Vaccination with IL-7 gene-modified autologous melanoma cells can enhance the anti-melanoma lytic activity in peripheral blood of patients with a good clinical performance status: a clinical phase I study

Recently, cytokine gene transfer into tumour cells has been shown to mediate tumour regression in animal models via immunomodulation. Consequently, a number of clinical protocols have been developed to treat cancer patients with cytokine gene-modified tumour cells. Here, we report the results of a clinical phase I trial using for the first time autologous, interleukin 7 gene-modified tumour cells for vaccination of ten patients with disseminated malignant melanoma. Melanoma cells were expanded in vitro from surgically removed metastases, transduced by a ballistic gene transfer technique and were then injected after in vitro irradiation s.c. at weekly intervals. Clinically, there was no major toxicity except for mild fever, and no major clinical response towards vaccination was observed. Eight of ten patients completed the initial three s.c. vaccinations and were eligible for immunological evaluation. Post vaccination, peripheral mononuclear cells (PBMCs) were found to contain an increased number of tumour-reactive proliferative as well as cytolytic cells, as determined by a limiting dilution analysis. In three of six patients, the frequencies of anti-melanoma cytolytic precursor cells increased between 2.6- and 28-fold. Two of these patients showed a minor clinical response. Analysis of the autologous tumour cell vaccines regarding IL-7 secretion after gene transfer, HLA class I and class II cell surface expression, secretion of immunosuppressive mediators (TGF-beta1, IL-10) and various melanoma-associated tumour antigens revealed a very diverse expression profile. In conclusion, vaccination using gene-modified autologous melanoma cells induced immunological changes in a group of advanced, terminally ill patients. These changes can be interpreted as an increased anti-tumour immune response. However, immunological modulation was most pronounced in patients in good physical condition. Therefore, patients with minimal tumour load or minimal residual disease might preferentially benefit from tumour cell vaccination in further studies. In order to evaluate the effects of the cytokine gene-modified tumour cell vaccines more precisely, an antigenically better defined vaccine is needed.     

Induction of antitumor immunity by interleukin-2 gene-transduced mouse mammary tumor cells versus transduced mammary stromal fibroblasts

BACKGROUND: Tumor cell-targeted cytokine gene transfer has been used to generate tumor cell vaccines, but this approach is limited by the need to establish and implant live tumor cells. PURPOSE: The purpose of this study was to determine if stromal fibroblasts could be used as an alternative vehicle for delivery of the cytokine interleukin-2 (IL-2) into the tumor microenvironment. We attempted to establish the feasibility of (a) genetic immunotherapy in a mammary tumor system and (b) engineering stromal fibroblasts as well as tumor cells. We compared the effects of tumor cell-mediated and stromal fibroblast-mediated local IL-2 expression on the generation of antitumor immune responses. METHODS: Retroviral vectors containing a human IL-2 gene were used to transduce a mouse mammary tumor line, 4TO7, and an immortalized but nontumorigenic fibroblast line established from syngeneic mammary fatpads. Expression of the IL-2 gene in transduced cells was determined by measuring IL-2 secretion, by RNA-polymerase chain reaction, and by immunochemistry. Groups of 5-12 BALB/c mice were injected with either 4TO7 cells or various doses of IL-2-secreting 4TO7 cells (4TO7-IL-2); tumor growth was monitored. To test whether local IL-2 expression by transduced cells could influence the growth of unmodified tumor cells, we determined tumor development in groups of mice treated with 4TO7 cells co-injected with either 4TO7-IL-2 cells or IL-2-secreting fibroblasts. RESULTS: 4TO7-IL-2 cells induced active immunity able to reject the immunizing tumor and to resist challenge with parental 4TO7 cells on the contralateral side. Mice pretreated with 4TO7-IL-2 were significantly protected compared with untreated control animals or mice pretreated with irradiated 4TO7 cells. The immunity induced by 4TO7-IL-2 cells did not protect against challenge with another subline, 4T1, which was derived from the same spontaneously arising mammary tumor as 4TO7. Co-injection of 4TO7 cells with 4TO7-IL-2 cells reduced tumorigenicity, whereas co-injection of 4TO7 cells with IL-2 secreting fibroblasts did not. CONCLUSION: Our results suggest that induction of anti-tumor immune response by local IL-2 production is most effective when the helper cytokine is secreted by the tumor cell. IMPLICATION: Our studies caution against the use of IL-2 gene-transduced syngeneic stromal cells as an alternative strategy of gene therapy for cancer. However, they may allow study of the mechanisms of tumor antigen recognition and the possible involvement of co-stimulatory signals for effective tumor vaccination by gene-modified cells.     

