GH Research PLC (NASDAQ: GHRS) January 2024 Corporate Presentation 1 This presentation has been prepared by GH Research PLC ("GH Research") for informational purposes only and not for any other purpose. Nothing contained

GH Research PLC (NASDAQ: GHRS) January 2024 Corporate Presentation 1

This presentation has been prepared by GH Research PLC ("GH Research") 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 GH Research or any director, employee, agent, or

adviser of GH Research. This presentation does not purport to be all-inclusive or to contain all of the information you may desire. This presentation does not constitute an offer to sell or the solicitation of an offer to buy securities, nor

shall there be any sale of these securities in any state or jurisdiction in which such offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction. This

presentation contains forward-looking statements, all of which are qualified in their entirety by this cautionary statement. Many of the forward-looking statements contained herein can be identified by the use of forward-looking words such as

"may", "anticipate", "believe", "could", "expect", "should", "plan", "intend", "estimate", "will", "potential" and "ongoing", among others, although not all forward-looking statements contain these identifying words. Any statements contained

herein that do not describe historical facts are forward-looking statements that are based on management's expectations and are subject to certain factors, risks and uncertainties that may cause actual results, outcomes, timing and

performance to differ materially from those expressed or implied by such statements. These factors, risks and uncertainties include, but are not limited to: the costs and uncertainties associated with GH Research's research and development

efforts; the inherent uncertainties associated with the conduct, timing and results of nonclinical and clinical studies of GH Research's product candidates; GH Research's expectations related to the clinical hold on the GH001 IND, including

plans and expectations for progressing any nonclinical programs and any other work to lift the clinical hold, the timing required to lift such clinical hold and for discussions with the FDA and the outcomes and resolution of such discussions;

GH Research's ability to obtain, maintain, enforce and defend issued patents; the adequacy of GH Research's capital resources, the availability of additional funding and GH Research's cash runway; and other factors, risks and uncertainties

described in GH Research's filings with the U.S. Securities and Exchange Commission. Except as otherwise noted, these forward-looking statements speak only as of the date of this presentation, and GH Research undertakes no obligation to

update or revise any of such statements to reflect events or circumstances occurring after this presentation. Because forward-looking statements are inherently subject to risks and uncertainties, some of which cannot be predicted or

quantified and some of which are beyond GH Research's control, you should not rely on these forward-looking statements as predictions of future events. The events and circumstances reflected in any such forward-looking statements may not be

achieved or occur and actual results could differ materially from those projected in the forward-looking statements. GH Research cautions you not to place undue reliance on the forward-looking statements contained in this

presentation. Disclaimer Regarding Forward-Looking Statements 2

SeekingUltra-Rapid, Durable Remissionsin Depression 3

Stage of Development PROGRAMS INDICATION PRECLINICAL PHASE 1 PHASE 2a PHASE

2b PHASE 3 CURRENT STATUS GH001Mebufotenin (5-MeO-DMT)for inhalation administration Treatment-Resistant Depression (TRD) Phase 2b RDBPC trial initiated(GH001-TRD-201) Bipolar II Disorder* (BDII) Phase 2a POC trial

initiated(GH001-BD-202) Postpartum Depression (PPD) Phase 2a POC trial initiated(GH001-PPD-203) GH002Mebufotenin (5-MeO-DMT) for i.v. administration Psychiatric or Neurological Disorder Phase 1 HV trial

completed(GH002-HV-105) GH003Mebufotenin (5-MeO-DMT) for nasal administration Psychiatric or Neurological Disorder Pre-clinical development ongoing 4 Complete Ongoing *Bipolar II disorder with a current major depressive

episode 5-MeO-DMT, 5-Methoxy-N,N-Dimethyltryptamine; i.v., intravenous; RDBPC, Randomized, Double-Blind, Placebo-Controlled; POC, Proof-of-Concept; HV, Healthy Volunteer Pipeline

The Problem for Patients with Depression Established Therapies are

Slow-Acting ... Remission Rates in TRD < 15% 5 (STARD study, Remission Rate Over Time, Treatment Step 1 = Citalopram) (STARD study, Remission Rates Treatment Steps 1 to 4) Average time to remission is ~6 weeks ~33% no remission

despite 4 treatment steps 2 or more prior therapies = TRD Adapted from Trivedi et al., Am J Psychiatry 2006 and Rush et al., Am J Psychiatry 2006 TRD, Treatment-Resistant Depression

