Managing Resistance with Confidence

1
Managing Resistance with Confidence

• Fabien Zoulim MD, PhD
• Liver Department and INSERM Unit 271, Hôpital
  Universitaire Hôtel Dieu
• Lyon, France

2
Anti-HBV Active Compounds
Currently approved for HIV
3
Mechanisms Involved in Viral Persistence/ Mutant
Escape
The Virus
The hepatocytes
cccDNA long half-life
Viral polymerase error rate / mutations
Infected cells Long half-life
Viral Quasi-species
Viral persistence
Selective pressure Antivirals Immune
response Others
Replication fitness Replication space
The host
Selection of escape mutants
1. Zoulim et al, Antiviral Research 2004
4
Definition of terms

• Genotypic Resistance Mutations in the HBV
  genome which have been found to develop during
  anti-viral therapy
• Virologic Breakthrough Rebound in HBV serum DNA
  levels following the development of genotypic
  resistance
• Clinical Breakthrough Virologic Breakthrough
  with increased ALT levels or worsening histology
• Phenotypic Resistance Decreased susceptibility
  (in vitro testing) to inhibition by anti-viral
  drugs associated with Genotypic Resistance.
• Cross Resistance Mutants selected by one agent
  that also confer resistance to other antiviral
  agents

5
Definition of terms

• Genotypic Resistance Mutations in the HBV
  genome which have been found to develop during
  anti-viral therapy
• Virologic Breakthrough Rebound in HBV serum DNA
  levels following the development of genotypic
  resistance
• Clinical Breakthrough Virologic Breakthrough
  with increased ALT levels or worsening histology
• Phenotypic Resistance Decreased susceptibility
  (in vitro testing) to inhibition by anti-viral
  drugs associated with Genotypic Resistance.
• Cross Resistance Mutants selected by one agent
  that also confer resistance to other antiviral
  agents

6
Incidence of Resistance in Treatment-naïve
Patients Over Time
FTC
LdT
ETV
ADV
LAM
80
71
65
60
55
46
Patients ()
40
29
23
18
20
13
11
5
3
?
?
?
?
?
?
0
0
?
?
?
?
?
?
0
Year 1
Year 2
Year 3
Year 4
Year 5
4. Colonno et al. Hepatology 200440 661A 5.
Xiong et al. EASL 2005
1. Lok et al. Gastroenterology 20031251714-1722
2. Schiffman et al. Hepatology 2004 40172A 3.
Lai, et al. Hepatology 200338262A
7
Polymerase Mutations Associated with Drug
Resistance
Pol/RT
RNaseH
spacer
Terminal protein
845 a.a.
1
183
349
692
(rt1)
(rt 344)
YMDD
A
B
C
E
D
I(G)
II(F)
ETV resistance associated with YMDD mutation
1. Allen et al. Hepatology 1998 271670-7 2.
Gilead data on file 3. Qi et al. J Hepatol
200440(suppl 1)20-1
4. Tenney et al. AAC 2004483498-507 5. Lai et
al. Hepatology 2003 38 262A
8
Patterns of LAM Genotypic Resistance Mutations

• 4 primary patterns

L180M M204I
(n215)
11
M204I
59
11
17
59
17
L180MM204V
V173LL180MM204V
1. Westland CE et al. J Viral Hepat. 20051267-73
9
Patterns of ADV Genotypic Resistance Mutations
(n35)
14
9
51
26
1. Gilead, data on file
10
Clinical Consequences of Resistance

• Demonstrated loss of clinical benefits
• Decreased rate of HBeAg seroconversion 1
• Reversion of histological improvement 2
• Increased rate of disease progression 3
• Severe exacerbations in patients with cirrhosis
  4,5
• Risk of graft loss and death in liver transplant
  patients 6
• Potential impact on public health
• Transmission of drug-resistant strains 7
• HBsAg mutations leading potentially to vaccine
  failure 8