Interleukin 12 gene therapy of MHC-negative murine melanoma metastases

Immunological gene therapy of cancer relies heavily on the activation of T cells, but tumors with defects in MHC gene expression are not recognized by MHC-restricted T cells. To investigate the potential of cytokine genes for the therapy of MHC-negative tumors, we transduced B78H1, a class I-negative murine melanoma clone, with a polycistronic vector carrying murine interleukin (IL)-12 genes. The clones studied produced 400-25,000 pg/ml IL-12; their in vitro growth properties were similar to those of parental cells. A complete inhibition of growth was observed in vivo both after s.c. and i.v. administration of all IL-12 clones. IL-12-transduced cells were also used as a therapeutic vaccine in mice bearing micrometastases by nontransduced parental cells. A significant (80-90%) reduction in the number of lung nodules was obtained. Immunohistochemical analysis and studies in immunocompromised hosts showed that T cells and natural killer cells had a significant role in the elimination of IL-12-releasing cells. In situ hybridization with cytokine probes detected a strong increase in the proportion of leukocytes positive for IFN-gamma, tumor necrosis factor alpha, IL-1beta, and IFN-inducible protein 10 at the site of rejection of IL-12-engineered tumor cells. However, it was clear that the loss of in vivo growth was also due to T-cell- and natural killer cell-independent factors, possibly related to the antiangiogenic properties of IL-12. In conclusion, tumor therapy based on IL-12 gene transduction was effective on a MHC-negative metastatic tumor, suggesting a possible application to MHC-defective human neoplasms.     

Adoptive immunotherapy with vaccine-primed lymph node cells secondarily activated with anti-CD3 and interleukin-2

PURPOSE: In preclinical studies, we have reported the ability to induce immune T cells in lymph nodes (LN) primed by in vivo vaccination with tumor cells admixed with a bacterial adjuvant. These LN cells can be activated and expanded ex vivo for the successful immunotherapy of established tumors. We have applied these methods to generate vaccine-primed LN in patients with advanced melanoma and renal cell cancer (RCC) for therapy. MATERIALS AND METHODS: Irradiated autologous tumor cells admixed with bacille Calmette-Guérin (BCG) were used to vaccinate patients. Seven days later, draining LN were removed for activation with anti-CD3 monoclonal antibody (mAb) followed by expansion in interleukin-2 (IL-2). Activated LN cells were administered intravenously (IV) with the concomitant administration of IL-2. RESULTS: A total of 23 patients were evaluated (11 melanoma and 12 RCC). Vaccine-primed LN were expanded ex vivo with a mean of 8.4 x 10(10) cells administered per patient. Among 20 patients assessed, 15 demonstrated minimal cytotoxicity of autologous tumor cells by the activated LN cells, with the remaining mediating nonspecific cytotoxicity. By contrast, a majority of the activated LN cells showed highly specific release of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interferon gamma (IFN-gamma) to autologous but not allogeneic tumor stimulation. This tumor-specific cytokine release was found to be major histocompatibility complex (MHC) class I-restricted, which indicates the involvement of CD8+ cells. Among 11 melanoma patients, one had a partial tumor response. Among 12 RCC patients, two had complete and two partial responses. A trend (P = .066) between the enhancement of delayed-type hypersensitivity (DTH) reactivity to autologous tumor after therapy and tumor regression was observed. CONCLUSION: Tumor vaccines can be used to induce immunologically specific T-cell responses against melanoma and RCC in draining LN. Anti-CD3/IL-2 activation of primed LN cells can be reliably performed for clinical therapy and appears to have activity in patients with metastatic RCC.     

