Nabiximols U.S. Development Program and Market Opportunity June 30, 2020 NASDAQ: GWPH

This presentation contains forward-looking statements that are based on our management’s beliefs and assumptions and on information currently available to management. Forward-looking statements include information about our current expectations for future events, including potential results of operations, the timing of clinical trials, the timing of regulatory filings and approvals, the timing and outcomes of regulatory or intellectual property decisions, the difficulty of predicting FDA and other regulatory approvals, demand for our commercially available products and products in development, and the clinical benefits, safety profile and commercial potential and potential pricing of nabiximols (marketed as Sativex® outside the US) Epidiolex®, and any product candidates. These forward-looking statements are subject to known and unknown risks, uncertainties, assumptions, including those associated with the COVID-19 pandemic, and other factors that could cause our actual results, performance or achievements to be materially different than any future results, performance or achievements expressed or implied by the forward-looking statements. Forward-looking statements represent our management’s beliefs and assumptions only as of the date of this presentation. You should read our most recent filings with the Securities and Exchange Commission (SEC) including our Annual Report on Form 10-K and our Quarterly Reports on Form 10-Q, including the Risk Factors set forth therein and our subsequent filings with the SEC, completely and with the understanding that our actual future results may be materially different from what we expect. Except as required by law, we assume no obligation to update these forward-looking statements publicly, or to update the reasons actual results could differ materially from those anticipated in the forward-looking statements, even if new information becomes available in the future.

2 JUNE 30, 2020 Welcome Justin Gover, Chief Executive Officer Welcome and Opening Remarks Justin Gover, Chief Executive Officer, GW Pharmaceuticals The Unmet Need in Spasticity Dr. Fred Lublin, Saunders Family Professor of Neurology; Director, The Corinne Goldsmith Dickinson Center, for Multiple Sclerosis, Icahn School of Medicine at Mount Sinai The MS Spasticity Treatment Paradigm Cinda Hugos, Associate Professor, Neurology Oregon Health & Science University; Research Scientist, VA Portland Health Care System Spinal Cord Injury Spasticity and Beyond Dr. Deborah Backus, Director of Multiple Sclerosis Research, Shepherd Center, Atlanta, Georgia Nabiximols Route to NDA Dr. Volker Knappertz, Chief Medical Officer, GW Pharmaceuticals Nabiximols Composition and Standardization Dr. Alan Silcock, Vice President, Research & Development, GW Pharmaceuticals Nabiximols U.S. Commercial Strategy and Opportunity Darren Cline, U.S. Chief Commercial Officer, GW Pharmaceuticals Q&A The Unmet Need in Spasticity Dr. Fred Lublin Multiple sclerosis (MS) is a chronic and progressive debilitating disease of the central nervous system

MS is the most prevalent inflammatory neurological disease of young adults.1

Affects approximately… Removes approximately… Is associated with…

progressively 900,000 – 6 years worsening 1 Million symptoms and disability3

people in the United States1 life expectancy2

People with MS struggle with a large number of symptoms Even people with mild MS have reported an average of 6 symptoms associated with their MS7

1. Wallin MT et al. The Lancet Neurology. 2019;18(3):269-285. 2. 2. Cutter GR et al. Multiple Sclerosis and Related Disorders. 2015;4(5):484-490 3. Scalfari et al. Brain 2010; 133(7): 1914–1929

6 Clinicians and patients often use different language to describe spasticity

Common clinical descriptors Common patient-centric descriptors

Increased muscle tone Can’t straighten, Constriction and restriction, Cramping, Heaviness, Inflexible, Lack of movement, Locked up, Muscles don’t relax, Muscles in constant contraction, Muscle stiffness, Hypertonia Muscle tightness, Not very functional, Overworked legs, Pressure, Pulling sensation, Really tight, Tense, Unreliable

Hyperreflexia Bounce, Freak out, Jerky motion, Jerky movement, Jumpy Spasms and frisky, Legs jump up, Looks like seizure, Shaking, Spasm, Spasmodic, Sudden kick, Twitches, Uncontrolled movement, Unexpected movements, Wild Clonus

7 Spasticity is a highly prevalent but variable symptom of MS

Spasticity can be focal (affecting a localized area) or generalized (affecting multiple areas), affect upper extremities of Patients with MS and/or lower extremities, and variably % experience spasticity3 include spasms, clonus, and increased >80 tone1,2 Transient external factors – such as fatigue, stress, hunger, temperature, menses, tight clothing – can alter an individual’s spasticity over time and affect 28% AND 2.3% clinical assessments1 Spasticity may vary across days 4 and through the day of people with MS of people with MS experience moderate experience completely or severe spasticity3 disabling spasticity3

