# 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), © Evommune, Inc. PMID40712576 (meningeal mast cells) --- # 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 / Peptide**100 **Antimicrobial** PAMP-12 VIP **fragments** **peptides** Vasopressin Dynorphin A Hemokinin-1**81** LL37 Neuropeptide FF MBP **Exogenous** B-defensin 2 ECP75 **71** **Other** Cortistatin-14 Icatibant **endogenous** B-defensin 3 Albumin Catestatin C48/80**58** CXCL14 Codeine CXCL4 Ciprofloxacin 50 **EVO756** 25 **10** **5** **MRGPRX2**0 **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**