Effect of denosumab versus zoledronic acid in preventing skeletal-related events in patients with bone metastases by baseline characteristics.

BACKGROUND: Analyses of phase III trials showed that denosumab was superior to zoledronic acid (ZA) in preventing skeletal-related events (SREs) irrespective of age, history of SREs, or baseline pain status. This analysis assessed the risk of SREs across additional baseline characteristics. PATIENTS AND METHODS: Patients (N = 5543) from three phase III trials who had breast cancer, prostate cancer, or other solid tumours and one or more bone metastasis were included. Superiority of denosumab versus ZA in reducing risk of first SRE and first and subsequent SREs was assessed in subgroups defined by the Eastern Cooperative Oncology Group performance status (ECOG PS), bone metastasis location, bone metastasis number, visceral metastasis presence/absence, and urinary N-telopeptide (uNTx) level using Cox proportional hazards and Anderson-Gill models. Subgroups except bone metastasis location were also assessed for each solid tumour type. RESULTS: Compared with ZA, denosumab significantly reduced the risk of first SRE across all subgroups (hazard ratio [HR] ranges: ECOG PS, 0.79-0.84; bone metastasis location, 0.78-0.83; bone metastasis number, 0.78-0.84; visceral metastasis presence/absence, 0.80-0.82; uNTx level, 0.73-0.86) and reduced the risk of first and subsequent SREs in all subgroups (HR ranges: ECOG PS, 0.76-0.83; bone metastasis location, 0.78-0.84; bone metastasis number, 0.79-0.81; visceral metastasis presence/absence, 0.79-0.81; uNTx level, 0.74-0.83). Similar results were observed in subgroups across tumour types. CONCLUSION: Denosumab was superior to ZA in preventing SREs in patients with bone metastases from advanced cancer, regardless of ECOG PS, bone metastasis number, baseline visceral metastasis presence/absence, and uNTx level.

Prevalence of depression in adults with haemophilia.

Multiple factors place adults with haemophilia at risk for depression. Health outcomes can be compromised in depressed patients secondary to increased risk taking behaviour and poor compliance with treatment recommendations. To assess the prevalence and risk factors associated with depression in adult patients with haemophilia treated at a haemophilia treatment centre. Adults with haemophilia were screened for depression during their annual clinic visit using the Patient Health Questionnaire 9 (PHQ-9), a validated tool for depression screening in adults. Depression was defined as a PHQ-9 score ≥ 5. Risk factors associated with depression were collected by chart review and correlated with depression scores. A total of 41 adult patients consented to the study and 37% met criteria for depression. Fifty-three per cent of patients with depression reported moderate to severe symptoms of depression (PHQ-9 score >10). Seventy-six per cent of patients with depression reported suffering functional impairment due to their depressive symptoms. Lack of social support and unemployment were significantly associated with higher PHQ-9 scores (P = 0.04 and P = 0.01 respectively). Adult patients with haemophilia have a high prevalence of depression. The addition of depression screening to the comprehensive care of adults with haemophilia may result in improved overall health outcomes and treatment adherence.

Incidence, risk factors, and outcomes of osteonecrosis of the jaw: integrated analysis from three blinded active-controlled phase III trials in cancer patients with bone metastases.

BACKGROUND: Osteonecrosis of the jaw (ONJ) has been reported in patients receiving bisphosphonates for metastatic bone disease. ONJ incidence, risk factors, and outcomes were evaluated in a combined analysis of three phase III trials in patients with metastatic bone disease receiving antiresorptive therapies. PATIENTS AND METHODS: Patients with bone metastases secondary to solid tumors or myeloma were randomly assigned to receive either s.c. denosumab (120 mg) or i.v. zoledronic acid (4 mg) every 4 weeks. On-study oral examinations were conducted by investigators at baseline and every 6 months. Oral adverse events were adjudicated by an independent blinded committee of dental experts. RESULTS: Of 5723 patients enrolled, 89 (1.6%) patients were determined to have ONJ: 37 (1.3%) received zoledronic acid and 52 (1.8%) received denosumab (P = 0.13). Tooth extraction was reported for 61.8% of patients with ONJ. ONJ treatment was conservative in >95% of patients. As of October 2010, ONJ resolved in 36.0% of patients (29.7% for zoledronic acid and 40.4% for denosumab). CONCLUSIONS: In this combined analysis of three prospective trials, ONJ was infrequent, management was mostly conservative, and healing occurred in over one-third of the patients. Educating physicians about oral health before and during bone-targeted therapy may help reduce ONJ incidence and improve outcomes.

