ESSA PharmaNASDAQ: EPIX; TSX-V: EPI

Non-Confidential Presentation, May 22nd 2019

Forward Looking StatementThis presentation may contain forward-looking statements. Forward-looking statements and information are subject tovarious known and unknown risks and uncertainties, many of which are beyond the ability of ESSA to control or predict,and which may cause ESSA’s actual results, performance or achievements to be materially different from those expressedor implied thereby. Such statements reflect ESSA’s current views with respect to future events, are subject to risks anduncertainties and are necessarily based upon a number of estimates and assumptions that, while considered reasonableby ESSA as of the date of such statements, are inherently subject to significant medical, scientific, business, economic,competitive, political and social uncertainties and contingencies. In making forward-looking statements, ESSA may makevarious material assumptions, including but not limited to the market and demand for the securities of ESSA, generalbusiness, market and economic conditions, obtaining positive results of clinical trials, and obtaining regulatory approvals.

Forward-looking information is developed based on assumptions about such risks, uncertainties and other factors set outherein and in ESSA’s Annual Report on Form 20-F dated December 13, 2018 under the heading “Risk Factors”, a copy ofwhich is available on ESSA’s profile on the SEDAR website at www.sedar.com, ESSA’s profile on EDGAR at www.sec.gov,and as otherwise disclosed from time to time on ESSA’s SEDAR profile. Forward-looking statements are made based onmanagement's beliefs, estimates and opinions on the date that statements are made and ESSA undertakes no obligationto update forward-looking statements if these beliefs, estimates and opinions or other circumstances should change,except as may be required by applicable Canadian and United States securities laws. Readers are cautioned againstattributing undue certainty to forward-looking statements.

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ESSA Corporate OverviewFocused on the development of novel therapies for the treatment of prostate and other hormone-driven cancers

Founded with technology licensed from The University of British Columbia and the BC Cancer Agency

Sites in Houston, South San Francisco and Vancouver

First-in-class N-terminal domain (NTD) inhibitors of the androgen receptor (“Anitens”)

EPI-7386 nominated as IND candidate

Initial clinical development focused on resistant mCRPC as a single agent with future development in combination with antiandrogens in CRPC and HSPC

Breast cancer in TNBC AR+

Listed on NASDAQ (EPIX) & TSX-V (EPI)

Cash balance of $8.6M(March 31, 2019)

Company Technology & Products Financial Details

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David R. Parkinson, MDPresident & Chief Executive Officer, Director

Peter Virsik, MS, MBAEVP & Chief Operating Officer

David S. Wood, MBA, CPA, CMAChief Financial Officer

Experienced Management Team

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Acquisition of Realm Therapeutics

Key Transaction Terms

Strategic Rationale

• On May 15, 2019, ESSA announced it will acquire 100% of Realm Therapeutics (“Realm”) with newly issued shares:

─ Realm’s issued and outstanding shares valued at approximately $21.5 million, which represents a 5% premium over Realm’s estimated net cash amount of $20.5 million at the closing of the acquisition

─ Realm Shareholders will be entitled to receive approximately 0.058 ESSA ordinary shares for each Realm share, valued at $3.19 per share 1

─ ESSA’s shareholders will have pro forma equity interest of approximately 54% 1

• The acquisition of Realm’s cash, combined with the the proposed additional financing, will deliver sufficient financial resources to achieve multiple value-inflection points and key near-term objectives in the coming two years including:

─ Completion of a Phase 1 clinical trial for EPI-7386 in patients with advanced prostate cancer;

─ Proof-of-concept clinical data from a Phase 1 trial for EPI-7386 in combination with anti-androgens in prostate cancer patients; and

─ Continued development of our early preclinical pipeline of novel anitens for the potential treatment of breast cancer

• We believe the Realm acquisition will bring in cash at a lower cost of capital and higher ESSA shareholder value than other financing options

51. Based upon a 60-day volume-weighted average price of $3.19 per share of ESSA as of the close of trading on May 14th, 2019, subject to a final adjustment based on Realm’s final net cash amount prior to closing of the acquisition

PUBLIC HEALTH PROBLEM

LARGE MARKET

VALIDATED THERAPEUTIC TARGET

NEED FOR NEW THERAPEUTIC STRATEGIES

Prostate Cancer Disease Landscape

61. Surveillance Research, American Cancer Society. 2018.2. Robinson D, et al. Cell. 2015.3. Katsogiannou M, et al. Cancer Treat Rev. 2015.