First Line MDD Second Line MDD Treatment-Resistant Depression (TRD) Patients

cycle through ineffective therapies for TRD Diagnosed: ~48M Treated (pharmacotherapy psychotherapy): ~24M Non-response to first line: ~13M Non-response to two prior lines: ~9M Large and Open Depression Market in the EU and

US 6 Company estimates based on: https://www.nimh.nih.gov/health/statistics/major-depression.shtml; Wittchen et al., The size and burden of mental disorders and other disorders of the brain in Europe 2010, European Neuropsychopharmacology

(2011); Rush et al., Acute and Longer-Term Outcomes in Depressed Outpatients Requiring One or Several Treatment Steps: A STAR*D Report, Am J Psychiatry 2006MDD, Major Depressive Disorder

Mebufotenin (5-MeO-DMT) and GH001 7 Mebufotenin

(5-Methoxy-N,N-Dimethyltryptamine, 5-MeO-DMT) Naturally-occurring psychoactive substance from tryptamine class Highly potent agonist on 5-HT1A and 5-HT2A receptors GH001 (Mebufotenin administration via a proprietary pulmonary inhalation

approach) Psychoactive effects with ultra-rapid onset (within seconds) and short duration (5 to 30 min) High propensity to induce peak experiences (PE), which may be a surrogate marker for therapeutic effects Intraday individualized dosing

regimen (IDR) for maximization of ultra-rapid and durable remissions Single visit initial treatment, with no structured psychotherapy Potential for convenient and infrequent retreatment Mebufotenin (5-MeO-DMT) Foundational IP

GH001 - Individualized Dosing Regimen (IDR) for Maximization of Ultra-Rapid and

Durable Remissions 8 GH001 Single Dose: Inter-Person Variability GH001 Individualized Dosing Regimen (IDR):Maximization of Ultra-Rapid and Durable Remissions MADRS score MADRS score MADRS score MADRS score Dose 1 Dose 1 Dose

2 Dose 3 Dose 2 Dose 1 No remission Remission Remission Remission Remission Hypothetical Patient 1 Hypothetical Patient 2 Hypothetical Patient 3 Hypothetical Patient 1 Hypothetical Patient 2 No remission No

remission No remission Dose 1 MADRS score Dose 1 MADRS, Montgomery- sberg Depression Rating Scale

Phase 1 Trial in Healthy Volunteers

GH001-HV-101 9 (Completed) Clinicaltrials.gov ID: NCT04640831

Design of Phase 1 Trial in Healthy Volunteers (GH001-HV-101) 10 GH001 2 mg

(n=4) GH001 6 mg (n=6) GH001 12 mg (n=4) GH001 18 mg (n=4) HV (n=18) Part A (Single Dose) Primary Endpoint: Safety until day 7 Peak Experience Scale (PE Scale)1 Part B (IDR) HV (n=4) Primary Endpoint: Safety until day 7 Peak

Experience Scale (PE Scale)1 GH001 IDR6, 12, 18 mg to achieve PE (up to 3 doses, 3h interval) GH001 Administration Day 1 Day 7 Key Assessments Safety PE Scale Cognitive function Safety Safety Cognitive function 1The PE Scale

averages answers scored by the subject by marking a visual analogue scale between 0 and 100 for the following three questions: 1. How intense was the experience; 2. To what extent did you lose control; 3. How profound (i.e., deep and

significant) was the experience? HV, Healthy Volunteer; PE, Peak Experience; IDR, Individualized Dosing Regimen

Part A (Single Dose) and Part B (IDR) - Safety 11 Study Safety Group

review No SAEs All ADRs mild, except two moderate (*) All ADRs resolved spontaneously Inhalation well-tolerated No noteworthy changes in vital parameters, except for temporary, non-clinically relevant increase in heart rate and blood

pressure shortly after administration of GH001 No clinically significant changes in safety laboratory analyses, psychiatric safety assessments or measures of cognitive function ADRs Part A (Single Dose) Part B (IDR) ADRs 2 mg (n=4) 6

mg (n=6) 12 mg (n=4) 18 mg (n=4) IDR1 (n=4) MedDRA Preferred Term Number of Events n n n n Abnormal dreams 1 Anxiety 1 1 Clumsiness 1 Confusional state 1 Euphoric

mood 1 Fatigue 1 1* Feeling hot 1 Flashback 1 Hallucination 1 Head discomfort 1 Headache 2 1 1 Heart rate

increased 1* Hyperacusis 1 Insomnia 1 Mental fatigue 1 Nausea 2 1 1 2 Vision blurred 1 SAE, Serious Adverse Event; ADR, Adverse Drug Reaction, an adverse event with

a relationship code to the investigational product of definite, probable, or possible, or where code is missing; IDR, Individualized Dosing Regimen 16 mg (n=1); 6-12 mg (n=2); 6-12-18 mg (n=1)