Interleukin 10 production by human melanoma

Interleukin 10 (IL-10) has the physiological role of down-regulating cell-mediated immunity. We have recently reported that mRNA for IL-10 was present in most metastatic melanoma tissues. The purpose of this investigation was to determine whether melanoma metastases produce IL-10 protein. Single-cell suspensions were prepared by enzymatic dissociation of 28 lymph node metastases and 7 s.c. metastases and cryopreserved. Of these 35 samples, 30 produced IL-10 after a 24-h incubation (median, 125.1 pg/ml). IL-10 production was slightly diminished after 25 Gy irradiation but almost completely abrogated after modification with the hapten dinitrophenyl. After 7 or 14 days in tissue culture, melanoma cells continued to produce IL-10 but only at about 10% of the levels of freshly dissociated tissues. Moreover, of eight melanoma cell lines established from these cultures, only one produced IL-10 protein. To determine whether IL-10 was produced by melanoma cells or tumor-associated leukocytes, single-cell suspensions were fractionated with anti-CD45 antibody-conjugated magnetic beads. In four of five samples, IL-10 production was increased by depletion of leukocytes, suggesting that the primary source was the melanoma cells themselves. This was confirmed by immunohistochemical staining of cytospin preparations and frozen tissue sections. Finally, 10 of 55 patients with clinically evident metastases showed elevations of circulating IL-10; three patients who had been melanoma-free developed high serum IL-10 levels, concurrent with the appearance of distant metastases. These data indicate that production of IL-10 is characteristic of metastatic melanomas and raise the possibility that this cytokine allows tumors to avoid or to modulate immunological attack.     

Sustained cytokine delivery for anticancer vaccination: liposomes as alternative for gene-transfected tumor cells

Vaccination with tumor cells genetically engineered to produce interleukin (IL)-2 is an attractive strategy to enhance antitumor immune responses. The improved antitumor immunity upon vaccination with IL-2 gene-modified tumor cells may be due to the prolonged presence of the cytokine at the vaccination site. Because liposomes have been used for sustained delivery of a variety of agents, we compared the protective effect of vaccines consisting of IL-2 gene-modified B16 melanoma cells to that of vaccines composed of IL-2 liposomes and irradiated melanoma cells. The results indicate that both approaches equally protect against a lethal challenge with B16 melanoma cells. More than 20% of the protected animals developed vitiligo at the vaccination and/or tumor challenge site.     

Differential effects of protein kinase C inhibitors on fibronectin-induced interleukin-beta gene transcription, protein synthesis and secretion in human monocytic cells

Tumor vaccination with dendritic cells (DC) presenting tumor antigens to T cells is a promising approach in immunotherapy. The aim of this study was to enhance T cell stimulatory ability of human DC by retroviral expression of the interleukin-7 (IL-7) gene. IL-7 has been shown to provide a potent costimulatory signal for the proliferation of T cells and the generation of cytotoxic T cells (CTL). DC were generated from human peripheral blood mononuclear cells (PBMC). DC were analyzed by light- and electron-microscopy, immunophenotype (CD1a+, CD14-, CD80+, CD86+, HLA-DR+) and functional assays. According to these criteria, 75-85% of the cells were DC. The cells did not produce measurable amounts of IL-7 spontaneously nor did they express the IL-7 receptor. A retroviral IL-7 expression vector was constructed. Retroviral infection was performed with either the LXSN-hIL-7 vector of its variant LXSN. Using the LXSN-hIL-7 vector, IL-7 production of 2296 pg/10(6) cells/24 h could be achieved on average. Transduction of DC was confirmed by RT-PCR in a CD1a-enriched cell fraction. Transduction efficiency by a control virus coding for beta-galactosidase was about 30%. In autologous mixed lymphocyte reaction (MLR), IL-7 transduced DC augmented T cell proliferation by a factor of two compared with unmodified or mock-transfected DC, and in allogeneic MLR there was a 2.7-fold increase in T cell proliferation. The increase in T cell proliferation could be correlated to IL-7 secretion by DC. Dendritic cells that have been simultaneously peptide-loaded and gene-modified to secrete IL-7 are a potential tool to amplify activation of tumor-specific T cells.     

Isolation perfusion in extracorporeal circulation with interleukin-2 and lymphokine-activated killer cells in the treatment of in-transit metastases from limb cutaneous melanoma