1. Haselkorn P et al. The Journal of Spinal Cord Medicine. 2005;28(2):173-199. 2. Milligan J et al. Canadian Family Physician. 2019;65:7.. 3. Bethoux F et al. The Patient - Patient-Centered Outcomes Research. 2016;9(6):537-546. 4. Hugos and Cameron Curr Neurol Neurosci Rep. 2019 Aug 30; 19(10): 79

8 Spasticity manifests within a complex web of MS symptoms

Pain: Around 60% of people with MS are bothered by pain associated with spasticity1

Sleep: Almost two-thirds of people with MS spasticity reported that it interferes with their sleep1

Bladder or bowel dysfunction: Spasticity contributes to pelvic floor and bladder sphincter dyssynergy3

Fatigue: Spasticity is thought to worsen fatigue, as people exert extra effort against resistant muscles4

Gait: Spasticity affects patients’ walking ability and confidence5

Sexual dysfunction: Muscle tightness or spasms in the arms, legs, or body interfered with sexual activity and satisfaction in 43% of people with MS2

1. Bethoux F et al. The Patient - Patient-Centered Outcomes Research. 2016;9(6):537-546. 2. Orasanu B et al. Multiple Sclerosis and Related Disorders. 2013;2(2):117-123. 3. Marola S et al. Open Med (Wars). 2016;11(1):509-517. 3. Preziosi G et al. Degener Neurol Neuromuscul Dis. 2018;8:79-90. 4. Holland NJ et al. Controlling Spasticity in MS; 2016. 5. J.C. Hobart et al Brain 2006, 129, 224–234

9 MS Spasticity clinical assessments and treatment guidelines merit re-evaluation

Muscle Tone Muscle Spasms Impact on Function Patient Experience

Numerical Rating Scale- √ √ √ √ Spasticity (Patient-reported)

Modified Ashworth Scale (Clinician assessment) √ X X X

Spasm Frequency √ (Patient-reported) X √ X

Clinical Global Impression √ √ √ X (Clinician assessment)

• The most recent Clinical Practice Guideline (Consortium of Multiple Sclerosis Centers) was released 15 years ago1 • Clinical assessments of muscle tone at a single timepoint in the clinic, such as the commonly-used Ashworth scale, do not capture the complete patient experience2,3

1. Haselkorn P et al. The Journal of Spinal Cord Medicine. 2005;28(2):173-199. 2. Sköld C et al. Arch Phys Med Rehabil. 1999;80(12):1548-1557. 3. Thompson AJ. Journal of Neurology, Neurosurgery & Psychiatry. 2005;76(4):459-463

10 No novel oral anti-spasticity agents in the last 25 years

For decades, the best available options for generalized spasticity have remained oral systemic anti-spasticity medications with suboptimal efficacy and adverse event profiles1,

1974 1977 1996

Dantrolene Baclofen Tizanidine

Despite current treatments

of MS patients still live with of MS patients ever self- 1/3 disabling spasticity 1 1/4 medicated with cannabis 2

Source: Bethoux F et al. The Patient - Patient-Centered Outcomes Research. 2016; Rizzo et al. Mult Scler 2004. Cofield et al. Neurol Clin Pract 2017

11 Spasticity clinical development is under-represented

Multiple Sclerosis Clinical Development Pipeline

NON-EXHAUSTIVE

Total Compounds in Development = ~24 • Although there are a number of therapies in development for MS more broadly, they have minimal impact on the future landscape for PI 1 (10) 4 5 spasticity treatment • The broader multiple sclerosis pipeline focuses on treatments that reduce relapses PII 1 1 2 8 (12) Immunomodulator and delay disease progression, rather than Monoclonal antibody focusing on specific symptoms, such as S1P modulator Cell therapy spasticity ACE inhibitor PIII 1 1 (2)

Source: National MS Society Website; GlobalData; Citeline; Clinicaltrials.gov; ClearView Analysis

12 The MS Spasticity Treatment Paradigm Cinda Hugos, MS, PT The Real-World Assessment of Spasticity

What are we talking about when we say spasticity?

Classic Definition Patient-Centered Descriptions (Lance, 1980) (Rizzo et al, 2004)

”Spasticity is a motor disorder, characterized Uses lay language to describe a broader range by a velocity-dependent increase in tonic of clinical characteristics of spasticity: stretch reflexes (muscle tone) with • Unusual tightening of muscles that feels like leg exaggerated tendon jerks, resulting from stiffness — early symptom hyper-excitability of the stretch reflex as one • Jumping of the legs — spasms or myoclonic jerks • A repetitive bouncing of the foot (clonus) component of the upper motor neuron (UMN) • Muscle cramping in legs or arms — spasms or syndrome.” cramps • Legs going out tight and straight — extensor spasms • Legs drawing up — flexor spasms

2 JUNE 30, 2020 Ask the Patient — Formal Assessment Using Standardized Scales

Standardized Ways to Ask the Patient — Scales and Questionnaires • (Penn) Spasm Frequency Scale1 • Multiple Sclerosis Spasticity Scale — 88 (MSSS-88)2 • Visual Analog Scales • Numeric Rating Scale for Spasticity (NRS-S)3

