Hepatitis B

1
Hepatitis B

• Jay H. Hoofnagle, M.D.
• Division of Digestive Diseases
• and Nutrition
• National Institute of Diabetes and Digestive and
  Kidney Diseases
• National Institutes of Health

FDA Advisory Panel Meeting August 7, 2002
2
Hepatitis B

• HBV, small double stranded DNA virus
• Hepadnaviridae
• Infection restricted to humans and higher apes
• High levels in blood (102 to 1010 copies/ml)
• Causes both acute and chronic hepatitis
• Parenteral, sexual and maternal-infant spread
• Marked geographic variation in incidence
• Common in Asia Africa, uncommon in the United
  States and Western Europe

3
Hepatitis B Virus
HBeAg
HBsAg
HBsAg
HBcAg
Sphere
HBsAg
Dane Particle
Tubule
4
(No Transcript)
5
Hepatitis B Virus RNAs
2.1kb RNA
2.4kb RNA
Pre-S1
Pre-S2
-strand
ORF-S
strand
3.5kb RNA
5
DR1
ORF-C
ORF-P
5
DR2
Pre-C
ORF-X
0.7kb RNA
6
Hepatitis B Viral Genome

• Circular, partially doubled-stranded DNA
• Four open reading frames
• HBsAg (pre-S1, pre-S2 and S)
• HBcAg (pre-core core)
• Polymerase (multifunctional)
• HBxAg (transactivating factor)
• Replicates largely in liver
• Through RNA intermediate and reverse transcription

7
Infectious cycle of hepatitis B virus
Y
Y
Y
degradation - antigen-specific - non-specific
Y
Y
Y
Y
Y
Virus - half-life 1-2 days -production
1011-1013/day mutation rate 1-3
x 10-5/site/yr
cell death
Zeuzem et al 2000
8
Hepatitis B Virus Mutants

• Variations in nucleotide sequence in one of the
  HBV genes can result in change in the virological
  and, in some cases, clinical features of the
  infection.
• S gene vaccine or HBIG escape mutants
• C gene can affect disease severity or
  serological and clinical manifestations
• P gene can effect replicative efficiency and
  resistance to antiviral therapy

9
Hepatitis B Core Antigen Mutants

• Nucleocapsid region Pre-core and Core
• Pre-core May result in inability to produce
  HBeAg. HBeAg-negative mutants. Most frequently,
  G?A at nt 1896.
• Core Substitutions in core region are frequent
  among pts with severe disease or resistance to
  interferon, in areas of major B cell and T cell
  epitopes, thus important in T cell cytotoxicity
  and viral clearance

10
HBeAg-negative Variants

• G?A at nt 1896 creates a stop codon in the
  pre-core region that therefore blocks the
  synthesis of HBeAg.
• nt 1896 is in the highly structured stem-loop ?
  encapsidation signal region of HBV RNA and
  base-pairs with nt 1858
• If nt 1858 is a T (ayw, adr, some adw), stem loop
  of ? is maintained by either G or A if it is a C
  (adw), stem loop is disrupted by A and
  replication is stopped.
• Thus HBeAg-negative variants are more common with
  genotypes B, C and D than genotype A

11
Outcome of Hepatitis B Virus Infection
35
Acute Hepatitis B
65

Asymptomatic subclinical infection
Fulminant Hepatitis
5
Chronic Hepatitis B
30
50
Inactive Carrier State
Cirrhosis
?
Liver Cancer
12
Typical Acute Hepatitis B
HBsAg
HBeAg
ALT
ALT and HBV DNA IU/L and million copies/ml
Symptoms
HBV DNA
Normal
Months After Exposure
13
Typical Chronic Hepatitis B
HBsAg
HBeAg
ALT and HBV DNA IU/L or million copies/ml
HBV DNA
ALT
Normal
Months After Exposure
14
Chronic Hepatitis B Transition to Inactive
Carrier State

