This document summarizes a study on the feasibility, safety, and efficacy of gene therapy for hepatocellular carcinoma (HCC) using herpes simplex virus thymidine kinase (HSV-TK) suicide gene therapy. 10 patients with advanced HCC received intratumoral injections of an adenoviral vector containing HSV-TK followed by the prodrug ganciclovir. The therapy was found to be feasible and safe. Higher doses of the vector were associated with greater transgene expression. One patient experienced long term tumor control for over 18 months with no additional therapy. The results suggest HSV-TK gene therapy may produce antitumor effects for HCC.

1. Prepared by
FOUD HOURANI

3. AGENDA
 Introduction
 Objectives
 Methods
 Results
 Conclusion
 References

4. 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.

5. 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.

6. 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

7. 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.

8. Thymidine kinase (TK) from herpes simplex virus (HSV)
have been used as suicide gene followed by ganciclover
(GCV) prodrug.
Prodrug
(GCV)
Expression of functional HSV-TK in transduced cells has HSV-tk
ability to transform a nontoxic prodrug such as ganciclovir
(GCV) into a toxic phosphorylated (GCV-triphosphate)
compound that competes with triphosphate as a substrate Drug (toxic) GCV
for DNA polymerase.
DNA
This causes inhibition of both nuclear and mitochondrial Polymer
ase
DNA synthesis leading to cellular death

9. 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 N T T T
neighboring tumor cells. N T T T
N N N N
N N N N
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

10. Procedures:
TK
gene CMV
HSV
Adenoviral
vector

11. 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
Protocol of administration:
iv. Cohort 4; 1012vp Patients were given twice-daily oral
valganciclovir at an equivalent dose of
v. Cohort 5; 2*1012vp 900mg for 14 days starting 2 days after
Ad.TK injection.

12. 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.

13. Patient evaluation:
Daily evaluation of Toxicity was re-
toxicity and a evaluated and response
comprehensive set of to therapy was
laboratory tests 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).

14. 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

15. RESULTS
• Patients characteristics:
None of the patients
received antineoplastic
chemotherapy or
immunosuppressant drugs
in the month previous to
Ad.TK injection.

16. • Toxicity:

17. • 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.

18. • 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.

19. • 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.

20. 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.

21.  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.

22.  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