acyclovir and Glioma

Despite aggressive standard of care (SOC) treatment, survival of malignant gliomas remains very poor. This Phase II, prospective, matched controlled, multicenter trial was conducted to assess the safety and efficacy of aglatimagene besadenovec (AdV-tk) plus valacyclovir (gene-mediated cytotoxic immunotherapy [GMCI]) in combination with SOC for newly diagnosed malignant glioma patients.. Treatment cohort patients received SOC + GMCI and were enrolled at 4 institutions from 2006 to 2010. The preplanned, matched-control cohort included all concurrent patients meeting protocol criteria and SOC at a fifth institution. AdV-tk was administered at surgery followed by SOC radiation and temozolomide. Subset analyses were preplanned, based on prognostic factors: pathological diagnosis (glioblastoma vs others) and extent of resection.. Forty-eight patients completed SOC + GMCI, and 134 met control cohort criteria. Median overall survival (OS) was 17.1 months for GMCI + SOC versus 13.5 months for SOC alone (P = .0417). Survival at 1, 2, and 3 years was 67%, 35%, and 19% versus 57%, 22%, and 8%, respectively. The greatest benefit was observed in gross total resection patients: median OS of 25 versus 16.9 months (P = .0492); 1, 2, and 3-year survival of 90%, 53%, and 32% versus 64%, 28% and 6%, respectively. There were no dose-limiting toxicities; fever, fatigue, and headache were the most common GMCI-related symptoms.. GMCI can be safely combined with SOC in newly diagnosed malignant gliomas. Survival outcomes were most notably improved in patients with minimal residual disease after gross total resection. These data should help guide future immunotherapy studies and strongly support further evaluation of GMCI for malignant gliomas.. ClinicalTrials.gov NCT00589875.

Topics: Acyclovir; Adenoviridae; Adult; Aged; Antiviral Agents; Brain Neoplasms; Chemotherapy, Adjuvant; Genetic Therapy; Genetic Vectors; Glioma; Humans; Immunotherapy; Middle Aged; Simplexvirus; Survival Analysis; Thymidine Kinase; Treatment Outcome; Valacyclovir; Valine

Despite aggressive therapies, median survival for malignant gliomas is less than 15 months. Patients with unmethylated O(6)-methylguanine-DNA methyltransferase (MGMT) fare worse, presumably because of temozolomide resistance. AdV-tk, an adenoviral vector containing the herpes simplex virus thymidine kinase gene, plus prodrug synergizes with surgery and chemoradiotherapy, kills tumor cells, has not shown MGMT dependency, and elicits an antitumor vaccine effect.. Patients with newly diagnosed malignant glioma received AdV-tk at 3 × 10(10), 1 × 10(11), or 3 × 10(11) vector particles (vp) via tumor bed injection at time of surgery followed by 14 days of valacyclovir. Radiation was initiated within 9 days after AdV-tk injection to overlap with AdV-tk activity. Temozolomide was administered after completing valacyclovir treatment.. Accrual began December 2005 and was completed in 13 months. Thirteen patients were enrolled and 12 completed therapy, three at dose levels 1 and 2 and six at dose level 3. There were no dose-limiting or significant added toxicities. One patient withdrew before completing prodrug because of an unrelated surgical complication. Survival at 2 years was 33% and at 3 years was 25%. Patient-reported quality of life assessed with the Functional Assessment of Cancer Therapy-Brain (FACT-Br) was stable or improved after treatment. A significant CD3(+) T-cell infiltrate was found in four of four tumors analyzed after treatment. Three patients with MGMT unmethylated glioblastoma multiforme survived 6.5, 8.7, and 46.4 months.. AdV-tk plus valacyclovir can be safely delivered with surgery and accelerated radiation in newly diagnosed malignant gliomas. Temozolomide did not prevent immune responses. Although not powered for efficacy, the survival and MGMT independence trends are encouraging. A phase II trial is ongoing.