HBsAg
HBeAg
ALT and HBV DNA IU/L and million copies/ml
HBV DNA
Anti-HBe
ALT
Normal
Months After Exposure
15
Evolution of HBeAg Negative Mutant
HBsAg
Anti-HBe
HBeAg
ALT
ALT and HBV DNA IU/L and million copies/ml
HBV DNA
Normal ALT levels
Months
16
Chronic Hepatitis B Three Clinical Forms

• HBeAg Positive Chronic Hepatitis B
• HBeAg, raised ALT, HBV DNA in serum and chronic
  hepatitis on biopsy
• HBeAg Negative Chronic Hepatitis B
• Anti-HBe, raised ALT and HBV DNA in serum,
  chronic hepatitis on biopsy
• Inactive HBsAg Carrier State
• Anti-HBe, normal ALT no HBV DNA, minimal
  nonspecific changes on biopsy

17
Chronic Hepatitis B Clinical Forms HBV DNA
levels

• HBeAg Positive Chronic Hepatitis B
• 107 to 1011 copies per ml
• HBeAg Negative Chronic Hepatitis B
• 104 to 108 copies per ml
• Inactive HBsAg Carrier State

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HBV DNA Detection
10
35,000
8
350
6
3.5
pg/mL
Log10 copies/mL
.035
4
2
.0035

Dynamic Range of Detection of HBV DNA 5 Assays
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Genotypes of Hepatitis B Virus
Type Subtype Geographical Distribution

• A adw, adw2, ayw1 US, Northern Europe, Africa
• B adw2, ayw1 China, Indonesia, Vietnam
• C adr, ayr China, Korea, Japan, Vietnam
• D ayw2, ayw3 Mediterranian, Middle East,
  India
• E ayw4 West Africa
• F adw4 Polynesia, US (rare)
• G Europe, US (rare)

20
Acute Hepatitis BSentinel County Study 1982-98

• Currently, HBV causes 34 of viral hepatitis
• Decline in incidence by 76 between 1987-98
• 20 hospitalized, 1 fatal
• Gradual rise in median age (27 to 32 yrs)
• More common in men than women
• African-Americans Hispanic whites whites
• Current proportions with risk factors
• Injection drug use 14
• Men who has sex with men 15
• Heterosexual activity 40
• Occupational exposure 2

Goldstein et al 2002
21
Acute Hepatitis B Incidence in the U.S. 1978-1998
HBsAg screening of pregnant women
Vaccine licensed
Routine infant immunization
OSHA Rule
Routine adolescent immunization
Infections per 100,000
Decline in high-risk heterosexuals
Decline in MSM HCW
Decline in injecting drug users
Year
Alter et al CDC
22
Chronic Liver Disease United States 1999
Other
Hepatitis B
NASH 10
Hepatitis C 57
Alcohol 25
Hepatitis B accounted for only 4.4 of
newly-diagnosed chronic liver disease
Bell et al 2001
23
Chronic Hepatitis BLong-Term Complications

• Cirrhosis
• Hepatocellular carcinoma
• Glomerulonephritis
• Polyarteritis Nodosa

24
Chronic Hepatitis BHistology

• Necroinflammatory Changes (Grade)
• Periportal inflammation and necrosis (piecemeal
  necrosis, interface hepatitis)
• Lobular inflammation and single cell necrosis
• Portal inflammation
• Fibrosis (Stage)
• Portal
• Septa formation
• Bridging fibrosis
• Cirrhosis

25
Chronic Hepatitis BHistology Scoring Systems

• Histology Activity Index (Knodell)
• Periportal necrosis inflammation (0-10)
• Lobular necrosis inflammation (0-4)
• Portal inflammation (0-4)
• Fibrosis
• None 0
• Portal fibrosis 1
• Bridging fibrosis 3
• Cirrhosis 4

26
Chronic Hepatitis BHistology Scoring Systems

• Histology Activity Index (Ishak)
• Periportal necrosis inflammation (0-4)
• Bridging necrosis (0-6)
• Lobular necrosis inflammation (0-4)
• Portal inflammation (0-4)
• Fibrosis
• None 0
• Portal fibrosis 1 or 2
• Bridging fibrosis 3 or 4
• Cirrhosis 5 or 6

27
Therapy of Hepatitis B
28
Chronic Hepatitis BGoals of Therapy

• Improve symptoms and quality of life
• Decrease infectivity
• Prevent progression of disease
• Hepatic Decompensation
• Death from liver disease
• What surrogate end-points
• correlate with these outcomes ?

