Vaccine of hepatitis E virus

Samir Haffar M.D.

Why we need a vaccine for hepatitis E virus?

Global Burden of HEV Genotypes 1 and 2 in 2005

• Methods Annual disease burden of G1 & 2 for 9 of 21 regions

Represent 71% of world’s populationDefined for Global Burden of Diseases, Injuries,

andRisk Factors Study (the GBD 2010 Study)

• Results Incident 20.1 million 95% Cr.I.: 2.8-37.0Symptomatic3.4 milliom 95% CrI: 0.5-6.5 Death 70.000 95% CrI: 12,400-

132,732Stillbirths 3.000 95% CrI: 1,892 –

4,424

CrI: Credible IntervalRein DB et al. Hepatology 2012 ; 55 : 988 – 997.

• Incubation period 3 – 8 weeks

• Prodromal phase Short

• Symptoms or jaundice Days to several weeks

• Most cases are self-limited

• Case fatality rate 0 – 10%20% in pregnant

women

Hoofnagle JH et al. N Engl J Med 2012 ; 367 : 1237 – 44 .

Clinical features of hepatitis EMost HEV infections have clinically silent course

• Inapparent or asymptomatic infection

• Anicteric hepatitis Biochemical abnormalities – No jaundice

• Icteric hepatitis Similar to other forms of viral hepatitis

• Severe hepatitis Leading to fulminant hepatic failure

• Acute-on-chronic liver disease

Clinical features of hepatitis E

Hepatic manifestations (common)

Aggarwal R & Shahid J. Hepatology 2011 ; 54 : 2218 – 2226.

• Acute pancreatitis• Hematological manifestations Thrombocytopenia, hemolysis• Autoimmune phenomena Membranous glomerulonephritis

Henoch-Schonlein purpura• Neurological syndromes Guillian-Barre syndrome

MeningoencephalitisPseudotumor cerebriCranial nerve palsiesBilateral pyramidal syndromePeripheral neuropathy

Extra-hepatic manifestations (Rare)

Aggarwal R & Shahid J. Hepatology 2011 ; 54 : 2218 – 2226.

Mostly as case reports or small case seriesBased usually on detection of anti-HEV IgM rather than HEV RNA

Serological diagnosis of Hepatitis E

Zakim & Boyer hepatology 2012 – 6th edition.

Chronic hepatitis EPreviously believed to be always self-limited

• First reported in 2008 in 8 French solid organ transplant recipientsreceiving immunosuppressive drugs, & recently developedtransaminase elevation, and had infection with genotype 3

• Also been reported in HIV infection, hematological diseases, or those receiving anticancer chemotherapy

• Liver histology shows portal hepatitis with lymphocytic infiltrate,piecemeal necrosis & fibrosis; and in some cases, liver fibrosis

• Persistent infection not reported with genotype 1 or 2 HEV, among otherwise healthy persons, or from highly endemic regions

Kamar N et al. N Engl J Med 2008 ; 358 : 811 - 817.

Course of HEV infection

Wedemeyer H et al. Gastroenterology 2012 ; 142 : 1388 – 1397.

Genotypes of HEV

• HEV is classified into four major genotypes

• All four genotypes are believed to represent a singleserotype which has facilitated efforts to develophepatitis E vaccines

HEV infections according to genotypeCharacteristic Genotypes 1 and 2

EpidemicGenotypes 3 and 4

Autochthonous Distribution Developing countries Developing & developed countries Pattern of spread Epidemic & sporadic Sporadic Species Human Swine, human Mode of spread Waterborne Foodborne Icteric illness High Low Age Adolescents & young older Sex M = W Higher in men Mortality High in pregnancy High in older Extra-hepatic features Few Neurologic Chronic infection None In immunosuppressed patients Therapy None known Ribavirin, PEG-IFN Prevention Vaccine Vaccine

Hoofnagle JH et al. N Engl J Med 2012 ; 367 : 1237 – 44 .

Worldwide prevalence of HEV

Endemic regions of hepatitis E

where >25% of acute viral hepatitis is due to HEVWedemeyer H et al. Gastroenterology 2012 ; 142 : 1388 – 1397.

Geographic distribution of different HEV genotypes

Wedemeyer H et al. Gastroenterology 2012 ; 142 : 1388 – 1397.