Topics: Acyclovir; Adenoviridae; Adjuvants, Immunologic; Adult; Aged; Antineoplastic Agents, Alkylating; Antiviral Agents; Brain Neoplasms; Cancer Vaccines; Combined Modality Therapy; Dacarbazine; Genetic Therapy; Genetic Vectors; Glioma; Herpesvirus 1, Human; Humans; Immunotherapy; Middle Aged; O(6)-Methylguanine-DNA Methyltransferase; Temozolomide; Thymidine Kinase; Treatment Outcome; Valacyclovir; Valine

Topics: Acyclovir; Antineoplastic Agents, Alkylating; Antiviral Agents; Brain Stem Neoplasms; Cognitive Dysfunction; Cranial Irradiation; Dacarbazine; Delirium; Dexamethasone; Diagnosis, Differential; Encephalitis, Herpes Simplex; Female; Glioma; Herpesvirus 1, Human; Humans; Leukocytosis; Magnetic Resonance Imaging; Seizures; Temozolomide; Young Adult

Topics: Acyclovir; Aged; Antiviral Agents; Brain Neoplasms; Diagnosis, Differential; Encephalitis, Varicella Zoster; Glioma; Gliosis; Humans; Immunocompetence; Magnetic Resonance Imaging; Male; Middle Aged; Valacyclovir; Valine; Young Adult

Herpes simplex virus 1 (HSV-1) mutants that lack the γ(1)34.5 gene are unable to replicate in the central nervous system but maintain replication competence in dividing cell populations, such as those found in brain tumors. We have previously demonstrated that a γ(1)34.5-deleted HSV-1 expressing murine interleukin-12 (IL-12; M002) prolonged survival of immunocompetent mice in intracranial models of brain tumors. We hypothesized that M002 would be suitable for use in clinical trials for patients with malignant glioma. To test this hypothesis, we (i) compared the efficacy of M002 to three other HSV-1 mutants, R3659, R8306, and G207, in murine models of brain tumors, (ii) examined the safety and biodistribution of M002 in the HSV-1-sensitive primate Aotus nancymae following intracerebral inoculation, and (iii) determined whether murine IL-12 produced by M002 was capable of activating primate lymphocytes. Results are summarized as follows: (i) M002 demonstrated superior antitumor activity in two different murine brain tumor models compared to three other genetically engineered HSV-1 mutants; (ii) no significant clinical or magnetic resonance imaging evidence of toxicity was observed following direct inoculation of M002 into the right frontal lobes of A. nancymae; (iii) there was no histopathologic evidence of disease in A. nancymae 1 month or 5.5 years following direct inoculation; and (iv) murine IL-12 produced by M002 activates A. nancymae lymphocytes in vitro. We conclude that the safety and preclinical efficacy of M002 warrants the advancement of a Δγ(1)34.5 virus expressing IL-12 to phase I clinical trials for patients with recurrent malignant glioma.

Topics: Acyclovir; Animals; Antiviral Agents; Aotidae; Brain; Cell Line; Chlorocebus aethiops; Drug Evaluation, Preclinical; Female; Gene Expression; Genetic Therapy; Genetic Vectors; Glioma; Humans; Interleukin-12; Magnetic Resonance Imaging; Male; Mice; Mice, SCID; Simplexvirus; Survival Analysis; Virus Replication; Xenograft Model Antitumor Assays

Suicide gene therapy using herpes simplex virus-thymidine kinase (HSV-TK)/ganciclovir (GCV), has been extensively tested for the treatment of glioma. Our previous study showed that exogenous wild type p53 (wt-p53) enhanced the anti-tumor effect of HSV-TK/GCV therapy. However, the use of GCV is hindered by its low penetration to the brain and its toxicity when used at higher dose. In the present study, we used another pro-drug, acyclovir (ACV), and examined the therapeutic efficacy of HSV-TK/ACV combining with wt-p53 in C6 glioma cells. We observed that wt-p53 combined with HSV-TK/ACV resulted in the super-additive anti-tumor effect in vitro. Exogenous wt-p53 significantly enhanced the sensitivity of TK positive C6 cells to ACV in vitro. Our in vivo experiment demonstrated that the effect of wt-p53 and HSV-TK/ACV combination therapy was better than that of HSV-TK/ACV alone. The survival time of tumor-bearing rats treated with wt-p53 in combination with HSV-TK/ACV was also significantly prolonged than those treated with HSV-TK/ACV alone. These results suggest that wt-p53 can enhance the therapeutic efficacy of HSV-TK/ACV both in vitro and in vivo. These findings are considerably valuable with the respect of using less toxic ACV as prodrug. This novel strategy could provide benefit to HSV-TK/prodrug gene therapy.

