A phase I trial of immunotherapy with intratumoral adenovirus-interferon-gamma (TG1041) in patients with malignant melanoma

Tryptophanyl-Transfer RNA Synthetase Is Involved in a Negative Feedback Loop Mitigating Interferon-γ-Induced Gene Expression

Aminoacyl-tRNA synthetases (aaRSs) are essential enzymes responsible for linking a transfer RNA (tRNA) with its cognate amino acid present in all the kingdoms of life. Besides their aminoacyl-tRNA synthetase activity, it was described that many of these enzymes can carry out non-canonical functions. They were shown to be involved in important biological processes such as metabolism, immunity, development, angiogenesis and tumorigenesis. In the present work, we provide evidence that tryptophanyl-tRNA synthetase might be involved in a negative feedback loop mitigating the expression of certain interferon-γ-induced genes. Mining the available TCGA and Gtex data, we found that WARS was highly expressed in cutaneous melanoma (SKCM) compared to other cancers and is of good prognosis for this particular cancer type. WARS expression correlates with genes involved in antigen processing and presentation but also transcription factors involved in IFN-γ signaling such as STAT1. In addition, WARS was found in complex with STAT1 in A375 cells treated with IFN-γ. Finally, we showed that knocking down WARS expression during IFN-γ stimulation further increases the expression of GBP2, APOL1, ISG15, HLA-A and IDO1.

Mathematical modeling for the combination treatment of IFN- γ and anti-PD-1 in cancer immunotherapy

When the immune-checkpoint programmed death-1 (PD-1) binds to its ligand programmed death ligand 1 (PD-L1) to form the complex PD-1-PD-L1, this complex inactivates immune cells resulting in cell apoptosis, downregulation of immune reaction, and tumor evasion. The antibody, anti-PD-1 or anti-PD-L1, blocks the PD-1-PD-L1 complex formation to restore the functions of T cells. Combination of anti-PD-1 with other treatment shows promising in different types of cancer treatments. Interferon-gamma (IFN-γ) plays an important role in immune responses. It is mainly regarded as a pro-inflammatory cytokine that promotes the proliferation of CD8⁺ T cell and cytotoxic T cell, enhances the activation of Th1 cells and CD8⁺ T cells, and enhances tumor elimination. However, recent studies have been discovering many anti-inflammatory functions of IFN-γ, such as promotion of the PD-L1 expression, T cell apoptosis, and tumor metastasis, as well as inhibition of the immune recognition and the killing rates by T cells. In this work, we construct a mathematical model incorporating pro-inflammatory and anti-inflammatory functions of IFN-γ to capture tumor growth under anti-PD-1 treatment in the wild type and IFN-γ null mutant melanoma. Our simulation results qualitatively fit experimental data that IFN-γ null mutant with anti-PD-1 obtains the highest tumor reduction comparing to IFN-γ null mutant without anti-PD-1 and wild type tumor with anti-PD-1 therapy. Moreover, our synergy analysis indicates that, in the combination treatment, the tumor volume decreases as either the dosage of anti-PD-1 increases or the IFN-γ production efficiency decreases. Thus, the combination of anti-PD-1 and IFN-γ blockade improves the tumor reduction comparing to the monotherapy of anti-PD-1 or the monotherapy of IFN-γ blockade. We also find a threshold curve of the minimal dosage of anti-PD-1 corresponding to the IFN-γ production efficiency to ensure the tumor reduction under the presence of IFN-γ.

Cytokine Responses to Adenovirus and Adenovirus Vectors

The expression of cytokines and chemokines in response to adenovirus infection is tightly regulated by the innate immune system. Cytokine-mediated toxicity and cytokine storm are known clinical phenomena observed following naturally disseminated adenovirus infection in immunocompromised hosts as well as when extremely high doses of adenovirus vectors are injected intravenously. This dose-dependent, cytokine-mediated toxicity compromises the safety of adenovirus-based vectors and represents a critical problem, limiting their utility for gene therapy applications and the therapy of disseminated cancer, where intravenous injection of adenovirus vectors may provide therapeutic benefits. The mechanisms triggering severe cytokine response are not sufficiently understood, prompting efforts to further investigate this phenomenon, especially in clinically relevant settings. In this review, we summarize the current knowledge on cytokine and chemokine activation in response to adenovirus- and adenovirus-based vectors and discuss the underlying mechanisms that may trigger acute cytokine storm syndrome. First, we review profiles of cytokines and chemokines that are activated in response to adenovirus infection initiated via different routes. Second, we discuss the molecular mechanisms that lead to cytokine and chemokine transcriptional activation. We further highlight how immune cell types in different organs contribute to synthesis and systemic release of cytokines and chemokines in response to adenovirus sensing. Finally, we review host factors that can limit cytokine and chemokine expression and discuss currently available and potential future interventional approaches that allow for the mitigation of the severity of the cytokine storm syndrome. Effective cytokine-targeted interventional approaches may improve the safety of systemic adenovirus delivery and thus broaden the potential clinical utility of adenovirus-based therapeutic vectors.

