Regulatory effects of interleukin-4 on tumor-infiltrating lymphocytes derived from human renal cell carcinoma.

We have studied the effects of interleukin-4 (IL-4) on the expansion, proliferation, phenotype, and antitumor activity of tumor-infiltrating lymphocytes (TIL) derived from human renal cell carcinoma. Cultures were obtained from three primary renal tumors and one group of tumor-invaded, regional lymph nodes. IL-4 induced a significant increase in lymphocyte expansion and proliferation, but the response was dependent on the concurrent dose of IL-2 in culture. Increased growth activity was only observed in those cultures receiving low doses (20 U/ml) of IL-2 (average increase of fold expansion of 6.5, P < 0.01) with no changes in growth activity in the high dose (1000 U/ml) cultures. The combination of low dose IL-2 and IL-4 (200 U/ml) promoted lymphocyte growth significantly better than high dose IL-2 alone, the current standard growth regimen for in vitro expansion of TIL. TIL grown in the presence of IL-4 significantly reduced the level of non-specific, non-major histocompatibility complex-restricted antitumor activity (P < 0.01 for allogeneic renal, nonrenal, and NK-sensitive K562 cells), while exhibiting no effect on the level of autologous killing. This is in contrast to previous findings of significant enhancement of autologous antitumor activity using IL-4 on tumor-specific, melanoma-derived TIL. We also evaluated the effects of irradiated autologous tumor stimulation (TIL:tumor ratio, 10:1) on TIL cultures. Addition of autologous tumor cells increased expansion and proliferation of all cultures regardless of concurrent lymphokines present in the culture media (average increase fold expansion of 2.21, P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Adoptive immunotherapy and metastasized cancer of the kidney. Regulator effects of interleukin-4 on tumor infiltrating lymphocytes (TIL)]

Adoptive immunotherapy is a new therapeutic approach of the treatment of advanced renal cell cancer. Experimental studies have shown that the cells with the highest cytolytic activity are tumor infiltrating lymphocytes (TIL). The effects of interleukin-4 (IL-4) on the expansion, proliferation, phenotype and antitumor activity of TIL were studied. Cultures were obtained from three primary renal tumors and one group of tumor invaded, regional lymph nodes. IL-4 induced a significant increase in lymphocytes expansion and proliferation, but the response was dependent of the concurrent dose of IL-2 in culture. TIL grown in the presence of IL-4 significantly reduced the level of non specific, non MHC restricted antitumor activity while exhibiting no effect on the level of autologous killing. The effects of irradiated autologous tumor stimulation on TIL cultures were also evaluated. Addition of autologous tumor increased expansion and proliferation of all cultures and significantly enhanced levels of autologous killing. IL-4 and autologous tumor stimulation are effective growth factors when used in combination with a lose dose IL-2 regimen and may be of significant benefit in the expansion of TIL for clinical trials.     

白细胞介素(IL)-2与IL-4对小鼠膀胱癌肿瘤浸润性淋巴细胞增殖及细胞毒性的协同调节作用

目的 探讨白细胞介素（ＩＬ）－２与ＩＬ－４对膀胱癌肿瘤浸润性淋巴细胞（ＴＩＬ）体外增殖及细胞毒性免疫调控的协同作用。方法 分离膀胱癌ＴＩＬ,置于含ＩＬ－２和（或）ＩＬ－２的完全培养基因中培养４周,定期计数ＴＩＬ增殖数量。四甲基偶氮唑蓝（ＭＴＴ）比色法检测ＴＩＬ细胞毒性。结果 对比单纯ＩＬ－２的培养条件,ＩＬ－２联合ＩＬ－４后４周时ＴＩＬ扩增数量是前者的１．６５倍（Ｐ〈０．０５）。在交靶比为１０：１时,ＴＩＬ对自体膀胱癌细胞（ＢＴＴ７３９）表现出高水平的杀伤活性（Ｐ〈０．０５）。联合培养的ＴＩＬ抗ＢＴＴ３９或小鼠淋巴瘤瘤株（ＹＡＣ－１）的活性与在单纯ＩＬ－２培养的条件下相比无显著改变（Ｐ均〉０．０５）。结论 ＩＬ－４对ＩＬ－２活化的膀胱癌ＴＩＬ增殖具有较强的正向调节效应,而对ＴＩＬ细胞毒性未见明显影响。     

