Exploring Novel Treatments for Rett Syndrome

This slide deck, led by Timothy John Feyma, MD, Pediatric Neurologist at Gilette Children’s Hospital, will explore novel treatments and quality-of-life improvement strategies for children and adults with Rett syndrome. 

STATEMENT OF NEED

Rett syndrome is a rare, debilitating neurodevelopmental disorder almost always associated with a spontaneous mutation in the methyl-CpG-binding protein 2 (MECP2) gene on the X-chromosome. Affected individuals experience loss of purposeful hand skills, abnormalities in gait, loss of spoken language, and stereotypic hand movements, with more severe manifestations including seizures, autistic features, autonomic nervous system dysfunction, breathing abnormalities, sleep disturbances, and cardiac abnormalities. While therapies for Rett syndrome are being investigated in clinical trials and have demonstrated modest benefit, no curative or effective disease-modifying treatments currently exist (Petriti et al, 2023). Therefore, the multidisciplinary team is challenged with the optimal management of complex comorbidities that persist throughout patients’ lives. This activity chaired by Timothy John Feyma, MD, Pediatric Neurologist at Gilette Children’s Hospital, will explore novel treatments and quality-of-life improvement strategies for children and adults with Rett syndrome.

TARGET AUDIENCE

Pediatric and adult neurologists, pediatricians, internists, family physicians, child and adult psychiatrists, nurse practitioners, physician assistants, nurses, and other health care professionals involved in the treatment of children and adults with Rett syndrome.

LEARNING OBJECTIVES

Upon completion of this activity, participants should be able to

Identify distinguishing features of Rett syndrome that can inform early and accurate diagnosis
Evaluate the safety, efficacy, and clinical utility of novel and emerging treatments for Rett syndrome in children and adults
Devise strategies to monitor and manage Rett syndrome symptoms in children and adults

1. Exploring Novel Treatments for Rett Syndrome Timothy John Feyma, MD Pediatric Neurologist Gillette Children’s Hospital

2. Disclosures Speaker’s bureau: Acadia Pharmaceuticals, PTC Therapeutics Grants/research support: Acadia Pharmaceuticals, Ionis, Neuren, PTC Therapeutics i3 Health has mitigated all relevant financial relationships

3. Learning Objectives Identify distinguishing features of Rett syndrome that can inform early and accurate diagnosis Evaluate the safety, efficacy, and clinical utility of novel and emerging treatments for Rett syndrome in children and adults Devise strategies to monitor and manage Rett syndrome symptoms in children and adults

4. Exploring Novel Treatments in Rett Syndrome What is Rett syndrome? History Diagnostic criteria Pathophysiology Epidemiology Monitoring and managing Rett syndrome What would the ideal care team look like? Novel and emerging t herapies Case studies Questions? Agenda

5. What Is Rett Syndrome?

6. What Is Rett Syndrome? Rett et al, 1966; Hagberg et al, 1983; Kyle et al, 2021. Initial recognition of a pattern: Andreas Rett published the first report in 1966 on females with early onset of developmental delay and regression, loss of communication and fine motor skills, developing stereotypic hand movements, and periodic breathing Bengt Hagberg simultaneously began collecting a case series of similar patients, and with increasing numbers, was able to publish his study in 1983, giving credit to Dr. Rett eponymously as he was first to publish on this matter

7. “Classic” Rett Syndrome Historical Overview Kyle et al, 2021. Progressive neurodevelopmental disorder primarily affecting girls Apparently normal development during the first 6-18 months of life Regression/hand stereotypies/language loss at 1-3 years of age, lasting weeks to months “Stationary” phase at 2-10 years with seizures, abnormal development, scoliosis, respiratory abnormalities Late deterioration at 10+ years with worsening global function and neurologic decline

8. Rett Syndrome Diagnostic Criteria First criteria published in 1984, updated in 2002, and updated again in 2010 Neul et al, 2010.