Hepatitis E virus

Genomic organization of HEV

Zakim & Boyer hepatology 2012 – 6th edition.

Short untranslated regions (UTR) at both endsThree open reading frames (ORFs)

ORF1: encodes nonstructural polyprotein (nsp)ORF2: encodes the viral capsid protein

ORF3: encodes small regulatory phosphoprotein

Assembly of HEV virions

Hoofnagle JH et al. N Engl J Med 2012 ; 367 : 1237 – 44 .

Open Reading Frame 2 (ORF-2)

Encodes viral capsid protein

N-terminal signal sequence (SS)Domain 1: RNA encapsidation

Domain 2: form core of viral capsidDomain 3: exposed on virus particle

Neutralization epitope (aa 458 – 607) in domain 3Binding of HEV to its cellular receptor

Aggarwal R & Jameel S. Hepatol Int 2008 ; 2 : 308 – 315.

ORF-2 & HEV vaccine

• Antibody elicited in humans & animals against ORF2is long lived, cross-reactive among diverse HEVgenotypes & neutralizes HEV in vitro

• ORF2 protein of HEV has been the antigen used for allvaccine studies thus far

• Full-length or truncated forms of the protein expressedin bacterial cells, insect cells, yeast, animal & plant cellshave emerged as potential vaccine candidates

Kamili S. Virus Research 2011 ; 161: 93 – 100.

Vaccine candidates for HEV

Kamili S. Virus Research 2011 ; 161: 93 – 100.

Light colored vertical bar indicates location of neutralizing epitopeBlue bars indicate proteins undergoing clinical evaluation

Preclinical & clinical studies of HEV

Pre-clinical evaluation of HEV vaccine candidatesORF-2 protein Amino acids Source Remarks

Expressed in E. coli TrpE-C2 221 – 660 BurmapE2 394 – 607 ChinaHEV 239 368 – 606 China Human CT

Expressed in insect Baculovirus-mediated Spodoptera litura larvae

56-kDa protein53-kDa protein62-kDa50 kDa (VLPs)62-kDa

112 – 607 112 – 577 112 – 660112 – 534112 – 660

PakistanBurmaBurmaBurmaIndia

Human CTOral route

Expressed in other system Yeast Pichia pastoris Transgenic tomato plants

HBV/HEVpE2

551 – 607394 – 607

ChinaChina

DNA vaccines Naked DNA plus protein

pJHEVpcHEVORF2+26 kDa

1 – 660 1 – 660

BurmaBurmaIndia

Stability Easy preparation

VLPs: Virus Like Particles

56 kDa vaccine Phase II – Double-blinded placebo-controlled RCT

ShresthaMP et al. N Engl J Med 2007 ; 356 : 895 – 903.

• 1 794 healthy subjects mostly male (99%) & young (mean 25y) • Compagny: GlaxoSmithKline Biologicals with the US army – Nepal • Randomization: HEV vaccine versus placebo• Primary end-point: prevention of clinically overt HEV infection• Predominantly if not exclusively genotype 1• 20 μg IM at 0, 1, 6 months• Follow-up period: 2 years post-vaccination• Efficacy after third dose: 95,5%• Side effects: increased injection-site pain

Limitation of 56 kDa vaccine

• Study subjects mostly men (>99%) & young (mean age 25 years)

• Primary end point was clinically overt HEV infectionauthors and did not study the HEV infection rate

• anti-HEV antibody titers declined significantly byend of the study, so that nearly 44% of subjects hadantibody titers below the level considered as protective

56 kDa vaccine

• GlaxoSmithKline did not pursue the manufacture ofthis vaccine despite its efficacy

• The firm estimates that there is little commercialpotential for the vaccine

Regulatory milestones of HEV 239 vaccine

• 2001 Researchers at Xiamen University modified a E. colistrain to produce protein stimulating immune systemin humans, to make protective antibodies against

HEV• 2000 Yangshengtang Group joint biotech laboratory with

the university & preclinical/clinical development began

• 2006 Laboratory given national status by Chinese Ministryof Science and Technology & relaunched as

NIDVD* • 2007 Yangshengtang set up subsidiary company (Innovax)

to take potential vaccines from CT to manufacturing• 2010 Publication of phase III trial of HEV 239 in Lancet• 2011 Vaccine approved by China FDA* NIDVD: National Institute of Diagnostics and Vaccine Development in Infectious Diseases

Human Vaccines Immunotherapeutics 2012 ; 8 : 1743 – 1744.

