new therapies to more effectively eliminate viral

©2019 ASSEMBLY BIOSCIENCES, INC.

New Therapies to More Effectively Eliminate Viral Replication

and Increase Cure Rates in CHB Patients

Richard Colonno, Uri Lopatin, Sandy Liaw, Ran Yan, Dawei Cai and Qi Huang

1st IASL - CFHPC Congress (Beijing June 2019)

Cautionary Note Regarding Forward-Looking Statements

The information in this presentation contains forward-looking statements regarding future events, including statements about theclinical and therapeutic potential of Assembly Biosciences’ HBV-cure program, the therapeutic potential of core protein inhibitors, the discovery and identification of new classes of core protein inhibitors, ongoing and planned preclinical studies and clinical studies in its HBV-cure program, and the plans, strategies and intentions related to its HBV-cure program. Certain forward-looking statements may be identified by reference to a future period or periods or by use of forward-looking terminology such as “anticipated,” “likely”, “may,” “potential,” or “predictive,” or “suggest.” Such forward-looking statements, which are intended to be covered by the safe harbor provisions contained in Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of1934, as amended, are just predictions and are subject to risks and uncertainties that could cause the actual events or results to differ materially. These risks and uncertainties include, among others: the scientific theory for core inhibitors is unproven and novel; top-line or initial data may not accurately reflect the complete results of a particular study or trial; outcomes of clinical studies are uncertain and results of earlier preclinical and nonclinical studies may not be predictive of future clinical studies results. These and other potential risks and uncertainties that could cause actual results to differ from the results predicted are more fully detailed under the heading “Risk Factors” in Assembly Biosciences’ Quarterly Report on Form 10-Q for the year ended March 31, 2019 filed with the Securities and Exchange Commission (the “SEC”) and any additional reports filed with the SEC following the date of this presentation. It is not possible for Assembly Biosciences management to predict all risks nor can it assess the impact of all factors on our business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained in any forward-looking statements. In light of these risks, uncertainties and assumptions, the forward-looking events and circumstances discussed in this presentation may not occur and actual results could differ materially and adversely from those anticipated. Any forward-looking statement speaks only as of the date on which it is made, and no obligation to update or revise any forward-looking statement is assumed, whether as a result of new information, future events or otherwise, except as required by law.

2

Strategic Approaches Being Pursued To Improve Cure Rates

3

Reduce HBsAg LevelsTo Restore

Immunologic Control

Immune Modulators To Stimulate and Modulate

Immunologic Control

Antivirals ToEliminate Residual Virus

and Prevent Generation of

cccDNA

Eliminate Existing cccDNA

siRNAAntisense RNASecretion Inh

Core InhibitorsEntry Inhibitors

TLR-7 AgonistTLR-8 AgonistRIG-I/NOD2

Agonist

CRISPR-Cas9

Our Focus is on Finding More Effective Antivirals – WHY?

CONFIDENTIAL 4

Prolonged Nuc Therapy Fails to Eliminate Viral Replication

0102030405060708090

100

Patie

nts

HB

V D

NA

“Tar

get D

etec

ted”

(%)

HBeAg pos Patients

HBeAg neg Patients

2 53 4Treatment Years

TDF Clinical Studies102 (HBeAg-) and 103 (HBeAg+)

Learnings from EASL 2019• Detected DNA represents infectious virus2

─ Residual viremia refractory to Nuc therapy─ Likely accounts for poor cure rates

• Over 80% of circulating HBsAg derived from integrated DNA3

─ HBsAg may not be an appropriate biomarker of cccDNA loss

─ HBsAg does NOT lead to reinfection and is NOT a marker of ongoing infection

• Appropriate biomarkers of cure is an open question in the field

• If DNA and RNA are undetectable, there is likely no remaining infectious virus

• cccDNA ONLY source of pgRNA and virus

5

PCR-detectable HBV DNA persists in 70-80% of patients despite TDF treatment for 5 years1

1Marcellin, et al., Poster 1861 AASLD 2014; 2Burdette et al., PS-150 EASL 2019; 3Podlaha et al., SAT-91 EASL 2019

New Therapies are Needed to Increase Cure Rates in CHB

Covalently Closed Circular DNA (cccDNA)

