瘤体内直接注射白介素2质粒复合物治疗小鼠肝癌

目的研究瘤体内直接注射白介素2质粒/阳离子脂质体复合物治疗小鼠肝癌的效果.方法将小鼠白介素2表达质粒(VR1110)与阳离子脂质体(Transfectam)按适当比例混合而形成复合物(VR1110/Transfectam).通过瘤体内直接注射此复合物治疗小鼠肝癌模型,并和卡介苗(BCG)的治疗相比较.结果瘤体内注射VR1110/Transfectam后,可在肿瘤组织中检测到小鼠IL-2 mRNA的表达.VR1110/Transfectam治疗组以及VR111/Transfectam/BCG治疗组肿瘤生长较其它组明显减慢,均显著提高小鼠的生存率(R＜0.05),但二者相差不明显.结论瘤体内直接注射VR1110/Transfectam复合物对小鼠肝癌的治疗作用明显,效果优于卡介苗,且方法简单,适合临床应用.     

阳离子脂质体介导的小鼠白细胞介素2基因修饰肝癌细胞瘤苗

目的 研究阳离了脂质体介导的小鼠白细胞介素2基因修饰肝癌细胞瘤苗的抗肿瘤作用。方法 利用阳离子脂质体Transfectam,将携带小鼠白细胞介素2（IL－2）基因的真核表达南粒VR1110,导入小鼠肝癌细胞H22;采用酶联免疫吸附测定法（ELISA）检测转染后经放射线照射、末经放射线照射和冻融后的细胞培养上清液中白细胞介素2的浓度;并研究转染后经放射线照射而制成的瘤苗的抗肿瘤效应。结果 转染后经放射线照射和末经放射线照射的H22细胞均持续分泌IL－2达30天以上;转染细胞在冻融后也能分泌IL－2;制备的瘤苗对小鼠肝癌模型肿瘤的生长有明显的抑制作用,并能明显提高荷瘤小鼠的生存率。结论 阳离了脂质体介导的小鼠细胞介素2基因转染后,能在肝癌细胞中有效表达,所制备的瘤苗可诱导有效的抗肿瘤效应。     

阳离子脂质体——病毒增强质粒复合物在肝细胞癌基因治疗中的应用

目的建立一种简便有效的非病毒基因治疗方法。方法用构建的含人ＩＬ┐２基因的腺相关病毒（ＡＡＶ）增强质粒（ｐＡＩ┐ｈＩＬ┐２）与新型阳离子脂质体（Ｄｏｓｐｅｒ）以适当比例混合形成复合物（Ｄｏｓｐｅｒ┐ｐＡＩ┐ｈＩＬ┐２）。体外转染小鼠肝癌细胞系ＭＭ４５Ｔ．Ｌｉ┐２，评估了人ＩＬ┐２基因表达情况。应用直接瘤体内注射方法评估了此方法介导ＩＬ┐２基因的抗肿瘤作用。结果应用Ｄｏｓｐｅｒ┐ｐＡＩ┐ｈＩＬ┐２复合物体外转染ＭＭ４５Ｔ·Ｌｉ，其ＩＬ┐２表达水平每毫升可达１７５Ｕ／４８小时，最高表达时间在转染后第４天（２２５Ｕ／ｍｌ），第１２天仍可表达３０Ｕ／ｍｌ。瘤体内直接注射Ｄｏｓｐｅｒ┐ｐＡＩ┐ｈＩＬ┐２复合物后，瘤组织内可检出ＩＬ┐２ｍＲＮＡ，治疗组肿瘤生长明显减慢，小鼠生存率（转染后３０天）明显提高（Ｐ＜０．０１）。结论Ｄｏｓｐｅｒ┐ＡＡＶ增强质粒复合物能有效介导ＩＬ┐２基因表达，产生较好的抗瘤效应，此方法简便、更适合于临床应用     

