Hepatocellular carcinoma (HCC)HCC is a primary malignancy of the hepatocyte, generallyleading 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 tochemotherapeutic.also chemotherapy still place a burden on patients.In general, most of medication for cancer diseases have a sideeffects such as hair loss, bleeding… etc.And more important, haven’t ability to distinguish betweencancer cells and normal cells.Because of that gene therapy may offer a promisingalternative treatment for cancer diseases.
Gene therapy “is the insertion,alteration, or removal of geneswithin an individuals cells andbiological tissues to treatdiseases”. http://en.wikipedia.org/wiki/Gene_therapy
To assess the feasibility and safety of single and repeated directintratumoral injections of Ad.TK followed by systemic GCVTo determine the maximal tolerated dose and the dose-limitingtoxicity 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. Prodrug (GCV)Expression of functional HSV-TK in transduced cells has HSV-tkability 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) GCVfor DNA polymerase. DNAThis causes inhibition of both nuclear and mitochondrial Polymer aseDNA synthesis leading to cellular death
A characteristic of the suicide gene is so-called “bystandereffect” which is to some extent caused by diffusion of the toxicdrug metabolite from transduced cells resulting in the death of N T T Tneighboring tumor cells. N T T T N N N N N N N NBy these mechanisms , gene transduction of a fraction oftumor 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
Procedures: TK gene CMV HSV Adenoviral vector
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*1010vpii. Cohort 2; 1011vpiii. Cohort 3; 2*1011vp Protocol of administration:iv. Cohort 4; 1012vp Patients were given twice-daily oral valganciclovir at an equivalent dose ofv. Cohort 5; 2*1012vp 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 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).
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 patientsreceived antineoplasticchemotherapy orimmunosuppressant drugsin the month previous toAd.TK injection.
• 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 genetherapy 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 28Nov. 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 Iclinican trial of thymidine kinase-based gene therapy in advanced hepatocellularcarcinoma. Cancer Gene Therapy, (17) 837-843