9. Rett Syndrome Diagnostic Criteria 2010 Neul et al, 2010. Rett Syndrome Diagnostic Criteria 2010 Consider diagnosis when postnatal deceleration of head growth observed Required for typical or classic Rett syndrome A period of regression followed by recovery or stabilization All main criteria and all exclusion criteria Supportive criteria are not required, although often present in typical Rett syndrome Required for atypical or variant Rett syndrome A period of regression followed by recovery or stabilization At least 2 of the the 4 main criteria 5/11 supportive criteria Main Criteria Partial or complete loss of acquired purposeful hand skills Partial or complete loss of acquired spoken language Gait abnormalities: impaired (dyspraxic) or absence of ability Stereotypic hand movements such as hand wringing/squeezing, clapping/tapping, mouthing and washing/rubbing automatisms Exclusion Criteria for Typical Rett Syndrome Brain injury secondary to trauma (peri- or postnatally), neurometabolic disease, or severe infection that causes neurological problems Grossly abnormal psychomotor development in first 6 months of life Supportive Criteria for Atypical Rett Syndrome Breathing disturbances when awake Bruxism when awake Impaired sleep pattern Abnormal muscle tone Peripheral vasomotor disturbances Scoliosis/kyphosis Growth retardation Small cold hands and feet Inappropriate laughing/screaming spells Diminished response to pain Intense eye communication - “eye pointing”

10. Variant Forms of Rett Syndrome IQ = intelligence quotient; MECP2 = methyl-CpG binding protein 2; CDKL5 = cyclin-dependent kinase-like 5; FOXG1 = forkhead box G1. Neul et al, 2010. Variant forms of Rett Syndrome Meets criteria for atypical Rett syndrome Assess for presence of clinical features of defined variant forms Preserved Speech Variant (Zapella Variant) Clinical Features Regression of 1-3 years, prolonged plateau phase Milder reduction of hand skills Better retained hand use Recovery of language after regression Mean age of recovery is 5 years Single words or phrases Milder intellectual disability (IQ up to 50) Autistic behaviors common Decreased frequency of typical Rett features Rare epilepsy Rare autonomic dysfunction Milder scoliosis and kyphosis Normal head circumference Normal height and weight in most Molecular Genetics Mutations in MECP2 found in the majority of cases Early Seizure Variant (Hanefeld Variant) Clinical Features Early onset of seizures Before 5 months of life Infantile spasms Refractory myoclonic epilepsy Seizure onset before regression Decreased frequency of typical Rett features Molecular Genetics Mutations in MECP2 rarely found Analysis for mutations in CDKL5 should be performed Congenital Variant (Rolando Variant) Clinical Features Grossly abnormal initial development Severe psychomotor delay Inability to walk Severe postnatal microcephaly before 4 months Regression in first 5 months Lack of typical intense “Rett” eye gaze Typical Rett autonomic abnormalities present Small cold hands and feed Peripheral vasomotor disturbances Breathing abnormalities while awake Specific movement abnormalities Tongue stereotypes Jerky movements of the limbs Molecular Genetics Mutations in MECP2 rarely found Analysis for mutations in FOXG1 should be performed

11. Role of Genetic Testing International Rett Syndrome Foundation, 2023. Not needed for diagnosis Simple blood test can confirm clinical diagnosis Can provide information about specific mutations Needed for patient to be eligible for clinical trials and natural history studies Diagnosis of Rett Syndrome

12. Rett Syndrome and MECP2 Amir et al, 1999. Image credit: Andreas Bolzer , Gregor Kreth, Irina Solovei, Daniela Koehler, Kaan Saracoglu , Christine Fauth , Stefan Müller, Roland Eils , Christoph Cremer, Michael R. Speicher, Thomas Cremer.

