Evommune AHS presentation Role of MRGPRX2 in Migraine.pdf

Dual Inhibition of Meningeal Mast Cells and Trigeminal Neurons via MRGPRX2 Antagonism in Migraine

Greg Dussor, PhD
Professor, Department of Neuroscience
The University of Texas at Dallas

Disclosures

Last Two Years

Potential COI	Organization
Advisory Boards	Delphian Therapeutics
Speaker/Speakers Boards	n/a
Consultant	Evommune
Grant Support for Research or Education	NIH, Evommune, Association of Migraine Disorders
Editorial Board	PAIN, PAIN Reports,Molecular Pain,Journal of Pain,Journal of Neuroscience,The Journal of Headache and Pain
Author Royalties	n/a
Other	Co-founder:PARMedics,Ted and Greg's Stock ownership:Acadia Pharmaceuticals

Mast Cells are Hypothesized to Contribute to Migraine

Anatomical Relevance

• Abundant in meninges and perivascular spaces – regions
innervated by trigeminal neurons

Neuroimmune Communication

• Trigeminal neuropeptides (CGRP, PACAP, VIP, Substance P)
activate mast cells

Release Nociceptive Mediators

• Histamine, cytokines and proteases sensitize sensory neurons

Positive Feedback Loop

• Increasing and sustaining migraine pain

Translational Support

• Mast cell activation linked to migraine-like responses in animal
models and higher prevalence of headache in mastocytosis

Dynamic Cross-Talk Between Meningeal Mast Cells and Trigeminal Sensory Neurons

Dynamic Cross-Talk Between Anatomical Relevance

Trigeminal Sensory Neurons innervated by trigeminal neurons

Inflammatory
Mediators

Mast Cell

Trigeminal Sensory
Neuron

Neuropeptides

MRGPRX2

MRGPRX2: Positioned as a Key Mediator of the Interactions Between Mast Cells and Sensory Neurons in the Meninges

MRGPRX2 is Expressed on Both Meningeal Mast Cells Expression Confirmed in and Trigeminal Sensory Neurons Disease-Relevant Tissues

Meninges

Pia Dura Mater Mater

Trigeminal Neurons: Primary sensory neurons mediating migraine pain Trigeminal Ganglia MRGPRX2 nuclei

Meningeal Mast Cells: Perivascular cells in the dura responsive to PACAP, VIP, Arachnoid and Substance P Brain Mater Skull Trigeminal Meningeal Mast Cells Afferents

Source: Evommune internal data (trigeminal neurons; in situ hybridization on human tissue samples),

MRGPRX2 Ligands Induce Migraine Attacks in Humans

MRGPRX2 Ligands are Associated PACAP, VIP, Substance P Infusion with Migraine All Induce Migraine-Like Headache

Neuropeptides in Migraineurs
Substance P Peptides
PACAP 1-27 hormones
PACAP 1-38 Protein / Peptide100 Antimicrobial
PAMP-12 VIP fragments peptides
Vasopressin Dynorphin A Hemokinin-181 LL37 Neuropeptide FF MBP Exogenous
B-defensin 2 ECP75 71 Other
Cortistatin-14 Icatibant endogenous
B-defensin 3 Albumin Catestatin C48/8058 CXCL14 Codeine CXCL4 Ciprofloxacin 50

EVO756 25 10 5 MRGPRX20 PACAP VIP Substance P

Drug PBO Sensory neuron Mast Cell

Similar to CGRP, which induces migraine in ~2/3 patients
Red: Ligands associated with migraine

Note: Data shown from PACAP-38; PACAP-27 also induces migraine. Sources: Adapted from PMID19052139, PMID34357396,

PMID37009867, Al-Khazali et al., (2026). Note that there have been multiple studies inducing headache/migraine with ligands and experimental paradigms / results differed. Data shown represent cumulative observations pooled across multiple trials and cannot © Evommune, Inc. support definitive conclusions.

	Prophylaxis		PACAP Inhibition Achieves CGRP-Like Efficacy in Migraine
	Mean Change in	Bocunebart (IV) 0 -3 -6 -6.2	Lundbeck’s Bocunebart Reduced Monthly Migraine Days by ~2 Placebo -4.2	Second Neuropeptide Axis Validated in Migraine Prevention PACAP is a key neuropeptide trigger of migraine attacks Antibody blockade reduced migraine frequency in controlled clinical study
	•	Monthly Migraine Days -9 CGRP inhibitors	Magnitude of benefit consistent with marketed Note: Lundbeck’s bocunebart is a humanized mAb that neutralizes PACAP. Results above from Phase 2 a study in migraine	Effect size falls within range observed for approved CGRP therapies
6	© Evommune, Inc.		prophylaxis (HOPE; N=237; single IV administration of bocunebart in patients that were a mix of episodic and chronic migraineurs). Source: Clinicaltrials.gov NCT05133323. Direct comparisons cannot be made in the absence of head-to-head trials because of differences in trial design, patient population and other factors.

