chronic hepatitis b - antiviral resistance in korea joint symposium/4.antiviral... ·...

Chronic Hepatitis BChronic Hepatitis B-- Antiviral Resistance in Korea Antiviral Resistance in Korea --

YoungYoung--Suk LimSuk LimUniversity of Ulsan College of MedicineUniversity of Ulsan College of Medicine

Asan Medical CenterAsan Medical CenterSeoul, KoreaSeoul, Korea

HBV Genome

• HBV polymerase lacks proof-reading function

• Estimated mutation frequency: 1.4-3.2 x 10-5

(approximately 10-fold higher than other DNA viruses)

• HBV production rate: 1011/day

• dynamic quasispecies

• partially double-stranded DNA genome

• about 3200 nucleotides

Evolution of HBV Resistance Mutations to Antiviral Drugs

• Primary resistance mutations

mutations directly responsible for the associated drug-resistance

• Compensatory (Secondary) mutations

- mutations that can restore replication fitness of primary resistant mutants

- ‘fix’ the primary drug-resistant mutations as a genetic archive with quasispecies memory

• Cross Resistance

mutants selected by one agent may also confer resistance to other antiviral agents

LamivudineLamivudine--Resistance Mutations Resistance Mutations at at HBV polymerase/RT domainHBV polymerase/RT domain

LMV Resistance rtL80V/I rtV173L rtM204V/I/SrtL180M

• primary resistance mutation• compensatory mutations• rtM204 mutation confers cross resistance to entecavir,

clevudine, telbivudine, emtricitabine

845 a.a.

Terminal Protein Spacer POL/RT RNaseH

A B C ED

1 183 349 (rt1) 692 (rt 344)

F__V__LLAQ__YMDDI(G) II(F)

Mechanisms of Resistance

S

Sensitive(wild type)

S

R

Sensitive

Resistant(rtM204V)

Lamivudine

S

Sensitive

Resistant(rtM204V+rtL180M)

R

Discontinuation

R

SensitiveS


LamivudineClevudineEntecavirTelbivudineEmtricitabine

R


SSensitive

Clinical Definitions - HBV Resistance to Antiviral Drugs -

• Genotypic Resistance

Detection of mutations in the HBV genome, known to confer resistance

• Virologic Breakthrough

Rebound in serum HBV DNA levels, more than 1 log10 cpm (10 fold)

• Biochemical (Clinical) BreakthroughIncrease of ALT levels (or worsening histology) with virologic breakthrough

Development of Antiviral Resistance

Antiviral DrugAntiviral DrugHBV DNA (Log)

6

5

4

3

2

1 log

Virologic Breakthrough

Development of Genotypic Resistance

Biochemical Breakthrough

ALT (IU/L)

80

40 (ULN)

nadir

Mutant / Wild type

165 (2)

120 (1)103 (2)

25 (5)

10 (9) 3 (3) 3 (3)

0

20

40

60

80

100

120

140

160

180

Inci

denc

e

0 1 2.5 5 7.5 10

Higher Retention of Mutant Virus Go with More Subsequent Occurrence of

Viral Breakthrough

Lee CH et. al. Gastroenterology. 2006;130(4)1144

Genotypic Assays for antiviral drug resistance of HBV

• Sequencing (direct or after cloning)

• Hybridization Assay (Line probe assay, LiPA)

• Restriction Fragment Length Polymorphism (RFLP)

• Restriction Fragment Mass Polymorphism (RFMP)

• Allele-specific PCR

• DNA Chip



- the best approach to identify new mutations

- unable to detect mixed populations of two or more HBV genotypes

- expensive and time-consuming





• DNA Chip




- more sensitive than direct sequencing- most commonly used method in Western countries




• DNA Chip







- can detect minor HBV populations comprising up to 5% of the total viral population (about 103 cpm)

- robust high throughput manner

- most commonly used methods in Korea

• DNA Chip

1992 1998 2003 2005 2006 1992 1998 2003 2005 2006 -- -- --

Interfer

on

Lamivu

dine

Adefovir

Entecav

ir

Clevudine

Peg-IF

N α-2a

Tenofovir

Telbivu

dine

Advances in Management of HBV Infection

HBV Therapies Approved in Korea

For Naïve CHB

• Interferon

• Peginterferon α-2a

• Lamivudine*

• Entecavir*

• Clevudine*

For LAM-Refractory CHB

• Interferon

• Peginterferon α-2a

• Adefovir dipivoxil*

• Entecavir*

*Approved only as monotherapy and after ALT flare

or biochemical breakthrough (ALT>80 IU/L)