表达白细胞介素-12质粒DNA抗小鼠肝癌皮下移植瘤的作用

目的 探讨瘤内注射mIL-12质粒DNA抗小鼠肝癌皮下移植瘤的作用。方法：构建真核表达质粒载体pDC511mIL-12，ELISA方法检测质粒载体在真核细胞中的表达，淋巴母细胞增殖法检测mIL-12的生物学活性；分别于小鼠肝癌H22皮下移植瘤内直接注射质粒DNA，观察各组小鼠存活时间、肿瘤体积变化及各组小鼠脾脏细胞毒T淋巴细胞(CTL)的活性：注射质粒DNA后1月进行瘤体组织病理学观察：结果：mIL-12基因治疗组与空载体对照组相比，肿瘤生长显著受抑制(F=4．10，P=0．03)，小鼠存活期显著延长(X^2=4．48，P=0．03)．并且小鼠脾细胞CTL杀伤活性增强。质粒DNA瘤内注射1月后，pDC511mIL-12组肿瘤病灶炎性细胞浸润明显，病灶内肿瘤细胞广泛坏死。结论：瘤内注射mIL-12表达质粒DNA可抑制小鼠肝癌皮下移植瘤生长，能提高机体抗肿瘤免疫应答。     

瘤内注射pSTbAT-脂质体复合物对裸鼠移植瘤抑制效应的实验研究

目的：构建血管生成抑制因子arresten基因的真核表达载体，并观察瘤内注射质粒DNA-脂质体复合物对裸鼠移植瘤生长的影响。方法：利用PCR方法，由重组质粒pGEM-Arr中扩增出基因；将该基因定向克隆于真核表达载体中。20只裸鼠皮下注射Hepp2细胞，成瘤后以成功构建的质粒DNA-脂质体复合物瘤内注射，治疗后采用免疫组化方法检测肿瘤血管密度，并利用arresten基因瘤内注射的方法对抑制肿瘤的效果进行分析。结果：我们成功构建arresten基因真核表达载体(psTbAT)。实验组肿瘤生长速度较对照组慢(实验组平均15．3个阳性血管／10个视野，对照组平均112．5个阳性血管／10个视野)。结论：瘤内注射arresten基因质粒-DNA复合物能抑制裸鼠移植瘤的血管生成，并能抑制移植瘤的生长。     

脂质体介导mIL-12基因与MHCⅠ基因联合对小鼠实验性肝癌的治疗作用

背景与目的：白细胞介素-12及MHCⅠ基因均已单独用于肿瘤基因治疗,为探索两者的抗肿瘤协同效应,本研究探讨小鼠白细胞介素-12（mIL-12)基因与同种异型的MHCⅠ（小鼠为H-2K）基因联合治疗Balb/C小鼠实验性肝癌。方法：分别应用含mIL-12基因,C57BL/6小鼠H-2K^bcDNA及绿色荧光蛋白（GFP）报告基因的真核表达质粒载体pcDNA3。体外经新型脂质体LipofectAMINE2000(LF2000)介导转染小鼠肝癌细胞株MM45T.Li,检测转染细胞外源基因的表达,将经LF2000介导pcDNA3/mIL-12与pcDNA3/H-2K^b转染的MM45T.Li细胞,注射于小鼠皮下,观察致瘤性的变化,在荷瘤Balb/C小鼠瘤内注射上述脂质体-DNA复合物,观察瘤体生长情况及小鼠生存期的改变。结果：LF2000介导pcDNA3/GFP转染MM45T.Li细胞的最佳条件为脂质体与DNA为3：1（μg：μg）,转染效率达30%,经LF2000介导pcDNA3/mIL-12与pcDNA3/H-2K^b转染的MM45T.Li细胞,RT-PCR检测有mIL-12和H-2K^bcDNA的特异扩增片段,WesternBlot检测显著有57kDaH-2K^b蛋白表达,ELISA检测mIL-12分泌量达48ng/ml/10^6细胞,经LF2000介导pcDNA3/mIL-12与pcDNA3/H-2K^b转染的MM45T.Li细胞,其致瘤性下降;荷瘤Balb/C小鼠瘤内注射该脂质体-DNA复合物,FACS检测显示小鼠脾脏淋巴细胞中CD3^ ,CD4^ 和CD8^ 的数量治疗组较对照组高,肿瘤生长相对缓慢,且pcDNA3/mILp-12与pcDNA3/H-2K^b联合治疗具有一定的正协同效应。结论：mIL-12基因与MHCⅠ基因联合治疗小鼠肝癌具有正协同效应,增强了抗肿瘤效果。     