Receptor(s) PACAP Engages to Induce Migraine Not Yet Clear

PACAP May Be Triggering Migraine
Through MRGPRX2

PACAP

MRGPRX2

VPAC1 VPAC2

PACAP Receptor	Relevant Tissue Expression	Clinical Validation In Migraine?
PAC1	Neurons¹	X
VPAC1 VPAC2	Cranial Vessels Neurons(?)	Not evaluated
MRGPRX2	Mast Cells Sensory Neurons	TBD

PACAP Causes Migraine-Like Behavior via MRGPRB2 1 as

1 PACAP Causes Migraine-Like Behavior via MRGPRB2 as Primary Receptor in vivo in Mice

Knockout of MRGPRX2 1 Reduced

MRGPRX2 Ligand PACAP

Induces Headache in vivo

1 PACAP injected directly onto
meninges of wild type and
knockout models

2 Facial withdrawal threshold
used as functional pain readout

1
Knockout of MRGPRX2 Reduced
PACAP-Induced Migraine Symptoms

1
• in vivo data support functional role of MRGPRX2 signaling
in migraine

MRGPRX2 is Expressed in Human Sensory Neurons: Greater in TG

Targeting MRGPRX2 in Neurons Could Provide Greater Benefit Over Targeting Only in Mast Cells

MRGPRX2 is Expressed by 25% of DRG Neurons

Dorsal root ganglia:
sensory neurons
nuclei

MRGPRX2 is Expressed by >50% of TG Neurons

MRGPRX2+/SCN10A+
MRGPRX2+/SCN10A-
MRGPRX2-SCN10A+
MRGPRX2-/SCN10A-

EVO756: Small Molecule Potently (low nM) Inhibits PACAP, Substance P, and VIP-Induced MRGPRX2 Activation in vitro

EVO756 Inhibits Migraine Relevant
Endogenous Ligands in X2-CHO Cells

PACAP 1-27 Concentration: 120 90

EVO756 Inhibits PACAP and SP-Induced
Primary Human Mast Cell Activation in vitro

PACAP 1-27 Concentration:
5 µM (~EC80)
CD107a IC50: 25.8 nM
CD63 IC50: 16.7 nM

SP Concentration:
30 µM (>EC80)
CD107a IC50: 38.3 nM
CD63 IC50: 42.2 nM

EVO756 Prevents Human DRG Sensory Neurons Activation

Targeting MRGPRX2 in Neurons Could Lead to Reduction in Neurogenic Inflammation and Itch/Pain Relief

Functional Calcium Mobilization System for Neuronal Activation

Tissue Bath

Icatibant

Positive Control (KCl)

Calcium Imaging Reveals that MRGPRX2 in Neurons is Active, and Its Activity Can be Blocked by EVO756

Neuronal
Activation in
Response to
ECP

Neuronal
Inhibition
by EVO756

EVO756 is Distributed in Migraine-Relevant Tissues

Sensory Neurons and Mast Cells are Present in Tissues Critical for Migraine Pathophysiology

With Perfusion
80 Dorsal Root Ganglia
Trigeminal Ganglia
Cranial Meninges

%EVO756
40 Skin:plasma Reference range % EVO756
20 (g tissue/mL plasma)

Hours Post Dosing

Skin: Plasma reference range used is from tissue distribution imaging study of radiolabeled 10mg/kg © Evommune, Inc. EVO756 in rats

MRGPRX2 Inhibition: a Promising New Direction in Migraine Therapy

• Multiple migraine triggers converge on MRGPRX2
— PACAP, VIP, and Substance P are all MRGPRX2
agonists

• MRGPRX2 positioned at the neuroimmune interface
— expressed on meningeal mast cells and >50% of
trigeminal neurons

• Preclinical support for a causal role in migraine —
PACAP-induced headache behavior attenuated in
MrgprB2 knockout mice

EVO756 MrgprB2 knockout mice

• EVO756 delivers differentiated dual inhibition —
blocks both mast cell degranulation and trigeminal
neuron activation, with delivery into migraine-relevant
tissues

• EVO756 is advancing toward Phase 2b as a
differentiated non-CGRP migraine therapeutic

EVO756 Interrupts the Migraine
Neuroimmune Circuit

Acknowledgements

evommune

• Amanda Jacobson

• Sreya Bagchi

• Lorena Riol-Blanco

• Grant support from
Evommune to UT Dallas

• Shiva Nematgorgani

• Jane Brandon

• Keerthana Nataranjan

• Ishwarya
Sankaranarayanan

• Joseph Lesnak

• Theodore Price