Suicide plus immune gene therapy prevents post-surgical local relapse and increases overall survival in an aggressive mouse melanoma setting.

In an aggressive B16-F10 murine melanoma model, we evaluated the effectiveness and antitumor mechanisms triggered by a surgery adjuvant treatment that combined a local suicide gene therapy (SG) with a subcutaneous genetic vaccine (Vx) composed of B16-F10 cell extracts and lipoplexes carrying the genes of human interleukin-2 and murine granulocyte and macrophage colony stimulating factor. Pre-surgical SG treatment, neither alone nor combined with Vx was able to slow down the fast evolution of this tumor. After surgery, both SG and SG + Vx treatments, significantly prevented (in 50% of mice) or delayed (in the remaining 50%) post-surgical recurrence, as well as significantly prolonged recurrence-free (SG and SG + Vx) and overall median survival (SG + Vx). The treatment induced the generation of a pseudocapsule wrapping and separating the tumor from surrounding host tissue. Both, SG and the subcutaneous Vx, induced this envelope that was absent in the control group. On the other hand, PET scan imaging of the SG + Vx group suggested the development of an effective systemic immunostimulation that enhanced (18)FDG accrual in the thymus, spleen and vertebral column. When combined with surgery, direct intralesional injection of suicide gene plus distal subcutaneous genetic vaccine displayed efficacy and systemic antitumor immune response without host toxicity. This suggests the potential value of the assayed approach for clinical purposes.

Methodology for Anti-Gene Anti-IGF-I Therapy of Malignant Tumours.

The aim of this study was to establish the criteria for methodology of cellular "anti-IGF-I" therapy of malignant tumours and particularly for glioblastoma multiforme. The treatment of primary glioblastoma patients using surgery, radiotherapy, and chemotherapy was followed by subcutaneous injection of autologous cancer cells transfected by IGF-I antisense/triple helix expression vectors. The prepared cell "vaccines" should it be in the case of glioblastomas or other tumours, have shown a change of phenotype, the absence of IGF-I protein, and expression of MHC-I and B7. The peripheral blood lymphocytes, PBL cells, removed after each of two successive vaccinations, have demonstrated for all the types of tumour tested an increasing level of CD8(+) and CD8(+)28(+) molecules and a switch from CD8(+)11b(+) to CD8(+)11. All cancer patients were supervised for up to 19 months, the period corresponding to minimum survival of glioblastoma patients. The obtained results have permitted to specify the common criteria for "anti-IGF-I" strategy: characteristics sine qua non of injected "vaccines" (cloned cells IGF-I(-) and MHC-I(+)) and of PBL cells (CD8(+) increased level).

Sodium phenylacetate (NaPa) improves the TAM effect on glioblastoma experimental tumors by inducing cell growth arrest and apoptosis.

BACKGROUND: Multiform glioblastomas represent the most aggressive brain tumors. Here, the cooperative effects of sodium phenylacetate (NaPa) and/or tamoxifen (TAM) on CNS1 and 9L glioblastoma cell lines in vitro and in an experimental animal tumor model were investigated. MATERIALS AND METHODS: The drug effects on cell cycle and apoptosis were investigated by flow cytometry. CNS1 cells were implanted subcutaneously in nude mice to form tumors which were then treated with NaPa, TAM or NaPa/TAM. RESULTS: A significant inhibitory effect of NaPa on the two glioma cell lines (LD50 of 10 mM) was observed. 10(-5) M of TAM inhibited approximately 35% of 9L cell growth, and 90% of CNS1 cell growth. When a combination of both drugs included 10(-9) M of TAM, inhibition of about 50% of 9L cell growth and 75% of CNS1 cell growth occurred. The NaPa/TAM combined treatment increased the number of G0/G1 arrested cells and apoptotic cells as compared to treatments with NaPa or TAM alone. Inhibition of CNS1 tumor growth were observed after a two week treatment with NaPa (32 mg/kg/day) or TAM (6 mg/kg/day). CONCLUSION: These results showed a synergistic effect between these two drugs on tumor cell proliferation, caused by cell cycle arrest in the G0/G1 phase and by induction of apoptosis.

In vitro and in vivo evaluation of two rational-designed nonpeptidic farnesyltransferase inhibitors on HT29 human colon cancer cell lines.