Study on adoptive immunotherapy with tumor-infiltrating lymphocytes (TIL) for renal cell carcinoma--amplification of IL-2-elicited TIL proliferation by OKT3-monoclonal antibody

Human autologous peripheral blood lymphocytes (PBL) and lymphocytes infiltrating renal cell carcinoma (TIL) were cultured with medium containing 1000 IU/ml of human interleukin 2 (IL-2). A high cytotoxic activity against fresh autologous as well as cultured allogenic tumor cells was developed. By culturing these lymphocytes with OKT3 monoclonal antibody during the initial 2 days of long-term culture, in terms of T cell activation signal, IL-2-driven lymphocyte proliferation was remarkably accelerated with maintenance of appreciable level of cytotoxic activity. The same culture method also induced an increase in OKT3 and IL-2 receptor positive lymphocyte population in LAK cells and TIL. This method may enable us to gain more autologous TIL in vitro for adoptive immunotherapy of renal cell carcinoma than the usual culture method with IL-2 alone. Five patients with metastatic renal cell carcinoma were treated with adoptive immunotherapy with TIL, LAK and IL-2. One patient with pulmonary metastasis has had a minor response which has lasted for 3 months so far. We have not experienced any serious side effects during the treatment.     

肿瘤浸润性淋巴细胞在白细胞介素-2、-4协同下局部过继免疫治疗膀胱癌的实验研究

目的　观察膀胱癌肿瘤浸润性淋巴细胞 (TIL)联合不同细胞因子瘤灶内过继免疫抗癌的效应及对机体全身抗肿瘤免疫机制的影响。方法　建立BTT73 9动物模型 ,分离、培养TIL。采用正交设计实验方法 ,将TIL、白细胞介素 (IL) 2、 4及三因素交互组合悬液分别直接注射至瘤体内 ,定期测量肿瘤体积 ,免疫治疗 2周后检测NK细胞活性、T淋巴细胞转刺激指数 ,观察组织学及超微结构变化。结果　比较对照组 ,治疗 2周时各TIL相关组均不同程度抑制了膀胱肿瘤体积的增长 ,且NK细胞活性及T淋巴细胞转化增殖能力得以提高 (P <0 .0 5 )。TIL/IL 2疗法明显抑制了瘤体的增长 ,免疫治疗 1周后即表现出协同增强效应 (P <0 .0 5 ) ,而NK细胞活性及T淋巴细胞转刺激指数也显著提高 (P <0 .0 5 )。TIL/IL 2 /IL 4组获得了较强的抗癌功效 ,但与TIL/IL 2组差异无显著性 (P >0 .0 5 )。超微结构变化显示出TIL强烈的溶癌现象。结论　TIL在细胞因子特别是IL 2协同下瘤灶内注射的局部免疫疗法 ,具有较强的抗膀胱癌效应 ,并显著提高了机体全身抗瘤免疫功能。     

Study of cytotoxicity of recombinant interleukin-2 (rIL-2) expanded tumor infiltrating lymphocytes (TIL) in renal cell cancer

We studied subsets and cytotoxicity of recombinant interleukin-2 (rIL-2) expanded tumor infiltrating lymphocytes (TIL) from renal cell cancer (RCC) patients. TIL were successfully expanded in 13 of 14 RCC cases using anti-CD3 during initial 48 hours of culture. Percentages of CD8 positive cells among rIL-2 expanded TIL at 1 tp 4 week(s) of culture were 56.2 +/- 15.1% (range 26.2 to 79.8%, N = 13) and not necessarily predominant over CD4 positive cells. NK and LAK activities of TIL at 3 to 6 weeks of culture were 31.6 +/- 15.8% (range 1.4 to 57.4%, N = 9) and 16.6 +/- 11.6% (range 3.8 to 35.6%, N = 6), respectively. Autologous and allogeneic RCC cytotoxicity of TIL at 3 to 4 weeks of culture were 17.9 +/- 19.7% (range 0 to 47.6%, N = 4) and 18.9 +/- 14.8% (range 0 to 47.3%, N = 12), respectively. Since there was no statistical difference between them, autologous specific cytotoxicity was not demonstrated. From these results of present study, it is unlikely that most of effector cells of rIL-2 expanded TIL in autologous RCC lysis are major histocompatibility complex restricted cytotoxic T cells. And we concluded that it is doubtful that TIL is significantly superior over LAK cells in immunotherapy of human RCC.     

