Prepared by FOUD HOURANI

AGENDA Introduction Objectives Methods Results Conclusion References

Hepatocellular carcinoma (HCC)

HCC is a primary malignancy of the hepatocyte, generally

leading to death within 6-20 months. • The sixth most common cancer disease. • The third leading cause of cancer related death. • >500 000 deaths per year.

The advance cases of HCC have a poor responses to chemotherapeutic. also chemotherapy still place a burden on patients. In general, most of medication for cancer diseases have a side effects such as hair loss, bleeding… etc. And more important, haven’t ability to distinguish between cancer cells and normal cells. Because of that gene therapy may offer a promising alternative treatment for cancer diseases.

Gene therapy “is the insertion, alteration, or removal of genes within an individual's cells and biological tissues to treat diseases”.

http://en.wikipedia.org/wiki/Gene_therapy

To assess the feasibility and safety of single and repeated direct

intratumoral injections of Ad.TK followed by systemic GCV

To determine the maximal tolerated dose and the dose-limiting

toxicity of Ad.TK.

To investigate the efficiency of Ad.TK/GCV system.

Thymidine kinase (TK) from herpes simplex virus (HSV)

have been used as suicide gene followed by ganciclover

(GCV) prodrug.

Expression of functional HSV-TK in transduced cells has

ability to transform a nontoxic prodrug such as ganciclovir

(GCV) into a toxic phosphorylated (GCV-triphosphate)

compound that competes with triphosphate as a substrate

for DNA polymerase.

This causes inhibition of both nuclear and mitochondrial

DNA synthesis leading to cellular death

Drug (toxic) GCV

HSV-tk

Prodrug (GCV)

DNA Polymer

ase

A characteristic of the suicide gene is so-called “bystander

effect” which is to some extent caused by diffusion of the toxic

drug metabolite from transduced cells resulting in the death of

neighboring tumor cells.

By these mechanisms , gene transduction of a fraction of

tumor cells is able to lead to the extensive tumor response.

To avoid the side effect of this mechanism against normal cell:

I. Directly injected vectors within tumor nodules.

II. Engineering vector to express HSV-TK under tumor

specific promoters such as alpha-fetoprotein

T

T T T

N

T T

N N

N N

N

N

N

N

N

Procedures:

HSV

Adenoviral vector

CMV TK

gene

Patient enrollment: • 10 patients of advance HCC have been recruited in this

study.

• The patients were divided into 5 cohorts, in each one, there are 2 patients.

• The dose-escalation of Ad.Tk injection plan as follow:

i. Cohort 1; 2*1010vp

ii. Cohort 2; 1011vp

iii. Cohort 3; 2*1011vp

iv. Cohort 4; 1012vp

v. Cohort 5; 2*1012vp

Protocol of administration: Patients were given twice-daily oral valganciclovir at an equivalent dose of 900mg for 14 days starting 2 days after Ad.TK injection.

Ad.TK injection

• The solution containing

Ad.TK was very slowly

injected into the tumor at

different sites so that one

injection was performed

every 2cm in diameter when

possible, in order to

maximize vector delivery

within the tumor mass.

Patient evaluation: Daily evaluation of

toxicity and a comprehensive set of

laboratory tests

Toxicity was re-evaluated and response

to therapy was assessed

If at this time tumor disease was stable or responding and no serious adverse reactions had been observed, a second dose was administered into the same nodule (maximum 3 doses of Ad.TK to the same patient).

Imaging studies:

• Proton emission tomography (PET) has been used to

monitoring the gene expression, using FHBG (a

flourine- 18 labeled penciclovir analog) as a

radiotracer

RESULTS • Patients characteristics:

None of the patients

received antineoplastic

chemotherapy or

immunosuppressant drugs

in the month previous to

Ad.TK injection.

• Toxicity:

• Treatment procedure:

o Intratumoral injection of

Ad.TK was feasible in 100% of

cases, Because;

i. No complications associated

with the procedure were

reported.

ii. No relevant side effects were

observed even among

patients with impaired liver

function.

• Transgene expression:

o TK expression in the tumor

as detected by PET was

dependent on the injected

dose of the adenovirus

being detectable in all

patients who received a

dose of ≥ 1012vp.

• Antitumor activity: o Overall median survival was 5

months.

o One patient treated with 1012 vp

had remarkable long-term

outcome. Both the injected tumor

and a distant, noninjected tumor

showed a slight increase in size for

3 months after injection, and then

tumor growth was arrested for 18

months. No other therapy was

given and she finally died 26

months after Ad.TK therapy.

o Three patients showed

stable disease under the

threshold of 1012vp.

o Two patients who received

2*1012 vp of Ad.TK showed

signs of inratumoral

necrosis on imaging

procedures.

CONCLUSION

The results show that prodrug activating gene

therapy of HCC using the TK/GCV system is feasible,

safe and able to produce an antitumor effect.

REFERENCES: Gene therapy available from http://en.wikipedia.org/wiki/Gene_therapy (accessed on 28 Nov. 2010) Sangro, B., Mazzolini, G., Ruiz, J., Ruiz, J., Quiroga, J., Herrero, I., Qian, C., Benito, A., Larrache, J., Olague, C., Boan, J., Penulas, I., Sadaba, B., and Prieto, J., 2010. A phase I clinican trial of thymidine kinase-based gene therapy in advanced hepatocellular carcinoma. Cancer Gene Therapy, (17) 837-843