Interleukin-12 gene therapy prevents establishment of SCC VII squamous cell carcinomas, inhibits tumor growth, and elicits long-term antitumor immunity in syngeneic C3H mice

Oncolytic Virus-Based Cytokine Expression to Improve Immune Activity in Brain and Solid Tumors

Oncolytic viral therapy has gained significant traction as cancer therapy over the past 2 decades. Oncolytic viruses are uniquely designed both to lyse tumor cells through their replication and to recruit immune responses against virally infected cells. Increasingly, investigators are leveraging this immune response to target the immunosuppressive tumor microenvironment and improve immune effector response against bystander tumor cells. In this article, we review the spectrum of preclinical, early-stage clinical, and potential future efforts with cytokine-secreting oncolytic viruses, with a focus on the treatment of brain tumors and solid tumors.

Animal models for the study of squamous cell carcinoma of the upper aerodigestive tract: a historical perspective with review of their utility and limitations. Part A. Chemically-induced de novo cancer, syngeneic animal models of HNSCC, animal models of transplanted xenogeneic human tumors

Understanding the complex histological, genetic and molecular changes that lead to malignant transformation of squamous epithelia of the head and neck will likely guide the development of methods for improved diagnosis, monitoring and treatment of head and neck squamous cell carcinoma (HNSCC). The development and use of animal models that closely mimic the histopathology and molecular pathogenesis of HNSCC in humans would greatly expand the research possibilities and provide a means of testing potential therapeutic agents. However, many available animal models of HNSCC fall short of this objective. In order for investigators to select the appropriate model to answer scientific questions, it is important to understand the benefits and limitations of available animal models for the study of HNSCC. The purpose of this work is to give an overview of the most pertinent animal models of HNSCC, and to discuss future directions of research in this field.

Antitumor and antiangiogenic effects of interleukin 12 gene therapy in murine head and neck carcinoma model

Interleukin-12 (IL-12) plays a critical role in producing an immune response, as indicated in many ways, e.g., induction of interferon-gamma (IFN-gamma), and augmentation of the cytotoxic activity of resting activated T cells and natural killer (NK) cells. In this study, we examined whether intratumoral injection of a recombinant retrovirus vector expressing IL-12s induce antitumor and antiangiogenic effects in a murine model using a murine head and neck squamous cell carcinoma (NR-S1). In vitro the levels of vascular endothelial growth factor (VEGF) mRNA and protein expression were decreased in IL-12 gene transfected NR-S1 cell. in vivo direct IL-12 gene therapy resulted in significantly remarkable inhibition of tumor growth compared to the control group. The tumor regression by direct IL-12 gene therapy was also associated with decreased vessel density, and apoptosis and increased infiltration of CD8(+) T cells and CD56(+) NK cells in the tumor increased. Also, the number of IFN-gamma expressed cells of spleen cells was increased in the treatment group compared with the control group. These results suggested that direct IL-12 gene therapy appears to be effective in reducing tumor growth by triggering both antiangiogenic effects and an immunological enhancing mechanism through induction of IFN-gamma.

Effective Intravenous Therapy of Murine Pulmonary Metastases with an Oncolytic Herpes Virus Expressing Interleukin 12

PURPOSE

There currently is no therapy that enhances the survival of patients with distantly metastatic squamous cell carcinoma (SCC). Engineered herpes oncolytic viruses are effective therapeutic agents when delivered directly to tumors in animal models, but their efficacy in treating disseminated disease is poorly defined.

EXPERIMENTAL DESIGN

We treated disseminated pulmonary SCC in mice with an interleukin (IL)-12-expressing oncolytic herpes virus (NV1042) or with the parent oncolytic virus (NV1023, IL-12 deficient) by i.v. tail vein administration.