Anti-tumor reactivity of human lymphokine activated killer (LAK) cells against fresh and cultured preparations of renal cell cancer

Immunotherapy utilizing the adoptive transfer of lymphokine activated killer (LAK) cells in conjunction with recombinant interleukin-2 (IL-2) is capable of mediating the regression of established cancer in a variety of animal tumor models as well as advanced metastatic cancers in humans. We have thus examined the variability of the anti-tumor lytic reactivity of LAK cells obtained from patients with metastatic renal cell cancer (RCC). Tumor cell suspensions were prepared by enzymatic digestion from 37 consecutive renal cell tumors. The mean (+/- SEM) total number of cells recovered was 1.5 +/- 2.2 X 10(9) cells per tumor. The percentage of tumor cells in the suspension was 39.1 +/- 3.3% (range: 6 to 75%). Thirteen of 13 different fresh renal tumor cell preparations tested in 57 experiments and tow of two renal tumor lines tested in 10 experiments were all lysed by LAK cells. RCC patients, like normal donors, generated good LAK effectors with broad antitumor activity against autologous as well as allogenic tumors. Both renal and nonrenal tumors were equally lysed by LAK cells. LAK killing of the erythroleukemic tumor lines K562 and Daudi was significantly better than the lysis of fresh autologous and allogeneic tumor targets or cultured RCC tumor lines. Short term tumor cultures derived from renal cancer preparations proved to be sensitive and reliable tumor targets for studying the in vitro killing by LAK cells. Clinical trials testing the therapeutic role of LAK cells and IL-2 in patients with advanced renal cell cancer are currently in progress.     

BCG激活膀胱肿瘤浸润淋巴细胞的抗肿瘤作用研究

为了探讨ＢＣＧ的抗肿瘤机理，从１５例手术切除的膀胱移行细胞癌新鲜组织标本中制备肿瘤浸润淋巴细胞（ＴＩＬ），分别在含ＢＣＧ或ＩＬ－２的全培养基中培养扩增，测定不同培养时间的抗瘤活性。结果：用活ＢＣＧ培养的ＴＩＬ第１２天对自体肿瘤细胞的杀伤活性达高峰，杀伤率为４８．３％；用ＩＬ－２培养的ＴＩＬ第１４天达杀伤高峰，杀伤率为４３．８％，用死ＢＣＧ培养的ＴＩＬ，其扩增结果和抗瘤活性均明显低于活ＢＣＧ及ＩＬ－２。提示ＢＣＧ对ＴＩＬ的直接激活作用可能是其抗肿瘤机理之一。     

Improved in vivo efficacy of tumor-infiltrating lymphocytes after restimulation with irradiated tumor cells in vitro

Background: We investigated different culture conditions for tumor-infiltrating lymphocytes (TILs) with regard to proliferation, phenotypic changes, in vitro cytotoxicity, and in vivo therapeutic efficacy. Methods: After enzymatic digestion of the murine fibrosarcoma, MCA-105, TIL cultures were initiated as pure lymphocyte (groups 1 and 2) or mixed lymphocyte/tumor suspensions (groups 3 and 4). Group 1 TILs were grown in culture medium containing 100 IU/ml recombinant interleukin-2 (rIL-2). Group 2 TILs were stimulated with solid-phase anti-CD3 monoclonal antibody (mAb) for 48 h and cultured in rIL-2 (100 IU/ml)-containing medium. Group 3, which consisted initially of a surplus of tumor cells, received the same treatment as group 2. Group 4 was also activated with anti-CD3 mAb and rIL-2 but was additionally restimulated weekly with irradiated tumor cells (TILs to tumor, 20:1). Results: Groups 1 and 2 showed up to twofold higher increases in TIL numbers compared with groups 3 and 4 by the end of culture week 5. Although the original lymphocyte/tumor cell suspension consisted of 12.0 ± 3.8% CD4⁺ T cells and 5.3 ± 3.3% CD8⁺ T cells, all four TIL cultures showed 80% CD8⁺ TILs and no CD4⁺ TILs by the end of culture week 4. In vitro cytotoxicity did not correlate with in vivo efficacy of the examined TIL cultures. By using the MCA-105 pulmonary metastases model in C57BL/6 mice, only suboptimal doses of TILs (2 × 10⁶) from group 4, which had been restimulated weekly with irradiated tumor, showed significant tumor eradication compared with all other treatment groups (p<0.01). Conclusions: We conclude that in vitro tumor restimulation of TILs improves in vivo efficacy, most likely through the education of tumor-reactive T cells.Presented at the 48th Annual Meeting of The Society of Surgical Oncology, Boston, Massachusetts, March 23–26, 1995.     