BACKGROUND: Therapies of advanced melanoma patients with interleukin-2 (IL-2) and cytotoxic lymphocytes have produced interesting results, but a larger diffusion of these treatments is limited by the severe side effects due to IL-2 systemic infusion. A strictly regional administration of IL-2 and cells by an isolation perfusion (IP) in extracorporeal circulation (ECC) for the treatment of regional melanoma metastases could improve tolerability and efficacy of this specific modality of immunotherapy. METHODS: Ten patients were submitted to adoptive immunotherapy with IL-2 and lymphokine-activated killer (LAK) cells by IP in ECC. The schedule of treatment included the first course of a 5-day systemic administration of IL-2 (Proleukin, EuroCetus 9-12 x 10(6) IU/m2/day continuous infusion); autologous LAK cells were obtained via leukapheresis and after in vitro activation were given (range 8-28 x 10(9)) along with IL-2 (120-2,400 IU/ml of perfusion priming) to the affected limb by IP; IL-2 (9-12 x 10(6) IU/m2/day) was also administered by systemic continuous infusion for 5 days starting on the day after IP. RESULTS: All patients concluded the treatment without any major local or systemic toxicities. Clinical responses included one complete and six partial remissions; three patients had stable disease. All patients are alive. Follow-up after IP ranged from 12 to 35 months (median: 22). The analysis of circulating lymphocytes revealed the rapid disappearance of LAK cells, suggesting their extravasation and/or endothelial adhesion in perfused tissues. CONCLUSIONS: IP with IL-2 and LAK cells is a new approach for the treatment of in-transit metastases due to cutaneous melanoma. The treatment appears to be feasible and reliable. Further biological and immunological studies should permit amelioration of the present modality of treatment.     

Recombinant adeno-associated virus for the generation of autologous, gene-modified tumor vaccines: evidence for a high transduction efficiency into primary epithelial cancer cells

To explore the potential of recombinant vectors based on recombinant adeno-associated virus (rAAV) for cancer vaccination, we investigated the transduction efficiency of rAAV into cancer cells ex vivo. Infection of human epithelial cancer cell lines with rAAV carrying reporter genes encoding beta-galactosidase (rAAV/LacZ) or luciferase (rAAV/Luc) resulted in high levels of reporter gene expression (>90% positive cells). In marked contrast, rAAV poorly transduced all murine tumor cell lines, as well as human hematopoietic cell lines. Either irradiation or adenovirus infection of tumor cells prior to rAAV infection induced a 10- to 100-fold increase of reporter gene expression. To determine the transduction efficiency of rAAV into primary cancer cells, freshly isolated, irradiated tumor cells from malignant melanoma and ovarian carcinoma patients were infected with rAAV/Luc, resulting in up to 6.9-fold higher levels of gene expression than in a HeLa tumor cell line. Time course experiments with freshly isolated tumor cells infected with rAAV/Luc showed maximal levels of luciferase expression between days 3 and 9 posttransduction. Simultaneous infection of primary tumor cells with up to three rAAV vectors containing genes encoding the immunostimulatory proteins B7-2 (CD86), p35 subunit of IL-12, and p40 subunit of IL-12 resulted in high expression of B7-2 in more than 90% of the tumor cells and in the secretion of high levels of IL-12. Taken together, our results demonstrate that rAAV efficiently transduces freshly isolated human, epithelial tumor cells and might therefore be a potent tool to produce improved, gene-modified cancer vaccines.     

Purification and characterization of multisquamase, the prothrombin activator present in Echis multisquamatus venom

Escape from immune surveillance is critical for tumor progression in metastatic melanoma. We assessed the function of melanoma-derived dendritic cells (DCs) in patients presenting simultaneously with responding (rM) or progressing (pM) melanoma metastases. These rare coincidences allowed us to compare syngeneically the function of tumor DCs. CD83+ DCs were purified freshly from large responding (rDCs) or progressing (pDCs) metastases following chemoimmunotherapy. rDCs were 5 times more potent inducers of allogeneic T-cell proliferation than the pDCs that were used as control. Phenotypic analysis showed a marked depression of CD86 expression on pDCs. Culture supernatants from pM showed production of Th2-type cytokines [interleukin-10 (IL-10)], whereas a Th1 pattern [IL-2, interferon-gamma (IFN-gamma), IL-12) predominated in rM. The IL-10 detected in progressing metastases was directly derived from melanoma cells. Culture supernatants from metastases applied to DC-supported allo-MLR assays suppressed T-cell responses by 50-75% in the case of pM, but not rM. Finally, in a co-stimulation-dependent anti-CD3 tolerance assay, pDCs (but not rDCs) induced anergy in syngeneic CD4+ T cells. Anergy could be overcome by addition of IL-12 or IL-2. Our results show that melanoma-derived factors convert DC-antigen presenting cell function to tolerance induction against tumor tissue, changing tumor DCs to "silencers" of anti-tumoral immune responses.     