1. Penn 1989 2. Hobart 2006 3. Farrar 2008

3 JUNE 30, 2020 Ask the Patient — Informal Assessment

• Use words meaningful to people • Stiffness • Jumping • Bouncing

• Ask about situational impact — function • Moving around in the home • In and out of bed, shower • Ask about sleep quality • Moving in the work environment • Moving in the community • Grocery store

4 JUNE 30, 2020 MS Patients with Spasticity are Fearful of…

Losing Their Ability to Walk1 Medication Dependence Side Effects

Tired of Surgical Injections Management

1. Bethoux 2011

5 JUNE 30, 2020 The Negative Impact of MS Spasticity — MS Patient Story

Featured image is not a patient Stepwise Approach to MS Spasticity Treatment

Rehabilitation/ Complementary Oral Injection Surgical Complementary Exercise and Integrative Medications Therapies Treatments and Integrative Medicine Medicine

Currently available treatments, alone or in combination, fail to provide complete or even optimal relief of MS spasticity symptoms

7 JUNE 30, 2020 MS Patients with Spasticity are Fearful

What Is Presently Available in the Cannabis Dispensary World

Unknown Ingredients

Unknown Unknown Doses Sources Black Box Don’t Want Topical to Smoke Products or Vape Are Vague Don’t Want to Eat Dispensary Cannabis Products

8 JUNE 30, 2020 Patients Would Welcome an FDA Approved Cannabis-Based Medication

• People are informed • Know there is evidence for benefit in MS and Safety and spasticity Efficacy Evidence • Know there is no standard for cannabis in the US, even where legal medically or recreationally Manufacturing • Trust the FDA process overall • Safety FDA • Efficacy Quality Approved • Manufacturing standards Standards Cannabis- • Standardized doses Based Products • Known side effect profiles • Likely interested at any stage of spasticity management Legality • Reimbursable medical expense Coverage • Insurance coverage

9 JUNE 30, 2020 Spinal Cord Injury Spasticity and Beyond: The Unmet Need Dr. Deborah Backus, PT, PhD Similarities and Differences Between Multiple Sclerosis (MS) and Spinal Cord Injury (SCI) Similarities and Differences Between MS and SCI

Multiple Sclerosis Spinal Cord Injury

3 JUNE 30, 2020 SCI

250,000–500,000 new SCI Violence 13.5% cases/year WORLDWIDE Sports-related Falls accidents 12,000 people in the US each year 30.5% 8.9% sustain SCI Other 8.7% Prevalence in US Motor 243,000–347,000 persons Vehicle Accidents 38.4% 80% experience spasticity

National Spinal Cord Injury Statistical Center, Facts and Figures at a Glance. Birmingham, AL: University of Alabama at Birmingham, 2020. Holtz KA, Lipson R, Noonan VK, Kwon BK, Mills PB. Prevalence and effect of problematic spasticity after traumatic spinal cord injury. Archives physical medicine rehabilitation. 2017 Jun 1;98(6):1132-8.

4 JUNE 30, 2020 Burden of Spasticity in SCI

I dream of the day when the signals between the neurons in my spinal cord again move like an octopus through the ocean. When my torso doesn't shake like a paint mixer. When my fingers don't move like the staff on a metronome. When my legs don't kick by themselves. When my head doesn't turn if I don't want it to. With patience there is time. With time there is hope. With hope there will be a cure.

From Carolyn at www.exploringspasticity.com

5 JUNE 30, 2020 Spasticity in SCI

Function Participation Quality of Life

Spasticity

McKay WB, Sweatman WM, Field-Fote EC. The experience of spasticity after spinal cord injury: perceived characteristics and impact on daily life. Spinal cord. 2018 May;56(5):478-86. Westerkam D, Saunders LL, Krause JS. Association of spasticity and life satisfaction after spinal cord injury. Spinal cord. 2011 Sep;49(9):990-4. Mahoney JS, Engebretson JC, Cook KF, Hart KA, Robinson-Whelen S, Sherwood AM. Spasticity experience domains in persons with spinal cord injury. Archives of physical medicine and rehabilitation. 2007 Mar 1;88(3):287-94.