Part A - Peak Experience (PE) Dose-Effectsand Inter-Person

Variability 12 Average fordose group PE Scale PE Threshold PE, Peak Experience

Part B - Peak Experience (PE)Effect of Intraday Individualized Dosing Regimen

(IDR) 13 PE Threshold PE, Peak Experience

(Completed) Phase 1/2 Trial inTreatment-Resistant

DepressionGH001-TRD-102 14 Clinicaltrials.gov ID: NCT04698603

15 Design of Phase 1/2 Trial in TRD (GH001-TRD-102) Phase 1 (Single

Dose) Phase 2 (IDR) GH001 12 mg (n=4) GH001 18 mg (n=4) TRD1 (n=8) Primary Endpoint: Safety until day 7 TRD1 (n=8) Primary Endpoint: MADRS remission day 7 (MADRS 10) GH001 IDR6, 12, 18 mg to achieve PE (up to 3 doses, 3h

interval) TRD, Treatment-Resistant Depression; PE, Peak Experience; MADRS, Montgomery- sberg Depression Rating Scale; IDR, Individualized Dosing Regimen; H, Hour; D, Day 1Defined as inadequate response to at least two adequate courses of

pharmacological therapy or one adequate course of pharmacological therapy and at least one adequate course of evidence-based psychotherapy Key Assessments MADRS H2 PE Scale Safety MADRS D1 Cognitive function Safety MADRS

D7 Cognitive function Safety GH001 Administration Day 1 Day 7

Phase 1 (Single Dose) and Phase 2 (IDR) - Safety 16 ADRs Phase 1 (Single

Dose) Phase 2 (IDR) ADRs 12 mg (n=4) 18 mg (n=4) IDR1 (n=8) MedDRA Preferred Term Number of Events n n Abdominal discomfort 1 Anxiety 2 Depressive symptom 1* Dizziness 1 Feeling

abnormal 1 1 Flashback 1 1 2 Headache 2 1 3 Muscle discomfort 1 Muscle spasms 1 Nausea 2* Paresthesia 1 Sensory disturbance 3 SAE, Serious Adverse Event; ADR, Adverse Drug Reaction, an adverse event

with a relationship code to the investigational product of definite, probable, or possible, or where code is missing; IDR, Individualized Dosing Regimen; C-SSRS, Columbia-Suicide Severity Rating Scale; MADRS, Montgomery- sberg Depression

Rating Scale 16-12 mg (n=6); 6-12-18 mg (n=2) Study Safety Group review No SAEs All ADRs mild, except three moderate (*) All ADRs resolved spontaneously Inhalation well-tolerated No noteworthy changes in vital parameters, except for

temporary, non-clinically relevant increase in heart rate and blood pressure shortly after administration of GH001 No clinically significant changes in safety laboratory analyses, psychiatric safety assessments or measures of cognitive

function No safety signal relating to suicidal ideation or suicidal behavior, based on C-SSRS and MADRS subscore item "suicidal thoughts"

Phase 1 (Single Dose) - Efficacy (MADRS) 17 2 of 4 (50%) in the 12 mg group

and1 of 4 (25%) in the 18 mg group had a MADRS remission at day 7 2 of 8 patients had a PE and both had a MADRS remission at day 7 MADRS Remission / Response / Improvement Rate Day 7 PE, Peak Experience; MADRS, Montgomery- sberg Depression

Rating ScaleMADRS remission = MADRS of 10; MADRS response = Reduction of 50% from baseline in MADRS; MADRS any improvement = any reduction from baseline in MADRS

Phase 2 (IDR) - Efficacy (MADRS) 18 Primary endpoint met: 7 of 8 patients

(87.5%) had a MADRS remission at day 7, p<0.0001 7 of 8 patients had a PE and 6 of those had a MADRS remission at day 7 MADRS Remission / Response / Improvement Rate Day 7 PE, Peak Experience; MADRS, Montgomery- sberg Depression Rating

ScaleMADRS remission = MADRS of 10; MADRS response = Reduction of 50% from baseline in MADRS; MADRS any improvement = any reduction from baseline in MADRS