13. Rett Syndrome and MECP2 (cont.) RNA = ribonucleic acid; BDNF = brain-derived neurotrophic factor. Tillotson et al, 2017; Tropea et al, 2009. MECP2 Encodes protein that is involved in regulating gene expression and implicated in diverse cellular processes based on its reported interaction with >40 binding partners, including transcriptional co-repressors, transcriptional activators, RNA, regulators of BDNF production, chromatin remodelers, microRNA-processing proteins, and splicing factors A multifunctional hub which integrates diverse processes that are essential in mature neurons Alteration in MECP2 thus impacts the expression of other genes that are not mutated! Although the brain seems to be the primarily affected site, not all target genes are known

14. MECP2 Rett Syndrome and MECP2 (cont.) Image courtesy of Oakland Symphony.

15. Rett Syndrome and X Inactivation X inactivation complicates things a bit too… Percy, 2016.

16. Rett Syndrome Overview: Summary Neul et al, 2010. The clinical diagnosis of Rett syndrome has been based on consensus clinical criteria Presence of an MECP2 pathogenic variant is not required for typical or atypical Rett syndrome diagnosis Key Points

17. Rett Syndrome Epidemiology There are an e stimated 6,000-9,000 individuals living with Rett syndrome in the US Median age of diagnosis is around 3 years of age More than 70% of individuals with Rett syndrome may live to age 45 Rett syndrome is associated with spontaneous pathogenic variants (mutations) in MECP2 on the X chromosome that are subject to X chromosome inactivation Kaur et al, 2001; Tarquinio et al, 2015b; Tarquinio et al, 2015a; Good et al, 2021; Vanderbilt University Medical Center, 2023.

18. Monitoring and Managing Rett Syndrome

19. Rett Natural History Study Neul, Benke et al, 2023; Stallworth et al, 2019. A substantial amount of what we know about Rett is derived from the Rett Natural History Study that was run from 2006-2021 Principal investigators: Alan Percy, MD, and Jeff Neul, MD, PhD >1,200 individuals with Rett syndrome (clinically and/or genetically diagnosed), CDKL5, FOXG1, and those with MECP2 mutations/duplications (male or female) that do not meet criteria for classical Rett syndrome

20. Rett Syndrome Comorbidities Fu et al, 2020b. Rett is still primarily a brain-based disease with far-reaching comorbidities Neurologic (prevalence %): Breathing abnormality (95%) Epilepsy (90%) Sleep dysfunction (80%-93%) Movement disorders (63%-84%) Behavioral issues (97%, 14% on med, Rett spells?)

21. Rett Syndrome Comorbidities (cont.) Tarquinio et al, 2017. Epilepsy (90%)

22. Rett Syndrome Comorbidities (cont.) Fu et al, 2020b. Rett is still primarily a brain-based disease with far-reaching comorbidities Cardiac (prevalence %): Prolonged QT interval (10%-18%) Gastrointestinal (GI): Constipation (80%) Reflux (40%) Growth abnormalities (40%) Endocrine: Puberty chronology changes (19%-28%) Low bone density (59%) Orthopedic: Scoliosis (80%) Hip displacement (50%) Fractures (28%-32%)

23. Rett Syndrome Treatment Fu et al, 2020a; Fu et al, 2020b. Most treatment is supportive and aimed at symptoms Therapies/adaptive needs Epilepsy Sleep Movement disorders Behaviors Autonomic

24. Rett Syndrome Caregiver Concerns Neul, Benke et al, 2023; RSRT and IRSF, 2022. What are the caregivers concerned about? 3/11/22 meeting US Natural History Study Data “It’s hard to pinpoint the top 1-3 concerns, as our child has about 10 major issues that change in ranking based on the day, week, month, from pervasive gross and fine motor impairment, non-verbal, hypotonia, uncontrolled epilepsy, dysphagia, dystonia, osteopenia, sleep issues, underactive and withdrawn affect, sensory processing delays, incontinence… and more” k ~ Paige N, comment submitted online Top 3 Most Troublesome Rett Syndrome–Related Health Concerns