Prevalence and risk factors associated with decreased bone mineral density in patients with haemophilia.

Osteoporosis in adult males is an under-recognized problem. Patients with haemophilia have several predisposing factors for developing decreased bone mineral density (BMD) including prolonged periods of immobility, reduced weight bearing and co-morbidities associated with bone loss. To establish prevalence and risk factors associated with decreased BMD in patients with haemophilia. Adults with moderate or severe haemophilia A or B underwent dual-energy X-ray absorptiometry (DXA). BMD was correlated to laboratory values, joint mobility measurements and physical activity questionnaires. Thirty patients completed evaluations. The median age was 41.5 years (range 18-61). Median lowest T-score by DXA was -1.7 (range: -5.8 to +0.6), with the femoral neck being the site of the lowest T-scores. Based on World Health Organization criteria, 70% of patients had decreased BMD. Twenty-seven per cent of the participants (n = 8) had osteoporosis and 43% (n = 13) had osteopenia. Variables associated with increased bone loss included lower serum 25-hydroxyvitamin D levels (P = 0.03), lower body mass index (P = 0.047), lower activity scores (P = 0.02), decreased joint range of motion (P = 0.046), HIV (P = 0.03), HCV (P = 0.02), history of inhibitor (P = 0.01) and age (P = 0.03). Adults with haemophilia are at increased risk for developing osteoporosis. A history of HCV and HIV infections, decreased joint range-of-motion, decreased activity levels, history of an inhibitor and low body weight predict bone loss and suggest a population to target for screening. A high prevalence of vitamin D insufficiency was observed. Future studies should investigate interventions, including vitamin D supplementation, to prevent bone loss and fractures for this at-risk population.

Phase II study of direct intralesional gene transfer of allovectin-7, an HLA-B7/beta2-microglobulin DNA-liposome complex, in patients with metastatic melanoma.

Cutaneous melanoma is one of the most rapidly increasing cancers in the United States. Because of the lack of effective treatment options and toxicities of most chemotherapeutic and radiation regimes, immunotherapies such as vaccination therapy represent an attractive approach for patients with advanced melanoma. The purpose of this study was to evaluate the response rate, time to progression, and survival of patients with metastatic melanoma treated by direct intratumoral injection with Allovectin-7 (a plasmid DNA encoding the genes HLA-B7 and beta2-microglobulin complexed with a cationic lipid mixture, DMRIE/DOPE. Fifty-two patients with metastatic melanoma were enrolled in this Phase II study. Therapy consisted of six intratumoral injections of 10 microg of Allovectin-7 over a 9-week period. Treatment was well tolerated. Treatment-related adverse events were mild to moderate, the most frequent of which were ecchymosis, pruritus (and/or discomfort at the injection site), and pneumothoraces. Regression of the injected lesion was observed in 18% of patients, including one complete response, three partial responses, and five minor responses. An overall response rate of 4% (two partial responses) was documented, and nine patients (18%) maintained stable disease for at least 11 weeks. Six patients remained alive 25.1 to 39.4 months from their first injection, including two patients with local (injected tumor) responses and one patient with an overall disease partial response. This study demonstrates that intratumoral administration of Allovectin-7 in metastatic melanoma is safe and can produce both responses in injected lesions and in overall disease. Clinical trials optimizing patient selection and combining Allovectin-7 with other modalities of therapy are currently ongoing in an effort to improve response rates.

Cationic lipid gene transfer of an IL-2 transgene leads to activation of natural killer cells in a SCID mouse human tumor xenograft.

