Aptose Corporate Presentation NASDAQ: APTO July 2020 TSX: APS - - PowerPoint PPT Presentation

Aptose Corporate Presentation

July 2020

www.aptose.com

NASDAQ: APTO TSX: APS

2 This presentation does not, and is not intended to, constitute or form part of, and should not be construed as, an offer or invitation for the sale or purchase of, or a solicitation of an offer to purchase, subscribe for or otherwise acquire, any securities, businesses and/or assets of any entity, nor shall it or any part of it be relied upon in connection with or act as any inducement to enter into any contract or commitment or investment decision whatsoever. This presentation contains forward-looking statements, which reflect APTOSE Biosciences Inc.’s (the “Company”) current expectations, estimates and projections regarding future events, including statements relating to our business strategy, our clinical development plans, our ability to obtain the substantial capital we require, our plans to secure strategic partnerships and to build our pipeline,

• ur clinical trials and their projected timeline, the efficacy and toxicity of our product candidates, potential new intellectual property, our plans, objectives, expectations and intentions; and other

statements including words such as “anticipate”, “contemplate”, “continue”, “believe”, “plan”, “estimate”, “expect”, “intend”, “will”, “should”, “may”, and other similar expressions. Such statements constitute forward-looking statements within the meaning of securities laws. Although the Company believes that the views reflected in these forward-looking statements are reasonable, such statements involve significant risks and uncertainties, and undue reliance should not be placed on such statements. Certain material factors or assumptions are applied in making these forward-looking statements, and actual results may differ materially from those statements. Those factors and risks include, but are not limited to, our ability to raise the funds necessary to continue our operations, changing market conditions, the successful and timely completion of our clinical studies including delays, the demonstration of safety and efficacy of our drug candidates, our ability to recruit patients, the establishment and maintenance of corporate alliances, the market potential

• f our product candidates, the impact of competitive products and pricing, new product development, changes in laws and regulations, uncertainties related to the regulatory approval process and
• ther risks detailed from time to time in the Company’s ongoing quarterly filings and annual reports.

Forward-looking statements contained in this document represent views only as of the date hereof and are presented for the purpose of assisting potential investors in understanding the Company’s business, and may not be appropriate for other purposes. The Company does not undertake to update any forward-looking statements, whether written or oral, that may be made from time to time by

• r on its behalf, except as required under applicable securities legislation. Investors should read the Company’s continuous disclosure documents available at www.sedar.com and EDGAR at

www.sec.gov/edgar.shtml, especially the risk factors detailed therein.

Investment Highlights

APTO-253 MYC Inhibitor

Only clinical stage agent directly targeting G-Quadruplex of notable MYC oncogene Phase 1b in dose level 4 for AML & MDS demonstrating safety and MYC inhibition

APTOSE

Strong leadership and strong balance sheet to advance clinical programs Clinical stage biotech company developing 1st-in-class targeted medicines Precision treatment of hematologic malignancies; life-threatening / orphan diseases

CG-806 Oral FLT3 / BTK Kinase Inhibitor

Inhibits all forms of FLT3 and BTK : Drivers of AML, CLL / NHL hematologic cancers Precision that suppresses multiple oncogenic pathways, yet spares safety targets Phase 1a/b trial ongoing for CLL & NHL Phase 1a/b trial in start-up phase for AML

Serving Patients and Market Opportunities

Potential to serve broadly CLL and AML patient needs Potential for near-term clinical POC and value creation with hematologic cancers

FDA Orphan Drug Designation in AML FDA Orphan Drug Designation in AML

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Delivery of 2020 First Half Goals On Track

q Following December 2019 financing, delivered goals during first half of 2020 q Maintained clinical development momentum through COVID-19 crisis period q CG-806 Phase 1 in R/R CLL & NHL Proceeding on Track