转基因表达的IFN-γ与重组IFN-γ对小鼠结肠癌的治疗作用

目的:评价IFN-γ转基因方法与肿瘤内注射重组IFN-γ对荷瘤小鼠的治疗作用。方法:用小鼠结肠癌细胞CT26接种于Balb/c小鼠皮下,建立小鼠皮下种植模型;小鼠成瘤后分成5组(每组9只),分别进行不同的干预。A组,瘤内注射阳离子脂质体Lipofectamine和含huIFN-γ全长基因的真核表达质粒pcDNA3-huIFN-γ的混合液,1周后重复1次;B组,瘤内注射重组huIFN-γ,每日1次,连续4周;C组,瘤内注射重组huIFN-γ,每周3次,连续4周;D组,瘤内注射生理盐水,每日1次,连续4周;E组,瘤内注射空载质粒pcDNA3与Lipofectamine的混合液,1周后重复1次。比较种植瘤的体积,并取肿瘤组织进行病理学检查及FCM分析。结果:与D、E组比较,A、B、C组抑瘤效应明显;A、B、C组皮下肿块镜下观察见大量淋巴细胞浸润,流式细胞仪检测显示CD3 、CD4 T淋巴细胞的百分率明显高于D、E组。结论:IFN-γ转基因治疗对荷瘤小鼠的肿瘤生长有抑制效应,转基因治疗组与重组IFN-γ每日给药组抑瘤效果相当,而优于重组IFN-γ间断给药组。     

阳离子脂质体介导的HSV-tk自杀基因疗法的体内外抗肝癌作用

为研究阳离子脂质体介导HSV-tk自杀基因系统的体内外抗肝癌作用,本课题用基因重组技术构建了含HSV-tk基因的重组逆转录病毒载体,命名为pLXT。用Lipofectin介导转染人肝癌细胞系SMMC-7721,经G418筛选抗性克隆及流式细胞仪分析,获得了持续表达HSV-tk的克隆细胞SM/tk。~3H-TdR掺入法测定表明HSV-tk/ACV系统对SM/tk细胞具有强杀伤力。将Lipofectin-pLXT复合物直接注射于鼠肝癌细胞(H22)实体瘤内,ACV治疗后监测抑瘤率,发现脂质体介导pLXT、ACV治疗组及裸pLXT注射、ACV治疗组平均瘤体积均显著小于其它六组对照组(P<0.001,P<0.05),前两者比较亦有显著差异(P<0.02)。空载体转染组和阴性对照组平均瘤体积及平均瘤重均无显著差异(P>0.05)。这些结果表明阳离子脂质体介导重组逆转录病毒载体基因转染的方法简便、安全、有效,且可使目的基因获得持续表达;在体内HSV-tk/ACV系统具有强的细胞毒作用,提示存在着强的旁观者效应。此外,瘤体内直接注射裸HSV-tk基因的治疗也有效。     

瘤内注射pSTbAT-脂质体复合物对裸鼠移植瘤抑制效应的实验研究

目的:构建血管生成抑制因子arresten基 因的真核表达载体,并观察瘤内注射质粒DNA 脂质 体复合物对裸鼠移植瘤生长的影响。方法:利用 PCR方法,由重组质粒pGEM Arr中扩增出基因;将 该基因定向克隆于真核表达载体中。20只裸鼠皮 下注射HepG 2细胞,成瘤后以成功构建的质粒 DNA 脂质体复合物瘤内注射,治疗后采用免疫组化 方法检测肿瘤血管密度,并利用arresten基因瘤内注 射的方法对抑制肿瘤的效果进行分析。结果:我们 成功构建arresten基因真核表达载体(pSTbAT)。实 验组肿瘤生长速度较对照组慢(实验组平均15.3个 阳性血管/10个视野,对照组平均112.5个阳性血 管/10个视野)。结论:瘤内注射arresten基因质粒 DNA复合物能抑制裸鼠移植瘤的血管生成,并能抑 制移植瘤的生长。     