Acute pulmonary lesions in sheep experimentally infected with bovine viral diarrhoea virus

Recombinant antibody-cytokine fusion proteins are immunocytokines that achieve high cytokine concentrations in the tumor microenvironment and thereby effectively stimulate cellular immune responses against malignancies. The activation and expansion of immune effector cells, such as CD8+ T lymphocytes, by interleukin-2 immunocytokines resulted in the eradication of established pulmonary and hepatic metastases of murine melanoma and colorectal carcinoma in syngeneic mouse models. These immunocytokines were equally effective in eliminating established bone marrow and liver metastases of murine neuroblastoma by activating natural killer cells. The effective eradication of metastases by immunocytokines resulted in significant prolongation in life span of mice over that of controls receiving equivalent mixtures of antibody and interleukin-2, which failed to reduce the growth of disseminated metastases. Proof of concept was established, indicating that immunocytokine-induced activation and expansion of immune effector cells in the tumor microenvironment can effectively eradicate established tumor metastases. This promising new approach to cancer immunotherapy may lead to clinical applications that improve treatment of cancer patients with minimal residual disease in an adjuvant setting.     

Bone marrow-generated dendritic cells pulsed with tumor extracts or tumor RNA induce antitumor immunity against central nervous system tumors

Recent studies have shown that the brain is not a barrier to successful active immunotherapy that uses gene-modified autologous tumor cell vaccines. In this study, we compared the efficacy of two types of vaccines for the treatment of tumors within the central nervous system (CNS): dendritic cell (DC)-based vaccines pulsed with either tumor extract or tumor RNA, and cytokine gene-modified tumor vaccines. Using the B16/F10 murine melanoma (B16) as a model for CNS tumor, we show that vaccination with bone marrow-generated DCs, pulsed with either B16 cell extract or B16 total RNA, can induce specific cytotoxic T lymphocytes against B16 tumor cells. Both types of DC vaccines were able to protect animals from tumors located in the CNS. DC-based vaccines also led to prolonged survival in mice with tumors placed before the initiation of vaccine therapy. The DC-based vaccines were at least as effective, if not more so, as vaccines containing B16 tumor cells in which the granulocytic macrophage colony-stimulating factor gene had been modified. These data support the use of DC-based vaccines for the treatment of patients with CNS tumors.     

Immunotherapy, including gene therapy, for metastatic melanoma

Current standard therapy for distant metastatic melanoma is ineffective and often compromises the quality of a patient's life. Immunotherapy is briefly reviewed in relation to its many forms: from local non-specific to the more recent specific vaccines, including those using specific melanoma peptides (e.g. from the proteins encoded by melanoma-associated gene (MAGE)) and those involving genetically transduced autologous melanoma cells using retroviral vectors in vitro. The mode of action of genetically transduced melanoma cells incorporating the granulocyte macrophage colony stimulating factor (GM-CSF) gene (GVAX) is presented as a paradigm for cytokine-mediated strategies. Trials of GVAX and other cytokine gene strategies are under way in Brisbane, Boston and Amsterdam, and some interim perspectives on the clinical outcomes and immunological mechanisms involved are sketched. Some of the compounding problems in immunotherapeutic strategies for cancer are identified, and possible adjunct manoeuvres for overcoming them are discussed.     

Stable transduction of the interleukin-2 gene into human natural killer cell lines and their phenotypic and functional characterization in vitro and in vivo

A variety of strategies have been attempted in the past to stably transduce natural killer (NK) cells with cytokine or other cellular genes. Here, we demonstrate the successful delivery of the interleukin-2 (IL-2) gene into two human NK cell lines, IL-2-dependent NK-92 and IL-2-independent YT, by retroviral transduction. An MuLV-based retroviral vector expressing human IL-2 and neor markers from a polycistronic message was constructed and transduced into a CRIP packaging cell line. By coincubation of NK cells with monolayers of CRIP cells or by using retrovirus-containing supernatants in a flow-through method, 10% to 20% of NK cells were stably transduced. Upon selection in the presence of increasing G418 concentrations, transduced NK cells were able to proliferate independently of IL-2 for more than 5 months and to secrete up to 5.5 ng/10(6) cells/24 h of IL-2. IL-2 gene-transduced NK-92 cells had an in vitro cytotoxicity against tumor targets that was significantly higher than that of parental cells and secreted interferon gamma (IFNgamma) and tumor necrosis factor alpha (TNFalpha) in addition to IL-2. Moreover, the in vivo antitumor activity of IL-2 gene-transduced NK-92 cells against established 3-day liver metastases in mice was greater than that of parental nontransduced NK cells. Stable expression of the IL-2 transgene in NK cells improved their therapeutic potential in tumor-bearing hosts. Thus, transduced NK cells secreted sufficient quantities of bioactive IL-2 to proliferate in vitro and mediated the antitumor effects both in vitro and in vivo in the absence of exogenous IL-2. These results suggest that genetic modification of NK cells ex vivo could be useful for clinical cancer therapy in the future.     

