Stoke Therapeutics : Targeted Augmentation of Nuclear Gene Output (TANGO) of SCN1A Reduces Seizures and Rescues Parvalbumin Positive Interneuron Firing Frequency in a Mouse Model of Dravet Syndrome – Oral Presentation

Targeted Augmentation of Nuclear Gene Output (TANGO) of SCN1A Reduces Seizures and Rescues Parvalbumin- positive Interneuron Firing Frequency in a Mouse Model of Dravet Syndrome

Annual Meeting of the American Epilepsy Society

December 4-8, 2020

Eric R. Wengert

Graduate Student in the lab of Manoj K. Patel

Department of Anesthesiology

University of Virginia

Disclaimer

This presentation has been prepared by Stoke Therapeutics, Inc. ("Stoke" or "our") for informational purposes only and not for any other purpose. Nothing contained in this presentation is, or should be construed as, a recommendation, promise or representation by the presenter or Stoke or any officer, director, employee, agent or advisor of Stoke. This presentation does not purport to be all-inclusive or to contain all of the information you may desire. Information provided in this presentation speaks only as of the date hereof. Stoke assumes no obligation to publicly update any information or forward-looking statement, whether written or oral, that may be made from time to time, whether as a result of new information, future developments, subsequent events, or circumstances after the date hereof, or to reflect the occurrence of unanticipated events.

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Dravet Syndrome

• Severe developmental and epileptic encephalopathy
• Caused primarily by physiologically loss-of-functionSCN1A mutations resulting in hypofunction of inhibitory interneurons
• Patients suffer refractory seizures, cognitive and motor impairments, and have a substantial risk for SUDEP
• Demand for therapeutic strategies that directly address genetic cause of disease

TANGO (Targeted Augmentation of Nuclear Gene Output) May Be Used to Treat Dravet Syndrome

Source: Lim, K.H., Han, Z., Jeon, H.Y. et al. Antisense oligonucleotide modulation of non-productive alternative splicing upregulates gene expression. Nat

Commun 11, 3501 (2020).

© Copyright 2020 Stoke Therapeutics, Inc. All rights reserved; TANGO is proprietary to Stoke Therapeutics.

Approach to Evaluate the Impact of a Single Dose of STK-001 ASO Treatment

• Seizure Monitoring

• Parvalbumin-positiveInterneuron Excitability

STK-001 Administration Reduces Seizure Frequency in DS Mice

0 1 2 3 4 5

STK-001 Administration Improves Survival in DS Mice

STK-001 Treatment Rescues Parvalbumin-positive Interneuron Excitability in DS Mice (1)

DS PV interneurons are hypoexcitable

STK-001 Treatment Rescues Parvalbumin-positive Interneuron Excitability in DS Mice (2)

• DS PV interneurons are hypoexcitable

• STK-001 treatment rescues the firing frequency to WT levels

STK-001 Treatment Rescues Parvalbumin-positive Interneuron Excitability in DS Mice (3)

• DS PV interneurons are hypoexcitable

• STK-001 treatment rescues the firing frequency to WT levels

• Interestingly, treating WT with STK- 001 slightly altered PV interneuron firing frequencies at high current injections

Conclusions and Future Directions

• STK-001reduced seizure frequency and extended survival in DS mice with no significant deleterious effects observed in WT mice
• Treatment with STK-001 rescues neuronal excitability of parvalbumin-positive inhibitory interneurons in DS mice, which supports the hypothesis that restoration of excitability to inhibitory interneurons is a viable approach toward rescuing DS mice from seizures and death
• Potential future evaluations:
• • Collect electrophysiology recordings of voltage-gated sodium channel activity
  • Explore effects on other inhibitory interneuron populations (SST, VIP, etc.)
  • Examine impact on network excitability (synaptic inhibition, etc.)
• STK-001is currently being evaluated in patients with Dravet Syndrome

Acknowledgements

University of Virginia, Department of Anesthesiology

Manoj K. Patel

Pravin K. Wagley

Samantha M. Strohm

Nuha Reza

Ian C. Wenker

Ronald P. Gaykema

Stoke Therapeutics

Anne Christiansen

Zhou Han

Sophina Ji

Gene Liau

Membrane and Action Potential Properties

	Resting Membrane	Input resistance	Action Potential	Rheobase	Action Potential	Upstroke	Downstroke	APD50
	Velocity
	Potential (mV)	(MΩ)	Threshold (mV)	(pA)	Amplitude (mV)	Velocity (mV/ms)	(ms)
	(mV/ms)
WT	-68.9 ±1.4	110±6	-34±1	239±24	56±2	355±14#&^	-225±13#	0.37±0.03#
PBS
WT	-68.3±1.0	139±13&^	-36±1	168±19&	62±2&	290±13*	-158±10*^	0.55±0.02*^
STK-001
DS	-69.9±1.0	102±7#	-35±1	290±22#^	55±2#	299±11*	-197±10	0.46±0.05
PBS
DS	-67.2±0.9	103±5#	-37±1	214±21&	57±2	301±11*	-197±9#	0.41±0.02#
STK-001

* indicates significance p≤0.05 compared to WT PBS

• indicates significance p≤0.05 compared to WT STK-001 & indicates significance p≤0.05 compared to Dravet PBS
  ^ indicates significance p≤0.05 compared to Dravet STK-001