Cytomegalovirus (CMV), the

hidden enemy in liver

transplantation

Ayman Alsebaey, MD. Lecturer of hepatology,

National liver Institute,

National Liver Institute Congress

Conrad, April 2015

The past, the

present, and

the future‏‏

Cytomegalovirus (CMV) is a double stranded DNA virus.

CMV infects 50−97% of the human population. It remains lifelong latent in

the hematopoietic cells.

MODE OF INFECTION IN LT STATUS

Primary CMV infection (D+/R−):

A sero−negative recipient receives organ from sero−positive donor.

Secondary CMV infection (Reactivation D±/R+):

The recipient is sero−positive and immunosuppression induces

reactivation of latent CMV infection.

Superinfection (D+/R+):

Both the donor and the recipient are sero−positive. Here there is

reactivation of the donor CMV.

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INCIDENCE OF CMV INFECTION IN LT RECIPIENTS

1. If no prevention used post LT, 18−30% of the recipients will develop

CMV disease especially in the 1st 3 months.

a. D−/R−: 1−2%.

b. D+/R−: up to 65%.

c. D±/R+: up to 20%.

2. With prevention by 3 month of valganciclovir or oral ganciclovir

prophylaxis:

a. D+/R−: 10−30%.

b. D±/R+: <10%.

3. Late CMV:

a. is the reactivation of CMV following 3 months prophylaxis so

prophylaxis should be prolonged to 6 months.

b. D+/R−: 15%.

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RISK FACTORS FOR CMV INFECTION IN LT RECIPIENTS:

Donor/Recipient status:

a. Risk of infection in CMV D+/R− > CMV D±/R+.

Immunosuppressive dose and prolonged use:

a. Lymphocyte-depleting drugs (alemtuzumab >anti−thymocyte globulin

>basiliximab).

b. High doses mycophenolate mofetil.

c. Sirolimus and everolimus decrease CMV replication.

Defects in innate immunity and cytokine defects:

a. Polymorphisms in mannose-binding lectin and toll-like receptor 2 genes.

Allograft rejection (bi-directional):

a. Rejection TNF CMV re−activation Pulse steroids.

b. Rejection increases CMV replication.

Co-infections with HHV-6 and HHV-7 : as being immunomodulatory.

Cold ischemia time, bacterial, fungal infections, sepsis, the amount of blood

loss and fulminant hepatic failure.

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Risk factors for CMV infection in LT recipients

Traditional Risk Factors Recently Described Risk Factors

CMV D+/R–

Lack of CMV−specific CD4+ T cells

Lack of CMV−specific CD8+ T cells

Allograft rejection

High viral replication

Type of organ transplant

Mycophenolate mofetil

Muromonab−CD3

Antithymocyte globulin

Alemtuzumab

HHV−6

HHV−7

Renal insufficiency

Toll−like receptor 2 polymorphism

Toll−like receptor 4 polymorphism

Mannose−binding lectin deficiency

Chemokine and cytokine defects

(interleukin 10, monocyte chemotactic

protein 1, C−C chemokine receptor

type 5)

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CLINICAL MANIFESTATIONS OF CMV DISEASE

DIRECT EFFECTS INDIRECT EFFECTS

Asymptomatic:

Only positive PCR

CMV syndrome (60%):

Fever, flu like

Myelosuppression with leukopenia and

neutropenia

Tissue-invasive CMV disease:

GIT (70%); esophagitis, gastritis,

enteritis, colitis.

Hepatitis.

Pneumonitis.

CNS disease.

Retinitis.

Intrauterine transmission.

Mortality

Acute allograft rejection

Chronic allograft rejection

Vanishing bile duct syndrome

Chronic ductopenic rejection

HAT

Hepatitis C virus recurrence

Allograft hepatitis, fibrosis

Allograft failure

Opportunistic and other infections

Fungal superinfection

Nocardiosis

Bacterial superinfection

Epstein−Barr virus and PTLD

HHV−6 and HHV−7 infections

Vascular thrombosis

New onset diabetes mellitus

Mortality IMMUNOMODULATORY & IMMUNE EXHAUSTION

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DIAGNOSIS

1. CMV NAT:

a. Rapid and more accurate (CMV DNA >RNA).

b. Quantitative, useful in initiation and follow up of treatment.

c. Prognostic:

i. Pre−treatment CMV DNA <18,200 IU/ml 1.5 fold higher

chance for CMV disease resolution.

ii. CMV suppression to <137 IU/mL is predictive of clinical response

to antiviral treatment.

2. pp65 antigenemia assay:

a. is secreted by CMV-infected peripheral blood leukocytes.

b. Comparable to NAT

c. Semi−quantitative, processed within 6−8 h of blood collection,

d. but requires a large sample volume, subjective interpretation of results

and falsely negative in patients with severe leukopenia.

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DIAGNOSIS:

1. Histopathology:

a. Gold standard for the

diagnosis of tissue-invasive

CMV disease though

invasive.

b. Cytomegalic cells with

positive

immunohistochemical testing.

c. Nowadays indicated to

exclude rejection and

diagnose

compartmentalization.

