Building a Leading Oncology FranchiseWells Fargo Securities Healthcare ConferenceSeptember 4, 2019

NASDAQ: MEIP

Forward-Looking Statements

• This presentation contains, and our officers and representatives may from time to time make, statements that are “forward-looking

statements” within the meaning of the safe harbor provisions of the U.S. Private Securities Litigation Reform Act of 1995. Examples of

forward-looking statements include, among others, statements regarding our development strategy; potential advantages of our

product candidates; the initiation and completion of preclinical and clinical studies and the reporting of the results thereof; the timing of

regulatory submissions and actions; the sufficiency of our existing cash; and all other statements relating to our plans, objectives,

expectations and beliefs regarding future performance, operations, financial condition and other future events (including assumptions

underlying or relating to any of the foregoing).

• These forward-looking statements rely on a number of assumptions concerning future events and are subject to a number of risks,

uncertainties, and other factors, many of which are outside of our control. Important factors that could cause our actual results and

financial condition to differ materially from those indicated in forward-looking statements include, among others: uncertainties relating

to the initiation and completion of preclinical and clinical studies; whether preclinical and clinical study results will validate and support

the safety and efficacy of our product candidates; the outcome of regulatory reviews of our product candidates; varying interpretation of

research and development and market data; risks and uncertainties relating to intellectual property and the other factors discussed

under the caption “Item 1A. Risk Factors” in our most recent annual report on Form 10-K and our most recent quarterly report on Form

10-Q.

• Any forward-looking statement made by us in this presentation is based only on information currently available to us and speaks only

as of the date on which it is made. In addition, we operate in a highly competitive and rapidly changing environment, and new risks

may arise. Accordingly, you should not place any reliance on forward-looking statements as a prediction of actual results. We disclaim

any intention to, and undertake no obligation to, update or revise any forward-looking statement. You are urged to carefully review and

consider the various disclosures in our most recent annual report on Form 10-K, our most recent Form 10-Q and our other public

filings with the SEC since the filing of our most recent annual report.

2

Two Drug Candidates in Studies to Support FDA Approval

Building a Leading Oncology Franchise

Clinical Pipeline of Four Independent & Partnered Programs

3*As of June 30, 2019, MEI had $79.8 million in cash, cash equivalents, short-term investments, and common stock proceeds collectible, with no outstanding debt.

Candidates Targeting Multiple Pathways Fuel Combination

Therapy Opportunities

Cash position of ~$80 million to Advance Programs*

PROGRAM INDICATION COMBINATIONS CLINICAL PROOF

OF CONCEPT

MARKETING APPROVAL

STUDY

COMMERCIAL

RIGHTS

ME-401PI3Kδ Inhibitor

Follicular Lymphoma

Relapsed/refractorySingle agent

Japan

B-Cell Malignancies

Relapsed/refractory

• Single agent

• Rituxan®(rituximab)

• Zanubrutinib

MEI RoW

VoruciclibCDK Inhibitor

B-Cell Malignancies & AML

Relapsed/refractory

• Single agent

• Venclexta® (Venetoclax)2 MEI Worldwide

ME-344Mitochondrial Inhibitor

HER2- Breast Cancer***

Treatment-naïve, early

stage

Avastin® (bevacizumab)MEI Worldwide

Late-Stage, Diversified, Clinical Pipeline

1. Phase 2 study intended to support an accelerated approval marketing application with FDA. 2. Amended protocol to evaluate voruciclib in combination with venetoclax subject to FDA approval.

PracinostatHDAC Inhibitor

Acute Myeloid Leukemia Vidaza® (azacitidine)

Myelodysplastic SyndromeVidaza® (azacitidine)

Phase 3 Pivotal Trial

Phase 2 Accelerated Approval Trial1

Clinical Collaboration

4

Combinatorial Potential with Other Major Oncology Drug Classes Across MEIP Pipeline