25. What Would the Ideal Care Team Look Like? PT = physical therapy; OT = occupational therapy; ST = speech therapy. Slide courtesy of Timothy John Feyma, MD. Coordination of multidisciplinary care is essential, with needs that may involve: Physical medicine and rehabilitation Pulmonology Pediatrics Neurology Orthopedics Gastroenterology Cardiology Sleep medicine Therapeutic disciplines (PT/OT/ST) Supportive Care for Rett Syndrome

26. Resources for Patients and Caregivers Genetic and Rare Diseases (GARD) Information Center Phone: [phone] International Rett Syndrome Foundation Phone: [phone] or 800-818-7388 National Institute of Child Health and Human Development (NICHD) Phone: [phone] National Institute of Mental Health (NIMH) Phone: [phone] or 866-415-8051 or 301-443-8431 National Organization for Rare Disorders (NORD) Phone: [phone] or 800-999-6673 Spanish: 844-259-7178 Rett Syndrome Research Trust https:// reverserett.org Supportive Care for Rett Syndrome NINDS, 2023.

27. Novel and Emerging Therapies

28. Novel and Emerging Therapies Collins et al, 2022. Most treatment is supportive and aimed at Rett symptoms, but emerging and novel therapies are progressing Brain-derived neurotrophic factor upregulation Fingolimod (failed) Ketamine MECP2 function restoration: Gene therapy X chromosome reactivation Genome editing RNA editing Antisense oligonucleotides in MECP2 duplication

29. Trofinetide for Rett Syndrome Collins et al, 2022; Neul, Percy et al, 2023. Mimic of insulin-like growth factor 1 as its tripeptide metabolite glycine-proline-glutamate (GPE): trofinetide Benefits neuronal survival and maturation through overlapping signaling pathways Crosses the blood-brain barrier Approved for the treatment of Rett syndrome in adults and pediatric patients 2 years of age and older

30. Trofinetide for Rett Syndrome (con t.) Neul, Percy et al, 2023. Randomized Phase 3 Study Participants screened n=208 All randomized participants n=187 Completed study n=70 Completed study n=85 Discontinued study: n=9 Adverse event: n=2 Protocol deviation: n=1 Withdraw consent: n=1 Other (COVID-19 quarantine measures): n=5 Discontinued study: n=23 Adverse event: n=16 Lack of efficacy: n=1 Noncompliance with study drug: n=4 Withdraw consent: n=1 Other (COVID-19 quarantine measures): n=1 Screening failures: n=40 Not meeting inclusion criteria: n=8 Meeting exclusion criteria: n=17 Withdrew consent: n=2 Other: n=13 Trofinetide n=93 Placebo n=94 Safety analysis (n=187; trofinetide n=93 and placebo n=93) Full analysis set (n=184; trofinetide n=91 and placebo n=93) Per-protocol set (n=179; trofinetide n=89 and placebo n=90)

31. Trofinetide for Rett Syndrome (cont.) Neul, Percy et al, 2023. Rett Syndrome Behaviour Questionnaire (RSBQ) total score Caregiver-completed Change from baseline to Week 12 45-item rating scale assesses range of symptoms of Rett Lowering score = less symptoms/improvement Clinical Global Impression-Improvement (CGI-I) Clinician-completed Score at Week 12 assesses improvement or worsening of patient’s illness as a whole 7-point Likert scale relative to baseline Lowering score = less symptoms/improvement Symptom Improvement

32. Trofinetide for Rett Syndrome (cont.) Neul, Percy et al, 2023. Symptom Improvement

33. Trofinetide for Rett Syndrome (cont.) Neul JL Nature Med 2023 Randomized Phase 3 Study

34. Trofinetide for Rett Syndrome (cont.) Neul, Percy et al, 2023. Adverse Events Trofinetide (n=93) Placebo (n=94) Diarrhea 81% 19% Vomiting 27% 10% Seizure 5% 9% Pyrexia 9% 4% Decreased appetite 5% 2% Irritability 7% - Adverse Events