2. Non useful tests:

a. Serology (Ig M and Ig G).

b. Viral cultures.

COMPARTMENTALIZED

CMV DISEASE:

1. Positive tissue CMV infection

with negative blood PCR.

2. So follow up of PCR may

escape viral detection as

preemptive therapy.

3. Commonly seen in the GIT

and retina.

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Methods Principle Sample and Equipment Turnaround Time Clinical Usefulness Advantages Disadvantages

Serology Antibody detection

(IgG, IgM)

Serology facility 6 h IgG indicates previous

infection

IgM implies acute or

recent infection

Screening of donors and

recipients before

transplantation

Screening transplant

recipients after

transplantation to detect

seroconversion

Delayed antibody

production in transplant

recipients (false-negative

results)

False-positive IgM

screening results

Virus culture

Tube culture Viral replication Recovery of PMN within few hours;

cell culture facility; light microscopy

2–4 wk Detection of

cytopathic effects

High specificity for

infection and disease

Phenotypic susceptibility

testing

Prolonged processing time

Low sensitivity

Rapid loss of CMV viability

ex vivo (false-negative

results)

Shell vial assay Viral replication Recovery of PMN within few hours;

cell culture facility;

immunofluorescence detection

16–48 h Infectious foci

detected by

monoclonal antibody

directed to immediate

early antigen (72 kDa)

of CMV

High specificity for CMV

infection and disease

More sensitive and rapid

than tube cultures

Relatively low sensitivity

compared with molecular

methods

Antigenemia pp65 Antigen Recovery of PMN within 4–6 h;

Cytospin; light microscopy or

immunofluorescence

6–24 h Number of CMV-

infected cells per total

(eg, 2 × 105) cells

evaluated; early

detection of CMV

replication

Rapid diagnosis of CMV

Guide for initiation of

preemptive therapy

Guide for treatment

responses

Subjective interpretation of

results

Requires rapid processing

Nucleic acid

detection

DNA or RNA Plasma, whole blood, leukocytes,

other body fluids

4–24 h Reported as CMV

copies per milliliter of

sample (should now

be standardized to

IU/ml of sample)

Detection of CMV

infection; monitor CMV

DNA decline;

surrogate marker for

antiviral drug

resistance

Highly sensitive

Correlation with clinical

disease severity

Guides preemptive

therapy

Rapid diagnosis of CMV

infection and disease

Monitor therapeutic

response

Modest positive predictive

value for CMV disease

Needs standardization

among various assays

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Prevention of CMV disease

post LT

Preemptive therapy

Antiviral prophylaxis

Hybrid approach

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PREEMPTIVE THERAPY

a. Regular weekly screening for +ve CMV PCR or +ve pp56 antigenemia till

week 12 especially after antilymphocyte antibody therapy.

b. Aim:

a. is to prevent progression to symptomatic clinical disease.

b. Once CMV is detected, start the treatment.

c. Less cost:

a. Offset by the cost of laboratory testing, increased logistic

coordination.

d. Less likely associated with late onset CMV disease.

e. Not effective in D+/R− liver recipients so antiviral prophylaxis is the rule.

f. Should be used only with D±/R+ liver recipients

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ANTIVIRAL PROPHYLAXIS

a. Administration of antiviral drugs such as valganciclovir to all patients at risk

of CMV disease after liver transplantation.

a. Used drugs: oral ganciclovir, I.V ganciclovir, valganciclovir.

b. Advantages:

a. Prevention of direct and indirect CMV effects.

b. Decreased incidence of herpes, bacterial, protozon infections, rejection

and mortality

c. Should be used to D+/R− liver recipients.

c. Disadvantages:

a. antiviral drug cost, drug-related toxicity and resistance.

b. incidence of late-onset CMV disease (esp. D+/R– LT recipients.

d. Valganciclovir vs. ganciclovir prophylaxis:

a. Oral ganciclovir is poorly absorbed so IV should be used.

b. Oral 950 mg valganciclovir = 5mg/kg IV ganciclovir.

c. New studies 450 mg = 950 mg valganciclovir.

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CMV disease in liver recipients

Valganciclovir Oral Ganciclovir

A randomized trial of 372 CMV D+/R– kidney, liver, pancreas,

and heart recipients

FDA has cautioned against valganciclovir prophylaxis in liver recipients,

although many experts still recommend its use in liver recipients

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a. Maribavir prophylaxis: is investigation drug that is less effective than oral

ganciclovir so is on hold.

b. CMV immunoglobulin: Its role when combined with anti CMV drugs is

debate.

HYBRID APPROACH

Prophylaxis is started for 3 month then preemptive strategy is the role.

LATE−ONSET CMV DISEASE

In high−risk CMV D+/R− individuals, the use of antiviral prophylaxis for

100 d has only delayed the onset of CMV disease to 3−6 month after liver

transplantation.

associated with allograft failure and mortality

Prevention:

Clinical follow-up with early treatment of CMV disease when

symptoms occur;

Virologic surveillance after completion of antiviral prophylaxis

Prolonging antiviral prophylaxis.