RESULTS

Lung IL-12 was 16.1 pg/mg and IFN-gamma was 4.3 pg/mg at day 1 after a single dose of NV1042 (5 x 10(7) plaque-forming units); levels of both were undetectable for NV1023. 5-Bromo-4-chloro-3-indolyl-beta-D-galactopyranoside histochemistry demonstrated viral infection of disseminated pulmonary tumor nodules by both vectors at day 1, with sparing of adjacent alveolar cells. NV1042-treated lungs showed no surface nodules at day 12, in contrast to NV1023-treated (92 +/- 27 surface nodules) and PBS-treated (225 +/- 9 surface nodules) lungs. Significantly enhanced survival was observed in NV1042-treated animals compared with NV1023- and PBS-treated animals (log rank < 0.05). In animals with a low tumor burden, 100% of NV1042-treated, 70% of NV1023-treated, and none of the control animals achieved long-term survival. NV1042 efficacy was similar to NV1023 efficacy in animals depleted of CD4/CD8 T lymphocytes, showing that IL-12 expression enhances oncolytic activity through immune effects. Histology showed no cytopathic effects in non-tumor-bearing lung, brain, spleen, liver, and pancreas after completion of viral therapy. No animals demonstrated any visible side effects attributable to viral therapy.

CONCLUSIONS

The i.v. delivery of an oncolytic herpes virus may achieve effective infection, oncolysis, and transgene expression at distant tumor sites. This approach to systemic therapy combining oncolysis with IL-12 immune stimulation led to significantly improved survival in animals with disseminated SCC.

Genetically engineered tumor cell vaccine in a head and neck cancer model

OBJECTIVES

Using a murine model, a novel tumor vaccine for head and neck squamous cell carcinoma expressing the granulocyte-macrophage colony stimulating factor (GM-CSF) gene was evaluated for its ability to protect against tumor challenge.

STUDY DESIGN

Mice vaccinated in the floor of the mouth with the GM-CSF tumor cell vaccine were challenged with parental tumor cells, and subsequent tumor development was monitored. Specificity of the antitumor response was demonstrated by vaccinating the mice and then challenging them with an unrelated but syngeneic radiation-induced fibrosarcoma tumor cell line, RIF. Irradiated (only) tumor cells were used as a control to see whether an augmented antitumor response was attributable to possible increased immunogenicity that could theoretically be induced by the irradiation.

METHODS

The GM-CSF gene was transduced into tumor cells via a retroviral vector. The tumor cells were irradiated to prevent replication in vivo. GM-CSF concentrations were determined using ELISA, and physiological activity was confirmed using a biological assay with a GM-CSF-dependent cell line.

RESULTS

Vaccination with genetically engineered tumor cells significantly protected against subsequent tumor challenge (5% level) when compared to control groups. Mice were not protected when vaccinated and challenged with the unrelated tumor cell line, RIF. Mice vaccinated with irradiated (only) tumor cells were not protected, either.

CONCLUSIONS

Vaccination with genetically engineered tumor cells offers significant protection from later tumor challenge. The response is systemic and tumor specific, not due to an inflammatory response. Irradiation of the tumor cells does not account for the augmented antitumor response. This work supports the continued investigation of the GM-CSF tumor vaccine for the treatment of head and neck squamous cell carcinoma.

Gene therapy for head and neck cancer

Head and neck cancer, because of its anatomic accessibility and poor overall survival rate, has become a frequent target of novel gene therapy intervention strategies. Viral and nonviral vectors have been used to transfer a variety of tumor suppressor genes, suicide genes, and immunologic genes into head and neck cancer cells in both the laboratory and clinical setting. Gene therapy as an isolated treatment modality will probably not replace standard treatment modalities in the management of head and neck cancer. It seems likely, however, that gene transfer will find its way into the multidisciplinary care of the head and neck cancer patient, where novel treatments are combined with standard therapies in order to maximize tumor response.

