Efficient tumor suppression by glioma-specific murine cytotoxic T lymphocytes transfected with interferon-gamma gene

Transplantation and Adoptive Cellular Therapy of Cancer: The Role of T-Cell Growth Factors

The ability to transfer cultured lymphocytes required the availability and the understanding of the use of the T-cell growth factors IL-2, IL-4, IL-7, and IL-12. Application of these cytokines in vitro and in vivo has allowed the modern development of adoptive transfer of tumor reactive lymphocytes to the modern immunotherapy of patients with cancer. In a randomized prospective study of IL-2 administration compared with IL-2 and lymphokine-activated killer (LAK) cells, no increase in response rate was observed. In a total of 90 patients randomized to receive LAK and IL-2 and 91 patients randomized to receive IL-2 alone, there were a total of 24 responses in patients receiving cells and IL-2 and 16 responses in those receiving IL-2 alone (no significant difference). There was some suggestion that complete responses were observed more often in melanoma patients treated with LAK and IL-2. The most interesting aspect of this study is the prolonged duration of responses, lasting for many months or years. Unfortunately, given the large numbers of variables that were examined, it became very difficult to demonstrate a clear-cut association between clinical outcome (response) and any variable that was routinely measured. Significant antitumor responses have been observed greater than expected with IL-2 alone, with the administration of tumor-infiltrating lymphocytes to patients with melanoma. We currently use hollow fiber devices (Cellco, Germantown, MD) to expand cells up through the many doublings required to generate approximately 1-2 × 1011 cells over a period of 6 wk in culture. In a recent review of the results in patients with melanoma treated on such regimens in combination with high-dose IL-2, an approximately 20-50% response rate has been observed. The factors associated with response are still unclear. Although we initially felt that it was associated with specific lysis, subsequent studies from our group suggest that the relevant factor is specific cytokine (INF-γ, GM-CSF, TNF) production upon tumor stimulation. Additional studies will need to be done to clarify these issues.

CD8(+) T cells armed with retrovirally transduced IFN-gamma

Interferon-gamma (IFN-gamma) is considered a key cytokine involved in the preventive and defensive responses of T cells against infectious pathogens and tumors. Therefore, the transgenic expression of IFN-gamma in specific T cells appears to be an obvious therapeutic possibility. To directly examine whether IFN-gamma production can be increased in T cells, we introduced an IFN-gamma encoding cDNA into IFN-gamma(-/-) and IFN-gamma(+/+) CD8(+) effector populations by retroviral transduction. Here, we show that CD8 T cells can be equipped with IFN-gamma that increases their capacity to secrete the cytokine. Despite constitutive retroviral IFN-gamma mRNA transcription, translation and secretion of IFN-gamma protein was tightly regulated and only observed in activated T cells. Neither proliferation nor cytolytic activity of CTL was affected by IFN-gamma transduction. Importantly, CD8(+) T cells retrovirally transduced with IFN-gamma exhibit augmented tumor suppressive capacity upon adoptive transfer into IFN-gamma(-/-) mice. Thus, T cells can be readily armed with IFN-gamma without risking immunopathology by dysregulated production of this highly potent proinflammatory cytokine.

Gamma interferon transduced 9L gliosarcoma. Cytokine gene therapy and its relevance to cellular therapy with alloreactive cytotoxic T lymphocytes

In earlier studies, we demonstrated that intratumoral infusions of alloreactive cytotoxic T lymphocytes (aCTL), sensitized to the major histocompatibility complex (MHC) antigens of the host, effectively retarded the intracranial growth of Fischer 9L gliosarcoma. We further demonstrated that continuous in vitro exposure to gamma-interferon (gammaIFN) upregulates MHC on 9L gliosarcoma cells and that they were better targets of anti-Fischer aCTL. We hypothesized that the efficacy of cellular therapy with aCTL could be further improved by in situ transduction of the tumor with retroviral vectors coding for gammaIFN, which would generate continuous secretion of the cytokine and maintain upregulated MHC expression by the tumor cells. 9L gliosarcoma and Herpes simplex virus thymidine kinase (tk) transductants of those cells were transduced with a retrovirus carrying the murine gammaIFN gene. By limiting dilution, clones of these cells, designated 9Lgamma 7, 9Lgamma tk8, and 9Lgamma tk10, which produced similar levels of gammaIFN (383-411 ng gammaIFN/10(6) cells/24 h) were isolated. The production of gammaIFN by one clone, 9Lgamma 7, was stable when monitored over 6 weeks in vitro. The clones also demonstrated upregulated MHC class I expression, and the tk-transduced clones maintained their sensitivity to ganciclovir. Compared to the wildtype cells, 9Lgamma 7 had approximate 6- and 1.5-fold increases in the relative antigen densities of MHC I and II, respectively. Addition of exogenous gammaIFN to 9Lgamma 7 cultures did not significantly increase the MHC expression. In cytotoxicity assays, 9Lgamma 7 cells, or 9Lgamma 7 incubated with exogenous gammaIFN, were better targets of aCTL than the parental 9L cells. The growth rate of 9Lgamma-transduced cells was decreased compared to the wildtype cells both in vitro and in vivo. Proliferation studies with transwell plated 9L, 9Lgamma 7, and 9Lgamma tk10 cells in various combinations revealed that the secreted cytokine itself caused a decrease in proliferation. However, the transduced cells exhibited a much reduced growth rate, which likely was a consequence of redirected metabolic activity of the cells. In vivo growth of the 9L and 9Lgamma 7 tumors in rat brains given identical inoculums similarly demonstrated significantly reduced 9Lgamma 7 tumor volumes at various timepoints, indicative of slower growth of the gammaIFN-producing tumors.