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200 day Val 100 day Val

CMV disease

A randomized trial compared 200 versus 100 days of

valganciclovir prophylaxis in 318 CMV D+/R– kidney recipients

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Antiviral Prophylaxis Preemptive Therapy

Efficacy • Highly efficacious for CMV

disease prevention

• Risk of late-onset CMV disease

• Prevents CMV disease but not

CMV infection

Logistics of use • Needs monitoring of potential

adverse effects such as

leukopenia

• Difficult to coordinate weekly

viral load testing and results

follow-up

• Viral load thresholds not

standardized

Late-onset CMV

disease

• Common among CMV D+/R–

transplant recipients

• Less common

Cost • Higher drug costs • Higher laboratory costs

Toxicity • Greater drug toxicity

(leukopenia and bone marrow

suppression)

• Less drug toxicity (shorter

courses of antiviral treatment)

Indirect effects (graft

loss, mortality, and

opportunistic infections)

• Reduction in indirect effects • May not reduce indirect effects

(limited data available)

Drug resistance • Yes (but still uncommon) • Yes (but still uncommon)

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TREATMENT

1. Used drugs:

1. Oral ganciclovir should not be used.

2. Oral valganciclovir and IV ganciclovir.

3. Less used drugs:

a. Cidofovir and foscarnet are high active, highly nephrotoxic.

b. IV immunoglobulin maybe adjuvant therapy.

2. Decrease to immunosuppressive level:

1. to allow the immune system to act against CMV.

2. Shift to mTor inhibitors.

3. Mild to moderate disease: oral valganciclovir and IV ganciclovir are

comparable.

4. Severe disease, high viral load, GIT invasion:

1. use only IV ganciclovir,

2. after improvement use oral valganciclovir.

5. Duration of treatment:

a. 14-21 day followed by 4-12 week prophylaxis to prevent relapse (35%).

6. End point of treatment: 2 negative PCRs one week apart.

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Antiviral drugs for CMV prevention and treatment

Drug Preemptive Therapy and

Treatment of CMV Disease Antiviral Prophylaxis Comments on Use and Toxicity

Valganciclovir • 900 mg by mouth twice daily • 900 mg by mouth once

daily

• Ease of administration

Leukopenia

Oral ganciclovir • Not recommended • 1 g by mouth 3 times

daily

• Low oral bioavailability

High pill burden

• Leukopenia

• Risk of resistance

IV ganciclovir • 5 mg/kg IV every 12 h • 5 mg/kg IV once daily • IV access

Leukopenia

Valacyclovir • Not recommended • 2 g by mouth 4 times

daily

• Kidney transplant recipients only

• Not recommended for heart, liver,

pancreas, lung, intestinal, and

composite tissue transplant recipients

High pill burden

• Neurologic adverse effects

Foscarnet • 60 mg/kg IV every 8 h (or 90

mg/kg every 12 h)

• Not recommended for

preemptive therapy

• Not recommended • Second-line agent for treatment

• Highly nephrotoxic

• Treatment of UL97-mutant

ganciclovir-resistant CMV

Cidofovir • 5 mg/kg once weekly × 2 then

every 2 wk thereafter

• Not recommended for

preemptive therapy

• Not recommended • Third-line agent

• Highly nephrotoxic

• Treatment of UL97-mutant

ganciclovir-resistant CMV

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1. It is a common with prolonged anti CMV drugs use e.g. antiviral

prophylaxis or preemptive therapy and D+/R– recipients.

2. It is detected when the viral load did not decrease from the baseline or

even breakthrough.

3. Incidence: is low (0.26%) but common with D+/R– recipients, over

immunosuppression and recurrent rejection.

4. Phenotypes:

a. Ganciclovir resistance is more common.

b. Isolated or cross resistance to cidofovir or foscarnet is less common.

5. Genetics:

a. UL97: phosphorylates ganciclovir to ganciclovir triphosphate. So

mutations cause only ganciclovir resistance.

b. UL54: activates ganciclovir triphosphate to inhibit CMV DNA

polymerase. So mutations cause ganciclovir resistance and

foscarnet and cidofovir resistance.

c. Combined mutations.

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DRUG-RESISTANT CMV INFECTION AND DISEASE

TREATMENT OF DRUG-RESISTANT CMV INFECTION

Decrease immunosuppression ±shift to mTOR inhibitors.

Genetic mapping of UL54 and UL97 genes.

UL54 mutations:

• Vaccines.

• intravenous immunoglobulin.

• Letermovir (AIC246): UL56 terminase inhibitor.

• Maribavir

• Brincidofovir (CMX001): prodrug of cidofovir

• Leflunomide: drug for rheumatoid arthritis inhibiting viral kinases.

• Artesunate: anti-malarial

• CMV-specific T cells.

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Thanks a lot