• Completed 150mg, 300mg, 450mg BID lower dose levels
• Now completing intermediate dose level 600mg BID
• Amendment to allow back filling of patients to boost number of patients
• Demonstrated BTK inhibition and induction of lymphocytosis in CLL patients
• Plan to move into higher dose levels 750 and 900mg BID during 2H2020

q CG-806 Phase I in R/R AML Proceeding

• Identified a dose that should be therapeutically active in AML patients
• New IND allowed in R/R AML patients at desired starting dose of 450mg BID

q CG-806 positioned for likelihood of CLL and AML responses over next 6-12 months

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CG-806

q Ongoing trial Ph1a/b for CLL / lymphoid malignancies as rBTKi q Initiating trial Ph1a/b for AML / myeloid malignancies as FLT3i q Small molecule “reversible” kinase inhibitor q Cluster-selective agent with highly unique kinome targeting profile q Developing across spectrum of lymphoid and myeloid hematologic malignancies q Retains potency on CLL & AML cells with mutations that render other agents ineffective

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1st-in-Class Oral Kinase Inhibitor

• Mutation Agnostic FLT3 Inhibitor
• Mutation Agnostic rBTK Inhibitor

“Cluster-Selective Kinase Inhibitor”: CG-806 Potently and Selectively Inhibits Clusters of Related Kinases

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• Mutation Agnostic
• Inhibits WT and all mutant forms of FLT3
• Inhibits WT and all mutant forms of BTK
• Simultaneously suppresses multiple oncogenic

signaling pathways

• Robust Safety Profile
• NOT a “dirty” kinase inhibitor
• Avoids kinases that negatively impact safety
• No drug-related AEs seen to date
• Inhibits Clusters of Kinases that Drive Lymphoid

and Myeloid Hematologic Malignancies

• BTK cluster → CLL & NHL
• FLT3 cluster → AML & MDS

PDGFR

TRKB

BTK FLT3 TRK

LCK ITK LYN B BLK BMX/ ETK BTK TRKC DDR2 TRKB TIE2 TRKA MET PDGFRa FLT3 MTS1 AURC AURA AURB CSF1R RET

Receptors

SRC HCK LYN A

CG-806 Suppresses Key Oncogenic Targets and Pathways in Myeloid & Lymphoid Malignancies

PDGFRα CSF1R STAT

JAK / STAT pathway

JAK PI3K SYK SRC

NFĸB pathway

Ras MAPK ERK BTK TEC AKT PLCγ2 S6K

PI3K / AKT / mTOR / S6K pathway

NFĸB PKC

MAPK / ERK pathway

IKK mTOR LYN

MYC

Cell Growth and Proliferation

7 FLT3mut AML BTKupreg CLL

BTKi FLT3i

CG-806 CG-806 CG-806 CG-806 CG-806 CG-806 CG-806 CG-806 CG-806 CG-806 CG-806 CG-806

Inhibited directly Inhibited indirectly

TRK A/B/C

CG-806 CG-806 CG-806 CG-806 CG-806 CG-806 CG-806 CG-806

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CG-806 Phase 1 Clinical Development Plan for Patients with Lymphoid (CLL/NHL) and Myeloid (AML) Malignancies

Phase 1a/b R/R CLL & NHL : Ongoing

• Seek to define safety, tolerance, PK, PD and RP2D
• Seek to inhibit P-BTK, induce lymphocytosis and observe responses in CLL/NHL patients
• R/R AML patients are acutely ill, and we did not wish to dose sub-therapeutically
• During CLL trial, identified a dose of 450mg likely “therapeutically active” for AML patients

CLL & NHL Lymphoid

Phase 1a/b in R/R AML : FDA Allowed New IND

• Seek to define safety, tolerance, PK, PD and RP2D
• Initiate dosing in AML patients at 450mg BID as a dose likely to be active
• Seek to inhibit P-FLT3, decrease PB blast counts and observe responses in AML patients

AML Myeloid

CG-806 Phase 1a/b Trial for Patients with CLL and NHL B-cell Cancers

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CG-806 for the Treatment of CLL & Lymphoid Malignancies

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Over Half (54%) CLL patients discontinue Ibrutinib by 44 Months(1,2)

• Patients resistant (C481S mutant), intolerant or refractory to ibrutinib

(1) Byrd et al. Blood ; 2019: 133(19): 2031-2042 | (2) Woyach et al. J Clin Oncol.; 2017: 35; 1-7