The treatment of established intracranial tumors by in situ retroviral IFN-gamma transfer

Current treatments for malignant gliomas are still largely ineffective in significantly improving prognosis. We have investigated the efficacy of treating established rat C6 glioma by in situ retroviral delivery of IFN-gamma cDNA. Ecotropic retrovirus packaging cells were transfected with a retroviral vector containing the mouse IFN-gamma gene. The IFN-gamma packaging cells were stereotactically implanted into established intracranial C6 glioma in immunocompetent Wistar rats, resulting in the eradication of these tumors. All IFN-gamma-treated rats survived to 92 days after C6 implantation (an arbitrary end point) compared with 14 days for controls. Analysis of these treated brains showed that the established C6 tumors had been completely eradicated by this time-point with brain morphology appearing normal. The IFN-gamma-mediated tumoricidal activity resulted from an apparent interplay of B and T cell components of the immune system, as well as the inhibition of tumor angiogenesis. This therapeutic strategy may provide an effective method of eradicating established intracranial tumors.

Gene therapy of cancer with interferon: lessons from tumor models and perspectives for clinical applications

Cytokine gene transfer is a current approach in studies of gene therapy of cancer IFNs represent valuable cytokines for these studies, since they exert multiple biological effects, including anti-tumor activities. Early studies have been focused on IFN-gamma. Recently, several reports have shown that the transfer of type I IFN (especially IFN-alpha) genes represents a powerful approach for inducing tumor suppression. Recent studies have underscored new IFN-induced activities on immune cells. This knowledge adds a further rationale for the use of IFN-alpha in strategies of gene therapy of cancer and can be exploited for the design of more selective and effective anticancer treatments.

Correlation of the therapeutic effect of activated tumor-draining lymph node cells with specific interferon-gamma production in vitro

It has been established that lymphocytes obtained from tumor-draining lymph nodes (DLN) are sensitized to the tumor antigen in vivo. Moreover, after being activated in vitro, these cells can be utilized for adoptive immunotherapy. In the present study, DLN cells, obtained from C57BL/6 mice with fibrosarcoma (MC-1), were activated and expanded with anti-CD3 monoclonal antibody followed by culture with recombinant interleukin-2 (rIL-2). These CD4- CD8+ CD25+ CD44+ T-cells showed specific antitumor efficacy to the pulmonary micrometastases of an autologous tumor, against which lymphokine-activated killer cells were ineffective; however, they did not show cytolytic activity in vitro. The supernatant, obtained by coculturing the activated DLN cells with MC-1 cells, exhibited the specific production of interferon-gamma (IFN-gamma) which was enhanced by rIL-2. The therapeutic effect of the activated DLN cells correlated with the specific IFN-gamma production better than with the cytolytic activity.

FADD gene therapy for malignant gliomas in vitro and in vivo

Fas/APO-1 (CD95), a cell surface cytokine receptor, triggers apoptotic cell death by specific agonist antibody, suggesting that Fas/APO-1 may be a promising target for treatment of tumors. In this study, we show that treatment with anti-Fas antibody effectively induced apoptosis in malignant glioma cell lines with high expression of Fas/APO-1 (n = 3). Malignant glioma cells with low or undetectable expression of Fas/APO-1 (n = 6), however, were resistant to Fas/APO-1-dependent cytotoxicity. The purpose of this study, therefore, was to determine whether resistant tumors could be made susceptible to apoptosis. FADD/MORT1 constitutes a novel protein that associates specifically with the cytoplasmic death domain of Fas/APO-1 and induces apoptosis. We investigated whether overexpression of FADD would induce apoptosis in malignant glioma cells without activating Fas/APO-1. Results indicated that about 85% of malignant glioma cells, regardless of Fas/APO-1 expression levels, underwent apoptosis after transient transfection with FADD expression vector. To further improve gene transfer of FADD into malignant glioma cells, we constructed a retroviral vector containing the FADD gene. The retroviral transfer of FADD gene significantly enhanced the transduction efficiency and effectively inhibited both in vitro and in vivo survival of malignant glioma cells through induction of apoptosis. These findings suggest that the FADD gene is a novel and useful tool for the treatment of malignant gliomas.