Head and neck cancer: gene therapy approaches. Part II: genes delivered

In Part I, the review summarised the safety of adenoviral vectors and provided insight into approaches being undertaken to improve the specificity, durability and potency of adenoviral delivery vehicles. In Part II, brief discussions are held regarding results of preclinical and clinical trials with a variety of different genes, which have demonstrated antitumour activity in squamous cell carcinoma of the head and neck region (HNSCC). Studies have been performed with a variety of immune modulatory genes. Preliminary results demonstrate activity with several cytokine genes, tumour antigen genes and co-stimulatory molecule genes. Despite only preliminary results, thus far, a theoretical attractive feature for the use of gene therapy for the enhancement of immune modulation is that local injection of the gene product appears to be well tolerated. It is also successful in inducing systemic immune response, potentially providing effect to metastatic sites distal from the injected site. Animal studies have confirmed efficacy in the use of specific targeting of molecules regulating cancer growth (EGF receptor [EGFR], super oxide dismutase [SOD], cyclin D1, E1A and Bcl-2). These approaches are discussed. However, the most significant clinical advances for the use of gene therapy in advanced HNSCC involves two agents: Adp53 and ONYX-015. Preliminary Phase I and II results suggest evidence of efficacy and justify accrual Phase III trials, which are currently ongoing.

In situ adenoviral interleukin 12 gene transfer confers potent and long-lasting cytotoxic immunity in glioma

Interleukin 12 (IL-12) isa cytokine that promotesan antitumor Th1-type pattern of differentiation in mature naïveT cells. Despite its therapeutic success in multiple animal models of cancer, the utility of systemically administered recombinant cytokine has been limited by its toxicity. This has encouraged the development of local IL-12 delivery systems through gene transfer. To determine the effect of local adenoviral delivery of IL- 12 on glioma immunogenicity, mice bearing GL-26 gliomas in the right corpus striatum were treated with direct intratumoral administration of AdmIL-12, AdLacZ, or normal saline. Survival was significantly prolonged in AdmIL-12-treated animals and immunohistochemistry demonstrated robust CD4+ and CD8+ T-cell infiltration in these mice compared to the two control groups. Glioma-infiltrating T lymphocytes from mice that received AdmIL-12 also demonstrated relatively increased, albeit statistically nonsignificant tumor killing. Based on IL-12's known ability to enhance Th1-type cytotoxic antitumor immune responses, we postulate our findings to be a result of localized induction of tumor immunity.

Characterization of a spontaneously arising murine squamous cell carcinoma (SCC VII) as a prerequisite for head and neck cancer immunotherapy

BACKGROUND

To develop novel therapeutic approaches for patients with head and neck malignancies, poorly immunogenic murine models of squamous cell carcinoma (SCC) need to be defined.

METHODS

The phenotype, growth characteristics, and responsiveness to tumor-specific T-cell transfer of a spontaneously arising murine SCC (SCC VII) were characterized.

RESULTS

SCC VII expresses major histocompatibility complex (MHC) class I molecules yet is resistant to tumor-specific T-cell killing and relatively insensitive to killing mediated by lymphokine-activated killer (LAK) cells. Intradermal tumors are reproducibly established after vaccination of 5 x 10(4) cells, and systemic micrometastases are apparent after intravenous administration of 2.5 x 10(4) cells. Immunotherapy of 3-day lung metastases using tumor-specific T cells and systemic interleukin-2 (IL-2) was ineffective in reducing the number of metastases in vivo.

CONCLUSIONS

SCC VII is a poorly immunogenic murine squamous cell cancer, which represents an ideal model for preclinical testing of immunotherapeutic approaches for patients with SCC of the upper aerodigestive tract.

Combination nonviral cytokine gene therapy for head and neck cancer

OBJECTIVE

To establish the feasibility and efficacy of combination nonviral murine interferon-alpha (mIFN-alpha)and murine interleukin-2 (mIL-2) or murine interleukin-12 (mIL-12) gene therapy for head and neck squamous cell carcinoma in a murine model.

STUDY DESIGN

Randomized controlled studies in a murine head and neck cancer model were performed to assess antitumor responses, secondary cytokine expression, and both natural killer (NK) cell and cytolytic T-cell (CTL) activity.

METHODS

Tumors were established in the floor of mouth in C3H/HeJ immunocompetent mice. Established tumors were directly injected with polymer-formulated murine interferon-alpha (mIFN-alpha), lipid-formulated mIL-2, and polymer-formulated mIL-12 alone or in combination. Primary and secondary cytokine expression,NK cell activity, and CTL activity were assayed.