CG-806 May Overcome Shortcomings of Ibrutinib & Other Agents

• “Non-covalent” : retains activity against WT and C481S-BTK enzyme
• Inhibits multiple “oncogenic rescue” pathways to potentially avoid R/R disease

Overexpressed BTK (Bruton’s Tyrosine Kinase) is Driver Kinase R/R CLL Patients Need BTK and Other Oncogenic Kinases Inhibited Patients Failing a Host of Other Agents

• Covalent BTKi, Non-covalent BTKi, BCL-2i, PI3Ki, Anti-CD20 Abs

CG-806 Non-Covalent Inhibitor Retains Potency Against Wildtype and C481S-BTK

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Retains potency against C481S-BTK Kinase CG-806 IC50 (nM) BTK-WT 8.4 BTK-C481S 2.5 IC50 (nM) TEC EGFR ErbB2 Ibrutinib 78 5.6 9.4 CG-806 >1,000 >1,000 >1,000

CG-806 Binds Non-Covalently to BTK X-ray Crystallographic Analysis:

• Reversibly binds to WT-BTK and C481S-BTK Active Sites
• Atypical Binding Mode Not Reported with Other Drugs
• Chemical Structure Distinct from Ibrutinib/Other BTKi’s

But, does NOT inhibit TEC, EGFR or ErbB2 kinases linked to ibrutinib related toxicities; including bleeding disorders, gut and skin toxicity and atrial fibrillation, respectively. Expect Superior Safety Profile for CG-806

CG-806

CG-806 Exerts Superior Breadth & Potency Compared to Ibrutinib on Patient Samples

• OHSU Measured the Ability of CG-806 or Ibrutinib to Kill Primary Cells from CLL Patients

Ex Vivo : IC50 transformed into a Heatmap of Sensitivity

“CG-806 is More Than Just a BTK Inhibitor”

• 1000x more potent than ibrutinib (SOC covalent BTKi) at killing malignant B-cells
• Targets driver (BTK-WT/Mutant) and rescue pathways operative in B-cell cancers
• Expect CG-806 to inhibit P-BTK and promote exfiltration (lymphocytosis)
• Expect CG-806 to apoptotically kill malignant cells in lymphoid tissues

Sensitive Resistant

IC50

CG-806

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CG-806 Phase 1a/b Clinical Trial Underway: First in Patients with R/R CLL & NHL Lymphoid Malignancies

Dose Expansion will occur once MTD or Therapeutic Dose is Reached to Define RP2D

Development Plan for Severe Unmet Needs in B Cell Tumors

Dose Escalation Phase

• Patients administered oral capsules
• Twice daily on a 28-day cycle
• Plan to perform 6 dose levels
• Accelerated titration design
• Planned expansion cohorts

CLL Patients Resistant or Intolerant to:

• Covalent BTK inhibitors (ibrutinib)
• BCL2 inhibitors (venetoclax)
• Anti-CD20 therapy (rituximab)
• PI3K inhibitors (idelalisib)
• Cytotoxic agents
• Non-covalent BTK inhibitors

PATIENT POPULATION

Relapsed or refractory CLL/SLL & NHL who failed or are intolerant to 2 or more lines of established therapy, or for whom no other treatment options are available

Patient Enrollment: 1, 1, 3x3

• Fewer patients early in the study, but…..
• Dose escalate quickly to effective dose

NHL Patients with Unmet Needs

• Richter’s Transformation
• Tx-refractory DLBCL
• Tx-refractory FL

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CG-806 Phase 1a/b Clinical Trial in CLL/NHL: Now Concluding Dosing Cohort 4 (600 mg BID)

Cohort 1: 150 mg BID (n=1) Completed Cohort 2: 300 mg BID (n=1) Completed Cohort 3: 450 mg BID (n=3) Completed Cohort 4: 600 mg BID (n=3) Ongoing Cohort 5: 750 mg BID (n=3) Planned Cohort 6: 900 mg BID (n=3) Planned

• Intra-patient dose escalation is

allowed if higher dose is safe in 3

• r more patients.
• Additional patients may be

enrolled (back filling) at dose levels previously declared safe.