Natural killer (NK) cells play an important role in combating infectious and malignant diseases and interleukin-2 (IL-2) has been shown to promote proliferation and activation of NK cells in vitro and in vivo. Here we investigate the effects of local cationic lipid-mediated IL-2 gene transfer on intratumoral accumulation and activation of NK cells in a SCID mouse tumor model. UM449 human melanoma tumors in SCID mice received intratumoral injections of DMRIE/DOPE admixed with VR1103, a DNA plasmid encoding the gene for human IL-2. Dissagregated tumor cells were tested for IL-2 secretion and were characterized using antibodies to asGM1, MAC-1, and F4/80 antigens. Granzyme A, a proteolytic serine esterase, was also measured in tumor cell lysates. IL-2 secretion from tumors injected with VR1103:DMRIE/DOPE peaked at 48 h after injection and fell to baseline levels on day 8. Intratumoral granzyme A activity was significantly increased in tumors injected with IL-2 plasmid:DMRIE/DOPE complexes, but not by an irrelevant plasmid DNA:DMRIE/DOPE control. Importantly, the growth of UM449 tumors was slowed in VR1103:DMRIE/DOPE-injected tumors. These results indicate that local cationic lipid-mediated gene transfer of IL-2 induces activation of intratumoral NK cells and slows tumor growth.

Loss of B7.2 (CD86) and intracellular adhesion molecule 1 (CD54) expression is associated with decreased tumor-infiltrating T lymphocytes in diffuse B-cell large-cell lymphoma.

Tumor-infiltrating CD8+ T-lymphocytes (T-TILs) are thought to be relevant to immunosurveillance of several tumor types including B-cell non-Hodgkin's lymphoma. B- and T-lymphocyte interactions via cellular adhesion molecules (CAMs), recognition molecules (HLAs), and costimulatory molecules (CSMs) are necessary for optimal antigen-specific T-cell activation to occur and may be important in generating effective host T-TIL responses. We previously found that low T-TIL response (CD8+ T cells < 6%) correlates with statistically shorter relapse-free survival in patients with diffuse large-cell lymphoma (DLCL). We now extend our observations in 71 DLCL patients by analyzing malignant B-cell expression of the following molecules important in T-cell activation: (a) recognition molecules [MHC I (MAS and MCA) and MHC II (HLA-DR, -DP, -DQ)]; (b) CAMs [leukocyte function antigen 1 (CD11a and CD18) and intracellular adhesion molecule 1 (CD54)]; and (c) CSMs [B7.1 (CD80) and B7.2 (CD86)]. Eighteen patients (25%) had low a T-TIL response, and 53 patients (75%) had a high T-TIL response. Overall, expression of the MHC class H molecules HLA-DR and HLA-DQ was most conserved. The loss of B7.2 (P = 0.04), intracellular adhesion molecule 1 (P = 0.0004), MAS (P = 0.02), and HLA-DR (P = 0.0004) expression was significantly associated with decreased T-TIL response. In 100% of patients with low T-TIL responses, at least one HLA, CAM, or CSM was undetectable on the malignant B cells by immunohistochemical staining (mean number of molecules lost = 2.67). In contrast, 49% of patients with high T-TIL responses had no losses in HLA, CAM, or CSM expression (mean number of molecules lost = 0.89). The mean number of absent molecules (HLA, CAM, or CSM) was significantly associated with T-TIL response (P = 0.0001). We conclude that loss of HLA, CAM, or CSM expression on malignant B cells is associated with a poor host T-cell immune response. In addition, because patients with low T-TIL response had lost expression of multiple cellular adhesion, recognition, and costimulatory molecules, our results suggest that a combination of immunorestorative therapies may be required to generate effective antitumor T-cell responses in B-cell DLCL.

Studies of direct intratumoral gene transfer using cationic lipid-complexed plasmid DNA.