Ex vivo expansion of tumor-draining lymph node cells using compounds which activate intracellular signal transduction. II. Cytokine production and in vivo efficacy of glioma-sensitized lymphocytes

We have investigated the anti-tumor activity of ex vivo activated and expanded T cells which had been sensitized in vivo to one of two different syngeneic rat glioma cell lines; D74 or RT-2. Rats were sensitized by inoculation of irradiated tumor cells into each hind foot pad. After 10 days, the tumor-draining lymph node (DLN) from each popliteal region was excised and prepared as a single cell suspension. Tumor-DLN lymphocytes were next activated overnight in RPMI-1640 medium containing 10% fetal bovine serum (FBS), Bryostatin-1 (5 nM), ionomycin (1 microM), and 20 U human recombinant interleukin-2 (IL-2) per ml. Culture for seven days in RPMI-1640 supplemented with FBS and IL-2 resulted in approximately 100-fold expansion of the lymphocyte population. Both D74- and RT-2-sensitized T cells constitutively secreted tumor necrosis factor-alpha, and both lymphocyte populations produced comparable amounts of the cytokine when co-cultured with either glioma cell line. Neither D74- and RT-2-sensitized effectors constitutively secreted gamma-interferon (gamma-IFN), but both populations produced gamma-IFN when exposed to either glioma cell line in vitro. D74-sensitized T cells released significantly more gamma-IFN than the RT-2 DLN lymphocytes. In vitro Chromium-release assays indicated that RT-2-sensitized T cells were more cytotoxic for RT-2 targets than for the D74 line and that D74-sensitized effectors were also more cytotoxic for RT-2 targets. To assess in vivo therapeutic efficacy, rats who had been inoculated intradermally with RT-2 cells three days earlier received an intravenous injection of RT-2- or D74-sensitized DLN cells (10(6) cells/gram body weight) expanded after activation with Bryostatin-1 and ionomycin or an equal number of lymphokine-activated killer (LAK) cells. Tumor diameters were measured daily and revealed that injection of glioma-sensitized lymphocytes led to the elimination of tumor while treatment with LAK cells had no therapeutic benefit. These results indicate, that at least for these two glioma lines, gamma-IFN release, rather than in vitro cytotoxicity, was a better predictor for in vivo immunotherapeutic efficacy of the glioma-sensitized, expanded T cells.

Growth inhibition of intracerebral rat glioma by transfection-induced human interferon-beta

In our previous study on liposome-mediated transfection of the human interferon-beta (HuIFN-beta) gene into subcutaneously implanted human gliomas in nude mice, we found that HuIFN-beta was produced and secreted by the tumor cells and that the growth of solid tumors was completely inhibited. The present study investigated the growth-inhibitory effect of liposomes containing the HuIFN-beta gene inserted into a vector (pSV2IFN-beta) on T9 rat glioma implanted into the brains of rats. Tumor cells and liposomes containing pSV2IFN-beta or other additives were simultaneously injected into the brains of rats. HuIFN-beta was detected in solid gliomas growing in the brains of rats injected with liposomes and magnetic resonance imaging (MRI) showed that tumor growth was inhibited. In addition, the latent period until the appearance of neurological symptoms was significantly prolonged in rats treated with liposomes containing pSV2IFN-beta. However, the survival time of the treated rats was not significantly increased.

Defective expression of interferon-gamma, granulocyte-macrophage colony-stimulating factor, tumor necrosis factor alpha, and interleukin-6 in activated peripheral blood lymphocytes from glioma patients

The ability of a mannoprotein antigen from Candida albicans (MP) or interleukin-2 (IL-2) to induce cytokines in cultures of peripheral blood mononuclear cells (PBMC) of glioma patients and healthy controls was evaluated by mRNA expression and by protein secretion. The subjects studied were all responsive to both MP and IL-2, as assayed by lymphoproliferation of PBMC cultures. In control subjects, MP and IL-2 were strong inducers of IFN-gamma, IL-1 beta, TNF-alpha, and GM-CSF mRNA expression, but only MP was able to induce considerable levels of IL-6 and IL-2 mRNA expression. In MP-activated PBMC from glioma subjects, a highly defective IFN-gamma, together with a significant reduction in TNF-alpha and GM-CSF mRNA expression, was observed. This impairment was paralleled by a decreased accumulation of IL-6 and IL-2 mRNA. The pattern of cytokine mRNAs in IL-2-activated PBMC of glioma patients confirmed the impairment of IFN-gamma mRNA expression paralleled by a reduction in IL-6, TNF-alpha and GM-CSF mRNA, compared with healthy subjects. Coherently, in PBMC cultures from glioma patients, there was a clear-cut decrease in the secretion of IL-6 and TNF-alpha and especially of IFN-gamma compared with healthy controls. No or very low levels of IL-4, IL-10, and TGF-beta 2 mRNA expression were detected in PBMC cultures of both glioma and control populations, irrespective of the activation conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Transfer of the IL-6 gene into a human colorectal carcinoma cell line and consequent enhancement of tumor antigen expression