Topics: Acyclovir; Animals; Antineoplastic Agents; Apoptosis; Cell Line; Cell Line, Tumor; Cell Survival; Combined Modality Therapy; Drug Synergism; Ganciclovir; Genes, p53; Genetic Therapy; Glioma; Humans; In Situ Nick-End Labeling; Magnetic Resonance Imaging; Male; Rats; Rats, Sprague-Dawley; Simplexvirus; Thymidine Kinase

We recently reported that an adenovirus-expressing mutant HSV-TK75 (AdCMV-TK75) radiosensitized rat syngeneic gliomas in combination with low concentrations of acyclovir (ACV) much more effectively than a virus expressing wild-type herpes simplex virus thymidine kinase (HSV-TK). In this report we have examined whether similar radiosensitizing effects are also seen with human glioma cells in vitro and in vivo.. Human U87 MG glioma cells were transduced with AdCMV-TK75 and exposed to ACV followed by single-dose irradiation and colony-forming survival assays. Similarly, U87 MG xenografts were infused with AdCMV-TK75 or Adbetagal control virus, followed by ACV administration and fractionated irradiation. Therapeutic efficacy was monitored by tumor growth.. U87 MG cells transduced with AdCMV-TK75 were significantly more sensitive to ACV (3 microM) than cells transduced with either wild-type HSV-TK or control virus. To determine whether human cells also demonstrate improved radiosensitization similar to that seen with rat glioma cells and tumors, we transduced U87 MG cells with either AdCMV-TK75, AdCMV-TK, expressing wild-type HSV-TK, or Adbetagal and then treated the cells with 3 microM of ACV. Cells transduced with AdCMV-TK75 were significantly more radiosensitive (dose enhancement ratio [D(37)]: 2.6) by colony-forming survival assay than cells transduced with either AdCMV-TK or Adbetagal. Furthermore, we found that U87 MG xenografts infused with AdCMV-TK75 by slow positive pressure infusion were more radiosensitive after administration of ACV than tumors infused with Adbetagal. A more dramatic result was achieved when fractionated irradiation was carried out concurrently with ACV administration, in which case AdCMV-TK75-treated tumors did not grow at all.. These results demonstrate that transduction of human glioma cells in vitro and infusion of xenografts in vivo with AdCMV-TK75 and treatment with concentrations of ACV that can be achieved in vivo produce similar radiosensitization, as previously reported with rat glioma cells and intracerebral syngeneic tumors. In addition, concurrent treatment with ACV and radiation therapy is more efficient than when ACV is administered before radiation therapy.

Topics: Acyclovir; Adenoviridae; Animals; Antiviral Agents; Combined Modality Therapy; Glioma; Herpesviridae; Humans; Mice; Mice, Nude; Mutation; Radiation Tolerance; Radiobiology; Thymidine Kinase; Transduction, Genetic; Transplantation, Heterologous; Tumor Cells, Cultured; Tumor Stem Cell Assay

