Genotype-Phenotype Correlation and Therapeutic Implications:

An mTOuR of Tuberous Sclerosis Complex and Epilepsy

Ajay Gupta, M.D.Head, Pediatric Epilepsy

Director, TSC ClinicProfessor, Department of Neurology

Cleveland Clinic Lerner School of MedicineCleveland Clinic

Objectives• Genotype-Phenotype Correlation of

epilepsy and comorbid Neuro-developmental disabilities in TSC and mTOR pathway epilepsies

• TSC therapeutics: Implications for Medical and surgical epilepsy treatment– mTOR drugs are FDA approved for other

TSC conditions – SEGA, Renal AML, Pulmonary LAM

TSC Natural History Database 2006

Study on Epilepsy

• N= 1657(1 month -81 years, median age 16 years)

Gupta A et al., Pediatric Neurology 2020

Gupta A et al., Pediatric Neurology 2020

TSC2 more frequent in epilepsy TSC2 more frequent in Infantile Spasms TSC2 more frequent in epilepsy onset< 2 years

Epilepsy onset <2 years: higher frequency of ID Epilepsy onset < 2 years: more severe ID (Trend) 23% had ID without epilepsy: all mild to moderate TSC 1 vs. 2: No difference in ID frequency Epilepsy had a significant effect on ID frequency

Gupta et al., Pediatric Neurology 2020

IQ Scores Correlation ToEpilepsy Onset Epilepsy Duration

Epilepsy onset age correlated to Low IQ scores Epilepsy duration DID NOT correlate to IQ scores Low IQ scores in TSC2>TSC1 but not a sginificant

differenceGupta et al., Pediatric Neurology 2020

Association of epilepsy and ASD in TSC (screened n=982)

P-value < 0.001

Frequency of ASD diagnosis was 23% in TSC ASD not diagnosed in any patient without epilepsy Higher ASD trend in TSC2 > TSC1 but not significant

Gupta et al., Pediatric Neurology 2020

Frequency of ASD in Epilepsy Onset< 2 year age < 5 year age

Frequency of ASD strongly associated with epilepsyonset < 2 years and < 5 years

TSC Genotype not significant, but trend towards TSC2

Gupta et al., Pediatric Neurology 2020

The study provided evidence that in TSC, Epilepsy is the

major driver of:• Intellectual disability (ID) • Autism spectrum disorder (ASD)• ADHD

Gupta et al., Pediatric Neurology 2020

TSC2 mutations are more frequent in epilepsy Epilepsy is major predictor of ID, ASD and ADHD ?Combined effect of TSC2 + Epilepsy

PTEN

TSC1 TSC2

Akt

PI3K

Ras

Nutrients

Protein Synthesis

4E-BP1

S6

S6K1elF-4E

mTOR

IGF-1R

Abl

Cell growth and proliferation

Cell orientation and migration

Angiogenesis Cell metabolism

Molecular Biology of TSC before 2010

Theoretically, mTORinhibitors could restore lost function in TSC patients

mTOR pathway is much more complex and involved in in Non-TSC partial epilepsies

Baldassari et al., J Med Genet 2016; 53: 503-5010

2019 - mTOR is a highly conserved signaling “hub” that integrates neuronal activity and a variety of synaptic inputs

mTORC2SirolimusinsensitivemTORC1

Sirolimussensitive

GATOR complex on mTORC1

mTORopathies And Refractory Focal Epilepsies

Nakashima et al., ANN NEUROL 2015;78:375–386

HMEG

• Study of epilepsy surgery: < 18 yr for FCD• 5/105 (~ 4%) had epilepsy due to a solitary

FCD but without other TSC MRI stigmata• Were later diagnosed with TSC

– TSC 2 (3/5) mutations– TSC 1 (1/5) mutations– 1/5 met diagnostic clinical criteria for TSC (no

mutation found on only TSC 1 sequencing)