6 JUNE 30, 2020 Current Management of Spasticity in SCI

Pharmacological Neurolytics • Baclofen • Botox • Tizanidine • Phenol • Gabapentin • Dantrolene • Diazepam

Surgical Rehab Interventions • Dorsal Rhizotomy • PT and OT: Casting, range • Implantation of pumps of motion, exercise • Non-invasive brain stimulation • Non-invasive peripheral stimulation • Muscle vibration • Epidural spinal cord stimulation

7 JUNE 30, 2020 Current Management of Spasticity in SCI: Neither Optimal nor Adequate

Side effects of pharmacological management:

Muscle weakness Drowsiness/difficulty Difficulty falling concentrating asleep/sleeping

Potentially negative impact on neuroplasticity or recovery

Adams MM, Hicks AL. Spasticity after spinal cord injury. Spinal cord. 2005 Oct;43(10):577-86. Elbasiouny SM, Moroz D, Bakr MM, Mushahwar VK. Management of spasticity after spinal cord injury: current techniques and future directions. Neurorehabilitation and neural repair. 2010 Jan;24(1):23-33. Theriault ER, Huang V, Whiteneck G, Dijkers MP, Harel NY. Antispasmodic medications may be associated with reduced recovery during inpatient rehabilitation after traumatic spinal cord injury. The journal of spinal cord medicine. 2018 Jan 2;41(1):63-71.

8 JUNE 30, 2020 Current Management of Spasticity in SCI: Neither Optimal nor Adequate

• Of 113 participants:

• People with SCI are NOT satisfied with the results

No Medication 35%

> 58% reported medication never Medication or rarely controlled spasticity 65%

McKay WB, Sweatman WM, Field-Fote EC. The experience of spasticity after spinal cord injury: perceived characteristics and impact on daily life. Spinal cord. 2018 May;56(5):478-86.

9 JUNE 30, 2020 Cannabis-Based Therapies for Spasticity in SCI?

• > 60% current and previous users with SCI reported using medical cannabis to address spasms1 • > 60% reported it offered “great relief” from symptoms, including spasticity, pain, sleeplessness and anxiety1 • More effective and fewer side effects than prescription medications1 • 70% of respondents used medical cannabis to reduce spasticity2 • Those who had never tried cannabis reported that they would mainly use cannabis to alleviate pain and spasticity if it were legalized3

1. Stillman M, Capron M, Mallow M, Ransom T, Gustafson K, Bell A, Graves D. Utilization of medicinal cannabis for pain by individuals with spinal cord injury. Spinal Cord Series and Cases. 2019 Jul 10;5(1):1-8. 2. Hawley LA, Ketchum JM, Morey C, Collins K, Charlifue S. Cannabis use in individuals with spinal cord injury or moderate to severe traumatic brain injury in Colorado. Archives of physical medicine and rehabilitation. 2018 Aug 1;99(8):1584-90. 3. Andresen SR, Biering-Sørensen F, Hagen EM, Nielsen JF, Bach FW, Finnerup NB. Cannabis use in persons with traumatic spinal cord injury in Denmark. Journal of rehabilitation medicine. 2017 Feb 5;49(2):152-60.

10 JUNE 30, 2020 Other Neurological Conditions and Spasticity

Cerebral Palsy > 17 million people worldwide MS 70% with spasticity > 2 million people worldwide Multiple Sclerosis 80% with spasticity Stroke 60% with pain > 7 million people worldwide SCI 30-80% with spasticity > 250,000 new cases worldwide 60% with pain 80% with spasticity 80% with pain Traumatic Brain Injury > 10 million people worldwide 17–20% with spasticity

Kuo CL, Hu GC. Post-stroke spasticity: a review of epidemiology, pathophysiology, and treatments. International J Gerontology. 2018 Dec 1;12(4):280-4. Pattuwage L, Olver J, Martin C, et al. Management of spasticity in moderate and severe traumatic brain injury: evaluation of clinical practice guidelines. J Head Trauma Rehab. 2017 Mar 1;32(2):E1-2. Stavsky M, Mor O, Mastrolia SA, et al. Cerebral palsy—trends in epidemiology and recent development in prenatal mechanisms of disease, treatment, and prevention. Frontiers in pediatrics. 2017 Feb 13;5:21.

11 JUNE 30, 2020 Beyond SCI Spasticity

Mechanism of action of cannabis-based therapies + similarities between conditions

Cannabis-based therapies may offer therapeutic relief of other symptoms and in other neurologic conditions:

Spasticity and Spasticity and neurogenic pain bladder dysfunction

12 JUNE 30, 2020 Nabiximols: Route to NDA

Dr. Volker Knappertz | June 30, 2020 NASDAQ: GWPH

EUROPEAN EFFICACY BRIDGE FROM EXECUTE MULTIPLE DATA HARMONIZED DISCUSS EXPANDING TRIALS PRESENTED NRS TO PROXIMATE PIVOTAL TRIALS FIVE TO NDA REQUIREMENTS INDICATION TO FDA SPASTICITY ENDPOINT SHOTS ON GOAL

• FDA accepts data based on • Legacy data from 15 years Supplement European data with Five new MS Spasticity (MS-S) Two pivotal Spinal Cord Injury NRS as supportive but and over 30 clinical trials one additional positive study, trials will commence later this Spasticity (SCI-S) studies are requires additional pivotal have been integrated and which would be sufficient to year and next year – any one of expected to commence data on a specific objective converted into the current submit NDA them will be able to bridge the measure of spasticity NDA standards NRS data FDA view of spasticity suggests Bridging study does not need to broad label is achievable over be a large phase 3 trial All other aspects of submission time – MS and SCI may be will be in place in H1 2021, if sufficient possible