We recently demonstrated in vitro that a mutant HSV-TK (mutant 75) expressed from an adenovirus (AdCMV-TK75) radiosensitized rat RT2 glioma cells significantly better than wild type HSV-TK (AdCMV-TK) in combination with acyclovir (ACV). To examine whether a similar improvement could also be observed in vivo, we tested these viruses in a syngeneic rat glioma tumor model (RT2/Fischer 344). First, we demonstrate that treatment with AdCMV-TK and ACV significantly radiosensitizes implanted gliomas and roughly doubles the mean survival time to 37 days, compared to 20 days for control animals implanted with Adbetagal-transduced cells (P<.02). Second, it was important to first examine the effect of AdCMV-TK75 and ACV on survival without any irradiation. We found that AdCMV-TK75 appeared to sensitize gliomas more efficiently than AdCMV-TK, although this difference was not significant ( P= .19 ). Third, and most importantly, in combined HSV-TK, ACV and irradiation experiments, we demonstrate that AdCMV-TK75 is superior over AdCMV-TK and significantly (P<.005) prolonged the survival of treated animals. Our results suggest that AdCMV-TK75 is far more efficient than AdCMV-TK in radiosensitizing rat glioma when administered in combination with ACV.

Topics: Acyclovir; Adenoviridae; Animals; Antiviral Agents; Apoptosis; Blotting, Western; Brain; Brain Neoplasms; Combined Modality Therapy; Dose-Response Relationship, Drug; Dose-Response Relationship, Radiation; Female; Genetic Vectors; Glioma; Mutation; Neoplasm Transplantation; Radiation-Sensitizing Agents; Rats; Rats, Inbred F344; Simplexvirus; Survival Rate; Thymidine Kinase; Transduction, Genetic; Tumor Cells, Cultured

Cancer suicide gene therapy affords the prospect of using the most optimal genes available because the source of the therapeutic gene is often irrelevant. Currently, there are numerous preclinical and clinical trials to develop tumor ablative therapies that use viral, yeast, or bacterial genes. One such gene, the herpes simplex virus type 1 (HSV-1) thymidine kinase (TK) is widely used as a suicide gene in combination with ganciclovir. In the study reported here, a restricted set of random sequences (semi-random) was introduced into the active site of HSV-1 TK, and the resulting variants were selected on the basis of their ability to confer increased ganciclovir or acyclovir sensitivity to Escherichia coli. Sequence analysis demonstrated that functional mutants contained three to five amino acid substitutions that are unique and novel combinations. On the basis of enzyme assay results, three mutants were identified for further analysis in vitro. These three mutants conferred substantial increased sensitivity to both ganciclovir and acyclovir when compared with IC50s of wild-type TK expressing rat C6 glioma cells. One mutant, SR39, was further evaluated in a xenograft tumor model in nude mice. Expression of SR39 in tumors was shown to prevent tumor growth at prodrug dosages that did not affect wild-type HSV-1 TK-expressing tumors. The use of any of these mutants as a suicide gene should provide a more effective and safer alternative to wild-type TK, because lower, less immunosuppressive doses of ganciclovir will be necessary for tumor ablation, and the use of acyclovir may now be possible.

Topics: Acyclovir; Animals; Binding Sites; Cell Death; Ganciclovir; Glioma; Herpesvirus 1, Human; Mice; Mutagenesis; Prodrugs; Rats; Thymidine Kinase; Transfection; Xenograft Model Antitumor Assays

Human glioma cell lines 8-MG-BA and 42-MG-BA were infected with retrovirus vector containing the herpes simplex virus thymidine kinase (HSVtk) gene. The effect of acyclovir (ACV), ganciclovir (GCV), and bromovinyldeoxyuridine (BVDU) on both, parental and HSVtk expressing glioma cells was studied in vitro. BVDU displayed the most potent cytotoxic properties in HSVtk-containing cells, however bystander killing of nontransduced parental cells in a mixture with HSVtk-containing cells was less potent, than observed for ACV or GCV. Taking into account the cytotoxic effect of different prodrugs used, as well as their ability to kill nontransduced bystander cells, ganciclovir was shown to be the most effective. Therefore the effect of GCV treatment on 8-MG-BA xenografts inoculated with PA-317JH5cl13 virus producer cells was further studied on nude mice.