RESULTS

The use of mIFN-alpha gene therapy in combination with either mIL-2 or mIL-12 resulted in significant antitumor effects as compared with each of the single cytokine and control treatment groups (P = .002). Increased levels of NK cell activity and tumor specific CD8+ cytotoxic T-lymphocyte activity were found in the combination mIFN-alpha and mIL-2 or mIL-12 groups. Augmented immune responses correlated with clinical antitumor effects.

CONCLUSIONS

The present study demonstrates that mIL-2 or mIL-12 augments tumor inhibition from mIFN-alpha and increases activation of NK and CD8+ T cells. These data support further investigation of polymer and lipid mediated delivery of cytokine genes for head and neck cancer.

Cytokine gene transfer enhances herpes oncolytic therapy in murine squamous cell carcinoma

Replication-competent, attenuated herpes simplex viruses (HSV) have been demonstrated to be effective oncolytic agents in a variety of malignant tumors. Cytokine gene transfer has also been used as immunomodulatory therapy for cancer. To test the utility of combining these two approaches, two oncolytic HSV vectors (NV1034 and NV1042) were designed to express the murine GM-CSF and murine IL-12 genes, respectively. These cytokine-carrying variants were compared with the analogous non-cytokine-carrying control virus (NV1023) in the treatment of murine SCC VII squamous cell carcinoma. All three viruses demonstrated similar infection efficiency, viral replication, and cytotoxicity in vitro. SCC VII cells infected by NV1034 and NV1042 effectively produced GM-CSF and IL-12, respectively. In an SCC VII subcutaneous flank tumor model in immunocompetent C3H/HeJ mice, intratumoral injection with each virus caused a significant reduction in tumor volume compared with saline injections. The NV1042-treated tumors showed a striking reduction in tumor volume compared with the NV1023- and NV1034-treated tumors. On subsequent rechallenge in the contralateral flank with SCC VII cells, 57% of animals treated with NV1042 failed to develop tumors, in comparison with 14% of animals treated with NV1023 or NV1034, and 0% of naive animals. The increased antitumor efficacy seen with NV1042 in comparison with NV1023 and NV1034 was abrogated by CD4(+) and CD8(+) lymphocyte depletion. NV1042 is a novel, attenuated, oncolytic herpesvirus that effectively expresses IL-12 and elicits a T lymphocyte-mediated antitumor immune response against murine squamous cell carcinoma. Such combined oncolytic and immunomodulatory strategies hold promise in the treatment of cancer.

Gene therapy for head and neck cancer

OBJECTIVES/HYPOTHESIS

New treatment methods are needed for head and neck cancer to improve survival without increasing morbidity. Gene therapy is a potential method of improving patient outcome. Progress in gene therapy for cancer is reviewed with emphasis on the limitations of vector technology and treatment strategies. Given the current technological vector limitations in transmitting the therapeutic genes, treatments that require the fewest number of cells to be altered by the new gene are optimal. Therefore an immune-based gene therapy strategy was selected in which the tumors were transfected with the gene for an alloantigen, human leukocyte antigen (HLA)-B7, a class I major histocompatibility complex (MHC). This would restore an antigen presentation mechanism in the tumor to induce an antitumor response. This gene therapy strategy was tested in patients with advanced, unresectable head and neck cancer.

STUDY DESIGN

Prospective trial.

METHODS

Twenty patients with advanced head and neck cancer who had failed conventional therapy and did not express HLA-B7 were treated with gene therapy using a lipid vector by direct intratumoral injection. The gene therapy product contained the HLA-B7 gene and the beta2-microglobulin gene, which permits complete expression of the class I MHC at the cell surface. Patients were assessed for any adverse effects, for changes in tumor size, for time to disease progression, and for survival. Biopsy specimens were assessed for pathological response, HLA-B7 expression, apoptosis, cellular proliferation, CD-8 cells, granzyme, and p53 status.

RESULTS

There were no adverse effects from the gene therapy. At 16 weeks after beginning gene therapy, four patients had a partial response and two patients had stable disease. Two of the tumors completely responded clinically, but tumor was still seen on pathological examination. The time to disease progression in the responding patients was 20 to 80 weeks. The median survival in patients who completed gene therapy was 54 weeks, compared with 21 weeks in patients whose tumors progressed after the first cycle of treatment. One patient survived for 106 weeks without any additional therapy. HLA-B7 was demonstrated in the treated tumors, and increased apoptosis was seen in the responding tumors.