• If a DLT occurs in 1 of 3 treated

subjects in a cohort, an additional 3 subjects will be treated.

CG-806 Steady-State Pharmacokinetics (CMIN) Achieve Circa-1µM Levels, Inhibit P-BTK and Induce Lymphocytosis in CLL Patients

Oral absorption and favorable steady-state PK : ~1µM steady state (Cmin) at dose level 3 Pharmacologic activity: Inhibition of 100% P-BTK in PBMC 4hr post-dose in CLL patient Pharmacologic activity: Induction of lymphocytosis in three CLL patients

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150mg BID CG-806 induced lymphocytosis in three CLL patients dosed in Cohorts 2 and 4, an indication of CLL cell exfiltration related to BTK inhibition: All three CLL patients entering study with an elevated lymphocyte count had increases in lymphocyte count during first week of CG-806 treatment.

PIA Assay Shows Exposure-dependent Inhibition of P-BTK, P-ERK, P-PDGFRα, P-SYK and P-FLT3

Pharmacologic activity: Consistent inhibition of phospho-BTK, P-ERK, P-PDGFRα, P-SYK and P-FLT3 at steady state with 300mg, 450mg and 600mg BID dose levels

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• Safety Profile

– Observed no unexpected toxicity trends to date

• Pharmacologic Activity

– Target Engagement: 100% inhibition of P-BTK in PBMC at 4hrs – Target Engagement: Plasma inhibits Phospho-Proteins in PIA assay – Target Engagement: BTK inhibition induces Lymphocytosis in CLL patients

• Oral Pharmacokinetics

– Oral absorption delivered circa-1uM trough plasma exposure levels (steady state)

• Dose Escalation

– Advancing efficiently – Plan to continue dose escalation to 750mg and 900mg BID

CG-806 Delivered Clinical Evidence of Safety, Pharmacologic Activity and Favorable Oral Pharmacokinetics

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CG-806 Phase 1a/b Trial for Patients with Acute Myeloid Leukemia (AML)

New IND Allowed by U.S. FDA

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AML: Deadly Cancer of Blood/Bone Marrow (Orphan Disease)

─ ~21,450 diagnosed this year / ~10,920 deaths this year1 ─ The 5-year survival rate for patients with AML approximately 28.3%

Limitations of Current FLT3 Inhibitors

• FLT3-ITD mutation is key driver in 25-35% of AML patients2,3
• Current “Dirty” agents (Midostaurin, etc.) are limited è Toxicity
• Current “Selective” (Gilteritinib, Quizartinib) agents not durable è Resistance
• Current agents susceptible to mutations in TP53, Ras, FLT3 (ITD/TKD/GK)

Desperate Need for Improved FLT3i → CG-806

• CG-806 potently inhibits all WT and mutant forms of FLT3: ITD/TKD/GK/WT
• CG-806 suppresses multiple oncogenic signaling pathways to avoid resistance
• CG-806 combines effectively with other therapies, i.e. venetoclax

CG-806 : A New Class of Drugs Only Agent to Inhibit BTK for CLL and FLT3 for AML

FLT3

Receptor Tyrosine Kinase FLT3-ITD: 25–30% High relapse risk, poor survival FLT3-TKD: 5–10% Resistance to FLT3 inhibitors Juxtamembrane domain Kinase 1 Kinase 2 C-terminus

Litzow MR. Blood. 2005

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• 1 2
• 1 0
• 8
• 6
• 4

5 0 1 0 0 1 5 0

B a /F 3 F L T 3 D 8 3 5 Y

L o g [D ru g ] (M ) % C e ll g ro w th

CG-806 Inhibits All Forms of FLT3 & Kills Cells with FLT3- D835Y Mutation More Potently than Other FLT3 Inhibitors