Topics: Acyclovir; Animals; Antiviral Agents; Blotting, Northern; Blotting, Western; Bromodeoxyuridine; Dose-Response Relationship, Drug; Electrophoresis, Polyacrylamide Gel; Ganciclovir; Genetic Therapy; Genetic Vectors; Glioma; Humans; Mice; Mice, Nude; Models, Chemical; Neoplasm Transplantation; Thymidine Kinase; Time Factors; Tumor Cells, Cultured

Adenovirus expressing herpes simplex virus-thymidine kinase (HSV-TK) sensitizes internal rat glioma cells to radiation in combination with acyclovir (ACV). However, relatively high concentrations of ACV (>10 microM) are required to obtain significant radiosensitization. Serum levels rarely reach more than the lower micromolar range, preventing the full use of this genetic approach to radiosensitize cells in vivo. To better use the lower concentrations of ACV available in sera, we constructed an adenovirus expressing a mutant HSV-TK (HSV-TK(75)) isolated for its approximately 20 times greater sensitivity to ACV than wild-type (wt) HSV-TK. We demonstrate that rat RT2 glioma cells infected with adenovirus AdCMV-TK(75) and exposed to either ACV or ganciclovir become more sensitive to lower concentrations (1-3 microM) of the drugs compared with cells infected with AdCMV-TK(wt), which expresses wt HSV-TK. Most importantly, the RT2 cells become more sensitive to low doses (2-4 Gy) of 60Co radiation than cells infected with an adenovirus expressing wt HSV-TK. This sensitization is accompanied by an increased rate of apoptosis. In summary, we show that infection of rat glioma cells with an adenovirus expressing a mutant HSV-TK sensitizes the cells to low doses of radiation after exposure to ACV at lower concentrations than those required for wt HSV-TK. This finding suggests that this mutant adenovirus may improve the in vivo efficacy of HSV-TK-based cancer gene therapy approaches.

Topics: Acyclovir; Adenoviridae; Animals; Antiviral Agents; Apoptosis; Blotting, Western; Brain Neoplasms; Combined Modality Therapy; Dose-Response Relationship, Drug; Dose-Response Relationship, Radiation; Genetic Vectors; Glioma; Mutation; Rats; Rats, Inbred F344; Simplexvirus; Thymidine Kinase; Tumor Cells, Cultured

With the advent of gene therapy, herpes simplex virus type I (HSV-1) thymidine kinase (TK) has garnered much interest as a suicide gene for cancer ablation. As a means to improve the overall efficacy of the prodrug-gene activation approach, as well as to reduce ganciclovir-mediated toxicity, a large library of mutant thymidine kinases was generated and screened for the ability to enhance in vitro cell sensitivity to the prodrugs, ganciclovir (GCV) and acyclovir (ACV). Enzyme kinetics of one thymidine kinase mutant from this library that contains six amino acid substitutions at or near the active site reveals a distinct mechanism for providing enhanced prodrug-mediated killing in mammalian cells. In in vitro rat C6 cell prodrug sensitivity assays the TK mutant (mutant 30) achieves nanomolar IC50 values with GCV and ACV, in contrast to IC50values of 30 microM and >100 microM, respectively, for wild-type TK. In a mouse xenograft tumor model, growth of mutant 30 expressing tumors is restricted by ganciclovir at a dose at least 10- fold lower than one that impedes growth of wild-type TK-expressing tumors. Furthermore, in the presence of GCV a substantial bystander effect is observable when only 20% of the tumor cells express mutant 30 whereas no restriction in tumor growth is seen in tumors bearing the wild-type TK under the same conditions. The enhanced sensitization to prodrugs conferred by mutant 30 is apparently due to a 35-fold increase in thymidine Km which results in reduced competition between prodrug and thymidine at the active site. This provides mutant 30 a substantial kinetic advantage despite very high Kms for both ganciclovir and acyclovir. Molecular modeling of the mutations within the active site suggests that a tyrosine substitution at alanine 168 (A168) alters thymidine and prodrug interactions by causing catalytically important residues to move. The use of mutant 30 in place of the wild-type TK should provide a more effective gene therapy of cancer.