June 30, 2020 GW Pharmaceuticals Investor Presentation 35 Clinical evidence to date Previous clinical trials show evidence of efficacy and safety Overview of European pivotal MS Spasticity clinical studies

Study 1 (Collin, et al) Study 2 (Novotna, et al) Study 3 (Markova, et al)

Double-blind, Randomized Parallel Enriched Randomized Withdrawal Study Enriched Study Group Study Part A: 4-week nabiximols run-in Part A: 4-week nabiximols run-in to Nabiximols or placebo for 6 weeks identify responders Part B: responders randomized to Study Design Study continue nabiximols or withdraw to placebo Part B: responders who demonstrated for 12 weeks worsening following washout randomized to nabiximols or placebo for 12 weeks

Part A: N = 572 N = 189 Part A: N = 191 Part B: N = 241 Part B: N = 106 Sample Size Sample

Primary: NRS–spasticity (mean change) Primary: NRS-spasticity (mean change) Primary: NRS spasticity (responder)

Key secondary: NRS–spasticity Key secondary: NRS–spasticity Key secondary: NRS-spasticity (mean (responder) Ashworth scale, spasms (responder) spasms, modified change), modified Ashworth scale

Efficacy Ashworth scale (mAS) Endpoints

Collin, et al. Eur J Neurol 2007; 14:290-96 Novotna, et al. Eur J Neurol 2011; 18(9):1122-31 Markova, et al. Int J Neursci 2019; 129(2): 119-128

37June 30, 2020 GW Pharmaceuticals Investor Presentation Independent replication of nabiximols efficacy – Three trials met primary endpoint (Numeric Rating Scale = NRS)

Favors Favors Study N Placebo Nabiximols Mean P-value Difference (95% CI)

1 189 -0.52 (-1.029, -0.004) 0.048

2 241 -0.84 (-1. 29, -0. 40) 0.0002

3 106 -1.90 (-2.73, -1.06) <0.0001

1 0 -1 -2 -3 Mean Difference (95% CI)

0-10 NRS Makes it Easy for Patients to Measure Accurately

• Patient reported daily measure • Integrates patient experiences beyond muscle tone and spasms Collin, et al. Eur J Neurol 2007; 14:290-96 • Easily administered and interpreted by patients and their physicians Novotna, et al. Eur J Neurol 2011; 18(9):1122-31 Markova, et al. Int J Neursci 2019; 129(2): 119-128 Farrar J et al. Clin Ther. 2008.

38June 30, 2020 GW Pharmaceuticals Investor Presentation NRS and Spasms: Study 2 efficacy detail

Part A Part B Part A Part B 4-week nabiximols run-in 12-week randomized nabiximols or placebo 4-week nabiximols run-in 12-week randomized nabiximols or placebo

7.5 12 SE) 7 ± 11 SE) ± 6.5 10 6 9 P=0.0046 10 NRS 10 ( NRS

- 5.5 8 5 P=0.0002 7 4.5 4 6 3.5 5

Mean Spasticity 0 3 4

1 2 3 4 5 6 7 8 9 Mean Spasm Frequency per Day ( 1 2 3 4 5 6 7 8 9 -3 -2 -1 10 11 12 -3 -2 -1 10 11 12

Baseline Endpoint Baseline Endpoint Screening Screening Study Period (Week) Study Period (Week)

Nabiximols (n=124) Placebo (n=117) Nabiximols (n=124) Placebo (n=117)

Correlation between NRS and spasm: r2 = 0.25 (p<0.0001)

39June 30, 2020 GW Pharmaceuticals Investor Presentation NRS and muscle tone: Study 3 study efficacy detail

Adjusted OR: 7.0 (95% CI: 3.0, 16.7; p<0.0001) Week 12 Difference: -0.24 (95% CI: -0.36, -0.11; p=0.0003) 100 -0.5

80 77.4% nabiximols (n=53) 60 nabiximols (n=53) Placebo (n=53) -0.25 -0.26 Placebo (n=53) 40

32.3% 20

-0.02 0 0 30% NRS responder rate Mean difference in modified Ashworth Scale (mAS)

Primary endpoint in 3 new MS trials is Lower Limb Muscle Tone-6 (LLMT-6), the average of 6 key mAS muscle groups

Compared to mAS, the LLMT-6 enhances the ability to detect the treatment effect.