5. Si Ahmed et al. Hepatology 200032 1078-88 6.
Mutimer et al. Gut 2000 46107-13 7. Thibault et
al. AIDS 2002 16 131-3 8. Torresi et al.
Virology 2002 293 305-13
1. Leung et al. Hepatology 2001331527-32 2.
Dienstag et al. Gastroenterology 2003124
105-17 3. Liaw et al. N Engl J Med 2004351
1521-31 4. Yuen et al. J Hepatol 200339 850-5
11
Antiviral response and lamivudine resistance
impact on progression of liver disease
25
Placebo (n215)
21
YMDD mutants (n209) (49)
20
Wild type (n221)
15
13
Patients with disease progression ()
10
5
5
0
0
6
12
18
24
30
36
Time (months)
1. Liaw et al. N Eng J Med 2004
12
Dynamics of LAM Resistance Emergence
Lamivudine
8 -
-600
7 -
-500
ALT (U/L)
6 -
-200
HBV DNA log copies/mL
5 -
-150
4 -
-100
3 -
-50
-0
Months
42
0
6
12
18
24
30
36
M
M
M
L
L/M
M
M
L
Codon 180
V
M
M/V
M
M
M/V
V
M
Codon 204
V
V
V
V
V
V
V
V
Codon 207
Selection of resistant virus
1. Si Ahmed et al. Hepatology 2000321078-88
13
Dynamics of LAM Resistance Emergence
Lamivudine
8 -
-600
Step 1 Rebound of serum HBV DNA
7 -
-500
ALT (U/L)
6 -
-200
HBV DNA log copies/mL
5 -
-150
4 -
-100
3 -
-50
PCR assay
-0
Months
42
0
6
12
18
24
30
36
M
M
M
L
L/M
M
M
L
Codon 180
V
M
M/V
M
M
M/V
V
M
Codon 204
V
V
V
V
V
V
V
V
Codon 207
1. Si Ahmed et al. Hepatology 2000321078-88
14
Dynamics of LAM Resistance Emergence
Lamivudine
8 -
-600
Step 2 Rise in serum ALT/AST
7 -
-500
ALT (U/L)
6 -
-200
HBV DNA log copies/mL
5 -
-150
4 -
-100
3 -
-50
-0
Months
42
0
6
12
18
24
30
36
M
M
M
L
L/M
M
M
L
Codon 180
V
M
M/V
M
M
M/V
V
M
Codon 204
V
V
V
V
V
V
V
V
Codon 207
1. Si Ahmed et al. Hepatology 2000321078-88
15
Clinical Profile of a Patient with A181V
0627-1557
400
9.0
ADV
ADVLAM
350
8.0
300
7.0
250
6.0
HBV DNA (log10 c/ml)
ALT (IU/L)
200
A181V
Log10 HBV DNA
5.0
ALT
150
4.0
100
3.0
50
0
2.0
Apr-00
Jul-00
Oct-00
Jul-01
Oct-01
Jul-02
Oct-02
Apr-03
Jul-03
Oct-03
Apr-04
Jul-04
Oct-04
Apr-05
Jul-05
Oct-05
Jan-01
Apr-01
Apr-02
Jan-03
Jan-04
Jan-02
Jan-05
Date
16
Clinical profile of a Patient with N236T and A181V
0624-1512
10
500
ADVLAM
Placebo
ADV
ADV
450
9
A181VN236N/T
400
8
350
7
300
HBV DNA (log10 c/ml)
ALT (IU/L)
6
250
200
5
Log10 HBV DNA
150
4
ALT
100
3
50
2
0
Jul-02
Jul-00
Oct-02
Jul-03
Oct-03
Jul-04
Apr-00
Oct-00
Jul-01
Oct-01
Apr-02
Apr-03
Apr-04
Oct-04
Apr-05
Jul-05
Oct-05
Jan-00
Jan-01
Apr-01
Jan-02
Jan-03
Jan-04
Jan-05
Date
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Impact on Clinical Practice

• Prevent
• Monitor
• Diagnose
• Manage when resistance emerges

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Preventing Resistancein Clinical Practice