Topics: Acyclovir; Amino Acid Sequence; Animals; Ganciclovir; Gene Transfer Techniques; Genetic Therapy; Genetic Vectors; Glioma; Herpesvirus 1, Human; Mice; Mice, Nude; Models, Molecular; Molecular Sequence Data; Mutation; Neoplasm Transplantation; Prodrugs; Rats; Thymidine Kinase; Transfection; Tumor Cells, Cultured

To establish the replicated-deficient recombinant adenovirus-mediated thymidine kinase/acyclovir (Adtk/ACV) system and to evaluate its suicide effect on rat C6 brain gliomas in vitro and in vivo.. The plasmid pAdtk and pJM17 were co-infected into 293 cells (adenovector packaging cells) and the results were identified by polymerase chain reaction (PCR) assay. After the glioma C6 cells were transduced by Adtk at different multiplicity of infection (MOI) and exposed to different concentrations of ACV or gancyclovir (GCV), the cell survival curves were studied, and the cell surface was observed with scanning electronic microscopy (SEM). C6 gliomas in vivo at different inoculation days were injected with Adtk intratumorally and ACV intraperitoneally daily, and the survival duration and histologic changes of the rats were observed.. The infectious Adtk virions had a suicide effect which was enhanced with the increase in MOIs of Adtk and ACV doses along with bystander effect. Under scanning electronic microscope, special pathologic changes were observed. ACV had a similar effect as GCV but a higher dose was used. The survival duration in day 3, day 6 and day 8 groups exceeded 90 days, and the rats in day 10 group survived 28.5 +/- 4.6 days, but the survival duration in untreated C6 group and AdLacZ/ACV (adenovirus-mediated LacZ/ACV) treated group were 16.8 +/- 3.1 and 14.0 +/- 2.2 days respectively.. Adtk/ACV system can effectively kill the rat brain gliomas in vitro and in vivo.

Topics: Acyclovir; Adenoviruses, Human; Animals; Brain Neoplasms; Ganciclovir; Gene Transfer Techniques; Genetic Therapy; Glioma; Rats; Rats, Sprague-Dawley; Recombinant Proteins; Thymidine Kinase; Tumor Cells, Cultured

Earlier studies have shown that genetically engineered herpes simplex viruses (e.g., HSV-1) are effective in killing malignant tumor cells both in vitro and in various murine tumor models. This report focuses on a panel of five genetically engineered viral mutants of the gamma(1)34.5 gene, which was shown previously to cause reduction in viral replication and associated neurovirulence of HSV. These include R3616, which has both copies of gamma(1)34.5 deleted, R4009, which has a stop codon inserted after codon 28 in both copies of the gamma(1)34.5 gene, R849, which contains a lacZ gene inserted in place of the gamma(1)34.5, R908, which lacks 41 codons in frame after codon 72 of the gamma(1)34.5, and R939, which carries a stop codon precluding the translation of the COOH-terminal domain of the gamma(1)34.5 gene. We report the following: (a) all five mutant HSVs were avirulent in experimental animals but were cytotoxic for human tumor cells in vitro and in vivo; (b) the gamma(1)34.5- HSV replicated in human glioma cells almost as efficiently as wild-type HSV-1(F) based on replication assays, in situ hybridization for viral DNA, and expression of infected cell protein 27; (c) capacity of mutant HSVs to kill human cells derived from glioblastoma multiforme (CH-235MG, D-37MG, D-54MG, D-65MG, U-251MG, U-373MG, and SK-MG-1), anaplastic astrocytoma (Hs-683), anaplastic glioma (U-87MG and U-138MG), gliosarcoma (D-32GS), or normal human astrocytes demonstrated that glioma cells varied in their susceptibility to HSV-mediated cytotoxicity and that cultured astrocytes were two to three orders of magnitude less susceptible to killing than were malignant glia; and (d) scid mice, which received 0.5 or 5 x 10(6) plaque-forming units of R4009, either were coinoculated at the time of intracranial transplantation with 106 U251MG or D-54MG human glioma cells or received the cells intratumorally 5 days after tumor induction and experienced significant increases in median survivals, with no histopathological indication of an infectious encephalitic process. Genetically engineered gamma(1)34.5- HSV mutants appear to be a potentially safe biotherapeutic agent for experimental treatment of uniformly fatal malignant brain tumors.