40June 30, 2020 GW Pharmaceuticals Investor Presentation Nabiximols safety profile and abuse potential is well established

Extensive clinical trial and post Most common adverse drug marketing experience: reactions (ADRs) in order of Nabiximols is well tolerated with incidence include: individualized dose titration comparing favorably to standard of care

100,000+ patient years of post Dizziness, fatigue, nausea, No significant reports of abuse or somnolence, vertigo, dry mouth, marketing safety data diversion. asthenia, and diarrhea 50 clinical trials across MS and other indications. ADRs occur more commonly in HAL study* completed. Schedule first 4 weeks and are mild or III is expected from DEA 3400+ patients exposed to moderate nabiximols in clinical trials

* Schoedel KA et al. Hum Psychopharmacol. 2011;26(3):224-36.

41 June 30, 2020 GW Pharmaceuticals Investor Presentation Nabiximols: Overview of planned studies in spasticity Planned Phase 3 MS Spasticity studies

Target Start Target Data Sample Size Design Endpoint (FPI) Readout

52 3-week treatment period, 2 way cross-over Muscle Tone (LLMT-6) Q4 2020 2021

Muscle Tone 190 3-week treatment period, 2 way cross-over Q1 2021 2022 (LLMT-6)

Muscle Tone 36 Single dose, 2 way cross-over, nabiximols responders Q1 2021 2021 /2022 (LLMT-6)

450 Double-blind, placebo-controlled, 12-week treatment period Spasm frequency Q4 2020 2022

Part A: nabiximols run-in to identify responders ~200 Part B: 12-week double-blind, placebo-controlled Spasm frequency Q2 2021 2023 randomized withdrawal

43 JUNE 30, 2020 GW Pharmaceuticals Investor Presentation Spinal Cord Injury may unlock broad spasticity indication

Approximate Target Start Target Data Design Endpoint Sample Size (FPI) Readout

Multiple spasticity ~100 Observational, 4-week clinical discovery study Q4 2020 2021 endpoints

Part A: nabiximols run-in to identify responders Muscle Tone ~100 Q2 2021 2022 Part B: single dose, 3 way cross-over (LLMT-6)

~400 Double-blind, placebo controlled, 12-week treatment period Spasm frequency H2 2021 2023

Spasticity in MS SCI is a logical FDA has a precedent in manifests mostly in the next population to approving drugs for lower extremities and is expand the spasticity irrespective of related to spinal cord nabiximols the underlying disease. evidence base. condition.

June 30, 2020 GW Pharmaceuticals Investor Presentation 44 Nabiximols: Beyond spasticity Post Traumatic Stress Disorder

• PTSD falls within the spectrum of anxiety and fear disorders

• The estimated annualized prevalence is 1.8% for men and 5.2% for women1

• ~ 65% PTSD patients are treated with pharmacotherapy2

• Of these, 75% of patients continue to experience anxiety and sleep disturbance symptoms3 Nabiximols offers potential to treat anxiety • Early evidence for both THC and CBD in the treatment of PTSD and reduce sleep disturbance addressing fear, extinction, improving emotional processing, and sleep disturbances The Phase 2 / 3 study in PTSD will randomize a total of 320 subjects and is on- track to initiate in the first half of 2021

1 Kessler et al. Biol Psychiatry. 2005;58:668–76. 2 Nobles et al. J Clin Psychiatry 2017; 78(5): e559-e566 3 Pruiksma et al. Psychol. Trauma 2016 ;8(6):697-701.

46 JUNE 30, 2020 38th Annual J.P. Morgan Healthcare Conference Nabiximols Composition and Standardization Alan Silcock What is Nabiximols?

• USAN definition: “highly characterized botanical extracts of defined chemotypes of Cannabis sativa L. The major chemical Minor cannabinoids constituents are the cannabinoids, delta-9-tetrahydrocannabinol Non- (THC) and cannabinoid cannabidiol (CBD). Important minor cannabinoids constituents are related cannabinoids and non-cannabinoid components alpha- and trans-caryophyllenes” • Nabiximols is an oromucosal spray which delivers 0.1mL of formulation per actuation • Each actuation delivers a consistent dose of cannabinoids (including 2.5mg CBD and 2.7mg THC) and non-cannabinoids • Molecular profile is unique to GW plant clones, >90% of the mass in the extract is characterised Principal cannabinoids • Levels of over 60 individual species are monitored as part of GW testing • Six main compound classes: Cannabinoids, Terpenes, Triglycerides, Sterols, Carotenoids, Fatty Acids

2 JUNE 30, 2020 How Is It Made?

GACP

Plants Unique GW plant clones grown in highly controlled conditions

Liquid CO2 Extract extraction GMP

Formulation and filling Formulated product

3 JUNE 30, 2020 Nabiximols — Reproducible Fingerprint, 5 Batches Overlaid

Terpenes Sterols Cannabinoids

4 JUNE 30, 2020 Control – a Decade in the Making

Chemical specification includes: • Cannabinoids • CBD • THC • >10 minor cannabinoids • Non-Cannabinoids • Trans- Caryophyllene • Alpha- FDA Botanical Drug Development Guideline for Industry (2016) Caryophyllene “Because of inherent difficulties in characterizing all chemical constituents in • Multiple other non- botanical drugs, establishing their identity relies not only on chemical cannabinoids characterization of molecules in the mixture, but also on other aspects, including control of the raw material(s) at the medicinal plant level, characterization of relative potency and activity by a biological assay, and/or clinically relevant specifications based on results of the multiple batch clinical studies.”