Cationic lipid-mediated gene transfer is a safe and effective means of delivering potent immunomodulatory cytokines directly into tumors. This approach avoids undesirable side effects, including systemic toxicities. To investigate key factors affecting intratumoral (i.t.) gene transfer, cationic lipid-DNA complexes were injected into subcutaneous human melanoma tumors in severe combined immunodeficient mice. Animals received i.t. injections of VR1103, a DNA plasmid encoding the gene for human interleukin-2 (IL-2), either alone or complexed with the cationic lipid N-(1-(2,3-dimyristyloxypropyl)-N,N-dimethyl-(2-hydroxyethyl) ammonium bromide/dioleoyl phosphatidylethanolamine (DMRIE/DOPE). Tumors were subcultured and supernatants were tested for IL-2 secretion by enzyme-linked immunosorbent assay. IL-2 secretion was consistently higher when lipid:DNA (L:D) complexes were formulated at high L:D ratios (wt/wt), and IL-2 transgene expression increased in a DNA dose-dependent manner. A comparison of naked plasmid and lipid-complexed DNA revealed that lipid complexes were more effective for i.t. gene transfer. Using an enhanced green fluorescent protein reporter plasmid and flow cytometry, i.t. transfection efficiency was 1.74% (+/- 1.08%). Tumor injection technique, including injection volume and location, had a limited impact on i.t. gene transfer. These results indicate that the formulation and dosage of cationic L:D complexes, but not injection technique, play a key role in determining the level of i.t. transgene expression.

Construction of new amplifier expression vectors for high levels of IL-2 gene expression.

The success of IL-2 gene therapy in cancer is in part dependent on the development of high level IL-2 gene expression vectors. Currently, expression vectors based on the human cytomegalovirus (CMV) promoter give the highest levels of expression. We have attempted to construct new IL-2 expression vectors to test whether gene expression can be further increased. The first approach was to use the new SR-alpha promoter to control IL-2 gene expression. The second approach was to combine the Tat transcription activator gene and the HIV 1 and 2 promoters in the same construct so that the levels of gene expression can be amplified. Transient transfection results using the human colon cancer cell line SW480 showed that the SR-alpha promoter yields similar levels of activity as the CMV promoter. However, the HIV 1 and 2 promoter-based amplifier constructs produced 11 and 28 times more secreted IL-2 than the CMV promoter control. The augmented activity of the amplifier constructs was dependent on the presence of the Tat gene and the transcriptional units must be placed in the same orientation. Reducing the size of the vectors by elimination of the neomycin selectable marker did not increase the activity of the constructs.

Polycations and cationic lipids enhance adenovirus transduction and transgene expression in tumor cells.

Replication-deficient adenovirus vectors are efficient vehicles for delivering therapeutic genes into mammalian cells. However, the high doses required to produce effective gene transfer in vivo can also cause unwanted cellular toxicity. To improve replication-deficient adenovirus transgene expression while minimizing adverse reactions, we have tested polycationic compounds for their ability to enhance adenovirus adsorption. We demonstrate increased transgene expression after mixing adenovirus preparations with polycations, cationic lipids, and CaCl2 prior to transduction in vitro. An E1-deleted adenovirus vector was admixed with various polycations, and beta-galactosidase (beta-gal) activity was evaluated. The optimal polycation concentrations for augmenting adenovirus-mediated gene transfer were 5-10 microg/mL polybrene, 400 microg/mL protamine sulfate, 10 microg/mL N-(1-[2,3-dioleoyloxy]propyl)-N,N,N-trimethylammonium methylsulfate (DOTAP), 2.5 microg/mL Lipofectamine, and 62.5 mM CaCl2. Polycations enhanced beta-gal expression in three of six established cell lines. Similar results were obtained using primary tumor cell cultures, where beta-gal expression was increased 1.5- to 10.7-fold (mean = 3.6) by polybrene, 1.8- to 7.5-fold (mean = 3.4) by DOTAP, and 2.3- to 10.4-fold (mean = 4.8) by protamine sulfate. Adenovirus transduction efficiency in two primary leukemia isolates was improved by 3- and 4.5-fold. We were unable to demonstrate any benefit when adenovirus was admixed with protamine sulfate prior to intratumoral injection in a xenogeneic severe combined immunodeficient mouse melanoma tumor model. Further studies will determine whether polycations can improve intratumoral gene transfer.