Core

Relaxed CircularDNA (rcDNA)

Polymerase

PregenomicRNA (pgRNA)

Nucleos(t)ide Pol Inhibitors (Nuc) • Current “Standard of Care” for HBV

• Safe, well tolerated, with minimal resistance

• Reduce HBV DNA

But Fail to ……• Fully eliminate virus• Prevent new cccDNA formation• Provide finite treatment duration

Cure is not possible without elimination of residual virus

6

Remaining Virus Able to Re-infect Liver When Nuc Therapy Stops

To improve cure rates…must eliminate residual virus to prevent reinfection

HB

V Vi

ral L

oad

Treatment Period

LLQ

Time (years)

7

LLQ = lower limit of quantification.

Key Findings of cccDNA Biosynthesis Studies

• No evidence to support existence of inactive subpopulation of cccDNA, as genetic changes are observed in the entire population of cccDNA

• Genetic source of resistance shown to be cccDNA• pgRNA closely reflects genetic composition of

cccDNA pools cccDNA pgRNA Virus

• Turnover of cccDNA from sensitive to resistant and from resistant to sensitive occurs in 12-16 weeks

• Suggests relatively rapid biologic turnover of both pgRNA and cccDNA pools and/or infected cells

12-16 weeks

Results indicate that existing cccDNA has a limited half-life, suggesting that therapies inhibiting establishment of new cccDNA may lead to higher cure rates for patients with HBV

8

Huang et al. Poster Thr-216 EASL Apr 2019

Critical Inhibitory Elements of New Treatment Paradigms

Eliminate Residual Virus Replication

….To Stop New Infection of Hepatocytes

Block Generation of New cccDNA

….To Allow Decay of Existing cccDNA

9

CIs Block Viral Replication and cccDNA Establishment

Core Protein Inhibitors (CIs)

Covalently Closed Circular DNA (cccDNA)

Packaging of pgRNA Core

Relaxed CircularDNA (rcDNA)

Polymerase

PregenomicRNA (pgRNA)

Traffickingto nucleus

• Inhibit multiple steps in viral replication cycle

• Achieve deeper levels of viral inhibition than Nucs alone

AND…..• Can block the formation of cccDNA

Goal is to use combination therapy to increase cure rates with finite

treatment duration

10

Superior Antiviral Effectiveness vs. ETV in Culture Assays

0.1 1 10 100 10000

25

50

75

100

HepAD38 Intracellular Viral Load

Multiple of EC50

Perc

enta

ge o

f Con

trol (

Vira

l DN

A) Nuc (ETV)Core Inhibitor (2158)Nuc+Core Inhibitor(ETV+2158)

EC50 = Effective Concentration yielding a 50% reduction in activity.

Cell Background

Level0.1 1 10 100 1000102

HepAD38 Intracellular Viral Load

103

104

105

106

107

HB

V D

NA

(cop

ies/

µl)

Multiple of EC50

Nuc (ETV)Core Inhibitor (2158)Nuc+Core Inhibitor(ETV+2158)

Core Inhibitors reduce virus levels deeper than Nucs

11

Core Inhibitors Inhibit Establishment of cccDNA in Infected Cells

60

0

20

40

80

100

120

140

0.001 0.1 100.01 1

60

0

20

40

80

100

120

140

Concentration (µM)

Con

trol (

%)

Nuc (ETV)Treatment 3 Hours After Infection

Concentration (µM)

Con

trol (

%)

0.001 0.1 100.01 1

Core Inhibitor (2158)Treatment 3 Hours After Infection

HBeAg HBsAg pgRNAViral DNA HBeAg HBsAg pgRNAViral DNA

Surrogate Markers of cccDNA

Huang Q, et al. Poster 922 AASLD Nov 2017

Infection of Primary Human Hepatocytes

Suppression of viral DNA

12

ABI-H0731

ABI-H2158

ABI-H3733

Relative Potency in Blocking cccDNA Generation

Time

HBVInfection

Capsid DNA Readout

cccDNA Readout

-1/-3 Hr 0 Hr 3 Hr 4 Days

CompoundAdded

HBV Infection of HepG2-NTCP Cells

Southern BlotsC

ontr

ol

1,00

0 nM

ETV

10,0

003,

333

1,11

137

012

341

Core inhibitor (nM)