(1)Ba/F3 isogenic cells kindly provided by Dr. Michael Andreeff at MDACC

FLT3-D835Y

CG-806 Superior to Other FLT3 Inhibitors on AML Cells with FLT3-D835Y Mutation

FLT3 Proteins (Fragments) CG-806 Kd (nM) FLT3 WT 0.24 FLT3 ITD 3.1 FLT3 D835Y 4.2 D835H 2.2 D835V 7.9 R834Q 6.4 N841I 0.8 K663Q 0.55 ITD / F691L 16

CG-806 Potent (Kd) FLT3 WT/Mutants

(1) Reaction Biology Corp. (2)

• Blood. 2009 Oct 1; 114(14): 2984–2992

(3) J Clin Oncol 32:5s, 2014 (suppl; abstr 7070) (4) Blood 2014 Jan 2; 123(1): 94-100 ; AACR Poster 2012 (5) ASH Oral Presentation 2016 N/A – Data not available / Not Applicable.

CG-806 Superior to Other FLT3-ITD Inhibitor

Drug IC50 (nM) CG-806(1) 0.8 Quizartinib(2) 8.8 Gilteritinib(3) 0.9 Crenolanib(4) 2 Midostaurin(2) 11 Nexavar(2) 79 Sutent(2) 1

CG-806

20

CG-806 Exerts Broad & Superior Killing Potency Compared to Various FLT3i on AML Patient Samples

Sensitive Resistant

IC50

• Measured IC50 of CG-806 and Other FLT3i’s to Kill Ex Vivo Primary Cells from >200 AML Patients
• IC50 transformed into a Heatmap of Sensitivity
• CG-806 greater potency in killing primary AML cells bearing wild-type FLT3 or FLT3-ITD

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Sensitivity of AML Patients Samples to CG-806: AACR 2019

Enhanced Potency in Samples with FLT3 and IDH1 Mutations Retains Potency in Samples with NPM1, p53, N-RAS and ASXL1 Mutations

1 0 0 2 0 0 3 0 0

C G - 8 0 6 E f f ic a c y in A M L P a t ie n t S a m p le s

A U C F L T 3 W T IT D IT D IT D T K D N P M 1 a ll a ll m u t W T a ll

ID H

A U C

*

W T M u t a t e d 1 0 0 2 0 0 3 0 0

A S X L 1

A U C W T M u t a t e d 1 0 0 2 0 0 3 0 0

T P 5 3

A U C

AML patient samples with FLT3 mutations (ITD or TKD), with or without concurrent mutations of NPM1, are highly sensitive to CG-806 AML patient samples with mutated IDH1 are more sensitive to CG-806 relative to the IDH WT or IDH2 mutations (p < 0.05) AML patient samples with TP53 WT and TP53 mutations equivalently sensitive to CG-806 AML patient samples with ASXL1 WT and ASXL1 mutations equivalently sensitive to CG-806 AML patient samples with NRAS WT and NRAS mutations equivalently sensitive to CG-806

Log Scale

CG-806 Gilteritinib Quizartinib Midostaurin 0.001 0.01 0.1 1 10 100

NRAS-MUT cohort (n=14)

I C 5 ( µ M ) ** ** **

Mean CG-806 0.9902 Gilteritinib 5.016 Quizartinib 5.278 Midostaurin 5.247

CG-806 Gilteritinib Quizartinib Midostaurin 0.001 0.01 0.1 1 10 100

NRAS-WT cohort (n=88)

IC50 (µM) ** ** **

Mean CG-806 0.3598 Gilteritinib 2.592 Quizartinib 1.232 Midostaurin 5.131

CG-806 Extends Survival in Dose Dependent Way in Mouse Model of AML After Oral Dosing for 28 Days

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+ +

p < 0.0001

0.00 0.25 0.50 0.75 1.00 30 60 90 120

Time (Days) Survival probability

CG−806

+ + + + +

Vehicle 10mg/kg 30mg/kg 100mg/kg 300mg/kg

6 4 11 11 7 11 11 9 3 11 11 11 11 11 11 11 11

300mg/kg 100mg/kg 30mg/kg 10mg/kg Vehicle 40 60 80 100 120

Time (Days) CG−806

Number at risk

+ Time (Days)