Phase 2 (IDR) - Efficacy (MADRS Change from Baseline) 19 Hour 2 Day 1 Day

7 GH001 p=0.0018 p<0.0001 p<0.0001 Primary endpoint met: 7 of 8 patients (87.5%) had a MADRS remission at day 7, p<0.0001 7 of 7 remissions from day 1 and4 of 7 remissions from 2 hours Baseline1 1Baseline mean MADRS=32

MADRS and PE - Observed Improved Outcome in Phase 2 (IDR) vs Phase 1 (Single

Dose) 20 Phase 2 (IDR) Phase 1 (Single Dose) 12 mg Phase 1 (Single Dose) 18 mg MADRS Remission Rate Day 7 87.5% (7 of 8) 50% (2 of 4) 25% (1 of 4) Mean MADRS Change Day 7 -24.4 (-76%) -21.0 (-65%) -12.5 (-40%) Rate of PE 87.5%

(7 of 8) 50% (2 of 4) 0% (0 of 4) Mean PE Score 90.4 (at final dose) 58.2 59.1 PE, Peak Experience; MADRS, Montgomery- sberg Depression Rating Scale; IDR, Individualized Dosing Regimen

(Completed) Phase 1 Clinical Pharmacology Trial in Healthy Volunteers

GH001-HV-103 21 Clinicaltrials.gov ID: NCT05163691

Design of Phase 1 Clinical Pharmacology Trial in Healthy Volunteers

(GH001-HV-103) 22 GH001 Administration Day 7 GH001 6 mg (n=8+2 placebo) GH001 12 mg (n=8+2 placebo) GH001 18 mg (n=8+2 placebo) HV (n=30) Single-Dose Part IDR Part HV (n=16) GH001 IDR6, 12, 18 mg to achieve PE (up to 3 doses,

1h interval, n=8) Key Assessments Safety Pharmacokinetics PE Scale Cognitive function Safety Cognitive function Safety Day 30 GH001 IDR6, 12, 18 mg to achieve PE (up to 3 doses, 2h interval, n=8) Primary Endpoint: Pharmacokinetic

profile of mebufotenin (5-MeO-DMT) and bufotenin HV, Healthy Volunteer; PE, Peak Experience;IDR, Individualized Dosing Regimen

Single Dose and IDR - Safety and Further Results Safety Review No SAEs All

ADRs mild All ADRs resolved spontaneously Inhalation well-tolerated No noteworthy changes in vital parameters, except for temporary, non-clinically relevant increase in heart rate and blood pressure shortly after administration of

GH001 No clinically relevant changes in ECG, safety laboratory analyses, peak flow, cognitive function, psychiatric safety assessments, including the C-SSRS Further Results Pharmacokinetic analyses and psychoactive effect assessments (PE

Scale) support that an interval down to 1 hour between individual doses of the IDR is feasible for future clinical trials 23 ADRs Single-dose IDR 6 mg (n=8) 12 mg (n=8) 18 mg (n=8) Placebo (n=6) 1h interval (n=8)1 2h interval

(n=8)2 MedDRA Preferred Term Number of Events n n n n n Abnormal dreams 1 Chest discomfort 1 Crying 2 2 Dizziness 1 Dry

mouth 1 Dyskinesia 1 Fatigue 1 2 1 Headache 3 1 1 1 Hypoesthesia oral 1 Paresthesia oral 1 Retching 1 Somnolence 1 Tachycardia 2 Tension 1 Tremor 1 SAE,

Serious Adverse Event; Adverse Drug Reaction, or ADR, an adverse event with a relationship code to the investigational product of definite, probable, or possible, or where code is missing; IDR, Individualized Dosing Regimen; C-SSRS,

Columbia-Suicide Severity Rating Scale; PE, Peak Experience 16 mg (n=1), 6-12 mg (n=3); 6-12-18 mg (n=4)26-12 mg (n=3); 6-12-18 mg (n=5)

(Initiated) Phase 2b Trial inTreatment-Resistant

DepressionGH001-TRD-201 24 EudraCT Number: 2022-000574-26

Design of Phase 2b Trial in TRD (GH001-TRD-201) 25 GH001 IDR Placebo IDR

n=80 Randomization 1:1 Up to 5 GH001 IDRs may be administered during the OLE pro re nata (PRN), based on specific re-treatment criteria D0 MADRS Primary Endpoint MADRS (per FDA guidance for rapid-acting

antidepressants*) D1 D7 B H2 Scheduled Visit Double-Blind Phase Open-label Extension Phase (OLE) D14 M2 M3 M4 M5 M6 M1 During the OLE, additional clinic visits can be scheduled if required for medical reasons D0 D1 D7 B