Immunotherapy of advanced malignancy by direct gene transfer of an interleukin-2 DNA/DMRIE/DOPE lipid complex: phase I/II experience.

PURPOSE: We have completed a phase I study, followed by three phase I/II studies, in patients with metastatic melanoma, renal cell carcinoma (RCC), and sarcoma in order to evaluate the safety, toxicity, and antitumor activity of Leuvectin (Vical Inc, San Diego, CA), a gene transfer product containing a plasmid encoding human interleukin (IL)-2 formulated with the cationic lipid 1, 2-dimyristyloxypropyl-3-dimethyl-hydroxyethyl ammonium bromide/dioleyl-phosphatidyl-ethanolamine (DMRIE/DOPE) and administered intratumorally. PATIENTS AND METHODS: Twenty-four patients were treated in the phase I study. Leuvectin doses were 10 microg, 30 microg, or 300 microg weekly for 6 weeks. In three subsequent phase I/II studies, a total of 52 patients (18 with melanoma, 17 with RCC, and 17 with sarcoma) were treated with further escalating doses of Leuvectin: 300 microg twice a week for 3 weeks, 750 microg weekly for 6 weeks, and 1,500 microg weekly for 6 weeks. RESULTS: There were no drug-related grade 4 toxicities and only one grade 3 toxicity, but the majority of patients experienced mild constitutional symptoms after treatment. In the phase I/II studies, 45 patients were assessable for response (14 with RCC, 16 with melanoma, and 15 with sarcoma). Two patients with RCC and one with melanoma have achieved partial responses lasting from 16 to 19 months and continuing. In addition, two RCC, three melanoma, and six sarcoma patients had stable disease lasting from 3 to 18 months and continuing. The plasmid was detected by polymerase chain reaction assay in the posttreatment samples of 29 of 46 evaluated patients. Immunohistochemistry studies on serial biopsy specimens showed increased IL-2 expression and CD8(+) infiltration after treatment in the tumor samples of several patients (12 and 16, respectively). CONCLUSION: Direct intratumoral injection of Leuvectin is a safe and possibly effective immunotherapeutic approach in the treatment of certain tumor types.

Transfection of primary tumor cells and tumor cell lines with plasmid DNA/lipid complexes.

Cancer vaccines that utilize genetically modified tumor cells require gene transfer methods capable of producing immunostimulatory doses of transgenes from fresh or short-term cultures of human tumor cells. Our studies optimize in vitro transfection of primary tumor cells using cationic lipids and a plasmid encoding the gene for human interleukin-2 (IL-2). Established tumor cell lines produced 10- to 100-fold more IL-2 than did fresh or short-term tumor cultures as measured by enzyme-linked immunoabsorbent analysis. Importantly, transfection of primary tumor cells produced immunostimulatory levels of IL-2 as determined by increased thymidine incorporation by autologous peripheral blood mononuclear cells and lymphokine-activated killer cell activity. IL-2 secretion by tumor cells persisted for at least 30 days post-transfection and was unaffected by freeze thawing or irradiation to 8000 rads. Multiple solid tumor types were successfully transfected, but normal blood mononuclear cells and leukemic blasts were resistant to transfection. Enzyme-linked immunoabsorbent analysis of the amount of IL-2 secreted into the medium by transfected tumor cells correlated with the percentage of tumor cells expressing intracellular IL-2 as measured by flow cytometry. Plasmids utilizing a cytomegalovirus promoter yielded superior transfection efficiencies compared with plasmids containing a Rous sarcoma virus promoter. These results suggest that a clinical vaccine trial using autologous tumor cells genetically modified to secrete IL-2 is feasible in patients with solid tumors.

Transfer and expression of the interferon gamma gene in human endothelial cells inhibits vascular smooth muscle cell growth in vitro.