29
Therapy of Chronic Hepatitis B Major Issues

• What are appropriate end-points?
• Are they the same for different forms of HBV?
• Loss of HBeAg
• Loss of HBsAg
• Loss of HBV DNA (fall below 105 copies/ml)
• Normalization of ALT
• Improvement in histology
• What amount of follow up is appropriate in
  assessing benefit of therapy?

30
Definition of Responses to Therapy in Chronic
Hepatitis B

• Type
• Virological Loss of HBeAg and/or HBV DNA
• Biochemical Normal ALT
• Histological Improvement in histology scores
• Complete All of above loss of HBsAg
• Timing
• Initial within first 6 mo of therapy
• End-of-therapy when therapy is stopped
• Sustained 6 or 12 mo after stopping
• Maintained present while continuing therapy

31
Virological Response in Chronic Hepatitis B

• Loss of HBeAg and fall of HBV DNA levels to below
  105 copies/mL
• Occurs in 25-48 of patients given a 4-5 month
  course of alpha interferon
• Occurs in 20-32 of patients given a 12 month
  course of lamivudine
• Occurs in 8-12 of patients on no therapy
• Is this response durable and does it result in
  long-term improvement in disease and lack of
  progression to cirrhosis and HCC?

32
Virological Response in Chronic Hepatitis B

• Loss of HBeAg cannot be used as an endpoint in
  patients with HBeAg-negative disease
• Generally rely upon decrease in HBV DNA to below
  105 copies/ml
• HBV DNA levels, however, can fluctuate widely,
  and with nucleoside therapy will rapidly return
  to baseline when treatment is stopped.
• How durable is decrease in HBV DNA without other
  changes in viral status?

33
Virological Response in Chronic Hepatitis B

• Loss of HBsAg and development of anti-HBs
• Occurs in 8 of patients given a 4-5 month course
  of alpha interferon
• Occurs in 1-2 of patients given a 12 month
  course of lamivudine
• Occurs in
• Extremely rare in treatment trials of
  HBeAg-negative chronic hepatitis B
• This response is durable and associated with
  resolution of liver disease

34
Biochemical Response in Chronic Hepatitis B

• Fall of ALT levels into the Normal Range
• Often accompanies loss of HBeAg or decrease in
  HBV DNA to below 105 copies/mL
• Not durable unless the decrease in HBV DNA is
  durable.
• Surrogate, indirect marker for decrease in
  necroinflammatory disease

35
Histological Response in Chronic Hepatitis B

• Improvements in Histology
• Used in virtually all studies of antiviral
  therapy
• Typically, improvement is called a 2 point
  improvement in HAI score (0-22) compared to
  baseline
• However, necroinflammatory scores can change
  rapidly and improve and worsen
• Fibrosis scores represent best evidence for
  progression of disease and are unlikely to
  improve with treatment

36
Alpha Interferon

• Human cytokine made by lymphocytes in response to
  viral infection
• Acts through cell-surface receptors
• Activates Jak/Stat system
• Induces transcription of proteins with antiviral
  activity (2-5 OAS, PKR, eIF2)
• Recombinant human alpha interferon
• Pegylated forms now available

37
Chronic Hepatitis BLong-term Response to
Interferon
Alpha Interferon
ALT
Anti-HBe
HBV DNA (dot blot)
HBeAg
Anti-HBs
HBsAg
Months After Start of Therapy
Patient A
38
Chronic Hepatitis BResponse to Interferon
Relapse
Alpha Interferon
ALT
HBeAg
HBeAg
Anti-HBe
HBsAg
Months After Start of Therapy
Patient B
39
HBeAg-Negative Chronic Hepatitis BResponse to
Interferon and Relapse
Alpha Interferon
-
-
-