6 4 11 11 7 11 11 9 3 11 11 11 11 11 11 11 11

300mg/kg 100mg/kg 30mg/kg 10mg/kg Vehicle 40 60 80 100 120

Time (Days) CG−806

Number at risk

• Study terminated on day 119
• 11 / 11 mice survived in the 100mg/kg group
• 11 / 11 mice survived in the 300mg/kg group
• 100% cure rates at two

highest dose levels

• No evidence of toxicity

at any dose

28-Days Dosing

Patient information: AML patient (FLT3-ITD) received Sorafenib+Azacitidine Tx and experienced CR after one cycle therapy; relapsed after 3 cycles of treatment and acquired a D835 mutation (now FLT3-ITD/D835)

CG-806

• Reduced leukemia cell burden
• Reduced splenomegaly
• Extended survival
• Active against patient-derived

FLT3-ITD / D835 AML

• Potential to treat emerging

FLT3i-resistant AML patients

50 100 500 1000 3000 10,000 1000 5000 10,000

CG-806(nM) Quizartinib (nM)

Annexin V positive (%) at 48h

Patient Derived Xenograft (PDX) Model

Model implanted with FLT3 ITD+D835 mutated primary AML cells. CG-806 Tx initiated d27 (QDx5/wk Orally). hCD45+/mCD45- leukemic cells in peripheral blood were quantitated with flow cytometry.

CG-806 Efficacy in PDX Model Against AML Patient Cells with FLT3 ITD + D835 Mutations

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Developing CG-806 for the Treatment of AML

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• Strong Rationale to Develop for AML with High Potential Value:

– Broadly potent against AML cells

• Patients with mutated FLT3, TP53, IDH1, IDH2, SRF2, ASXL1 and RAS
• Patients with WT-FLT3 (approximately 70% of R/R AML patients)

– More potent than other FLT3 inhibitors on >200 AML patient samples – Delivers cures in xenograft models of human AML without toxicity

• Phase 1 : Include R/R AML Patients with Unmet Needs

– Patients who failed other FLT3 inhibitors – Patients who failed IDH-1 inhibitors – Patients who failed venetoclax – Patients with mutated p53, mutated RAS – Patients with wild type-FLT3 – Patients unfit for intensive therapies

• Initiating dosing with 450mg BID expected to be

a therapeutically active dose (see next slide)

• Potential to rapidly differentiate CG-806 from
• ther FLT3i’s

Cyto/Molecular Heterogeneity of AML

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CG-806 Phase 1a/b Dose Escalation in R/R AML: Starting at Potentially Therapeutic Dose (450 mg BID)

CG-806 600mg BID CG-806 450mg BID CG-806 300mg BID CG-806 150mg BID

Starting dose for Phase 1 a/b dose escalation In R/R AML

Patient plasma inhibitory activity against FLT3-WT in EOL-1 cells. In CLL/NHL B-cell cancer patients, 450mg BID CG-806 delivered plasma levels that completely inhibit Phospho-FLT3 in a standard PIA assay. This suggests the 450mg BID dose will be therapeutically active in patients with AML.

Lancet Oncol. 2017 Aug; 18(8): 1061–1075.

Approved dose

Patient plasma inhibitory activity against FLT3-ITD in Molm14 cells.

CG-806 P-FLT3 Data from Phase 1a/b in R/R CLL & NHL Gilteritinib P-FLT3 Data from Phase 1/2 in R/R AML

Developing CG-806 Broadly Across Hematologic Malignancies

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• Uniquely and Selectively Inhibits Clusters of Kinases
• Targets kinases that are drivers of hematologic malignancies (lymphoid and myeloid)
• Yet, avoids kinases generally associated with toxicity
• Phase 1a/b Ongoing in R/R CLL & NHL Lymphoid Cancer Patients
• Targeting BTK and multiple survival pathways to treat patients failing other agents
• Observed safety, pharmacologic activity and predictable PK characteristics
• Continuing to dose escalate and seek safety, PD responses and efficacy responses
• Phase 1a/b Starting in R/R AML Myeloid Cancer Patients
• Targeting FLT3 and multiple survival pathways to treat patients failing other agents
• Plan to initiate dosing at active level; Potential for rapid development and value creation