133

565

4,565ABI-H0731

ABI-H2158

ABI-H3733

Cap

sid

Mel

ting

(Rea

dout

= rc

DN

A)cc

cDN

A In

hibi

tion

(Rea

dout

= c

ccD

NA)

125

334

5,447

EC50 (nM)

Concentration (nM)

Perc

ent o

f Con

trol

Inhibition of cccDNA Establishment

0

20

40

60

80

100

10 100 1000 10000

37332158731

Colonno et al. Oral EASL Apr 2019

13

Interim Review of ABI-H0731 Phase 2a Studies (EASL - Apr 2019)

14

24 weeks

Study 20147 HBeAg+ / 26 HBeAg-

Study 20225 HBeAg+

3:2 1:1

Study 211Nuc + 731 (300 mg)

≤ 1-year open label extension

Nuc + 731 (300 mg)

Nuc + PBO

ETV + 731 (300 mg)

ETV + PBO

Dou

ble

Blin

d

Nuc Suppressed Patients Rx Naïve Patients

Lalezari et al. Oral LB-07 EASL Apr 2019

Assessment of multiple efficacy endpoints and safetyat Week 24

D1 Wk 12 Wk 24Study 201 73 65 11Study 202 25 24 12

Metrics at Time of Interim Analysis

Study 201 202

Demographics HBeAg +(n = 47)

HBeAg –(n = 26)

HBeAg +(n =25)

Asian (%) 87 81 96

Genotype B,C (%) 83 46 88

Mean Baseline Values

ALT (U/L) 27 25 57

HBV DNA (log10 IU/mL) BLQ BLQ 7.8

HBV RNA (log10 copy/mL) 5.9a ≤ 2.3b 8.0

HBsAg (IU/mL) 5,569 2,970 57,179

HBeAg (PEU/mL) 29 N/A 791a 37/47 patients with baseline RNA > 200; b 4/26 patients with RNA > 200 copies)

Blinded, Pooled Safety – Well Tolerated with Favorable Safety Profile

Blinded Summary of TEAEs (Studies 201 and 202) at interim data cut • No SAEs or treatment related discontinuations or interruptions• Adverse events were mostly mild, infrequent, and considered unrelated to study drug • No Flares on treatment• No clinical AE > grade 2 • 3 patients with rash considered “possibly related” (2x grade 1, 1x grade 2); none

associated with systemic findings• 1 patient in each study with a grade 2 AE considered possibly related to study drug

─ Macular/maculopapular rash–resolved on antihistamine (Study 201)─ ALT increase–resolved with continued treatment (Study 202)

15


Study 202: Superior DNA Reductions with 731 Combination

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0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.00 5 10 15 20 25

ETV 731 + ETV

Treatment Week

HB

V D

NA

Red

uctio

n L

og10

IU/m

L

• Significantly faster and deeper reductions in HBV DNA levels, as early as Week 2 (P=.03)

• Among subjects with abnormal ALT at entry, more rapid ALT normalization seen in combination arm

– 5/7 vs. 0/5 by Week 4 (P <.05)– 7/7 vs. 2/5 by Week 12 (P <.05)

Mean Log10 HBV DNA Decline

Week ETV ETV + 731 P Value

12 3.29 4.54 <.011

24 3.99 5.94 <.005HBV DNA assessed by Roche Cobas qPCR; LOQ = 20 IU

HBV DNA Declines

n = 12

n=12

n=6

n=6

*

**

*Statistically significant at (P < .05 or better)


Study 202: Superior RNA Reductions with 731 Combination

17

0.0

0.5

1.0

1.5

2.0

2.5

3.00 5 10 15 20 25

ETV 731 + ETV

Treatment Week

HB

V R

NA

Red

uctio

n (lo

g 10

cop

ies/

mL)

Mean Log10 HBV RNA Decline

Week ETV 731 + ETV P Value

12 0.44 2.27 <.005

24 0.61 2.54 <.005

• All patients on combination achieved a rapid decline in RNA levels

HBV RNA assessed by RT qPCR; LOQ = 200 copies/mL

HBV RNA Declines

n = 12

n = 12

n = 5

n = 6


Study 201: Elimination of Detectable Virus Only on Combination

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Nuc Monotherapy 731 Combo Therapy