AFP/ANGIO/TK靶向性融合基因治疗人原发性肝癌的效果观察

目的：研究pcDNA3／AFP／angio／tk靶向性融合基因系统对人原发性肝癌皮下移植瘤的治疗效果。方法：建立人原发性肝癌裸小鼠皮下移植瘤模型。将荷瘤裸小鼠随机分为5组（每组6只）：肿瘤对照组；空质粒组；GCV组；pcDNA3／angio／tk组及pcDNA3／AFP／angio／tk组。瘤内分别注射不同的质粒，同时于裸鼠腹腔内注射GCV，在第二次瘤内给药后第2天及第三次瘤内给药后第15天，分别处死裸鼠进行检测（每次3只）病理学检查；原位末端标记（TUNEL）法检查细胞原位凋亡；透射电镜观察细胞超微结构变化。结果：病理学检查结果显示，prDNA3／AFP／angio／tk融合基因瘤内注射可明显抑制肿瘤生长。TUNEL法检测显示．pcDNA3／AFP／angio／tk组凋亡指数明显高于肿瘤对照组。透射电镜观察细胞超微结构变化，发现pcDNA3／AFP／angio／tk组有明显的细胞凋亡发生。结论：pcDNA3／AFP／angio／tk靶向性融合基因系统可显著抑制肿瘤的生长，而且作用效果优于pcDNA3／angio／tk融合基因系统（P〈0.05）。     

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.     

In vivo tumor co-transfection with superantigen and CD80 induces systemic immunity without tolerance and prolongs survival in mice with hepatocellular carcinoma

BACKGROUND: Since transfection of established tumors with immunostimulatory genes can elicit antitumor immunity, we treat mouse HCC with in vivo transfection of superantigen SEA and/or costimulatory molecule CD80 and evaluated the safety and efficacy. METHODS: Mice with HCC were treated with lipid-complexed plasmid DNA encoding staphylococcal enterotoxin A and/or CD80. Then the mice were evaluated for tumor regression, systemic immunologic responses, survival times and treatment-associated toxicity. RESULTS: Of all treated mice, the overall response rates (complete or partial remission) for SEA, CD80 and SEA/CD80 treated mice in this study were 65%, 60% and 75% separately, and were significantly higher than that of untreated mice. Most of the treat mice completed the therapy without any significant reaction. CTL activity increased with time of treatment and correlated temporally with an objective tumor response. Also our results indicated that local intratumoral expression of SEA did not lead to detectable deletion or anergy of SEA-reactive spleen T cells. Survival times for hepatoma mice in this study treated by intratumoral injection of SEA, CD80 and SEA/CD80 were prolonged significantly (P < 0.01) compared with the control mice.     

Neoadjuvant treatment of hepatic malignancy: an oncolytic herpes simplex virus expressing IL-12 effectively treats the parent tumor and protects against recurrence-after resection