HBV DNA
HBsAg
ALT
Anti-HBe
Months After Start of Therapy
Patient C
40
Interferon for Chronic Hepatitis B Problems

• Effective in only 1/3rd of cases
• Expensive
• Side effects are common and can be severe
• Not appropriate for many categories of pts
• Immune suppressed
• Renal failure or dialysis
• Solid organ transplant
• Decompensated liver disease

41
Lamivudine

• Negative enantiomer of 3-thiacytidine
• Both an unnatural nucleoside and chain terminator
  
• Highly active against HBV in vitro
• Dose 100 mg, once daily by mouth
• Approved for use in chronic hepatitis B as one
  year course of therapy
• Continuous, long-term use is common but must be
  considered experimental

42
Lamivudine TherapyMaintained Response
Therapy with Lamivudine (100 mg/d)
ALT
108
HAI Scores Pre 14 Yr 1 4 Yr 4 1
HBV DNA
106
HBV DNA Levels
HBeAg
104
HBsAg
102
Patient B
43
HBeAg-Negative Chronic Hepatitis B
Lamivudine
HAI 4 200 copies/ml
HAI 13 53.1 million copies/ml
HAI 1 Liver Biopsy HBV DNA
ALT
HBsAg and Anti-HBe
Months After Start of Therapy
Patient C
44
Lamivudine TherapyViral Resistance
Therapy with Lamivudine (100 mg)
wt
1010
108
HBV DNA
YVDD
HBV DNA Levels
106
ALT
104
102
Normal
HAI Scores Pre 14 Yr 1 10 Yr 4 17 (Cirrhosis)
Patient D
45
Lamivudine for Chronic Hepatitis BHistology
Activity Index Scores
9.8
9.9
8.4
7.1
Total HAI Scores (0 to 18)
2.5
1.3
9
9
9
13
13
4
46
Lamivudine for Chronic Hepatitis B Fibrosis
Scores
4.3
4.2
3.9
3.3
2.9
Fibrosis Score (0 to 6)
1.3
9
9
9
13
13
4
47
Lamivudine TherapyLate Relapse
Therapy with Lamivudine (100 mg/d)
ALT
108
HAI Scores Pre 14 Yr 1 4 Yr 4 1
HBV DNA
106
HBV DNA Levels
HBeAg
104
HBsAg
102
Patient B
48
85
50
49
Lamivudine

• The major shortcoming of long-term lamivudine
  therapy for hepatitis B is emergence of
  lamivudine resistance
• Occurs in 20-30 of patients per yr, approaching
  90 by 5 yrs
• Loss of HBsAg, but not loss of HBeAg, appears to
  reliably predict long-term benefit ability to
  stop lamivudine
• Future studies should focus on combinations that
  might prevent resistance

50
Optimal Therapy of Hepatitis B?

• Monotherapy or combination therapy?
• For a defined period (48 wks) or continuous?
• For all pts or only those with mod-severe
  disease?
• If monotherapy, which agent?
• If combination, which combination?
• Standard interferon and lamivudine
• Pegylated interferon and lamivudine
• Lamivudine and adefovir
• Lamivudine and entecavir

51
Management of Hepatitis B

• Initial evaluation Routine liver tests, HBsAg,
  HBeAg anti-HBe, HBV DNA, anti-HDV, abdominal US
• If ALT elevated HBV DNA present liver biopsy
  and assess for therapy
• Reserve therapy for patients with significant
  underlying liver disease
• Therapy?

Lok, Heathcote Hoofnagle 2001
52
Therapy of Chronic Hepatitis B Future Directions

• Focus must be on combination therapy
• Long term outcomes with histological verification
  of long-term benefit
• Loss of HBsAg might be a gold standard
• Appropriate directions
• Combinations of alpha interferon lamivudine
• Nucleoside combinations without cross-reactive
  resistance (lamivudine adefovir or entecavir)
• Novel approaches immunological or molecular