APTO-253 Phase 1a/b Ongoing

Small Molecule MYC Inhibitor For the Treatment of AML

• 1. MYC dysregulation is key driver of AML, certain B-cell cancers and solid tumors
• 2. MYC gene expression potently inhibited by APTO-253
• 3. Ph1a/b trial for AML/MDS ongoing with APTO-253
• 4. APTO-253 first agent to inhibit MYC expression and well tolerated in patients

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Tremendous Interest in Targeting MYC as a Cancer Treatment

APTO-253 Targets DNA regulatory motif in promoter of MYC gene

─

NOT the MYC protein

APTO-253 Inhibits MYC gene expression (mRNA)

─

Depletes cells of MYC protein → induces apoptosis

• APTO-253 inhibits MYC expression
• Causes induction of p21
• Triggers cell cycle arrest/apoptosis

MYC protein regulates multitude of key biological processes

─

Transcription factor binds to hundreds of genes

Dysregulated in >50% of all human cancers

─

Reprograms signaling pathways to support survival

Direct targeting of MYC protein is challenging

─

Generally considered “undruggable” – no active site

MYC

APTO-253

APTO-253 Phase 1 Trial :

Safely Inhibits MYC Expression in AML & MDS Patients

• AML Patient: Dose Level 1 (20mg/m2)
• Sampled pre-dose and 24 hr. post-dose day 1, 8, 15, 22
• MYC Suppression & Well Tolerated
• Observed inhibition of MYC expression in PBMC
• MDS Patient: Dose Level 2 (40mg/m2)
• Sampled pre-dose and 24 hr. post-dose day 1, 8, 15, 22
• MYC Suppression & Well Tolerated
• Observed inhibition of MYC expression in PBMC

C 1 D 1 C 1 D 8 C 1 D 1 5 C 1 D 2 2 0 . 0 0 0 . 0 1 0 . 0 2 0 . 0 3 0 . 0 4 0 . 0 5

P a t ie n t #

m R N A ( n o r m a l i z e d t o G A P D H ) M Y C

• AML Patient: Dose Level 3 (66mg/m2)
• Sampled pre-dose and 24 hr. post-dose day 1, 8, 15, 22
• MYC Suppression & Well Tolerated
• Observed inhibition of MYC expression in PBMC

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APTO-253 Ongoing Phase 1b Dose Escalating Clinical Trial

• To date, well-tolerated & no drug-related SAEs
• Now dosing patient in dose level 4 (100mg/m

2)

• Planning to dose escalate to 150mg/m

2 dose level

• Dose Level 1 (20mg/m

2)

Completed 1 AML Patient

• Dose Level 2 (40mg/m

2)

Completed 1 MDS Patient

• Dose Level 3 (66mg/m

2)

Completed 3 AML Patients

• Dose Level 4 (100mg/m

2) Ongoing

3 Patients Required

○ 2 Completed 28d Cycle ○ 1 Underway 28d Cycle

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CG-806 1H: Seek FDA allowance for AML trial 2H: Seek clinical activity in AML patients 2H: Seek clinical activity in B-cell cancer patients 1-2H: Presentation of clinical data during EHA (B-cell) and ASH (B-cell & AML) APTO-253 1-2H: Continue dose escalation in AML/MDS patients 2H: Explore additional cancer indications 2H: Presentation of clinical data during ASH

2020 Anticipated Catalysts

Preclinical Stage Clinical Proof-of-Concept Pivotal Stage

CG-806 CG-806 APTO-253 APL-581

Pan-BTK Pan-FLT3

B-Cell Malignancies AML / MDS Planned

MYC BRD4/JAK

AML / MDS Single Agent AML Single Agent

Aptose: WW CG: Korea Aptose: WW CG: Korea Aptose: WW Aptose / Ohm

CLL NHL AML MDS AML MDS Hematologic Cancers TARGET RIGHTS INDICATIONS DRUG

√ √ √

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Thank You!

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