Hepatitis B

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

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

Hepatitis B Virus HBeAg

HBsAg HBcAg

HBsAg

Sphere

HBsAg

Dane Particle

Tubule

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 A A A A A AA A A AA A

5’

ORF-P DR2

Pre-C

ORF-X

0.7kb RNA

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

degradation

Y

Y

- antigen-specific - non-specific

Y

Y

Y

Y

Y

Y

Infectious cycle of hepatitis B virus

Virus - half-life: -production: mutation rate:

1-2 days 1011 -1013 /day 1-3 x 10-5 /site/yr

cell death Zeuzem et al: 2000

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

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

HBeAg-negative Variants • G→A at nt 1896 creates a stop codon in the precore 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

Outcome of Hepatitis B Virus Infection 35%

Acute Hepatitis B

65%

Asymptomatic subclinical infection

<1%

Fulminant Hepatitis 5%

Chronic Hepatitis B 30%

50%

Inactive Carrier State

Cirrhosis

?

Liver Cancer

IU/L and million copies/ml

ALT and HBV DNA

Typical Acute Hepatitis B 1000 HBsAg 900 HBeAg 800 700 ALT 600 500 Symptoms 400 HBV DNA 300 200 100 Normal 0 0

1

2

3

4

5

6

12

Months After Exposure

24

36

48

60

Typical Chronic Hepatitis B HBsAg

IU/L or million copies/ml

ALT and HBV DNA

800

HBeAg

700 600 500

HBV DNA

400 300 ALT

200 100

Normal

0 0

1

2 3 4 5 6 12 Months After Exposure

24

36

48

60

Chronic Hepatitis B: Transition to Inactive Carrier State IU/L and million copies/ml

ALT and HBV DNA

800

HBsAg

700

``

HBeAg

600 500 400

HBV DNA

300 200

Anti-HBe

ALT

100 Normal

0 0

1

2

3

4

5

6

12 24 36 48 60 72 80

Months After Exposure

Evolution of HBeAg Negative Mutant

IU/L and million copies/ml

ALT and HBV DNA

HBsAg HBeAg

450 400 350 300 250 200 150 100 50

Anti-HBe

ALT

HBV DNA

Normal ALT levels

0 0

3

6

9

12

15

18

21

Months

24

27

30

33

36

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

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 < 101 to 104 copies per ml

HBV DNA Detection 35,000

8

350

6

3.5

4

.035

2

.0035

qualitative PCR

quantitative PCR (Amplicor)

bDNA (Versant)

Hybridization (Abbott)

Hybridization (Digene)

Dynamic Range of Detection of HBV DNA: 5 Assays

pg/mL

Log10 copies/mL

10

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)

Acute Hepatitis B

Sentinel 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

Acute Hepatitis B Incidence in the U.S.: 1978-1998

Vaccine licensed

200

Infections per 100,000

HBsAg screening of pregnant women

Routine infant immunization

OSHA Rule

150

Routine adolescent immunization

100 Decline in high-risk heterosexuals

50 Decline in MSM & HCW

0 78

80

82

84

86

88

Year

Decline in injecting drug users

90

92

94

96

Alter et al: CDC

98

Chronic Liver Disease: United States 1999 r Othe sB titi pa He

NASH 10%

Alcohol 25% Hepatitis B accounted for only 4.4% of newlydiagnosed chronic liver disease

Hepatitis C 57%

Bell et al 2001

Chronic Hepatitis B Long-Term Complications • • • •

Cirrhosis Hepatocellular carcinoma Glomerulonephritis Polyarteritis Nodosa

Chronic Hepatitis B Histology • 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

Chronic Hepatitis B Histology 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

Chronic Hepatitis B Histology 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

Therapy of Hepatitis B

Chronic Hepatitis B Goals 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 ?

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?

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

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?

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?

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 <1% of patients on no therapy ■Extremely rare in treatment trials of HBeAgnegative chronic hepatitis B ■This response is durable and associated with resolution of liver disease

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

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

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

Chronic Hepatitis B

Long-term Response to Interferon Alpha Interferon

500 ALT

ALT (U/L)

400

HBV DNA (dot blot)

300

Anti-HBe

HBeAg

200

Anti-HBs

HBsAg

100 0 -2

0

1

2

3

4

5

6

Months After Start of Therapy

9

12

18

24

Patient A

Chronic Hepatitis B

Response to Interferon & Relapse Alpha Interferon

1400

ALT (U/L)

1200

ALT

1000 HBeAg

800

Anti-HBe

HBeAg

600 400

HBsAg

200 0 -4

-2

0

1

2

3

4

5

6

9

12

18

24

Months After Start of Therapy Patient B

HBeAg-Negative Chronic Hepatitis B Response to Interferon and Relapse 800 700

ALT (U/L)

HBV DNA

600 500 400 300 200

Alpha Interferon +

-

+

-

-

+

+

HBsAg ALT

Anti-HBe

100 0 -12 -8 -4 -2 -1

0

1

2

3

4

5

6

9

12 18 24

Months After Start of Therapy Patient C

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

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

Lamivudine Therapy Maintained Response Therapy with Lamivudine (100 mg/d)

500

ALT

400

HBV DNA

300

HBeAg

200

108

HAI Scores: Pre: 14 Yr 1: 4 Yr 4: 1

106 104

HBsAg

100

102

0 -2

0

2

4

6

8

10 12 18 24 30 36 42 48

M onths After Starting Therapy Patient B

HBV DNA Levels

ALT Levels (U/L)

600

HBeAg-Negative Chronic Hepatitis B Lamivudine Liver Biopsy HBV DNA 600

HAI = 13 53.1 million copies/ml

HAI = 4 200 copies/ml

HAI = 1 <100 copies/ml

ALT (U/L)

500 400

ALT

300 HBsAg and Anti-HBe

200 100 0 -4 -2

0

3

6

9 12 15 18 21 24 30 36 42 48 54

Months After Start of Therapy Patient C

Lamivudine Therapy: Viral Resistance

Therapy with Lamivudine (100 mg) 500 400

wt

1010

HBV DNA

108

300

YVDD 106

200

ALT

100 0

Normal

Pre 0

102

2

4

6

8

10 12 18 24 30 36 42 48

Months After Starting Therapy Patient D

104

HBV DNA Levels

ALT Levels (U/L)

600

HAI Scores: Pre: 14 Yr 1: 10 Yr 4: 17 (Cirrhosis)

Total HAI Scores (0 to 18)

Lamivudine for Chronic Hepatitis B Histology Activity Index Scores Pre

12 10

1 year

9.8

4 years 9.9 8.4 7.1

8 6 4 2

2.5 13

1.3 13

0 Maintained

9

9

4

Resistance

9

Lamivudine for Chronic Hepatitis B: Fibrosis Scores Pre

Fibrosis Score (0 to 6)

6 5

1 year

4.2

4 years

4

3.3 2.9

3 2 1

4.3

3.9

1.3 13

13

9

9

4

0 Maintained

Resistance

9

Lamivudine Therapy Late Relapse Therapy with Lamivudine (100 mg/d)

500

ALT

400 300

HBV DNA

200

HBeAg

100

108

HAI Scores: Pre: 14 Yr 1: 4 Yr 4: 1

106 104

HBsAg

102

0 -2 0

2

4

6

8 10 12 18 24 30 36 42 48 54 60

Months After Starting Therapy Patient B

HBV DNA Levels

ALT Levels (U/L)

600

Percent with Resistance (%)

100

85%

p = 0.001 80

HBeAg +

60

50%

40

HBeAg 20

0 0

6

12

18

24

30

Months of Therapy

36

42

48

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

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

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

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