cDNA encoding the human IL gene (580 bp), inserted into a retroviral expression vector carrying neomycin resistance selective marker, was introduced into HT-29 human colon carcinoma cells by lipofection. Interleukin-6 activity was measured by ELISA and bioassay using B9 cells. Interleukin-6 secreted by transfected HT-29 cells was shown to be biologically active. The expression of the human tumor associated antigen CEA (carcinoembryonic antigen), HLA classes I and II, and ICAM-1 antigens in the transfected HT-29 cells were also analyzed by flow cytometry. Significant enhancement in the expression of CEA but not in the expression of HLA class I, HLA class II and ICAM-1 antigens, was observed in the transfected HT-29 cells as compared to the parental HT-29 cells. These results provide experimental evidence that enhancement of tumor antigen expression on tumor cells can be induced by IL-6 gene transfection, and suggest another potential role for the use of IL-6 gene transfer in the immunotherapy of human cancers.

Interleukin-2-responsive wound-infiltrating lymphocytes in surgical adjuvant cancer immunotherapy

Wound-infiltrating lymphocytes (WIL) were assessed in murine models of localized sarcoma and carcinoma to evaluate the role of interleukin-2 (IL-2)-responsive lymphocytes in adjuvant immunotherapy. Following tumor resection, IL-2 or diluent was injected at the surgical site for 6 days. Surgical site tissues were harvested and digested in a triple enzyme mixture, and single cell suspensions were prepared. Thy 1.2+ lymphocytes were isolated by incubating cells with monoclonal anti-Thy 1.2 antibody-coated magnetic beads. Lymphocyte-bead complexes were extracted with a magnet and cultured in medium containing IL-2 (100 units/ml) for 1-3 weeks. Perioperative IL-2 immunotherapy led to a three- to four-fold increase in WIL yield. WIL from IL-2-treated mice also demonstrated enhanced cytolysis of the autologous tumor and bound to activated endothelial cells with greater avidity than did the controls. We conclude that perioperative IL-2 therapy augments the yield, as well as the cytolytic and adhesive properties, of wound-infiltrating lymphocytes.

Factors influencing transient expression in cytotoxic T cells following DEAE dextran-mediated gene transfer

A number of transfection protocols have been tested for the introduction of exogenous DNA into cytotoxic T cells. These included electroporation, lipofection, calcium phosphate coprecipitation, polybrene-assisted gene transfer, and DEAE dextran-mediated transfer. Only the latter gave significant and reproducible transfection efficiencies coupled with low toxicity. The DEAE dextran protocol was optimized for the transfection of a transcription reporter construct pRSVcat into a cloned cytotoxic cell line. Among the parameters investigated were cell density, amount of input DNA, concentration of DEAE dextran, DNA adsorption time, temperature, use of permeabilization and expression facilitators, and recovery time. The optimized protocol was then used to demonstrate the presence of cis-acting regulatory regions in the 5'-flanking sequences of two cytotoxic cell-specific serine protease genes and, in addition, was shown to be applicable to other cloned T-cell lines.

Interferon gamma and tumor necrosis factor have a role in tumor regressions mediated by murine CD8+ tumor-infiltrating lymphocytes

We have investigated the mechanisms whereby adoptively transferred murine CD8+ lymphocytes mediate tumor regressions. Noncytolytic, CD8+ tumor-infiltrating lymphocytes (TIL) eradicated established lung tumors in irradiated mice. Many cytolytic and noncytolytic CD8+ TIL cultures specifically secreted interferon gamma (IFN-gamma) and tumor necrosis factor when stimulated with tumor cells in vitro. The effectiveness of TIL when adoptively transferred to mice bearing micrometastases correlated better with their ability to specifically secrete lymphokines than with their cytotoxicity in vitro. In 14 of 15 tests, therapeutically effective TIL specifically secreted IFN-gamma in vitro, whereas only 1 of 11 ineffective TIL specifically secreted IFN-gamma. In contrast, only 8 of 15 therapeutically effective TIL were cytolytic. Antibodies to TNF inhibited the effectiveness of two adoptively transferred TIL cultures. In five experiments, antibodies to IFN-gamma abrogated the ability of four different CD8+ TIL cultures to mediate tumor regressions, indicating that secretion of IFN-gamma is an essential part of the mechanism of action of TIL.