• Prostate cancer is the 2nd

most common cause of male cancer deaths1

• Each year in the US, ~165,000 men are diagnosed and ~29,000 die due to prostate cancer

• Over $5B in global sales generated in 2017 by leading anti-androgens, Zytiga® (abiraterone acetate) and Xtandi®(enzalutamide)

• Prostate cancer disease progression is associated with androgen receptor (AR) signaling. 2,3,4

• An estimated ~60% of mCRPC tumors post-Xtandi or Zytiga failure may still be AR-driven 5

• Despite new therapies, mCRPC anti-androgen resistance is inevitable 6,7

4. Azad AA, et al. Clin Cancer Res. 2015.5. Wyatt. JAMA. 2016. 6. Watson PA, et al. Nat Rev Cancer. 2015.

7. Attard G, et al. ASCO Annual Meeting. 2017.

Current Anti-androgen Therapies Target the Androgen Receptor Ligand Binding Domain

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• All current anti-androgens function through the ligand-binding domain of the androgen receptor

• Known anti-androgen resistance mechanisms develop at the ligand binding domain

ANDROGEN

Zytiga® (abiraterone acetate)Eligardä, Lupron® (leuprolide)Zoladex® (goserelin)Firmagon® (degarelix)

N-terminal domain DNA-binding domain Ligand-binding domain

Erleada® (apalutamide)Xtandi® (enzalutamide)Nilandron® (nilutamide)Casodex® (bicalutamide)Eulexin® (flutamide)

Inhibit androgen synthesis

Block androgen binding

AR Amplification1

Splice variants3,4,5

Promiscuous activation (i.e., glucocorticoids, progesterone) 6,7

Gain-of-function mutations1,2

Anti-androgen Resistance Mechanisms

6. Chen EJ, et al. Clin Cancer Res, 20157. Culig Z, et al. Cancer Res, 1994

4. Mostaghel EA, et. Al. Clin Cancer Res, 20115. Sun S, et al. J Clin Invest, 2010

1. Azad AA, et al. Clin Cancer Res, 20152. Joseph JD, et al. Cancer Discov, 20133. Antonarakis ES, et al. NEJM, 2014

Targeting the AR NTD: Novel Transcription Factor Inhibition of Androgen-driven Prostate Cancer Biology

• Novel method of inhibiting the AR

• Proposed binding of Anitens to Tau-5 region of AF1 1

• Anitens active against multiple forms of AR:

o Wild-type AR, LBD mutant AR, and splice-variant AR2,3,4

81. De Mol E, et al. ACS Chem Biol. 2016.2. Andersen RJ, et al. Cancer Cell. 2010.

N-terminal domain DNA-binding domain Ligand-binding domain

Granted unique USAN drug stem of “Aniten” as an N-terminal inhibitor of AR

3.De Mol E, et al. ACS Chem Biol. 2016.4.Yang YC, et al. Clin Cancer Res. 2016.

EPI362

C404

438

Tau-5

Aniten

DESIGN An adaptive Phase 1 first-in-man dose escalation / dose expansion study

DOSE EPI-506 (EPI-002 active) oral once-daily or twice-daily dosed as a soft-gel capsule

POPULATIONmCRPC patients progressing after abiraterone, enzalutamide, or both; allowed to have also failed one regimen of docetaxel chemotherapy

STUDY SIZE 28 patients

ENDPOINTS Safety, PK, maximum tolerated dose, recommended Phase 2 dose

STUDY STATUS Completed at 5 sites in US and Canada

First-Generation EPI-506 Phase 1 Study in Patients w/mCRPC

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EPI-002 (active drug)

EPI-506 (tri-acetate prodrug)

OO

(S)(S)

O(S)(S)

O

Cl

O

EPI-506O

O O

EPI-002

First-Generation EPI-506 Phase 1 Data Demonstrates Signs of Anti-Tumor Activity Despite Suboptimal PK Profile

• Significant first-pass metabolism seen: minimal exposure time above target IC50• PSA declines in resistant tumors, but too little and not sustained

0 6 12 18 241

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EPI-002 PK - day 8

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1800 mg bid simulatedEPI-002 cell IC50

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g32

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g36

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mg

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mg

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mg

640

mg

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mg

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mg

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mg

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)

Patients receiving < 1280 mgPatients receiving > 1280 mg

320

mg

Maximal PSA Change at Any Time from Start of Multi-dose Period (N=27)

EPI-506: Safe and Well-tolerated Until Very High Doses

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Most Commonly Reported Adverse Event > 10% All Grades, N (%)Diarrhea, nausea 13 (46%)

Fatigue 7 (25%)

Decreased appetite, pain in extremity 6 (21%), each

Vomiting 5 (18%)

Back Pain 4 (14%)

Abdominal distension, anemia, arthralgia, musculoskeletal pain, UTI 3 (11%), each

Adverse Events ≥ Grade 3 N (%) Relationship to Study DrugAnemia 3 (11%) Not related.