CONCLUSION

Significant advances have been made in the field of gene therapy for cancer. Alloantigen gene therapy has had efficacy in the treatment of cancer and can induce tumor responses in head and neck tumors. Alloantigen gene therapy has significant potential as an adjunctive treatment of head and neck cancer.

Neoadjuvant interleukin-12 immunogene therapy protects against cancer recurrence after liver resection in an animal model

OBJECTIVE

To evaluate the neoadjuvant use of a herpes simplex viral (HSV) amplicon vector expressing the murine interleukin-12 (IL-12) gene.

SUMMARY BACKGROUND DATA

Surgery is the most effective therapy for hepatic malignancy. Recurrences, which are common, most often occur in the remnant liver and are due partly to growth of residual microscopic disease in the setting of postoperative host cellular immune dysfunction. The authors hypothesized that engineering tumors to secrete IL-12 in vivo would elicit an immune response directed at residual tumor and would reduce the incidence of recurrence after resection.

METHODS

Solitary hepatomas were established in Buffalo rat livers and directly injected with 106 particles of HSV carrying the gene for IL-12, lacZ (beta-galactosidase) or with saline. One week after injection, the animals were challenged with an intraportal injection of 106 tumor cells, with subsequent resection of the hepatic lobe containing the previously established macroscopic tumor nodule, recreating the clinical scenario of residual microscopic cancer.

RESULTS

Hepatoma cells transfected with HSV-IL-12 produced high levels of IL-12 in vitro and in vivo. A significant local immune response developed, as evidenced by a progressive increase in the number of CD4(+) and CD8(+) lymphocytes in the tumor. Treatment of established hepatomas with HSV-IL-12 protected against growth of microscopic residual cancer after hepatic resection. Sixty-four percent of the animals treated with HSV-IL-12 had zero or one tumors compared with 30% of HSVlac-treated and 24% of saline-treated animals.

CONCLUSIONS

This neoadjuvant immune strategy may prove useful in reducing the incidence of cancer recurrence after hepatic resection.

Engineered herpes simplex virus expressing IL-12 in the treatment of experimental murine brain tumors

Genetically engineered, neuroattenuated herpes simplex viruses (HSVs) expressing various cytokines can improve survival when used in the treatment of experimental brain tumors. These attenuated viruses have both copies of gamma(1)34.5 deleted. Recently, we demonstrated increased survival of C57BL/6 mice bearing syngeneic GL-261 gliomas when treated with an engineered HSV expressing IL-4, as compared with treatment with the parent construct (gamma(1)34. 5(-)) alone or with a virus expressing IL-10. Herein, we report construction of a conditionally replication-competent mutant expressing both subunits of mIL-12 (M002) and its evaluation in a syngeneic neuroblastoma murine model. IL-12 induces a helper T cell subset type 1 response, which may induce more durable antitumor effects. In vitro studies showed that, when infected with M002, both Vero cells and murine Neuro-2a neuroblastoma cells produced physiologically relevant levels of IL-12 heterodimers, as determined by ELISA. M002 was cytotoxic for Neuro-2a cells and human glioma cell lines U251MG and D54MG. Neurotoxicity studies, as defined by plaque-forming units/LD(50), performed in HSV-1-sensitive A/J strain mice found that M002 was not toxic even at high doses. When evaluated in an intracranial syngeneic neuroblastoma murine model, median survival of M002-treated animals was significantly longer than the median survival of animals treated with R3659, the parent gamma(1)34.5(-) mutant lacking any cytokine gene insert. Immunohistochemical analysis of M002-treated tumors identified a pronounced influx of CD4(+) T cells and macrophages as well as CD8(+) cells when compared with an analysis of R3659-treated tumors. We conclude that M002 produced a survival benefit via oncolytic effects combined with immunologic effects meditated by helper T cells of subset type 1.