Intimal hyperplasia in blood vessels is primarily caused by the migration and proliferation of vascular smooth muscle cells. Excessive intimal thickening characterizes atherosclerosis as well as bypass graft and angioplasty failures. Endothelial cell-smooth muscle cell interactions and local cytokine production are important regulators of smooth muscle cell growth. Interferon gamma (gamma-IFN), a product of T lymphocytes found in atherosclerotic lesions, inhibits smooth muscle cell proliferation in vitro. To determine if local delivery of gamma-IFN may be useful in the treatment or prevention of vascular proliferative diseases, we transferred the human gamma-IFN gene into endothelial cells isolated from human arteries and microvessels using a retroviral vector. Biologically active gamma-IFN was produced and secreted by gamma-IFN transduced endothelial cells, but not by control, nontransduced cells, or cells identically transduced with E. coli beta galactosidase (beta-gal). To more closely approximate the microenvironment of blood vessels, subconfluent smooth muscle cells were plated in coculture with control, nontransduced endothelial cells, gamma-IFN transduced endothelial cells, or beta-gal transduced endothelial cells. Smooth muscle cell growth was inhibited 30-70% by coculture with gamma-IFN transduced endothelial cells compared to coculture with beta-gal transduced or control endothelial cells (p < 0.05). Our results suggest endothelial cells modified to produce gamma-IFN may be a useful therapy in proliferative vascular diseases.

Phase I study of direct gene transfer of an allogeneic histocompatibility antigen, HLA-B7, in patients with metastatic melanoma.

PURPOSE: To determine the safety, toxicity, and efficacy of direct intratumoral injection of an allogeneic major histocompatibility complex (MHC) class I gene, HLA-B7, in a cationic lipid vector (Allovectin-7; Vical Inc, San Diego, CA) in patients with metastatic melanoma. PATIENTS AND METHODS: Seventeen HLA-B7-negative patients were treated with intralesional injection of Allovectin-7. Twelve patients received a single intralesional injection containing 10 micrograms (four patients), 50 micrograms (five patients), or 250 micrograms (three patients) of plasmid DNA. Five patients received two or three injections of 10 micrograms DNA to a single tumor site at 2-week intervals. Tumor biopsies pretherapy and 2 and 4 weeks after gene injection were obtained to determine expression of the plasmid by polymerase chain reaction (PCR), reverse transcriptase (RT)-PCR, flow cytometry, and immunohistochemistry. RESULTS: Toxicities were related to technical aspects of the injections or biopsies. These included pain, hemorrhage, pneumothorax, and hypotension. Two patients were hospitalized overnight for observation. Seven patients (50%) had tumor responses insofar as the injected nodule decreased > or = 25% by radiologic or physical examination. One patient with a single site of disease achieved a complete remission. Ninety-three percent of the patients' post-gene therapy biopsies contained HLA-B7 plasmid DNA, mRNA, or protein. CONCLUSION: Intratumoral injection of the allogeneic histocompatibility gene, HLA-B7, in a lipid vector can be performed safely at plasmid DNA doses < or = 250 micrograms. The safety profile and biologic activity of this therapy warrants further studies to define the mechanism of action, predictors of response, and antitumor efficacy of this approach.

Advances in the biological therapy and gene therapy of malignant disease.

Biological and gene therapy of cancer have become important components of clinical cancer research. Advances in this area are based on evidence for the presence of tumor antigens, antitumor immune responses, evasion of host control by tumors, and the recognition of host defense failure in cancer patients. These mechanisms are being corrected or exploited in the development of biological and gene therapy. Over the last decade, 9 biological therapies have received Food and Drug Administration approval, and another 12 appear promising and will likely be approved in the next few years. Our approach to gene therapy has been to allogenize tumors by the direct intratumoral injection of HLA-B7/beta2-microglobulin genes as plasmid DNA in a cationic lipid into patients with malignant melanoma. In four Phase I studies, we found a 36% response by the local injected tumor and a 19% systemic antitumor response. In other cancers, gene transfer, expression, and an intratumoral T-cell response were seen, but no clinical response was seen. A variety of follow-up studies with HLA-B7 and other genes are planned. Evasion of host control is now a major target of gene therapy. Strategies to overcome this include up-regulation of MHC and introduction of cell adhesion molecules into tumor cells, suppression of transforming growth factor and interleukin 10 production by tumor cells, and blockade of the fas ligand-fas interaction between tumor cells and attacking lymphocytes. With these approaches, it seems likely that gene therapy may become the fifth major modality of cancer treatment in the next decade.