5

MEI Drug Candidates Select Combinations Potential Indications

FL

MCL

MZL

MDS

Solid Tumor

CLL/ SLL

AMLAzacitidine

Anti-angiogenic

BCL2i

BTKi

Anti-CD20ME-401

Voruciclib

ME-344

Pracinostat

DLBCL

B-cell Malignancies*

• >100K new CLL / NHL U.S. cases in 2018

• ~ 5% of cancers in the US

AML**

• ~20K new U.S. cases 2018

• 32% of adult leukemias

MDS**

• ≥ 10K U.S. cases annually

• 30% of MDS → to AML

HER2- Breast Cancer***

• 200K New U.S. cases annually

MEI Retains Commercial Rights to Majority of Programs

Opportunities to Address Significant Unmet Needs

6

$1B+ Markets

*https://www.cancer.org/cancer/chronic-lymphocytic-leukemia/about/key-statistics.html; https://www.cancer.org/cancer/non-hodgkin-lymphoma/about/key-statistics.html; https://www.cancer.org/research/cancer-facts-statistics/all-cancer-facts-figures/cancer-facts-figures-2018.html# **https://www.cancer.org/cancer/acute-myeloid-leukemia/about/key-statistics.html; https://www.cancer.net/cancer-types/leukemia-acute-myeloid-aml/statistics; https://www.cancer.org/cancer/myelodysplastic-syndrome/about/key-statistics.html; https://www.mds-foundation.org/what-is-mds/ ***https://www.breastcancer.org/symptoms/understand_bc/statistics; https://ww5.komen.org/BreastCancer/TumorCharacteristics.html. All citations accessed June 2, 2019.

Chronic Lymphocytic Leukemia

& Small Lymphocytic Lymphoma 7,000

Mantel Cell Lymphoma 2,000

DLBCL 20,000

Marginal Zone Lymphoma 6,000

~50,000 Addressable Patients

Across Multiple Indications

Focus on Select B-Cell Malignancy Indications

7Company estimates

Follicular Lymphoma 15,000

ME-401: Differentiated PI3Kδ Inhibitor with Potential Best-in-Class Profile

ME-401

Distinct

Structural

Class

Best-in-Class Potential

Differentiated Pharmaceutical Profile

PI3Kδ Target Significance

ME-401: A Differentiated Next-generation Candidate for a New Chapter in PI3Kδ Inhibition

9

Opportunities:

✓ Utility across B-

cell malignancies

✓ Multiple unmet

needs

✓ Many combination

possibilities

ME-401

10

PI3Kδ Inhibition: A Mechanism at a Crossroads of B-cell Malignancy Signaling

• Mechanism relevant to

multiple indications

• Axis for potential benefit via

monotherapy or combination

• Potential to achieve deep

and durable responses

PI3Kδ: Central to B-Cell

Signaling

ME-401

Rapid Tissue

Distribution

Penetrates

Tumor Cells

Accumulates

in Tumor

Cells

Selectively

Binds

PI3Kδ

Tightly and

Stably Binds

to PI3Kδ

High Potency at

Low Plasma

Concentrations

11

• Dose schedule flexibility providing potential to maintain clinical benefit while minimizing adverse events of special interest common to other PI3Kδ agents

• Versatility for combination therapy opportunities

ME-401: A Next-generation PI3Kδ Inhibitor with Potential to Redefine the Class

ME-401

ME-401: A Distinct Chemical Class of PI3Kδ Inhibitor with Optimal Pharmacologic Profile

ParsaclisibIncyte

UmbralisibTG Therapeutics

DuvelisibVerastem

IdelalisibGilead

ME-401MEI Pharma

12

ME-401

ME-401 Phase 1b Study: Patient Characteristics

13

FL (N = 54) CLL/SLL (N = 17)

Total

(N = 71)

CS

(n = 31)

IS

(n = 23)

CS

(n = 9)

IS

(n = 8)

Age, in years

Median (range)

≥65 years

65 (47-81)

17 (55%)

61 (38-82)

9 (39%)

60 (50-79)

3 (33%)

72 (46-80)

7 (88%)

65 (38-82)

36 (51%)

Sex: Male / Female, % 71 / 29 69.6 / 30 78/22 87/13 73/ 27

Prior anti-lymphoma therapy

Median prior therapies (range)

≥2 prior lines of therapy

Prior anti-CD20 antibody

2 (1-10)

17 (55%)

30 (97%)

2 (1-6)

18 (78%)

22 (95%)

1 (1-2)

2 (22%)

7 (78%)

1 (1-3)

3 (37.5%)

5 (62.5%)

2 (1-10)

40 (56%)

64 (90%)

ICML 2019

ME-401

High Rate of Responses Across Patient Groups

14

Evaluable PatientsFL

(N = 50)

CLL/SLL

(N = 14)

Total

(N = 64)

All groups 40/50 (80%) 14/14 (100%) 54/64 (83%)

By treatment arm

ME-401 monotherapy

ME-401 + rituximab

30/38 (79%)

10/12 (83%)

11/11 (100%)

3/3 (100%)

41/49 (84%)

13/15 (87%)

By schedule

IS group

CS group

15/20 (75%)

25/30 (83%)

5/5 (100%)

9/9 (100%)

20/25 (80%)

34/39 (87%)