Topics: Acyclovir; Animals; Antiviral Agents; Astrocytes; Brain Neoplasms; Chlorocebus aethiops; Cytopathogenic Effect, Viral; DNA, Viral; Genetic Engineering; Glioma; Herpesvirus 1, Human; Humans; Immediate-Early Proteins; Mice; Mice, SCID; Transplantation, Heterologous; Vero Cells; Virus Replication

The antiviral drug acyclovir, an analogue of purine, was found to selectively enhance the radiosensitivity of rodent tumor cells which were transduced with the herpes simplex virus thymidine kinase gene (HSV-tk). 9L rat glioma cells transduced with HSV-tk and treated with acyclovir (20 micrograms/ml) for 24 hr before or after irradiation were highly sensitive to radiation, as compared with non-transduced glioma cells. When 9L cells transduced with HSV-tk gene were exposed to acyclovir and radiation, the sensitizer enhancement ratio (SER) was 1.6. In vivo, a significant increase in the median survival time of rats with 9L-tk tumors was observed when acyclovir was administered before and after single-dose irradiation, relative to the survival time of similar rats receiving radiation alone. The results show that an antiviral agent can selectively enhance cell killing by radiation in cells transduced with the HSV-tk, and suggest that the addition of HSV-tk gene therapy to standard radiation therapy will improve the effectiveness of treatment for brain tumors.

Topics: Acyclovir; Animals; Antiviral Agents; Brain Neoplasms; Cell Survival; Ganciclovir; Genetic Therapy; Glioma; Male; Radiation-Sensitizing Agents; Rats; Rats, Inbred F344; Simplexvirus; Thymidine Kinase; Transduction, Genetic

The paper reports the construction of retroviral vector pLNTK carrying HSV-tk gene driven by PGK promoter and the successful transfer into human glioma cell SHG44. The in vitro study confirmed that ayclovir (ACV) sensitive level of the gene-transferred glioma cell (SHGLNTK) was 1,000 times that of SHG44. 3H-TdR incorporation confirmed that the DNA replication in SHGLNTK was considerably suppressed when treated with ACV. The in vivo study confirmed that ACV could suppress tumor formation of the SHGLNTK cells. In situ gene transfer treatment of nude mice carrying SHG44 tumor showed good therapeutic results. Such treatment may be used as an innovative method for brain tumor therapy.

Topics: Acyclovir; Animals; Antimetabolites; Brain Neoplasms; DNA, Neoplasm; Gene Transfer Techniques; Genetic Therapy; Glioma; Humans; Mice; Mice, Inbred BALB C; Mice, Nude; Neoplasm Transplantation; Thymidine Kinase; Tumor Cells, Cultured

The antiviral agents ganciclovir, 1-beta-D-arabinofuranosylthymine (araT), acyclovir, and 5-iodo-5'-amino-2',5'-dideoxyuridine were cytotoxic to rat C6 glioma cells expressing retrovirally transferred herpes simplex virus (HSV) type 1 thymidine kinase (TK) coding sequence, with concentrations that inhibited cell survival by 50% (IC50 values) of 0.06, 3, 13, and 23 mumol/L, respectively. In C6 cells not expressing HSV-TK, the IC50 value for ganciclovir was 140 mumol/L and a concentration of 1 mmol/L killed more than 99% of the cells. The other antiviral agents tested were less toxic in nontransduced cells. Compared with retrovirally transduced cells, transduction of C6BU1 cells with an adenovirus vector containing the coding sequence for HSV-TK (Ad.RSVtk) increased the cellular activity of the viral kinase up to 600-fold with increasing multiplicity of infection (MOl). Cells transduced with Ad.RSVtk exhibited as much as a fivefold and 12-fold decrease in IC50 value for ganciclovir and araT, respectively, compared with retrovirally transduced cells. Sensitivity to antiviral drugs increased with increasing exposure to Ad.RSVtk, with IC50 values of 0.6 and 0.005 mumol/L for araT and ganciclovir, respectively, at an MOl of 1000. These data suggest that adenoviral transfer of HSV-TK will allow the use of less toxic drugs or lower concentrations of toxic drugs such as ganciclovir for directed antitumor therapy in vivo.