35. Trofinetide for Rett Syndrome (cont.) Neul, Percy et al, 2023; Daybue TM prescribing information, 2023. Tips: GI management is key Full doses are prescribed, but individual physicians may adjust dose to tolerability Patient Weight Trofinetide Dosage Trofinetide Volume 9 kg to <12 kg 5,000 mg twice daily 25 mL twice daily 12 kg to <20 kg 6,000 mg twice daily 30 mL twice daily 20 kg to <35 kg 8,000 mg twice daily 40 mL twice daily 35 kg to <50 kg 10,000 mg twice daily 50 mL twice daily ≥50 kg 12,000 mg twice daily 60 mL twice daily Dosage and Management

36. Case Studies

37. Case Study 1: JE Slide courtesy of Timothy John Feyma, MD. First seen at our clinic in 1999 at 1 year and 10 months, with developmental regression and parental concern for Rett syndrome Unremarkable pregnancy with term delivery Previously: Rolled at 5 months Sat at 7 months Crawled + 3 words at 9 months At 21 months, not walking but could pull to stand until then Began to hand wring, lost hand acquisition of toys, and lost ability to pull to stand 26-Year-Old

38. Case Study 1: JE (cont.) MRI = magnetic resonance imaging. Slide courtesy of Timothy John Feyma, MD. At 2 years and 3 months, had completed MRI brain, Prader-Willi syndrome, Angelmann syndrome, Fragile X studies, and karyotype Family came to clinic asking about “testing for Rett syndrome, specifically interested in a new DNA test developed at Baylor College of Medicine” 26-Year-Old

39. Case Study 1: JE (cont.) Slide courtesy of Timothy John Feyma, MD. 26-Year-Old Over time, major issues have included: Kidney stones Neuromuscular scoliosis—repaired Gastrostomy tube (08/29/2022) Cholecystectomy Epilepsy Static development

40. Case Study 1: JE (cont.) Slide courtesy of Timothy John Feyma, MD. 26-Year-Old Epilepsy has been tough to control on current monotherapy with lamotrigine, yet a history of meds trials including: Medical cannabis through the State of Minnesota program Valproate, which did not control seizures and caused hair loss Oxcarbazepine, which did not control seizures despite being optimized Topiramate, which did not control seizures despite being optimized Levetiracetam, which did not work after it was optimized Rufinamide, which disrupted sleep and caused poor appetite issues and did not control seizures. Could not be optimized because of side effects Clobazam, which did not control seizures and caused worsening urinary retention  Cenobamate , which worsened seizures

41. Case Study 1: JE (cont.) Slide courtesy of Timothy John Feyma, MD. 26-Year-Old

42. Case Study 1: JE (cont.) Slide courtesy of Timothy John Feyma, MD. 26-Year-Old

43. Case Study 2: SY EEG = electroencephalogram. Slide courtesy of Timothy John Feyma, MD. Born at term after uncomplicated pregnancy M ilestones were delayed from the first year of life  Crawled at 13 months Walked at 2 years of age Minimal verbal development. Her vocalizations are minimal Normal MRI at 17 months of age Normal EEG at 20 months of age Whole exome sequencing at 23 months of age: 5-Year-Old

44. Case Study 2: SY (cont.) Slide courtesy of Timothy John Feyma, MD. Over time, major issues have included: Formal diagnosis of classical Rett syndrome Continued slow development Epilepsy controlled on levetiracetam/lamotrigine Trofinetide trial 5-Year-Old

45. Case Study 2: SY (cont.) Slide courtesy of Timothy John Feyma, MD. On trofinetide: More hand use Better attention More non-verbal communication Better gross motor coordination Currently SY claps her hands pretty much all the time while she is awake

46. Key Takeaways Rett syndrome is still a clinical diagnosis, but most often due to an X-linked genetic disorder that is a cause of developmental regression and lifelong neurologic impairment Rett syndrome patients require a multidisciplinary team to manage the many manifestations that Rett can present with, as shown in the Natural History study While many treatments are being developed and on the horizon, trofinetide is the only FDA-approved treatment specifically for Rett syndrome