Disease assessment at end of Cycle 2, 6 and then every 6 months

Lugano criteria for FL and iw-CLL for CLL/SLL

ICML 2019

ME-401

Progression Free Survival: Median Not Yet Reached

FL: Progression-Free Survival (N=54) CLL/SLL: Progression-Free Survival (N=17)

15

6 FL (IS x4 and CS x2) and 2 CLL/SLL (CS x2) responders and continuing

therapy after reverting from IS to CS due to PD on IS were censored

IS (N=23)

CS (N=31)

IS (N=8)

CS (N=9)

ICML 2019

ME-401

Intermittent Dosing Schedule Demonstrates Improved Tolerability Compared to Continuous Dosing Schedule

16

Drug Related Adverse

Events of Special Interest

(AESI

Grade 3

CS Group

(N = 40)

IS Group

(N = 31)

Diarrhea/colitis 8 (20.0%) 3 (9.7%)

Rash, all types 4 (10.0%) 0

ALT/AST increased 3 (7.5%) 1 (3.2%)

Mucositis 1 (2.5%) 0

Pneumonia/Pneumonitis 5 (12.5%) 1 (3.2%)

ICML 2019

ME-401

Time to Grade 3 Drug-Related Adverse Events of Special Interest Improved on IS

17

Group Patients with Gr 3 AESI

CS 15 (38%)

IS 5 (16%)

Time to Grade 3 Adverse Event

ICML 2019

IS (N=23)

CS (N=31)

ME-401

Monotherapy Treatment Paradigm for R/R FL: The TIDAL Phase 2 Study Accelerated Approval Approach

Open Label

All subjects

ME-401 60mg qd

(CS) X 2 cycles

N=150

Group AME-401 60mg qd (CS)

until toxicity or PD (N=75)

Group BME-401 60mg qd, 1 wk on / 3wks off (IS)

until toxicity or PD (N=75)

Screening (28 Days)

Randomized (within

2 Days of Day1)

Disease assessments on

Day 1 of cycles 3, 5 and 7

Disease assessments approximately every 12

wks. on Day 1 of cycle 10,13,16,19,22 and 25

CS = Continuous Schedule IS = Intermittent Schedule 18

At toxicity:

Change to IS

At PD:

Discontinue

At toxicity: Re-challenge

at resolution with IS

At PD:

Change to CS

ME-401

The Near-Term Opportunity: Relapsed/Refractory FL, a Significant and Expanding Addressable Market

19

~9,000 U.S. Patients

With Relapsed/Refractory

Follicular Lymphoma

$1B: Potential

Addressable

Market

~15,000 diagnosed with follicular

lymphoma in 2018 (U.S.)

>50% relapse after each

remission

100K: U.S. follicular

lymphoma prevalence

Company estimates

ME-401

EFFICACY

SAFETY

DURABILITY

OF RESPONSE

High Response Rate:83% ORR in CLL/FL (n=54 evaluable)

Differentiated AE Profile:10% AESI

Durable Responses:Median DOR has not been reached;

Median follow-up >9 months

Opportunities for:

• Multiple indications

and lines of

treatment

• Combinatorial

treatments

20ICML 2019

ME-401: A Next-generation PI3Kδ Inhibitor with Potential to Redefine the Class

Voruciclib: A CDK Inhibitor

Voruciclib

CDK9: A Potential High Impact Target Regulating Two Important Proteins

• CDK9 inhibits:

⎼ MCL-1 (myeloid leukemia

cell differentiation protein,

an anti-apoptotic protein)

and

⎼ MYC (regulator of

proliferation, apoptosis,

differentiation and

metabolism.)

22

Voruciclib

Voruciclib: Potential to Overcome Venetoclax Resistance

• Combination opportunities across multiple indications, including:

⎼ AML, CLL & DLBCL

231 Blood. 2016 Jun 23;127(25):3192-201 2 J Clin Oncol. 2017 Mar 10;35(8):826-833; 3 Sci Rep. 2017 21:7(1): 18007

Venetoclax inhibits BCL2

but not MCL1Voruciclib inhibits MCL1

via CDK9 inhibition

Increased MCL1 is an established venetoclax

resistance mechanism1

Voruciclib

Voruciclib/Venetoclax Synergy Supported by MultiplePre-clinical Studies Including: AML, CLL and DLBCL*

24

Luedtke, D.A., et. al., Voruciclib, an Oral, Selective CDK9 Inhibitor, Enhances Cell Death Induced by the Bcl-2 Selective Inhibitor Venetoclax in Acute Myeloid Leukemia. Poster presented at: American Society of Hematology Annual Meeting, December 1-4, 2018; San Diego, CA. Paiva et al. Cyclin-Dependent Kinase Inhibitor P1446A Induces Apoptosis in a JNK/p38 MAPK-Dependent Manner in Chronic Lymphocytic Leukemia B-Cells. 2015 Nov 25;10(11):e0143685. . Dey J, Deckwerth TL, Kerwin WS, Casalini JR, Merrell AJ, Grenley MO, et al. Voruciclib, a clinical stage oral CDK9 inhibitor, represses MCL-1 and sensitizes high-risk diffuse large B-cell lymphoma to BCL2 inhibition. Sci Rep 2017;7:18007.