The objective of the study was to evaluate the utility of NV1042, a replication competent, oncolytic herpes simplex virus (HSV) containing the interleukin-12 (IL-12) gene, as primary treatment for hepatic tumors and to further assess its ability to reduce tumor recurrence following resection. Resection is the most effective therapy for hepatic malignancies, but is not possible in the majority of the patients. Furthermore, recurrence is common after resection, most often in the remnant liver and likely because of microscopic residual disease in the setting of postoperative host cellular immune dysfunction. We hypothesize that, unlike other gene transfer approaches, direct injection of liver tumors with replication competent, oncolytic HSV expressing IL-12 will not only provide effective control of the parent tumor, but will also elicit an immune response directed at residual tumor cells, thus decreasing the risk of cancer recurrence after resection. Solitary Morris hepatomas, established in Buffalo rat livers, were injected directly with 10(7) particles of NV1042, NV1023, an oncolytic HSV identical to NV1042 but without the IL-12 gene, or with saline. Following tumor injection, the parent tumors were resected and measured and the animals were challenged with an intraportal injection of 10(5) tumor cells, recreating the clinical scenario of residual microscopic cancer. In vitro cytotoxicity against Morris hepatoma cells was similar for both viruses at a multiplicity of infection of 1 (MOI, ratio of viral particles to target cells), with >90% tumor cell kill by day 6. NV1042 induced high-level expression of IL-12 in vitro, peaking after 4 days in culture. Furthermore, a single intratumoral injection of NV1042, but not NV1023, induced marked IL-12 and interferon-gamma (IFN-gamma) expression. Both viruses induced a significant local immune response as evidenced by an increase in the number of intratumoral CD4(+) and CD8(+) lymphocytes, although the peak of CD8(+) infiltration was later with NV1042 compared with NV1023. NV1042 and NV1023 reduced parent tumor volume by 74% (P<.003) and 52% (P<.03), respectively, compared to control animals. Treatment of established tumors with NV1042, but not with NV1023, significantly reduced the number of hepatic tumors after resection of the parent tumor and rechallenge (16.8+/-11 (median=4) vs. 65.9+/-15 (median=66) in control animals, P<.025). In conclusion, oncolytic HSV therapy combined with local immune stimulation with IL-12 offers effective control of parent hepatic tumors and also protects against microscopic residual disease after resection. The ease of use of this combined modality approach, which appears to be superior to either approach alone, suggests that it may have clinical relevance, both as primary treatment for patients with unresectable tumors and also as a neoadjuvant strategy for reducing recurrence after resection.     

In vivo growth inhibitory effect of iterative wild-type p53 gene transfer in human head and neck carcinoma xenografts using glucosylated polyethylenimine nonviral vector

Polyethylenimine (PEI) derivatives are polycationic nonviral vectors for gene transfer. Previous results achieved in vitro in head and neck cancer cells demonstrated that glucosylated PEI yields higher gene transfer efficiency and longer transgene expression than unsubstituted PEI. Using glucosylated PEI, p53 gene transfer was successfully achieved with subsequent recovery of P53 protein expression and induction of spontaneous apoptosis. The present study reports in vivo data achieved in human head and neck squamous cell carcinoma xenografted mice. Using biotinylated PEI and histochemistry analysis, the vector was found to diffuse in the proliferating cells of the tumor tissue, sparing necrotic areas. No diffusion was observed inside keratinized area composed of nonproliferating, mature differentiated cells. Using green fluorescent protein (GFP) transfection and fluorescence microscopy, the transgene expression was mainly observed at the periphery of the tumor containing proliferating cells. GFP expression appeared lower inside the tumor depth. Quantitative transgene expression kinetics was then determined using luciferase as reporter gene. The maximal transgene expression was achieved 48 hours after intratumoral injection of glucosylated PEI/DNA complexes. The highest gene transfer efficacy was achieved 48 hours after two intratumoral injection. After transfection of wild-type p53, tumor growth inhibition was observed in tumor-bearing mice receiving intratumoral injection of glucosylated PEI/DNA complexes repeated twice weekly. Tumor growth inhibition was maintained under continuous treatment using the same schedule. In all experiments, no noticeable toxicity was observed. The present results demonstrate the feasibility and the tumor growth inhibition potency of nonviral gene transfer using glucosylated polyethylenimine.     

Intramuscular electroporation delivery of IL-12 gene for treatment of squamous cell carcinoma located at distant site