FTase inhibitors constitute a new class of potential cancer therapeutics, especially in colorectal cancer where K-ras-selective mutations exist and have a role in tumorigenesis. The synthesis and biological evaluation of two nonpeptidic molecules (13 and 16) designed on the basis of a zinc chelator imidazole linked to two aromatic fragments able to fit in the "exit groove" and in the "A2 binding site" of FTase are described. These molecules are characterized respectively by a flexible phenylmethyl chain and a more constrained scaffold so as to evaluate their respective influences on site recognition. They have been evaluated in vitro and in vivo against human colon cancer cell lines and 13 not only inhibited tumor growth but also showed no toxic effects at the dose used.

"Suicide" gene therapy of breast cancer cells is only cytostatic in vitro but anti-tumoral in vivo on breast MCF7-ras tumor.

Gene therapy with Herpes Simplex Virus thymidine kinase gene (HSV-tk) is effective in various tumor models in vitro and in vivo. We compared the efficacy of the HSV-tk gene therapy in vitro and in vivo in MCF-7 and MCF7-ras cells which form tumor in athymic mice. After viral infection, cells were treated with GCV (Ganciclovir) and live cells were counted. The in vitro treatment significantly inhibited cell growth but did not induce early and late apoptosis, measured, respectively, by annexin or by propidium iodide staining and a significant cell death. The HSV-tk/GCV treatment of MCF7-ras tumor in athymic mice showed a significant inhibition of tumor development until 60 days post-treatment. Some mice showed a complete tumor eradication without tumor regrowth after the end of treatment. In conclusion, we demonstrated that the HSV-tk/GCV system is not very efficient in vitro, but very efficient in vivo in our animal breast cancer model.

Anti-proliferative and antitumoral activities of a functionalized dextran (CMDBJ) on the 1205 L-U human tumor melanoma cells.

Carboxy methyl dextran benzylamide jorge (CMDBJ) is a derivatized dextran prepared from native dextran after random carboxymethylation of hydroxyl groups on D-glucose units (CM) and consecutive conversion of some carboxylate groups to benzylamide structures (B). This polymer exhibits an inhibitory action upon the proliferation of 1205 L-U human melanoma cells. At low concentrations, this compound exerts a cytostatic effect whereas, at higher concentrations, a cytotoxicity appears within 24 hours of treatment. The 1205 L-U cell line forms subcutaneous angiogenic tumors in athymic mice and, after several weeks, spontaneously forms micrometastasis in the lungs. We demonstrated that the CMDBJ treatment of animals not only reduces the rapid growth of primary tumors but also induces tumor regression and tumor necrosis. Moreover, CMDBJ treatment blocks the appearance of lung metastasis. Pleiotrophin (PTN), heparin-binding angiogenic growth factor, is secreted by 1205 L-U cells and breast tumor MDA-MB 231 cells. CMDBJ, as an inhibitor of heparin-binding growth factor activities, suppresses the mitogenic activity of conditioned media from 1205 L-U and MDA-MB 231 on endothelial HUVEC cells. We conclude that CMDBJ can inhibit the in vitro cell proliferation of 1205 L-U cells and 1205 L-U tumor development in athymic mice and that PTN secreted by these cells could be involved in this inhibition.

IGF-I: from diagnostic to triple-helix gene therapy of solid tumors.

Alterations in the expression of growth factors and their receptors are associated with the growth and development of human tumors. One such growth factor is IGF-I (insulin-like growth factor I ), a 70-amino-acid polypeptide expressed in many tissues, including brain. IGF-I is also expressed at high levels in some nervous system-derived tumors, especially in glioblastoma. When using IGF-I as a diagnostic marker, 17 different tumors are considered as expressing the IGF-I gene. Malignant glioma, the most common human brain cancer, is usually fatal. Average survival is less than one year. Our strategy of gene therapy for the treatment of gliomas and other solid tumors is based on: 1) diagnostic using IGF-I gene expression as a differential marker, and 2) application of "triple-helix anti-IGF-I" therapy. In the latter approach, tumor cells are transfected with a vector, which encodes an oligoribonucleotide--an RNA strand containing oligopurine sequence which might be capable of forming a triple helix with an oligopurine and/or oligopyrimidine sequence of the promotor of IGF-I gene (RNA-IGF-I DNA triple helix). Human tumor cells transfected in vitro become down-regulated in the production of IGF-I and present immunogenic (MHC-I and B7 expression) and apoptotic characteristics. Similar results were obtained when IGF-I antisense strategy was applied. In both strategies the transfected cells reimplanted in vivo lose tumorigenicity and elicit tumor specific immunity which leads to elimination of established tumors.