• Use regimens with good tolerability and
  convenience to support adherence
• Use drugs with optimal antiviral potency
• Maximize genetic barriers to resistance
• Choose drugs with a low incidence of resistance
  over time
• Avoid sequential monotherapy and treatment
  interruptions
• Consider de novo combination therapy
• Anticipate the implications of resistance on the
  availability of future effective options

1. Richman J Virol 2001271670-7 Zoulim Antivir
Res 2004 641-15
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In Vitro Cross-Resistance Testing

• NucleosideAnalogues
• Lamivudine
• Clevudine
• Entecavir
• Emtricitabine
• Valtorcitabine
• Telbivudine

NucleotideAnalogues Adefovir Tenofovir
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Acyclic Nucleotides
Tenofovir Disoproxil Fumarate (TDF)
Adefovir
21
LAM Genotypic Mutations In Vitro Susceptibility
to Acyclic Nucleotides

Fold-Change from Wild-Type
V173L
L180M


L180M

L180M

Compound

M204V

M204V

M204I

M204I

Adefovir


1.1

1.1

1.8

2.1

0.8

1.8

2.1

0.7

Tenofovir






Reduced susceptibility
Resistant
Sensitive
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L and D Nucleoside Analogs
L-Nucleoside
D-Nucleoside
Lamivudine
Emtricitabine
Entecavir
Clevudine
Telbivudine
23
LAM Genotypic Mutations In Vitro Susceptibility
to Acyclic Nucleotides
Reduced susceptibility
Resistant
Sensitive
24
ADV Genotypic Mutations In Vitro Susceptibility
to Nucleos(t)ide Analogs
Reduced susceptibility
Resistant
Sensitive
Qi et al, DDW 2004 Xiong, EASL 2005
25
HBV Antiviral TherapyCross Resistance In Vitro
N236T
L180M
A184G
M204V
A181V
M250V
V173L
M204I
S202I
LAM
ETV
LdT
ADV
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In Vitro vs Clinical Results

• ADV1
• Similar serum HBV DNA reductions in patients
  regardless of Lam-R mutation patterns
• Entecavir2,3
• Reduced efficacy in LAM-experienced patients
• 0.5 mg in naïve patients - 6.98 log at wk 48
• 1.0 mg in Lam-resistant patients - 5.14 log at wk
  48
• Telbivudine4
• Selected for YMDD mutations in 5 to 12 of
  patients

1. Westland CE et al. J Viral Hepat.
20051267-73 2. Chang T et al. 55th AASLD.
2004 Boston, MA. Abstract 70. 3. Sherman M et
al. 55th AASLD. 2004, Boston, MA. Abstract 1152
Lai, 2003.
27
Risk of Sequential Monotherapy Multi-drug
Resistance
Wild type
LAM-R
ADV-R
1. Zoulim Antivir Res 2004 64 1-15
28
Evolution of viral quasi-species with a de novo
combination therapy
29
Preventing Lamivudine Resistance with de novo
Combination Therapy
100
80
60
Incidence of resistance ()
34
40
21
20
18
20
12
11
5
2
1
0
LAM
LAM
LAM
LAMADV
LAMPeg
LAMPeg
LAMLdT
LdT
LAM
Marcellin 2
Lau 3
Sung 1
Lai 4
After 1 year of therapy
1. Sung et al. J Hepatol 2003 38 (suppl
2)25-26 2. Marcellin et al. N Engl J Med 2004
351 1206-17
3 Lau et al. Hepatology 200440171A 4 Lai et al.
Hepatology 200338262A
30
Monitoring for Drug Resistance

• Serum HBV DNA is the best available measure
• Use a sensitive PCR-based HBV DNA assay
• Use the same assay over time
• Adapt frequency of assessments according to
• Disease severity
• Mild liver disease at least every 6 months
• Advanced disease/cirrhosis at least every 3
  months
• Drug resistance profile