Clinical milestones of HEV 239 vaccineAll studies conducted in China during 2005 – 2009

Phase I2005

Safety – Guangxi province – 44 volunteers of ages 21-5520 μg HEV vaccine at 0 – 1 month

Phase IIa Dose schedule & dose escalation – 457 subjects 2 schedules: 0 – 6 & 0 – 1 – 6 mo anti-HEV IgG seroconversion higher in 3-dose groupDifference not statistically significant (100% vs. 98%)GMC of anti-HEV IgG significantly higher in 3-dose group

Phase IIb 155 subjects – 4 groups – 3 doses of 10, 20, 30, 40 μg 100% seroconversion in all four groupsHigh-dosage groups (20, 30 & 40 μg) showed higher anti-HEV IgG GMC levels than 10-μg dosage groupAE similar among four dosage groups

Phase III2007 – 2009 Large scale double blind placebo-controlled RCT

Zhang J et al. Vaccine 2009 ; 27 : 1869 – 74.

HEV 239 vaccine – Hecolin®Phase III – Double blind placebo-controlled RCT

• 112 604 healthy subjects, men & women, 16 – 65 years

• Compagny: Xiamen Innovax Biotech – China

• Randomization: HEV vaccine versus HBV vaccine

• Primary end-point: prevention of clinically overt HEV infection

• Genotype 1 & 4 prevalent – Predominant genotype 4

• 30 μg IM at 0, 1, 6 months

• Follow-up period: 13 month post-vaccination

• Efficacy after third dose: 100%

• No side effects

Zhu FC et al. Lancet 2010 ; 376 : 895 – 902.

In December 2011,

the China Food & Drug Administration

approved the hepatitis E vaccine Hecolin®

for use in subjects ≥ 16 year old

Who should get the vaccine?

• Travelers to endemic areas

• Pregnant women in endemic areas

• Food industry workers

• Aged persons

• During HEV outbreaks (100% efficacy after 2 doses/1mo)

• Organ transplantation receptors• Patients with underlying chronic liver disease

High risk groups

Wu T et al. Human Vaccines & Immunotherapeutics 2012 ; 8 : 823 – 827.

Questions remain to be answered

• HEV infection rate (focus was on clinical disease rate) • Titer of protective antibodies• Duration of protection afforded by the vaccine• Used for post-exposure prophylaxis• Safety in Pregnant women

People younger than 15 y or older than 65 y

Chronic liver disease

Immunosuppressed patients

Safety of Hecolin® in pregnant womenPost-hoc analysis

• Safety of the vaccine for pregnant women was demonstrated by preliminary analysis in 37 pregnantwomen who inadvertently received 1, 2 or 3 doses of HE vaccine during pregnancy

• The vaccine was well toleratedThe babies born in the vaccine group were as healthy as those born in the control group

Wu T et al. Hepatology 2012 ; 55 : 2038.

Financial aspects of Hecolin®

• Development of Hecolin® cost about 500 million renminbior $80 million, much of which came from Chinesegovernment through the university

• The vaccine will be sold to distributors in China at cost of 110 renminbi ($17.60) per dose

• Innovax expects sales to reach 62 million renminbi in 2013

Human Vaccines Immunotherapeutics 2012 ; 8 : 1743 – 1744.

Xiamen University and Innovax are in talks with the

World Health Organization (WHO) to register Hecolin

with the organization’s Prequalification Programme,

which makes medicines available to agencies such as:

• the United Nations Children’s Fund

• the Joint UN Programme on HIV/AIDS

Park SB. Nature 2012 ; 491 : 21 – 22.

Jeremy Farrar Director of Oxford University Clinical Research Unit

“New companies operating with different funding modelsoffer a great opportunity, & one which could have a

profound impact.”

“We have to be sure that these vaccines can be used anywhere”

“It would be a great shame if these products were not available outside China”

Park SB. Nature 2012 ; 491 : 21 – 22.

Conclusion

Though several questions remain to be answered,

the successful clinical testing of this vaccine is amajor step forward in the future control of HEV

Thank You