Residual viremia not eliminated by Nuc

Patient Treatment Week

Nuc M 0 2 4 8 12 16 20 24

1TDF

2TAF

3TDF

4TDF

Patient Treatment Week

Nuc M 0 2 4 8 12 16 20 24

5TAF

6TAF

7ETV

8TAF

9TDF

10TAF

HBV DNA PCR Assay To Quantitate Low Level Viremia• DNA purified from longitudinal serum samples (0 – 24 Wk)

• PCR amplification (40-45 cycles) using individually optimized primers

At Week 24, longitudinal serum samples were assayed for detectable virus using sensitive PCR assay

Residual viremia decline below detection (2-5 IU/mL)


Study 201: RNA Reductions to BLQ Only on Combination

19

Results for HBeAg Positive Patients with RNA >LOQ at Baseline (N = 38)

0

10

20

30

40

50

60

70

80

90

100

0 4 8 12 16 20 24

Nuc+731(n=25)

Nuc(n=13)

Perc

enta

ge o

f Pat

ient

s <2

00 C

opie

s/m

L R

NA

Time (Weeks)


Study 201: Summary of Results at Time of Interim Analysis

• Antigen declines anticipated to follow elimination of residual viremia and RNA

• High level expression of HBsAg from integrated sequences limits ability of Core Inhibitors to decrease HBsAg levels from this source

• Study subjects continue to be treated and monitored in open label Study 211

Patients Treated 24 Weeks*

Treatment Nuc 731 + Nuc

DNA (TND1) 0/4 (0%) 5/6 (83%)

RNA (<200 Copies/mL) 0/3 (0%)2 3/6 (50%)

HBeAg ≥ 0.5 Log10 Decline 0/3 (0%) 1/6 (17%)

HBsAg ≥ 0.5 Log10 Decline 0/4 (0%) 0/6 (0%)*Subjects with available data1 Target not detected by ASMB semi-quantitative PCR

2 a 4th subject on Nuc was BLQ at baseline


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ASMB Core Inhibitor Program Summary

• Core inhibitors have the potential to be the backbone of future HBV regimens─ Highly potent antivirals that disrupt viral replication at multiple steps─ Potential to eliminate residual viremia (deficiency of Nuc therapy)─ Inhibit the generation of new cccDNA

• Summary of Interim Data for Phase 2a Studies on ABI-H0731─ Favorable safety profile (AEs and lab abnormalities generally considered unrelated, grade 1 and

transient)─ Combination of 731+Nuc demonstrated superior antiviral activity vs. Nuc alone

• In Rx-naïve patients, faster and deeper declines in HBV DNA observed starting at Week 2• DNA reductions to below limits of high-sensitivity PCR assay observed in Nuc “suppressed” patients • Significant HBV RNA declines In both studies

─ Elimination of residual viremia will likely be required to prevent new cccDNA formation and increase cure rates

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22

Acknowledgements

• The Patients• The (many) clinical study teams

• Assembly Biosciences

Office of Xiaoli MaQuest Clinical Research(GI) Research and EducationAsia Pacific Liver CenterSchiff Center for Liver DiseasesToronto General HospitalQueen Mary HospitalSouthern California Research CenterThomas Jefferson University HospitalToronto Liver CenterIcahn School of Medicine at Mount Sinai Medical Associates Research Group

Johns Hopkins University School of Medicine Stanford University Medical CenterInfectious Disease CareKing's College Hospital GI Research InstituteNYU Langone Medical CenterDigestive Disease AssociatesOffice of S Chan, MDWaikato Hospital,Pfleger Liver Institute at UCLACedars-Sinai Medical Center Auckland Clinical Studies

Virology: Qi Huang, Ran Yan and Dawei CaiClinical: Steve Knox, Katia Alves, Linda Baher and Vivian HueyRegulatory: Eric Ruby, Christina Schmidt, Na YuDMPK: Dongmei Qiang, Marc Evanchik

Thank You!

CONFIDENTIAL 23

new therapies to more effectively eliminate viral

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