Hirfanoglu & Gupta, Pediatr Neurol 2010; 42: 343-347

TSC MRI Phenotype of Solitary FCD

Hirfanoglu & Gupta, Pediatr Neurol2010; 42: 343-347

Suspect TSC if FCD:- Infantile

spasms/early onset epilepsy

- Ca++ in FCD- Familial epilepsy

TSC treatment of Epilepsy with Anti-seizure Drugs

• Infantile Spasms (not TSC specific FDA approval)– Vigabatrin (GABAergic drug) considered to

have better efficacy in TSC– ACTH (Complex Neuropeptide with

Adrenocorticotrophin hormonal effects)• TSC specific FDA approval

– Epidiolex (Cannabinoid receptors): Median reduction in frequency 48%; Responder rates > 50% seizures was 44% in pivotal trials

Therapeutic Implications BeyondTraditional ASDs

• Treatment with mTOR inhibitors - Yes• Prevention of epilepsy – in process• Refining epilepsy surgery - ?

– using PET ligands for unique pathology– MRI and Neurophysiological biomarkers

• Post-operative treatment to prevent seizure recurrence (residual regions)?

• Combination therapies?

Age 1.8-10.9 years, 139 screened, 23 recruited who completed the study, Funded: Dutch Epilepsy Foundation/TSC association

1 year study, Cross-over design: Sirolimus for 6 months added to AEDs – either during the 1st half or 2nd half of the 12 months study period

Overwater IE et al., Neurology 2016; 87: 1011-18

EXIST – 3 Everolimus Trial• A Placebo-controlled Study of Efficacy & Safety of 2

Trough-ranges of Everolimus as Adjunctive Therapy in Patients With TSC & Refractory Partial-onset Seizures (EXIST-3)

• > 2 year age• The study consists of 4 phases for each patient

– Baseline phase: Screening Week – 8 to Randomization visit at Week 0

– Core phase: randomization at Week 0 to Week 18– Extension phase: Week 18 until 48 weeks – Post Extension Phase

Lancet 2016; 388: 2153-63

Therapeutic Implications: EXIST 3 TRIAL

• Seizure efficacy: 12 weeks treatment– Responder rates: 28% (LT, 3-7ng/mL),

40% (HT, 9-15ng/mL) vs Placebo (15%) – Median % reduction: LT:HT:Placebo-

29%:39%:15%– Dose of Everolimus – 3-6mg/m2, increase

slowly for trough of 5-15 ng/mL• Common mTOR drug side effects

– Stomatitis, diarrhea, URIs, fever, cough, pneumonitis, rash

Lancet 2016; 388: 2153-63

Preventing epilepsy using VGBin infants with TSC

• Phase IIb prospective, randomized, placebo-controlled, double-blind clinical trial.

• Enrolled 80 infants with TSC who are < 6 months of age prior to the onset of their first seizure

• The primary outcome measure is cognitive assessment scores on the Bayley Scales of Infant and Toddler Development at 24 months.

NINDS funded

Epilepsy Surgery in TSC: SchoolsEpileptogenic Tuber/Region Localization

Scalp VEEG + MR tuber of interest (Usually most

dominant)

+ AMT PET +Grids)

SPECT + MEG +Grids/intraop

ECOG

Invasive

Phased surgery with use of intracranial

grids/strips

Noninvasive

FDG PET:MRI + DTI +MEG + Intraop ECOG

?SEEG

AMT-PET: TSC Epilepsy Surgery

Kagawa K et al., J Child Neurol, 2005

B & C: multifocal FDG PET

D & E: AMT PET

FDG PET

AMT PET

Ictal onset

N=18; 13 with adequate tuber sampling

Focal onset seizures in distantly located tubers Merit of SEEG over Intraop in such cases

Ostrowsky-Coste et al., 2018; 175: 163-182

TSC is a model of genetic epilepsy where treatmentadvances are being made based on the study ofpathobiology of the disease

THANK YOU