 93 patients were given DAYBUE, and their results were compared with those of 94 patients who were given a placebo (treatment without any active medication).

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Up to 40-week study

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154 patients

Following the 12-week LAVENDER clinical trial, eligible patients and their families were given the option to continue treatment with DAYBUE (or start treatment with DAYBUE if they had previously received a placebo).

Participation in the clinical trial included these requirements:

Patients in LAVENDER all had a diagnosis of typical Rett syndrome according to the Rett Syndrome Diagnostic Criteria, and a documented mutation in the MECP2 gene. And, to reflect how unique Rett syndrome is for each person, patients in both groups of the study had a range of symptoms and disease severity.

DAYBUE use in young children:

Use of DAYBUE in patients aged 2 to 4 is supported by an open-label study where a total of 13 patients received DAYBUE for at least 12 weeks, and 9 patients received DAYBUE for at least 6 months.

Changes were assessed in the signs and symptoms of Rett syndrome in the LAVENDER trial

Because caregivers possess such a deep knowledge of their child, they contributed directly to the evaluation of the overall effectiveness of DAYBUE. Doctors evaluated if patients improved or got worse, while caregivers looked for changes in the signs and symptoms of Rett syndrome.

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Caregivers used the Rett Syndrome Behaviour Questionnaire (RSBQ) to evaluate changes in the signs and symptoms of Rett syndrome.

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Doctors used the Clinical Global Impression-Improvement (CGI-I) scale to evaluate if a patient had improved or worsened.

Kate, age 9, living with Rett syndrome, with her parents

Learn about Kate's experience with DAYBUE

Read her story

Kate, age 9, living with Rett syndrome, with her parents

Study results

Caregivers evaluated changes in a range of symptoms using the Rett Syndrome Behaviour Questionnaire (RSBQ)

What does the RSBQ measure?

An instrument used in studies of Rett syndrome, the RSBQ is a measurement scale used by caregivers to evaluate 45 items representing symptoms of Rett syndrome. Caregivers were asked to rate each item as it relates to their child using a 0- to 2-point scale. In this scale, a score of 0 means “not true,” 1 means “somewhat or sometimes true,” and 2 means “very true or often true.”

These are examples of the types of symptoms that caregivers evaluated.

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Hand movements or stereotypies

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Repetitive behaviors

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Nighttime behaviors

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Facial expressions

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Eye gaze

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What could improvements look like?

After caregivers completed the RSBQ, the scores of the 45 items were added up to determine the RSBQ total score. The maximum possible score was 90.

To determine how symptoms were impacted by treatment, researchers looked at how much the average RSBQ total score changed for all patients in the clinical trial at 12 weeks of treatment.

What did caregivers observe at 12 weeks?

Change in average RSBQ total score from the start of the trial to Week 12

The patients receiving DAYBUE showed an almost

3x greater decrease in average RSBQ total score

from the start of the trial when compared with placebo. A lower score meant signs and symptoms of Rett syndrome were less severe.

For this evaluation, there were 76 patients in the DAYBUE group and 85 in the placebo group.

Before starting treatment, the average RSBQ total score for the DAYBUE group was 43.7. For the placebo group, the average RSBQ total score before treatment was 44.5.

*Results varied between patients in the clinical trial. Individual results may vary with DAYBUE.

Doctors evaluated improvement or worsening of Rett syndrome using the Clinical Global Impression-Improvement (CGI-I) scale

Improvement or worsening in individuals was evaluated starting from before treatment began through the 12-week trial. They did this using a 7-point scale, starting from 1, which meant “very much improved,” to 7, which meant “very much worse.”

What did doctors see at 12 weeks?

At 12 weeks, doctors saw a global improvement in Rett syndrome signs and symptoms in patients receiving DAYBUE when compared to patients receiving the placebo.

Kate, age 9, living with Rett syndrome

Because each individual with Rett syndrome is unique—with a unique set of symptoms—improvements with DAYBUE may be different for everyone.

Kate, age 9, living with Rett syndrome

Understanding the possible side effects of DAYBUE

As with any medication, it’s important to talk to your child’s doctor about the possibility of side effects with DAYBUE. Not every person will experience the same side effects; and for some people, certain side effects, such as diarrhea and vomiting, may be more severe than others.

Side effects may include:

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Diarrhea is a common side effect of DAYBUE that can sometimes be severe. Diarrhea may cause your child to lose too much water from their body (dehydration). Tell your doctor if your child has diarrhea while taking DAYBUE. Your doctor may ask you to increase the amount your child drinks or give antidiarrheal medicine as needed.

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Weight loss:

DAYBUE can cause weight loss. Tell your doctor if you notice your child is losing weight at any time during treatment with DAYBUE.

Information about diarrhea from the DAYBUE clinical studies:

  • More than 8 out of 10 patients (85%) treated with DAYBUE experienced diarrhea

  • In those treated with DAYBUE, almost 5 out of 10 (49%) had diarrhea that would not go away, or that came back after it had stopped, even when pausing DAYBUE treatment, reducing the amount of DAYBUE given, or using antidiarrheal medicine

  • Diarrhea was mild or moderate in more than 9 out of 10 cases (96%)

  • None of the patients in the clinical studies had to go to the hospital because of diarrhea

(the 12-week clinical trial):

  • 5 out of 10 patients (51%) treated with DAYBUE used antidiarrheal medication

  • Patients experienced diarrhea regardless of previous history of constipation

Learn about how to help manage possible side effects

Management guidance

Is DAYBUE right for your child?

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The DAYBUE Overview Brochure provides information about DAYBUE clinical trial results, safety facts, and helpful treatment tips.

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The DAYBUE Treatment Discussion Guide is a tool you can use to talk to your child’s doctor about DAYBUE.

Support by your side

Acadia Connect is a patient and family support program that connects you and your family with educational support and resources throughout the DAYBUE treatment journey.

Call 1-844-737-2223, MondayFriday, 8:00AM to 8:00PM ET to learn more about how Acadia Connect can provide you and your child with support throughout the DAYBUE treatment journey.

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