New Oral Agents

Future agents

• Telbivudine (LdT)

• Tenofovir

• Emtricitabine

New experimental agents

• LB80380

• Pradefovir

• Alamifovir

• Valtorcitabine

• Torcitabine

High potency in reducing HBV DNA level

High rate of HBeAg seroconversion

Few adverse events or toxicity

Cost-effective

Long-term, low rate of drug resistance

Ideal antiIdeal anti--viral agent viral agent

Lamivudine-Resistance


L-dT Resistance rtM204I

ADV Resistance rtA181T/V rtN236T

ETV Resistance rtT184G rtS202I rtM250V

TFV Resistance rtA194T/rtV214A/rtQ215S

HBV polymerase/RT domainHBV polymerase/RT domain

845 a.a.


A B C ED

1 183 349 (rt1) 692 (rt 344)

YMDDF__V__LLAQ__I(G) II(F)

Long-term LAM therapy can lead to the emergence of resistant viruses

01020304050607080

1 2 3 4 5 6 7 8Years

Patients with

YMDDmutants

(%)

90

15%

40%

55%66% 69%

1. Leung NW, et al. Hepatology. 2001;33:1527-1532. 2. Yuen et al AASLD 2005

High lamivudine resistance with poor early HBV suppression

Yuen et al. Hepatology. 2001; 34:785-791

Patients(%)

Serum HBV DNA Level at 6 months (copies/mL)

0

20

40

60

80

100

8% 13%

32%

64%

Serum DNA at month 6 vs.LAM resistance by month 61

< 200(n = 12)

< 3 log10(n = 23)

< 4 log10(n = 41)

> 4 log10(n = 118)

Wild Type (n=221)YMDDm (n=209) (49%)

Time after randomization (months)

0

5

10

15

20

25

0 6 12 18 24 30 36

% with disease

progression

Placebo (n=215)

YMDDm

WT

Placebo

5%

13%

21%

Disease Progression by YMDD Status

Liaw YF, et al. N Engl J Med. 2004;351:1521-1531.

Hepatitis flares and Serious Adverse Events with Lamivudine resistance mutations

Lok AS, et al. Gastroenterology. 2003;125:1714.

hepatitis flareLiver Disease Related

Serious Adverse Events

Clinical consequencesof Lamivudine resistance

It is now clear that drug-resistant HBV is not a benign or attenuated virus.

Disease progression, loss of initial benefit, fulminant hepatic failure and death can occur.

Management of

Lamivudine-Resistant HBV

Continuation or Discontinuation of Lamivudine

Events within 12 mo. after emergence of YMDD mutations

ALT flare (>5x ULN)

Decompensation HBeAg seroconversion

0

25

50

75Continued (n=66)Discontinued(n=68)

% *

*

*

* P > 0.05

11% 7%

Liaw YF, et al. Antivir Ther. 2004;9:257.

Continuation or Discontinuation of Lamivudine

• Hepatitis flares and decompensation frequently occur after emergence of YMDD mutations regardless of continuation or discontinuation of lamivudine therapy .

• Compensatory mutations will be selected during continued lamivudine treatment leading to subsequent viral rebound and possibly hepatitis flares.

• Patients with confirmed lamivudine-resistance should receive effective rescue therapy.

0

10

20

30

50

Patie

nts

(%)

43.7%

End of treatment

24 weeks post-treatment

7/16 5/16

31.2%40

HBsAg seroconversion

In 13% of patientsat week 72

Shi et al. APASL 2007

Peg-Interferon alfa-2ain Asian patients with NA resistance

12 wks PEGASYS + LAM → 12 wks of PEGASYS monotherapyHBeAg seroconversion

(with HBV DNA <105 copies/mL)

Peters MG et al, Gastroenterology 2004; 126: 91-101

Adefovir alone or in combination with lamivudine in lamivudine-resistant HBV

(small, short-term study)

* p<0.001 comparedto lamivudine

ADV+LAM* (n=20)

ADV (n= 19)*

LAM (n=19)

Weeks of Therapy0 8 16 24 32 40 48

Change in HBV DNA

(log10

copies/mL)

37% frequency of grade 3 ALT flare in switchover to ADV alone

0.00.0

-- 3.63.6-- 4.04.0

-5

-4

-3

-2

-1

0

1

Increased Risk of Adefovir Resistance inPatients with Lamivudine-Resistant CHB

after Adefovir Monotherapy

Incidence of ADV-Resistance at 48 wks of ADV monotherapy

Genotypicmutation

Virologic breakthrough

0

10

20naive (n=38)

LMV-resistant (n=57)

%*

*

0%

18%

7%0%

* P < 0.01

Lee YS, et al. Hepatology 2006;43:1385.