5 JUNE 30, 2020 Positive CMC FDA Interactions

• Extensive engagement with FDA CMC and botanical review division from 2005 • Applicability as a botanical product • Requirements for characterization of extracts • Approach to fingerprinting and control of specification • USAN approved – 2008 • CMC meeting held Q4 2019 • Reconfirmation of nabiximols being considered to fall under the 2016 Botanical Guidelines • Agreement on GWs analytical and control strategy • Agreement on use of an extended control strategy for future activities

6 JUNE 30, 2020 Nabiximols Commercial Strategy and Opportunity Darren Cline Nabiximols may address broad spasticity conditions, unlocking blockbuster revenue potential

ILLUSTRATIVE

Cerebral Palsy NMSOD

MSS MSS Post-Stroke Tomorrow Future

ALS Traumatic Spinal Brain Injury Cord Injury

Initial Nabiximols Indication Future Nabiximols Opportunity

Expansion into adjacent spasticity populations Core initial focus in multiple sclerosis could drive commercial value and spasticity (MSS) strengthen leadership position

Source: Physician Interviews; Patient Interviews.

54 January 14, 2020 38th Annual J.P. Morgan Healthcare Conference Spasticity can be debilitating for MS patients, often impacting both daily activities and overall emotional health

Patient-reported Emotional Impact Patient-reported Impact on ADLs

84% of MS spasticity (MSS) patients suffer from rigidity fear anxiety Loss of control 70% of MSS patients report urinary/bladder sleepless helpless dysfunction

70% of MSS patients have some level of dependent walking impairment resigned exhausted 51% of MSS patients suffer from sleep hopelessness isolated disturbances burden on family 48% suffer from fatigue MSS-related fatigue depressed

Sources: NARCMS Survey; Rizzo et al., 2004; Oreja-Guevara et al., 2013; Coghe et al., 2015; Stevenson et al., 2014; Berger et al., 2013; Zwibel, 2009; Arroyo et al., 2014; Milinis et al., 2016

55 January 14, 2020 38th Annual J.P. Morgan Healthcare Conference Spasticity is a common symptom of multiple sclerosis significantly impacting over 80% of patients

In 2019, U.S. claims data indicates >70% of MS Patients treat their spasticity ~575 K diagnosed MS patients in pharmacologically1 the US and growing ~2% per year Spasticity Treatment Current Use (%)

Oral Medications ~50% Stretching ~43% Spasticity Home Exercise Program ~36% occurs in up to Light Pressure / Stroking ~14% Physical Therapy ~10% Heat Therapy ~7% Cold Therapy ~5% 84% Occupational Therapy <5% Intrathecal Baclofen <5% of MS patients Botulinum Toxin <5% Phenol Injection <5%

Sources: Dilokthornsakul. Neuro. 2016; Simpson. J Neuro Neurosurg Psych. 2011; Simpson. Front Neurol. 2018; Voskuhl. Nat Rev Neurol. 2012; Wallin. Neuro. 2019; National MS Society Website; ClearView Analysis. Survey (n=20,969) Rizzo 2004 Milinis. Mult Scler Relat Disord. 2016; Morley. Disabil Rehabil. 2013; 1: Treatment Approaches for MS spasticity by NARCOMS participants Physician Interviews. 56 January 14, 2020 38th Annual J.P. Morgan Healthcare Conference A lack of treatment advancements for generalized spasticity over the past 20 years has created considerable unmet need for novel therapies

No treatment innovation in the past Despite current treatments 20 years of MS patients still live with uncontrolled 1/3 spasticity 1977 1996 2016

Oral Tizanidine Botulinumtoxin of MS baclofen (focal spasticity) 26-50% patients 84%Intrathecal baclofen pump are self-medicating with cannabis

Sources: Bethoux F et al. The Patient - Patient-Centered Outcomes Research. 2016;9(6):537-546 ; Rizzo et al. Mult Scler 2004. NARCMS Survey 2014; MSS = Multiple Sclerosis Spasticity.

57 January 14, 2020 38th Annual J.P. Morgan Healthcare Conference Market research suggests nabiximols offers a meaningful improvement compared to existing treatments

“I would rate my interest in this treatment as a 4 or 5 out of 5. It looks better than what I take now.” Key Drivers of Patient Perspectives

• Patients interpreted the efficacy of “That sounds so exciting – I’ve been on so Efficacy nabiximols as superior to other oral agents many muscle relaxants that haven’t worked, I want to try something new.”