Combination therapy with suicide and cytokine genes for hepatic metastases of lung cancer

Metastases of lung cancer are a major cause of treatment failure. To evaluate the therapeutic efficacy of gene therapy in metastatic lung cancer, we used adenoviral (ADV) mediated transfer of the herpes simplex virus thymidine kinase (HSV-tk) gene and the cytokine gene interleukin-2 (IL-2) to treat a murine model of metastatic lung cancer in the liver. Hepatic metastases were established by intrahepatic implantation of LL2 cells in syngeneic recipient mice. One week after tumor implantation, various replication defective ADV vectors were injected intratumorally. Treatment with a vector expressing the HSV-tk followed by ganciclovir administration with ADV.tk resulted in significant regression of tumor (p<0.01) as well as prolongation of survival (p<0.001). While a vector expressing mouse IL-2 ADV.IL-2 alone was ineffective, combination therapy with HSV-tk resulted in further tumor regression and improvement of animal survival (p<0.05). These results demonstrate that suicide and cytokine genes can be utilized in combination to treat metastatic lung cancer in vivo.     

Gene-based strategies for the immunotherapy of cancer

T lymphocytes play a crucial role in the host's immune response to cancer. Although there is ample evidence for the presence of tumor-associated antigens on a variety of tumors, they are seemingly unable to elicit an adequate antitumor immune response. Modern cancer immunotherapies are therefore designed to induce or enhance T cell reactivity against tumor antigens. Vaccines consisting of tumor cells transduced with cytokine genes in order to enhance their immunogenicity have been intensely investigated in the past decade and are currently being tested in clinical trials. With the development of novel gene transfer technologies it has now become possible to transfer cytokine genes directly into tumors in vivo. The identification of genes encoding tumor-associated antigens and their peptide products which are recognized by cytotoxic T lymphocytes in the context of major histocompatibility complex class I molecules has allowed development of DNA-based vaccines against defined tumor antigens. Recombinant viral vectors expressing model tumor antigens have shown promising results in experimental models. This has led to clinical trials with replication-defective adenoviruses encoding melanoma-associated antigens for the treatment of patients with melanoma. An attractive alternative concept is the use of plasmid DNA, which can elicit both humoral and cellular immune responses following injection into muscle or skin. New insights into the molecular biology of antigen processing and presentation have revealed the importance of dendritic cells for the induction of primary antigen-specific T cell responses. Considerable clinical interest has arisen to employ dendritic cells as a vehicle to induce tumor antigen-specific immunity. Advances in culture techniques have allowed the generation of large numbers of immunostimulatory dendritic cells in vitro from precursor populations derived from blood or bone marrow. Experimental immunotherapies which now transfer genes encoding tumor-associated antigens or cytokines directly into professional antigen-presenting cells such as dendritic cells are under evaluation in pre-clinical studies at many centers. Gene therapy strategies, such as in vivo cytokine gene transfer directly into tumors as well as the introduction of genes encoding tumor-associated antigens into antigen-presenting cells hold considerable promise for the treatment of patients with cancer.     

Efficient adenovirus-mediated gene transduction of normal and leukemic hematopoietic cells

We evaluated the efficiency of adenovirus-mediated gene transfer into normal and malignant human hematopoietic cells. An E-1 and E-3 deleted, replication-defective recombinant Ad.RSV beta gal vector was used and the transduction efficiency was studied at a multiplicity of infection of 13 p.f.u. per cell. Approximately 40-50% of normal monocytes were transduced, whereas purified normal resting T cells and B cells were resistant to infection. We showed that 50-80% of primary chronic myeloid leukemia cells (CML, n = 12) were efficiently transduced in contrast to CML, successful transduction of resting primary chronic B lymphocytic leukemia cells required appropriate preactivation of targeted cells. A novel protocol for the efficient transduction of adenovirus into B-CLL cells was presented. We showed that anti-CD40 mAb or CD40 ligand acts in synergy with rhIL-4 to enable the transduction of approximately 50-75% of B-CLL cells (B-CLL, n = 6). Expression of beta-galactosidase in transduced CML cells and B-CLL cells was detected for at least 15 days after transduction. The present studies underline the utility of adenovirus vectors for the construction of cytokine gene-modified tumor vaccines for the treatment of hematopoietic malignancies such as CML and B-CLL.     