Establishment of a new human renal cancer cell line (TC-1) and its productivity of interleukin-6 (IL-6)]

We established a new cell line (TC-1) from primary site of a renal cell carcinoma (RCC) patient. Its doubling time in tissue culture was 20 hours at 45th passage and mycoplasma contamination test was negative. The karyotypic analysis demonstrated a human karyotype with a modal number of 70. A consistent chromosomal abnormality was noted such as No. 4 monosomy, No. 7 trisomy and a loss of Y chromosome. Electron microscopic examination showed a brush border, vacuoles and abundant glycogen granules in the cytoplasm, which was compatible with RCC cells. This cell line was transplantable to nude mice and the grown tumor closely resembled the original tumor, i.e. clear cell type and hypervascularity. High titer of interleukin-6 (IL-6) was detected in the supernatant of TC-1 cell culture (approximately 5 ng/ml) as well as in sera of nude mice bearing this tumor (260 pg/ml). Exogenous IL-6 did not enhance the TC-1 cell proliferation as determined by cell count. Flow cytometric analysis could not demonstrate the existence of IL-6 receptor on the cell surface. These results suggested the produced IL-6 did not act as an autocrine growth factor in the cell line. Additional IL-1 alpha to the culture medium induced 3-4 times higher concentration of IL-6 in the culture supernatant compared with that of non-stimulating cells, while exogenous TNF alpha did not stimulate IL-6 production.     

肿瘤浸润淋巴细胞在肾细胞癌原位表达的特点

目的:研究肾细胞癌组织中肿瘤浸润淋巴细胞(TIL)的分布特点及其与预后的关系.方法:对52例肾透明细胞癌组织T,辅助T及自然杀伤细胞(NK细胞)进行原位免疫组化研究,并与病人预后作相关性分析.结果:TIL细胞中主要为T细胞,占70%;TIL细胞表达的程度对肾细胞癌患者预后的影响较大(P<0.01);TIL细胞亚群之间的表达为正相关.结论:TIL在对抗肾细胞癌中起较重要的作用,它们的表达程度影响预后.     

Characterization of novel anti-tumor effector cells in long-term cultures of human tumor-infiltrating lymphocytes

TIL were isolated from human solid tumors and cultured in rIL 2. Long-term TIL lines from primary tumors showed a shorter lag period, better expansion, and higher anti-tumor activity in vitro than those from metastatic tumors. The anti-tumor effector cells in TIL and A-PBL cultures had CD3+ Leu 19+ and CD3- Leu19+ phenotypes and morphology consistent with LGL/LAK cells. These cells mediated lysis of both autologous and allogeneic fresh tumor cell targets, while CD3+ Leu19- cells had little or no antitumor cytotoxicity.     

Interferon-alpha suppresses the antiapoptotic effect of NF-kB and sensitizes renal cell carcinoma cells in vitro to chemotherapeutic drugs

BACKGROUND: Immunochemotherapy (ICT) with interleukin-2 (IL-2) and interferon-alpha (IFNalpha) with a secondary effector (5-fluorouracil, 5 FU) is the only promising treatment for advanced renal cell carcinoma (RCC). With IFNalpha, besides the activation mechanisms of the immunosystem, a direct antitumor effect on tumor cells is expected. MATERIALS AND METHODS: NF-kB activity in three permanent cell lines (Hep2, HepG2, HT29) and in primary RCC cell lines was measured after incubation with tumor necrosis factor-alpha (TNFalpha), IFNalpha, IFN-gamma, TNFalpha+IFNalpha, and IFNgamma+TNFalpha, respectively. NF-kB activity and induction of apoptosis by chemotherapeutic drugs (5FU and doxorubicin) were determined in cells transfected with a constitutively active NF-kB p65 or a dominant negative IkB. RESULTS: NF-kB signaling induced by TNFalpha is suppressed by IFNalpha and IFNgamma in the permanent cell lines and in the primary RCC tumor cell cultures. In an in vitro ICT model we show that pretreatment of RCC with IL-2 and IFNalpha leads to a diminished NF-kB response to TNFalpha. In certain tumors, this correlates with increased susceptibility to investigated chemotherapeutic drugs as shown by annexin stain and cell elimination. Modulation of the cellular NF-kB state by a constitutively active p65 or a dominant negative IkB mimics this effect. The IkB construct leads to the same effects as IL-2/IFNalpha pretreatment as shown by predominant elimination of the transfected cells from the overall population, while introduction of p65 leads to a partial rescue from the effect of IL-2 and IFNalpha. The described effect, however, applies only to a selection of primary cell cultures. CONCLUSIONS: Besides the immunomodulation effects, treatment of RCC with IL-2/IFNalpha leads to a proapoptotic state in certain tumors. The relevant mediator seems to be IFNalpha by suppression of the antiapoptotic effect of NF-kB. These data can provide an experimental base for correlation with real patient outcome after ICT.     