Genotypic assay ; RFMP

Cumulative Incidence of Adefovir-Resistance in Lamivudine-Resistant CHB patients treated

with Adefovir MonotherapyGenotypic Resistance Virologic Breakthrough

25.4%Genotypic assay

; RFMP

Yeon JE, et al. Gut 2006;55:1488.

Adding-on vs. Switching-to Adefovir in Lamivudine-Resistant HBeAg(-) CHB

Incidence of Genotypic Resistance

Genotypic assay ; direct sequencing

ADV

LAM + ADV

Rapti I, et al. Hepatology 2007;45:307.

When should we add Adefovir on Lamivudine ?

Lampertico P, et al. Hepatology 2005;42:1414.

Achievement of PCR Undetectability on Entecavir

40%40%

NaNaïïveve

HBeAg +HBeAg +

LVD RefractoryLVD Refractory

0 0 50 100 150

N = 319N = 319

N = 345N = 345

N = 178N = 178

HBeAg HBeAg --

% P

atie

nts

w/H

BV

DN

A <

300

Cop

ies/

mL

10

20

30

40

50

70

60

80

90

100

Treatment (Weeks)

94%94%

Genotypic resistance in naive patientsGenotypic resistance in naive patientsGenotypic resistance in LAMGenotypic resistance in LAM--R patientsR patientsGenotypic resistance plusGenotypic resistance plus viral rebound in LAMviral rebound in LAM--R patientsR patients

Colonno R, et al. Hepatology. 2006;44:229A-230A.

Incidence of Entecavir Resistance

1 2 30

10

20

30

40

0.1 0.4 1.1

6

14

32

1

10

25

Genotypic assay ; direct sequencing

Year

%

ETV Resistance Profile• ETV-R was only observed in patients with preexisting

LAM-R virus (M204 V/I and/or L180M).

• Resistance to ETV appears to occur through a two-hit mechanism with initial selection of M204V/I mutation followed by amino acid substitutions at rtI169, rtT184, rtS202, or rtM250.

• LAM should be discontinued to decrease the risk of entecavir resistance.

T184, S202 or M250

M204V ± L180MM204V ± L180M

Lamivudine Entecavir

Tenofovir for Lamivudine-Resistant CHB

• Nucleotide analogue, structurally similar to adefovir, equipotent in wild-type and LAM-R HBV (In vitro).

• Because tenofovir appears to be less nephrotoxic, the approved dose is much higher than that of adefovir, 300 mg versus 10 mg daily.

• Thus, tenofovir has more potent antiviral activity than adefovir.

• No randomized controlled trials in HBV.

* including HIV/HBV coinfection (n=21), and HBV/kidney Tpl (n=5).Van Bommel et al. Hepatology. 2004;40:1421-1425.

HB

V D

NA

(log

copi

es/m

L)10

Weeks

Tenofovir vs Adefovir in Patients with Lamivudine Resistance

(not randomized)

Tenofovir*(300 mg/day, n=35)

Adefovir(10 mg/day, n=18)

P < 0.001

Recommendations for the Tx of LAM-R CHB• It is better to start rescue therapy as soon as genotypic

resistance is detected before the development of virologic breakthrough.

• Therefore, careful monitoring of genotypic resistance is needed during antiviral therapy for early detection and early rescue of drug resistance.

• Adefovir add-on is preferred over switch (increased rate of adefovir resistance with switch) and preferred over entecavir (high rate of novel mutations in patients with lamivudine resistance).

• If entecavir is used, lamivudine should be stopped as continued presence of lamivudine-resistant mutations will increase the risk of entecavir resistance.

• Tenofovir, 300 mg daily, appears to be superior to ADV, 10 mg daily, in suppressing LAM-resistant strain HBV.