Plasmid DNA gene therapy: studies with the human interleukin-2 gene in tumor cells in vitro and in the murine B16 melanoma model in vivo.

The plasmid DNA vector pVCL-1102 containing the coding sequence for the human IL-2 gene was evaluated for expression in tumor cells in vitro and in vivo. In vitro transfection of murine B16 tumor cells with pVCL-1102 resulted in the expression of 36,000 IU (5.7 micrograms) of biologically active IL-2/10(6) cells/48 h. In vitro transfection of human tumor lines and primary cultures from human biopsies with pVCL-1102 resulted in the expression of 1,289 to 9345 IU of IL-2/10(6) cells/48 h and 30 to 794 IU of IL-2/10(6) cells/48 h, respectively. In vivo, direct intratumor injection of pVCL-1102 resulted in retention of intact plasmid DNA in the tumor tissue and IL-2 secretion by cell cultures derived from the injected tumors. Formulation of pVCL-1102 with the cationic lipid DMRIE/DOPE inhibited DNA degradation and enhanced in vivo transfection efficiency over plasmid DNA alone. Antitumor activity of the pVCL-1102/DMRIE/DOPE complex was evaluated in a B16 melanoma model in mice. An IL-2-specific effect could not be demonstrated in a subcutaneous model because the intratumor injection of plasmid DNA lacking the IL-2 coding sequence also resulted in a significant reduction in tumor volume. However, an IL-2-specific effect was observed when B16 cells were transfected in vitro prior to implantation into the mouse. Transient transfection of B16 cells with pVCL-1102 rendered the cells less tumorigenic in vivo and produced a significant reduction in tumor volume. These data demonstrate that a plasmid DNA expression vector can be used to deliver the IL-2 gene to tumor cells in vitro and in vivo, resulting in the expression of significant levels of IL-2 protein. These data also illustrate the need for the use of appropriate controls when evaluating the in vivo biological activity of plasmid DNA in murine tumor models.

Cytokine regulation of low density lipoprotein receptor gene transcription in HepG2 cells.

Elevated plasma levels of cytokines have been demonstrated in inflammatory, malignant, and infectious diseases. These disease states are often associated with abnormal lipid metabolism and reductions in plasma cholesterol levels. To determine if inflammatory cytokines could influence hepatic lipid metabolism, we evaluated low density lipoprotein (LDL) receptor function and gene expression in cytokine stimulated HepG2 cells, a hepatoblastoma-derived cell line which shares many functional similarities with normal hepatocytes. Tumor necrosis factor-alpha (TNF) and interleukin-1 beta (IL-1) increased LDL binding to HepG2 cells in a dose-responsive manner. Other cytokines including macrophage-colony stimulating factor, granulocyte macrophage-colony stimulating factor, and gamma-interferon had no significant effects on LDL binding. Increased binding in response to TNF or IL-1 was paralleled by increased steady-state levels of LDL receptor mRNA. Evaluation of LDL receptor mRNA half-life revealed no significant change in mRNA stability between control and TNF- or IL-1-stimulated cells. A fusion gene construct consisting of 1563 base pairs of the 5'-flanking DNA of the human LDL receptor gene was coupled to a luciferase reporter gene, transfected into HepG2 cells, and promoter activity was assayed after TNF and IL-1 challenge to the cells. TNF and IL-1 increased promoter activity 200-400%, while treatment with LDL inhibited promoter activity by 70-85%. TNF or IL-1 co-incubation with LDL could not override transcriptional inhibition by LDL. Pretreatment with cycloheximide prevented induction of LDL receptor mRNA by TNF, but not by IL-1, suggesting stimulation of LDL receptor transcription by TNF requires protein synthesis. We propose that TNF and IL-1, acting via distinct signal transduction pathways, increase surface LDL receptors by increasing gene transcription. Our findings suggest that cytokine-induced hypocholesterolemia may be related to TNF and/or IL-1 stimulation of hepatic LDL receptor gene expression and function.