Inhibitory Effects of Interleukin-4 on Human Renal Cell Carcinoma Cells In Vitro: In Combination with Interferon-α, Tumor Necrosis Factor-α or Interleukin-2

Background: Immune cytokines have been shown to play important roles in regulating the growth of neoplastic cells, as well as the function of immune cells. The present study assessed the effects of interleukin (IL)-4 alone, and in combination with recombinant interferon (IFN)-α2b, or with IL-2, or with tumor necrosis factor (TNF)-α on the in vitro proliferation of human renal cell carcinoma (RCC) cell-lines.
Methods: Growth-inhibitory effects of IL-4 alone, and in combination with other cytokines, on three human RCC cell-lines, Caki-1, CURC-II, and A-498, were measured by the [³H]thymidine incorporation assay.
Results: IL-4 inhibited proliferation of all three human RCC cell-lines (P< 0.001). The maximum growth inhibition of RCC cell-lines by IL-4 alone was observed at the concentration of 1 to 3 ng/mL, depending on the cell-line. Antihuman IL-4 antisera was able to reverse the growth-inhibitory effects of IL-4 on Caki-1 in a dose-dependent manner, proving that the growth inhibition was mediated by IL-4 itself. When other cytokines were added in combination with IL-4, only IFN-α2b resulted in significant additional growth inhibition ( P < 0.005). However, when the proliferation was compared to that of RCC cells that were not treated with any cytokine, all combinations produced marked growth inhibition. Conclusion: Our data suggest that IL-4 alone, or in combination with IFN-α2b, can be used to develop new strategies for treatment of human RCC.     

Augmentation of cytotoxicity of tumor infiltrating lymphocytes by interleukin-2 in gastric cancer patients

Lymphocyte infiltration into tumor has been regarded as an expression of host reaction against tumor, but the natural cytotoxicity of tumor infiltrating lymphocytes (TLL) is often very low. In order to augment this low cytotoxicity, TIL of gastric cancer patients were cultured with interleukin-2 (IL-2) in vitro. On the other hand, immunopotentiators (OK432, PSK) were injected into gastric cancer intralesionally under endoscopy. By the in-vitro culture with IL-2, the cytotoxicity of TIL was augmented against both targets of K562 and MNN28 (gastric carcinoma cell line). In particular, the augmentation of cytotoxicity against MKN28 was more obvious in TLL than PBL (peripheral blood lymphocytes). In the ascitic lymphocytes, the in-vitro culture with IL-2 induced autologous tumor cell killing. Intralesional injection of OK432 or PSK augmented the natural cytotoxicity of TIL, and the ratio of OKT8 and Leu7 cells increased in the TIL of OK432-injected group.     

Inhibition of lymphocyte function by glioblastoma-derived transforming growth factor beta 2

Human glioblastoma cells secrete an inhibitory factor termed "glioblastoma-derived T-cell suppressor factor" (G-TsF). A member of the transforming growth factor beta (TGF beta) family, G-TsF is identical to TGF beta 2. The present study investigated the effect of G-TsF/TGF beta 2 on the proliferative and cytotoxic properties of tumor-infiltrating lymphocytes (TIL's) isolated from malignant gliomas after expansion in vitro with interleukin-2 (IL-2). The results demonstrate that the IL-2 (5 to 20 U/ml)-dependent proliferative response of glioma-derived TIL's was inhibited 70% to 85% by G-TsF/TGF beta 2 and that the inhibitory effect could be reduced by using increasing concentrations of IL-2 (100 to 200 U/ml). Tumor necrosis factor alpha (TNF alpha) enhanced the IL-2-dependent proliferation of TIL's cultured in low concentrations of IL-2 (10 U/ml); however, neither TNF alpha nor interferon gamma was able to reduce the inhibitory effect of TGF beta 2 on TIL proliferation. In addition, TGF beta 2 suppressed 60% to 100% the cytotoxic response of glioma-derived TIL's against several tumor targets, including autologous glioma cells, and the suppressive effect was shown to be reduced by increasing concentrations of IL-2.     