Adefovir-Resistance


L-dT Resistance rtM204I

ADV Resistance rtA181T/V rtN236TETV Resistance rtS184G rtS202I rtM250V

TFV Resistance rtA194T/rtV214A/rtQ215S

HBV polymerase/RT domainHBV polymerase/RT domain

845 a.a.


A B C ED

1 183 349 (rt1) 692 (rt 344)

YMDDF__V__LLAQ__I(G) II(F)

Incidence of Adefovir Resistance with Adefovir Monotherapy

in HBeAg-Negative NA naïve CHB Patients

Borroto-Esoda K. EASL 2006. Abstract 483.

30 311

18

29

08

13 16

0 2 6 10 11

Year 1 Year 2 Year 3 Year 4 Year 50

20

40

60

80

100

Patie

nts

(%)

Genotypic resistance Virologic rebound† Clinical breakthrough

*Cumulative probabilities calculated by life-table analysis.†Presence of genotypic resistance plus HBV DNA rebound; confirmed ≥ 1 log10 copies/mL increase in HBV DNA from nadir and/or having never achieved HBV DNA suppression ≤ 4 log10 copies/mL.

Higher HBV DNA at Year 1 Predictive of Year 3 ADV Resistance

Locarnini S, et al. EASL 2005. Abstract 36.

HBV DNA at Year 1 (log10 copies/mL)

Genotypic Resistance at Year 3 (%)

4%

67%

26%

0

20

40

60

80

100

(n = 80)< 3

(n = 31)3-6

(n = 3)> 6

Risk factors for the development of adefovir resistance

• Old age

• High baseline HBV DNA load

• Suboptimal early viral suppression

• Short-duration of LAM overlap in LAM-R HBV

(adding-on is better than switching to ADV)

• Presence of LAM-R HBV mutants

; The main LMV resistance mutations rtM204V/I do not confer cross-resistance to adefovir, but the minor LMV resistance mutations rtA181T as well as the rtQ215S are partially cross-resistant to lamivudine in vitro.

Management of

Adefovir-Resistant HBV

In Vitro Cross-Resistance Analysis

Drugs Efficacy against various HBV strains

Wild LAM-R ADF-Rtype (L180M+M204V) (N236T)

Lamivudine + - +

Clevudine + - +

Telbivudine + - +

Emtricitabine + - +

Entecavir + +/- +

Adefovir + + -

Tenofovir + + +/-1. Zoulim F. Antiviral Res. 2004;64(1):1-15. 2. Brunelle et al. Hepatology. 2005;41:1391-1398. 3. Locarnini et al. EASL 2005. Abstract 36.

Practical Optionsfor the Tx of ADR-R CHB

• In patients with no prior exposure to other NA

– add lamivudine

– add (> or switch to) entecavir

• In patients with prior LAM-R, switched to ADV

– add lamivudine

– add (> or switch to) entecavir

– switch to tenofovir (when approved)

in combination with lamivudine or entecavir

Case: Adding on LMV for ADV-R

Marcellin P and Asselah T. J Hepatol 2005;43:920.Yeon JE, et al., Gut 2006;55:1488-1495.Villeneuve JP, et al. J Hepatol 2003;39:1085–1089.

S.K. Fung SK, et al., J Hepatol 2006;44:283–290.

Case: Switching to ETV for ADV-R

Ratziu V, et al., Comp Hepatol 2006;5:1.

Case: Switching to Tenofovir for ADV-R

Prevention of Antiviral Drug Resistance in Patients with CHB

• Current therapy of CHB has limited long-term efficacy.

• Once antiviral-resistant HBV mutants have been selected, they are archived (retained in the virus population) persistently even if treatment is stopped.

• Thus, the best way to reduce the emergence of drug resistance is to select the right patients, right time to start treatment and the right antiviral agent(s).


• Select the right patients

Patients with minimal disease and those who are unlikely to achieve sustained response should not be treated with NA

• Select right time to start treatment

• Select the right antiviral agent(s)




Start therapy at right time with clear indication to maximize antiviral activity






The most potent NA with the lowest rate of genotypic resistance should be administered.

APASL Seoul 2008APASL Seoul 20082008. 3. 232008. 3. 23--2626

See you in Seoul, KoreaSee you in Seoul, Koreaありがとうございましたありがとうございました..

Thank you for your attention!!Thank you for your attention!!

chronic hepatitis b - antiviral resistance in korea joint symposium/4.antiviral... ·...

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