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ABT-199 10MPK

ABT-199 10MPK + Voruciclib 200MPK

V2

AML DLBCL

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A n n V + / P I +

A n n V + / P I - C I < 0 . 8 5

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C I < 0 . 3 0

* * *

* * *

* * * * * *

An

nexin

V

+ cells (%

)

V2

Voruciclib

Voruciclib Phase 1 Study

• Study population⎼ Relapsed/Refractory B-cell Malignancies

⎼ AML After Treatment with Standard Therapy

⎼ Standard 3-6 patients/group (3+3)

• Endpoints⎼ Safety and Tolerability

⎼ Pharmacokinetics

⎼ Biologic Correlative Studies

⎼ Objective response rates/MRD negativity (B-cell malignancies)

⎼ CR/Cri rate

25

Voruciclib single agent

Dose escalation

Venetoclax + Voruciclib dose

escalation

50

mg

100

mg

150

mg

200

mg

250

mg

50

mg

100

mg

150

mg

200

mg

250

mgV2

• Multiple preclinical model systems demonstrate V2 activity at ~ 0.5 to 1.5 mM*• Phase I PK results suggest active steady state plasma levels achievable at 150-200mg daily; MTD=350mg** Luedtke, D.A., et. al., Voruciclib, an Oral, Selective CDK9 Inhibitor, Enhances Cell Death Induced by the Bcl-2 Selective Inhibitor Venetoclax in Acute Myeloid Leukemia. Poster presented at: American Society of Hematology Annual Meeting, December 1-4, 2018; San Diego, CA. Paiva et al. Cyclin-Dependent Kinase Inhibitor P1446A Induces Apoptosis in a JNK/p38 MAPK-Dependent Manner in Chronic Lymphocytic Leukemia B-Cells. 2015 Nov 25;10(11):e0143685. . Dey J, Deckwerth TL, Kerwin WS, Casalini JR, Merrell AJ, Grenley MO, et al. Voruciclib, a clinical stage oral CDK9 inhibitor, represses MCL-1 and sensitizes high-risk diffuse large B-cell lymphoma to BCL2 inhibition. Sci Rep 2017;7:18007.

ME-344: A Novel Tumor Selective Mitochondrial Inhibitor

ME-344

ME-344 In Combination with Bevacizumab in Her2-negative Breast Cancer Patients Demonstrates Anti-tumor Activity

27

-60

-40

-20

0

20

40

60

-60

-40

-20

0

20

40

60Arm A Arm B Arm A Arm B

All Patients Patients with Vascular Normalization (PET)

Ab

so

lute

(%

) K

i67 C

han

ge (

days 0

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Ab

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lute

(%

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days 0

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ASCO 2019 ME-344 Poster

Pracinostat: Potential Best-in-Class Phase 3 HDAC Inhibitor

Pracinostat

….... In Two Ongoing Studies in AML and MDS

• 75+ w/ newly

diagnosed AML

• Unfit for intensive

chemo

Phase 3AML 500 patients:

Pracinostat (60 mg) + Aza

vs. Aza monotherapy

Primary

endpoint:

Overall Survival

Enrollment

expansion:

60 pts

Pracinostat + Aza

≤ 40 patients:

Pracinostat (45

mg) + Aza

Primary endpoints:

Overall Response

&

One Year Survival

Updated Interim Review: 9%:

discontinuation due to early AE

(N=55) (ASH 2018)

• High/Very high risk

• No prior HMA’s

Phase 2MDS

29

Key Upcoming Milestones Across Portfolio

• ME-401

⎼ Data updates from Phase 1B combination studies in B-cell

malignancies

⎼ Accelerated approval study in R/R follicular lymphoma

• Voruciclib

⎼ Phase 1B study initiation in combination with Venetoclax

⎼ Phase 1 data updates

• ME-344

⎼ Evaluate development opportunities leveraging demonstration

of anti-tumor activity published at ASCO 2019

• Pracinostat

⎼ Phase 2 data from MDS dose-optimization study

30

Building a Leading Oncology FranchiseWells Fargo Securities Healthcare ConferenceSeptember 4, 2019