47. Questions?

48. References Amir RE, Van den Veyver IB, Wan M, et al (1999). Rett syndrome is caused by mutations in X-linked MECP2, encoding methyl-CpG-binding protein 2. Nat Genet, 23(2):185-8. DOI:10.1038/13810 Burbank K (2021). Oakland Symphony conductor Michael Morgan dies at 63. Available at: https://www.sfgate.com/news/ bayarea /article/Oakland-Symphony-Conductor-Michael-Morgan-Dies-At-16402367.php Collins BE & Neul JL (2022). Rett syndrome and MECP2 duplication syndrome: disorders of MeCP2 dosage. Neuropsychiatr Dis Treat, 2022(18):2813-2835 DOI:10.2147/NDT.S371483 Daybue TM (trofinetide) prescribing information (2023). Acadia Pharmaceuticals, Inc. Available at: https:// daybuehcp.com / daybue-pi.pdf Fu C, Armstrong D, Marsh E, et al (2020a). Consensus guidelines on managing Rett syndrome across the lifespan. BMJ Paediatr Open, 4(1):e000717. DOI:10.1136/bjmpo-2020-000717 Fu C, Armstrong D, Marsh E, et al (2020b). Multisystem comorbidities in classic Rett syndrome: a scoping review. BMJ Paediatr Open, 4(1):e000731; DOI:10.1136/bmjpo-2020-000731 Good KV, Vincent JB & Ausio J (2021). MECP2: the genetic driver of Rett syndrome epigenetics. Front Genet, 12:620859. DOI:10.3389/fgene.2021.620859 Hagberg B, Aicardi J, Dias K & Ramos O (1983). A progressive syndrome of autism, dementia, ataxia, and loss of purposeful hand use in girls: Rett’s syndrome: report of 35 cases. Ann Neurol, 14(4):471-479. DOI:10.1002/ana.410140412 International Rett Syndrome Foundation (2023). Rett syndrome diagnosis. Available at: https:// www.rettsyndrome.org /about- rett -syndrome/ rett -syndrome-diagnosis/ Kaur S, Christodoulou J, Adam MP, et al (2001). MECP2 disorders. GeneReviews ® [Internet]. Seattle (WA): University of Washington, Seattle; 1993 [updated]. PMID:20301670 Kyle SM, Vashi N & Justice MJ (2018). Rett syndrome: a neurological disorder with metabolic components. Open Biol, 8(2):170216. DOI:10.1098/rsob.170216 National Institute of Neurological Disorders and Stroke (2023). Rett syndrome. Available at: https:// www.ninds.nih.gov /health-information/disorders/rett-syndrome#toc-how-can-i-or-my-loved-one-help-improve-care-for-people-with-rett-syndrome- Neul JL, Benke TA, Marsh ED, et al (2023). Top caregiver concerns in Rett syndrome and related disorders: data from the US Natural History Study. Res Sq. [Preprint] DOI:10.21203/rs.3.rs-2566253/v1 Neul JL, Kaufmann WE, Glaze DG, et al (2010). Rett syndrome: revised diagnostic criteria and nomenclature. Ann Neurol, 68(6):944-950. DOI:10.1002/ana.22124 Neul JL, Percy AK, Benke TA, et al (2023). Trofinetide for the treatment of Rett syndrome: a randomized phase 3 study. Nat Med, 29(6):1468-1475. DOI:10.1038/s41591-023-02398-1 Percy AK (2016). Progress in Rett syndrome: from discovery to clinical trials. Wien Med Wochenschr , 166(11):325-332. DOI:10.1007/s10354-016-0491-9 Rett A (1966). On an unusual brain atrophy syndrome in hyperammonemia in childhood. Wein Med Wochenschr , 116(37):723-726.