AST elevated 2 (7%) Probably related, Possibly related.

Neutropenia 2 (7%) Not related.

Abdominal pain, diarrhea 1 (4%), each Possibly related.

ALT elevated, amylase elevated, angina, hypertension, dizziness postural 1 (4%), each Probably related.

Arthralgia, gastrointestinal hemorrhage, pain in extremity, syncope, thrombocytopenia, urinary retention

1 (4%), each Not related.

Lessons Learned: A Blueprint for Next Generation Anitens

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Experience informed the specifications for a next-generation Aniten compound:• Higher potency• Less metabolism with a longer half-life• Maintain on-target specificity• Ease of manufacturing / shelf-life stability• Commercial formulation

Process to discover next-generation Aniten:• Strengthened ESSA’s chemistry and preclinical team in early 2018• Augmented external chemistry efforts to expand the synthesis of new molecules

o >400 new compounds designed; >250 compounds screened in vitro for potency and ADME profile• Selected EPI-7386 as the IND candidate

In Vitro Potency and Stability of Next-Generation Anitens

13CONFIDENTIAL

Stability threshold

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In Vitro Half-Life Stability (min)

Potency threshold

Target compounds

• Significant gains made in in vitro potency and stability compared to EPI-002• Preclinical characterization limited to only the most potent and stable compounds

Enzalutamide

EPI-002 potency is >> 4500nM

TPP CRITERIA STATUS SPECIFICS

Increased potency In vitro potency goal achieved (>20X more potent than EPI-506 / 002)

ENZ-resistant activity In vitro cellular activity in numerous ENZ-resistant cell lines and models

Xenograft in vivo activity Equal anti-tumor activity to ENZ in ENZ-sensitive LNCaP xenograft model; improved anti-tumor activity in ENZ-resistant VCaP model

Clean off-target profile Nuclear receptor & CEREP screening indicates minimal off-target binding

Reduced metabolism Much less metabolized in vitro than EPI-506 / 002

In vivo PK profile Mouse/rat/dog metabolism & PK studies support once-daily dosing and predict significant human exposures with >24hr half-life

Simple to manufacture Manufacturing process straightforward

Combination potential Solid dosage; minimal drug-drug interaction predicted

Strong IP coverage IP broadly filed on new Anitens; patent expirations anticipated 2037+

Next-Generation Aniten EPI-7386 Product Characteristics

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EPI-7386 Cellular Potency Increased > 20X Compared to EPI-002

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• Next-generation anitens exhibit cellular potency’s in a similar magnitude to the leading anti-androgens in a full-length androgen receptor cellular model

0.01 0.1 1 10 1000

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LNCa

P AR

E-Lu

c %

inhi

bitio

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EnzalutamideBicalutamideApalutamideDarolutamideEPI-002EPI-7386

Compound IC50 (nM)* nEPI-002 9,580 2

EPI-7386 421 5Enzalutamide 154 5Bicalutamide 242 7Darolutamide 616 3Apalutamide 4,540 3

* Assay is conducted in LNCaP cells containing the T878A LBD AR mutation utilizing the PSA(6.1kB) luciferase reporter plasmid

EPI-7386- Significantly Improved In Vitro Metabolic Stability & Mouse & Dog PK

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• EPI-7386 in vitro hepatocyte stability significantly improved over EPI-002

• EPI-7386 displays favorable mouse & dog pharmacokinetic profile

0 4 8 12 16 20 241

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Mean Plasma conc after PO dosing in male CD-1 mice

Time (hr)[p

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EPI-7386 - PO5 mg/kg

ENZA - PO5 mg/kg

EPI-002 -PO5 mg/kg

Hepatocyte T1/2 (min)Compound HumanEPI-002 38

EPI-7386 >360Enzalutamide >360

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• EPI-7386 shows activity in AR-V7-driven cellular models whereas ENZ does not

LNCaP95 Cell Proliferation Androgen Receptor PSA Luciferase

Similar reduction of PSA-luciferase when driven by AR-V7 only (green) or a combination of AR-V7 and full-length AR (red)