Gene therapy with IL-12 has been shown to elicit potent systemic antitumor response in a variety of tumors. Although direct intratumoral injection is the most commonly used delivery route for gene therapy of solid tumors, the skeletal muscle has been shown to be an ideal tissue for gene delivery to produce systemic gene expression. We have previously demonstrated that electroporation delivery of a reporter gene to muscle enhances the transfection efficiency and the level of gene expression by two to three logs. We report here that intramuscular (i.m.) injection of as little as 10 microg of the IL-12 DNA plasmid followed by electroporation prevents squamous cell carcinoma (SCCVII) tumor establishment in up to 40% of experimental animals and reduces the volume of established tumors by 75% compared to controls (P<.05). By comparison, there was no difference in tumor growth observed between IL-12 injection alone and injection of empty vector with or without electroporation. The induction of antitumor activity by i.m. electroporation delivery of the IL-12 gene is associated with an increase in IL-12 expression in muscle and serum. The level of IL-12 expression in muscle and serum was 1500 pg/tibialias muscle and 170 pg/mL serum, respectively, at day 6, after the gene was delivered by electroporation. In contrast, the level of IL-12 when the gene was injected without electroporation was hardly detectable after subtracting the background level of IL-12 detected in na?ve mice. The high level of IL-12 expression led to a 170-fold induction of IFN-gamma expression in serum at day 6 after i.m. electroporation delivery of IL-12 DNA plasmid, which was equal to 1450 pg/mL in the serum. The induction of antitumor activity by i.m. electroporation delivery of the IL-12 gene also correlates with increased CD8+ T-cell population in peripheral blood but not in spleen. Our findings suggest that i.m. delivery of IL-12 gene using electroporation is an effective method of inducing a systemic antitumor response against SCC.     

Role of immature myeloid Gr-1+ cells in the development of antitumor immunity

One of the mechanisms by which tumor cells evade the immune system is the lack of proper antigen-presenting cells. Improvement in host immunity against tumor cells can be achieved by promoting the differentiation of dendritic cells (DCs) from immature myeloid cells (Gr-1(+)Ly-6C(+)F4/80(+)) that accumulate in the bone marrow and lymphoid organs of mice with large tumor burdens. The enriched immature myeloid cells inhibit T-cell proliferation and tumor-specific T-cell response, which can be reversed by the differentiation of immature myeloid cells or depletion of F4/80(+) cells. Sorted Gr-1(+)/F4/80(+) immature myeloid cells differentiated into CD11c(+) cells that express CD80 and I-A/I-E (MHC class II) in the presence of recombinant murine granulocyte macrophage colony-stimulating factor (GM-CSF). Furthermore, intratumoral gene delivery of GM-CSF not only promoted the differentiation of carboxyfluoroscein succinimidyl ester-labeled immature myeloid cells into CD11c(+) cells with the characteristics of mature DCs (CD80(+), I-A/I-E(+)) but also enhanced innate natural killer and adaptive cytolytic T-cell activities in mice treated with interleukin (IL)-12 and anti-4-1BB combination therapy. More importantly, intratumoral delivery of GM-CSF and IL-12 genes in combination with 4-1BB costimulation greatly improved the long-term survival rate of mice bearing large tumors and eradicated the untreated existing hepatic tumor. The results suggest that inducing the maturation of immature myeloid cells, thus preventing their inhibitory activity and enhancing their antigen-presenting capability, by GM-CSF gene therapy is a critically important step in the development of effective antitumor responses in hosts with advanced tumors.     

Administration route‐dependent induction of antitumor immunity by interferon‐alpha gene transfer

Type I interferon (IFN) protein is a cytokine with pleiotropic biological functions that include induction of apoptosis, inhibition of angiogenesis, and immunomodulation. We have demonstrated that intratumoral injection of an IFN‐α‐expressing adenovirus effectively induces cell death of cancer cells and elicits a systemic tumor‐specific immunity in several animal models. On the other hand, reports demonstrated that an elevation of IFN in the serum following an intramuscular delivery of a vector is able to activate antitumor immunity. In this study, we compared the intratumoral and systemic routes of IFN gene transfer with regard to the effect and safety of the treatment. Intratumoral injection of an IFN‐α adenovirus effectively activated tumor‐responsive lymphocytes and caused tumor suppression not only in the gene‐transduced tumors but also in distant tumors, which was more effective than the intravenous administration of the same vector. The expression of co‐stimulatory molecules on CD11c⁺ cells isolated from regional lymph nodes was enhanced by IFN gene transfer into the tumors. Systemic toxicity such as an elevation of hepatic enzymes was much lower in mice treated by intratumoral gene transfer than in those treated by systemic gene transfer. Our data suggest that the intratumoral route of the IFN vector is superior to intravenous administration, due to the effective induction of antitumor immunity and the lower toxicity. (Cancer Sci 2010)