• Patients were enthusiastic about the safety “I have most of these side effects from my Safety and profile, citing that adverse events were MS anyway, so they don’t bother me at Tolerability significantly improved compared to SOC all.”

Dosing and • Most patients perceived the oral spray as “I like the oral spray instead of a pill, I Route Of similarly or more convenient than oral pills already take a lot of pills each day, so the variety is nice.” Administration

Sources: Physician Interviews; Patient Interviews.

58 January 14, 2020 38th Annual J.P. Morgan Healthcare Conference ~80% of patients noted moderate-to-high interest in nabiximols, with the majority citing willingness to ask their physician about the product

“This would be very positive for “I don’t see why I wouldn’t try this. The someone like me who can’t control current drug I take has some bad side their spasticity. If you’re doing a trial, I’d effects, and the benefit is modest.” love to participate.”

Patient Interest in Nabiximols

>60% of patients 80% of patients citied would proactively ask a moderate-to-high about nabiximols at interest in nabiximols their next doctors visit

Sources: Physician Interviews; Patient Interviews.

59 January 14, 2020 38th Annual J.P. Morgan Healthcare Conference U.S. patients and physicians cited high use of cannabis in multiple sclerosis spasticity today, further indicating existing demand for nabiximols

Patient Perspectives Healthcare Provider (HCP) Perspectives

of interviewed patients of patients use cannabis indicated they used for multiple sclerosis ~50% cannabis products ~30% spasticity today, semi-regularly or when according to physicians available and nurses

Sources: Physician Interviews; Patient Interviews.

60 January 14, 2020 38th Annual J.P. Morgan Healthcare Conference U.S. payers perceived MS spasticity as an area of high unmet need, citing nabiximols as an attractive, differentiated approach

Current Payer MS spasticity is not strictly managed by Management of payers given the largely generic market MSS

Payer Payers acknowledge there are limited MS Perception of spasticity treatments and current options Unmet Need have problematic side effects for patients

Payer feedback on nabiximols was positive, citing Payer Reactions the MOA, improved safety profile, and proven to Nabiximols efficacy as key benefits

Sources: Payer Interviews.

61 January 14, 2020 38th Annual J.P. Morgan Healthcare Conference We are continuing to invest in pre-launch activities to ensure successful commercialization of nabiximols

Physician and Patient Advisory Boards NARCOMS Survey on Cannabis Use Partnership with NARCOMS to create, Interactive discussions with physicians, administer, and publish a patient survey patients, and digital influencers regarding use and opinions of cannabis in MS

Nabiximols Value Story Development Commercial Infrastructure Thorough collation of historical nabiximols Evaluating field force size and structure to data accompanied with payer feedback to ensure successful commercialization develop value story

Survey and Publication on MS Spasticity Nabiximols Pricing Potential Robust patient survey in development to highlight the impact spasticity has on MS Evaluating pricing options patients

Sources: Internal GW.

62 January 14, 2020 38th Annual J.P. Morgan Healthcare Conference Market awareness, demand and adoption of Epidiolex suggests a strong foundation for nabiximols in today’s market

Majority of Pre-commercialization physicians (~70%) efforts generated Strong cited a preference Significant significant awareness of Demand for for an FDA- Epidiolex before launch Pre-launch FDA approved product Awareness Approved Product

Proven ~97% of All U.S. Successfully Tracking Indication Favorable Access Insured Patients to Expand Expansion to Product Have Epidiolex Label into Adjacent High Coverage For Core Unmet Need Conditions Indications

63 January 14, 2020 38th Annual J.P. Morgan Healthcare Conference Life cycle development opportunities for nabiximols represent sizable patient populations, with high unmet need, and large commercial potential

MS and SCI Spasticity •High incidence of spasticity and enduring unmet need •More than >500 K addressable patients across both conditions Multiple •Estimated peak U.S. sales of ~$450 M and ~$350 M in MS spasticity and Post-Stroke Sclerosis SCI spasticity, respectively

ALS Other Spasticity Opportunities Spinal Cord Cerebral •Spasticity is common across many diseases Palsy Injury •Research suggests more than 1 M addressable spasticity patients in the Traumatic U.S. across select indications Brain Injury NMOSD •Provides nabiximols with strong life cycle development potential PTSD Post-traumatic Stress Disorder •Significant unmet need with an estimated ~1.5 M addressable patients in U.S.

Source: Physician & Patient Interviews; ClearView Analysis. PTSD: Post-traumatic Stress Disorder; NMOSD: Neuromyelitis Optica Spectrum Disorder; MSS: Multiple Sclerosis Spasticity; ALS: Amyotrophic Lateral Sclerosis.

64 January 14, 2020 38th Annual J.P. Morgan Healthcare Conference •THANK YOU!

Nasdaq: GWPH • Stephen Schultz • Vice President, Investor Relations • [email protected] • 401-500-6570