Topics: Acyclovir; Adenoviruses, Human; Animals; Arabinonucleosides; Avian Sarcoma Viruses; Brain Neoplasms; Drug Resistance; Ganciclovir; Genes, Viral; Genetic Vectors; Glioma; Promoter Regions, Genetic; Rats; Recombinant Fusion Proteins; Simplexvirus; Thymidine; Thymidine Kinase; Transfection; Tumor Cells, Cultured

Malignant gliomas are the most common malignant brain tumors and are almost universally fatal. A genetically engineered herpes simplex virus-1 mutant with decreased neurovirulence, dlsptk, has been shown to kill human glioma cells in culture and in animal models. However, intracranial inoculation of dlsptk is limited by fatal encephalitis at higher doses. Therefore, additional engineered and recombinant herpes simplex mutants with demonstrated reduced neurovirulence (AraAr9, AraAr13, RE6, R3616) were examined as antiglioma agents. One long-term human glioma cell line and two early-passage human gliomas in culture were destroyed by all four viruses tested. In a subcutaneous glioma model, AraAr13, RE6, and R3616 retained substantial antineoplastic effects in nude mice when compared with controls (one-sided Wilcoxon rank test, P < 0.05 for one or more doses each). When tested in a nude mouse intracranial glioma model, both RE6 and R3616 significantly prolonged average survival without producing premature encephalitic deaths at two doses (log-rank statistic, P < 0.007). Histopathological studies of the brains of surviving animals revealed minimal focal encephalitis in two of three RE6-treated animals and no evidence of encephalitis in either one of three RE6-treated or in three of three R3616-treated animals. No evidence of residual tumor was seen in four of the six surviving animals. Additionally, both RE6 and R3616 were found to be susceptible to the common antiherpetic agent acyclovir, adding to their safety as potential antiglioma agents. Recombinant and engineered viruses that minimize host toxicity and maximize tumoricidal activity merit further study as antineoplastic agents.

Topics: Acyclovir; Animals; Brain Neoplasms; Encephalitis; Female; Glioma; Herpes Simplex; Humans; Mice; Mice, Nude; Mutation; Neoplasm Transplantation; Simplexvirus; Transplantation, Heterologous; Tumor Cells, Cultured

Twelve cases of malignant gliomas (anaplastic astrocytoma 4, glioblastoma 8, recurrent 3, primary 9) were treated with ACNU and radiation with sensitizing agents after the surgical removal of the tumor. BUdR, Vidarabine (Ara-A), Aciclovir (ACV) were applied for sensitizing agents. BUdR was administrated intraarterially prior to radiation (380 rad, two times a week), and Ara-A and ACV intravenously during and after the radiation. Total dosage of the radiation was 50-60 Grey for each case. All recurrent and eight primary patients died. The mean survival time of the recurrent patients was 17.7 months, while that of the primary patients was 13.4 months. One of the primary patient was glioblastoma and is still surviving more than 24 months by now. The complete response (CR) rate of the primary tumor patients observed by computerized tomography (CT) scan was 5/9. We can expect the availability of this trial for malignant gliomas because of high CR rate in primary tumor cases.

Topics: Acyclovir; Adolescent; Adult; Aged; Brain Neoplasms; Bromodeoxyuridine; Combined Modality Therapy; Evaluation Studies as Topic; Female; Glioma; Humans; Male; Middle Aged; Nimustine; Radiation Injuries; Radiation-Sensitizing Agents; Radiotherapy Dosage; Remission Induction; Vidarabine