In vivo tumor transfection with superantigen plus cytokine genes induces tumor regression and prolongs survival in dogs with malignant melanoma

In vivo transfection of established tumors with immunostimulatory genes can elicit antitumor immunity. Therefore, we evaluated the safety and efficacy of intratumoral injections of a bacterial superantigen with a cytokine gene in dogs with malignant melanoma, a spontaneous and highly malignant canine tumor. 26 dogs with melanoma were treated with lipid-complexed plasmid DNA encoding staphylococcal enterotoxin B and either GM-CSF or IL-2. Dogs were evaluated for treatment-associated toxicity, tumor responses, immunologic responses, and survival times. The overall response rate (complete or partial remissions) for all 26 dogs was 46% (12 of 26), and was highest in patients with smaller tumors. Toxicity was minimal or absent in all dogs. Injected tumors developed marked infiltrates of CD4+ and CD8+ T cells and macrophages, and tumor regression was associated with development of high levels of antitumor cytotoxic T lymphocyte activity in peripheral blood lymphocytes. Survival times for animals with stage III melanomas treated by intratumoral gene therapy were prolonged significantly compared with animals treated with surgical tumor excision only. Thus, local tumor transfection with superantigen and cytokine genes was capable of inducing both local and systemic antitumor immunity in an outbred animal with a spontaneously developing malignant tumor.     

Epidemiology of trichinellosis in lynx in Finland

To examine the possibility of cytokine gene therapy in relation to pancreatic cancer, we evaluated the antitumor effect of human pancreatic carcinoma cells (AsPC-1) which were retrovirally-transduced with several kinds of cytokine genes. These cells were inoculated into BALB/c nude mice and their tumor volumes were assessed. The in vitro growth rate of the transduced cells was not different from that of a parental cell line. Among the transduced cells, human interleukin (IL)-6-transduced AsPC-1 and mouse granulocyte macrophage colony-stimulating factor-transduced AsPC-1 cells showed a significant retardation of tumor growth compared with a parental cell line. In the cases of AsPC-1 cells transduced with the human IL-2 or mouse IL-4 gene, small tumors were generated but thereafter they regressed completely. Histological examinations showed monocytic cell infiltration around the tumors of IL-2- or IL-4-producing cells. These data suggest that secretion of IL-2 or IL-4 from tumor cells can induce an antitumor effect even in the defective condition of mature T cells.     

Interstitial brachytherapy procedures for brain tumors

This report characterizes the immunological host response to a syngeneic murine mammary carcinoma along with variants genetically modified to express B7-1 or secrete GM-CSF and interleukin-12 (IL-12). MT-901 is a subline of a mammary adenocarcinoma that was chemically induced in the Balb/c host. It was found to be weakly immunogenic by immunization/ challenge experiments, and it induced tumor-specific T-cell responses in lymph nodes (LN) draining progressive subcutaneous tumors. Tumor clones expressing B7-1 or secreting GM-CSF exhibited reduced tumorigenicity without completely abrogating tumor growth, whereas IL-12 elaboration lead to complete tumor growth inhibition. In vivo subcutaneous inoculation of a transgenic cell clone secreting GM-CSF (240 ng/10(6) cells/24 hours) resulted in significantly enhanced T-cell reactivity of tumor-draining lymph node (TDLN) cells as compared to wild-type TDLN cells. This finding was obtained from observations assessed by several different methods, including: 1) in vitro cytotoxicity, 2) in vitro interferon-gamma release, and 3) adoptive transfer in mice with established tumor. Moreover, the transfer of activated LN cells derived from mice inoculated with GM-CSF-secreting tumor cells resulted in the prolonged survival of animals with macroscopic metastatic disease, which was not evident utilizing LN cells from mice inoculated with wild-type tumor. By contrast, clones that expressed B7-1 or IL-12 (4 ng/10(6) cells/24 hours) did not elicit enhanced tumor-reactive TDLN cells compared with wild-type tumor when assessed in the adoptive transfer model. The autocrine secretion of GM-CSF by transduced tumor cells was found to serve as an effective immune adjuvant in the host response to this weakly immunogenic tumor.