1. Locarnini et al. Antivir Ther
20049679-93 2. Keeffe et al. Clin
Gastroenterol Hepatol287-106
31
Diagnosis of Resistance

• Define treatment failure
• Confirmed rebound of viral replication by gt 1.0
  log as compared with the nadir of antiviral
  efficacy
• Rule out non-HBV-related causes of failure
• Adherence
• Individual metabolic factors?
• Confirm resistance with HBV mutant detection
• Identifying mutations will help guide future
  therapy (cross-resistance)

1. Locarnini et al. Antivir Ther 2004 9 679-93
Brunelle et al. Hepatology2005
32
Diagnosis of Resistance
Antiviral
1 log
HBV DNA change from baseline (log 10 c/mL)
1 log
Time
1. Locarnini et al. Antivir Ther 20049679-93
33
Managing Resistance

• Better than no treatment in some patients? 1
• Risk of disease reactivation and worsening 2
• Selection of additional resistance mutations 3
• Risk of ALT flare during transition 4,5
• Consider risk of cross-resistance 6
• Risk of multiple drug resistance
• May be more effective against mutant than
  wild-type 7
• Consider risk of cross-resistance 6

Continue the current treatment
Switch to a new drug(s)
Add a new drug(s)
5 Peters et al. Gastroenterology 2004126
91-101 6 Zoulim Antivir Res 2004 641-15 7 Chin
et al. AAC 2001 45 2495-501
1. Leung et al. Hepatology 2001331527-32 2.
Liaw et al. N Engl J Med 2004 351 1521-31 3.
Delaney et al. AAC 2001 121-35 4. Gish et. al.
J. Hepatol 2004 (suppl 1)127
34
First Line Treatment Strategiesto Delay
Resistance
35
Managing ResistanceHow to Choose a New Drug

• According to resistance profile
• In vitro phenotypic assays
• Evaluation of drug susceptibility in tissue
  culture
• According to clinical efficacy profile
• ADV effective on all patterns of LAM-R mutants1
• LAM effective on N236T mutants2 and reduced
  susceptibility on A181V mutants
• ETV double dosage required to inhibit LAM-R
  mutants
• Less effective than on wild-type virus3
• 7.4 ETV resistance at one year

1. Westland et al. J Virol Hepatitis
2004111-7 2. Xiong et al. J Hepatol 2003 38
(suppl 2)182 3 Sherman et al. Hepatology
200440 (suppl 1) 664A
36
Managing ResistanceAdd-on or Switch?

• Simple mutants pre-exist
• Genetic variants harboring multiple mutations
  have less chance to pre-exist or to occur
• Re-treatment leads to a rapid re-emergence of
  resistant mutants
• cccDNA represents a genetic archive for a more
  rapid re-selection of resistant mutants
• Less resistance when combining drugs with
  different cross-resistance profiles

3. Maynard et al. J Hepatol 2005 42 279-81 4.
Zoulim et al. Antiviral Chem Chemother
200415299-305
1. Richman Hepatology 200032 866-7 2. Zoulim
et al. Hepatology 200338 1353-5
37
Managing ResistanceAdd-on or Switch?

• Adding on or switching to ADV has demonstrated
  the same short term efficacy in LAM-R patients
  with compensated liver disease1
• However, adding ADV to ongoing LAM prevents ADV
  resistance in the long term

The two patients started with LAMADV then LAM
was stopped and ADV resistance emerged
while patients were on ADV monotherapy
1. Zoulim et al EASL 2005 Maynard et al J
Hepatol 2005 2. Peters et al. Gastroenterology
200412691-101 Xiong EASL 2005
38
Summary

• Current standard of care is monotherapy
• Select drug with high barrier to development of
  resistance
• Favorable cross resistance profile
• Long term, sequential monotherapy selects for
  multiple drug resistant viruses
• Combination therapy has the potential to slow
  resistance development
• Using drugs with distinct mechanism of resistance
  
• In first line therapy and after treatment failure
• Need to be further evaluated in clinical studies

39
Thank You