Renal cancer specific antitumor activities of a mouse monoclonal antibody K2.7 to human renal cell carcinoma]

We have prepared a mouse monoclonal antibody (mAb) K2.7 (IgG3) by immunizing mice with renal cancer cell (RCC) line OS-RC-2. In a serological analysis by protein A assay, 25 out of 31 RCC lines reacted with the mAb K2.7 but none of the 50 other cell lines from different organs except for 2 cell lines did. In immunohistological analysis by indirect immunoperoxidase assay, 66 out of 72 renal cancer tissues showed positive staining. Metastatic lesions of renal cancers also reacted similarly to the primary lesion. Some restricted normal tissues including tubules of normal kidney showed positive staining. Specific antitumor activities of mAb K2.7 against RCC lines were investigated in vitro by complement dependent cytotoxicity (CDC) and antibody dependent cell mediated cytotoxicity (ADCC) assays. In CDC assay, all of the 9 RCC lines were killed by mAb K2.7 and normal human serum, and killing activities of mAb K2.7 presumably depend on the number of antibody molecules bound to the cell surface. Sera from 9 patients with renal cancers including low and high stages showed the same killing activities to 3 RCC lines as normal human serum. In the ADCC assay, peripheral leukocytes (PBLs) from 4 healthy donors showed strong killing activities to RCC lines. Killing activity differed with the individual. PBLs from the same 9 patients as in the CDC assay showed significantly positive killing activity against 3 RCC lines. These findings suggest the usefulness of mAb K2.7 for the specific immunotherapy of renal cancer.     

Tumor-infiltrating lymphocytes derived from human renal cell carcinoma: Clonal analysis of its characteristics

Aim:   To assess the characteristics of activated tumor-infiltrating lymphocytes (TIL), we report the isolation, growth response, and functional analysis of a CD4^- CD8⁺ TIL-clone derived from human renal cell carcinoma (RCC).
Methods:   Bulk TILs were expanded from a human RCC and the lymphocytes were separated into a CD8⁺ enriched population. Subsequently, using the limiting dilution technique, a TIL clone was established and its growth response, phenotype and cytotoxic activity were analyzed.
Results:   A clone, T16-13, by day 94 numbering 1 × 10⁷ cells, was harvested and characterized as a CD4^- CD8⁺ clone. On day 144, the cytotoxic activity of this clone against the autologous tumor was relatively high (2.3 ± 0.7 LU₃₀/10⁶ cells). Meanwhile, against allogeneic renal tumors, there was no cytotoxic activity (−0.1 LU₃₀/10⁶ cells).
Conclusions:   A TIL clone possessing modest autologous tumor-specific cytotoxicity can be isolated from human RCC. The characteristics analysis of various TIL clones may provide a better understanding of an RCC tumor microenvironment and may help to establish new modalities for the treatment of patients with metastatic kidney cancer.     

Gene therapy using cationic multilamellar liposomes containing human interferon-beta gene against renal cell carcinoma

The anticancer activity of cationic multilamellar liposomes containing human IFN-beta gene (IAB-1) against renal cell carcinoma (RCC) was examined. Concentrations of IFN-beta protein were measured by an enzyme-linked immunosorbent assay. The cytotoxic activity of IAB-1 against RCC cells and normal renal proximal tubule endothelial cells (RPTEC5899) was examined by the microculture tetrazolium dye assay. For the in vivo study, the NC65 RCC cell line was inoculated into severe combined immunodeficiency mouse. The RCC cells treated with IAB-1 secreted significant amounts of IFN-beta protein. Significant in vitro cytotoxic activity of IAB-1 against RCC cells was observed. In contrast, treatment of RCC cells with recombinant IFN-beta protein resulted in less cytotoxicity. No significant cytotoxicity was seen in RPTEC5899 cells. Apoptosis was observed in RCC cells treated with IAB-1. The size of NC65 RCC cancers transfected with IAB-1 in mice was significantly smaller than that receiving injection of empty liposomes or recombinant IFN-beta protein. These findings show that IAB-1 may have significant antitumor activity against RCC, and suggest its potential clinical application for gene therapy against RCC.