AR-V7-Driven Prostate Cancer Model

Full-Length AR-Driven Prostate Cancer Model

Non AR-Driven Prostate Cancer Model

EPI-7386 Active in ENZ-Resistant AR-V7-Driven Cellular Models

EPI-7386 Exhibits Similar Anti-tumor Activity to ENZ in ENZ-Sensitive LNCaP Xenograft Model

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• LNCaP is driven by full-length androgen receptor and ENZ shows excellent activity

• ENZ was dosed at a supratherapeutic doseo ENZ dose was 2X the human

exposure while EPI-7386 was ½ the exposure of ENZ

• Despite differences in exposure, EPI-7386 displays similar efficacy to ENZ

• VCaP (castrate) growth is initially driven by AR-overexpression followed by AR-V7-driven growth

• Significant & sustained antitumor activity observed with EPI-7386 & Combo groupo Enzalutamide tumors escape after

day 24 and become resistant

• Compared to ENZ, EPI-7386 exhibits no signs of resistance or loss of activity through day 52

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EPI-7386 Exhibits Better Anti-Tumor Response vs. ENZ in an ENZ-Partial Resistant VCaP Xenograft Model

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Waterfall plot on d41 dosing

Enzalutamide - 15 mg/kg- PO qd

Combo Enza - 15 mg/kg / EPI-7386 - 60/30 mg/kgEPI-7386 - 30 mg/kg- PO qd

EPI-7386 Exhibited Improved Individual Anti-Tumor Responses vs. ENZ in a VCaP Xenograft Study on Day 41

The Combo demonstrates a homogeneous tumor response èAdvantage of targeting the AR through two mechanisms

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Arm Progressive Disease (PD)

Stable Disease (SD)

Partial Response (PR)

Complete Response (CR)

ENZ (15 mpk) 4 (57%) 3 (43%) 0 (0%) 0 (0%)

EPI-7386 (30 mpk) 1 (14%) 5 (71%) 0 (0%) 1 (14%)

COMBO (ENZ+EPI-7386) 0 (0%) 1 (20%) 4 (80%) 0 (0%)

Clinical Development Strategy

• Phase I dose escalation trial in patients progressing on current anti-androgens

• Detailed biological characterization of individual patient tumors

• Dose escalation with real-time dose/PK/tumor biological effect correlations with clinical efficacy/tolerability

• Opportunity for seamless Phase I/extension/Phase II clinical trialso Possibility exists for accelerated registration/approval strategies

• IND filing and clinical trial initiation anticipated Q1 2020

• Opportunity for early Phase I combination trial with anti-androgens

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Initial mCRPC Market Opportunity for EPI-7386

Initial Indication: For the treatment of patients with mCRPC progressing on second generation antiandrogens.

221. Eligible patients are estimated as the yearly mortality incidence due to prostate cancer.2. American Cancer Society Cancer Statistics, 2019; Ferlay, J. et al. Cancer Statistics, European Journal of Cancer, 2018.

Territory mCRPC Eligible Patients per Year 1,2

Monthly Price3

Months / Patient4

Total Market Opportunity

US 31,620 $7800 6 months $1.5B

EU28 81,540 $3700 6 months $1.8B

US+EU28 113,160 $3.3B

3. Evaluate Pharma, 2018; 4. Estimate from Medivation 1Q2016 Quarterly Conference Call, 2016.

EPI-7386 Market Share25% 50% 75%

Net Sales (US + EU28) $800M $1.6B $2.4B

• Market opportunity for EPI-7386 in combination with second generation antiandrogens in earlier CRPC or hormone-sensitive prostate cancer patients is several fold larger than this initial mCRPC market

Financial Position & Capitalization (March 31, 2019)

Nasdaq: EPIX ; TSXV: EPI-VCash $8.6M

Debt Principal $4.6M

Shares ~8.0M- I/O shares and prefunded warrants

Warrants ~500k @ $35.36

Stock Options ~1.1M @ $4.59

Top Shareholders Blackstone Group LP., Omega Fund Management LLC., BVF Inc., Eventide Asset Management LLC.

Covering Analysts David Martin, Bloom Burton; Joe Pantginis, HCW

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STATUS SPECIFICS

Select final Aniten molecules for selectivity and xenograft preclinical studies

Medical conference presentation(s) of the initial preclinical findings of Aniten molecules

IND candidate selection and initiation of IND-enabling studies

Medical conference presentation of the preclinical findings of Aniten molecules in antiandrogen-resistant prostate models and in combination with antiandrogens

Q1 IND filing of the next-generation Aniten

Q1 First patient dosed in phase 1 mCRPC study with next-generation Aniten

ESSA Upcoming Milestones

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