The Unitary Micro-Immunotherapy Medicine Interferon-γ (4 CH) Displays Similar Immunostimulatory and Immunomodulatory Effects than Those of Biologically Active Human Interferon-γ on Various Cell Types

As a cytokine, gamma-interferon (IFN-γ) is considered a key player in the fine-tuned orchestration of immune responses. The extreme cellular sensitivity to cytokines is attested by the fact that very few of these bioactive molecules per cell are enough to trigger cellular functions. These findings can, at least partially, explain how/why homeopathically-prepared cytokines, and especially micro-immunotherapy (MI) medicines, are able to drive cellular responses. We focused our fundamental research on a unitary MI preparation of IFN-γ, specifically employed at 4 CH, manufactured and impregnated onto sucrose-lactose pillules as all other MI medicines. We assessed the IFN-γ concentration in the medium after dilution of the IFN-γ (4 CH)-bearing pillules and we evaluated in vitro drug responses in a wide range of immune cells, and in endothelial cells. Our results showed that IFN-γ (4 CH) stimulated the proliferation, the activation and the phagocytic capabilities of primary immune cells, as well as modulated their cytokine-secretion and immunity-related markers’ expression in a trend that is quite comparable with the well-recognized biological effects induced by IFN-γ. Altogether, these data provide novel and additional evidences on MI medicines, and specifically when active substances are prepared at 4 CH, thus suggesting the need for more investigations.

Engineered Cytokines for Cancer and Autoimmune Disease Immunotherapy

Cytokine signaling is critical to a range of biological processes including cell development, tissue repair, aging, and immunity. In addition to acting as key signal mediators of the immune system, cytokines can also serve as potent immunotherapies with more than 20 recombinant products currently Food and Drug Administration (FDA)-approved to treat conditions including hepatitis, multiple sclerosis, arthritis, and various cancers. Yet despite their biological importance and clinical utility, cytokine immunotherapies suffer from intrinsic challenges that limit their therapeutic potential including poor circulation, systemic toxicity, and low tissue- or cell-specificity. In the past decade in particular, methods have been devised to engineer cytokines in order to overcome such challenges and here, the myriad strategies are reviewed that may be employed in order to improve the therapeutic potential of cytokine and chemokine immunotherapies with applications in cancer and autoimmune disease therapy, as well as tissue engineering and regenerative medicine. For clarity, these strategies are collected and presented as they vary across size scales, ranging from single amino acid substitutions, to larger protein-polymer conjugates, nano/micrometer-scale particles, and macroscale implants. Together, this work aims to provide readers with a timely view of the field of cytokine engineering with an emphasis on early-stage therapeutic approaches.

Insights into the Molecular Mechanisms Behind Intralesional Immunotherapies for Advanced Melanoma

The incidence of cutaneous melanoma, a highly malignant skin cancer, is increasing yearly. While surgical removal of the tumor is the mainstay of treatment for patients with locally confined disease, those with metastases face uncertainty when it comes to their treatment. As melanoma is a relatively immunogenic cancer, current guidelines suggest using immunotherapies that can rewire the host immune response to target melanoma tumor cells. Intralesional therapy, where immunomodulatory agents are injected directly into the tumor, are an emerging aspect of treatment for in-transit melanoma because of their ability to mitigate severe off-target immune-related adverse events. However, their immunomodulatory mechanisms are poorly understood. In this review, we will summarize and discuss the different intralesional therapies for metastatic melanoma with respect to their clinical outcomes and immune molecular mechanisms.

Combination immunotherapies implementing adoptive T-cell transfer for advanced-stage melanoma

Immunotherapy is a promising method of treatment for a number of cancers. Many of the curative results have been seen specifically in advanced-stage melanoma. Despite this, single-agent therapies are only successful in a small percentage of patients, and relapse is very common. As chemotherapy is becoming a thing of the past for treatment of melanoma, the combination of cellular therapies with immunotherapies appears to be on the rise in in-vivo models and in clinical trials. These forms of therapies include tumor-infiltrating lymphocytes, T-cell receptor, or chimeric antigen receptor-modified T cells, cytokines [interleukin (IL-2), IL-15, IL-12, granulocyte-macrophage colony stimulating factor, tumor necrosis factor-α, interferon-α, interferon-γ], antibodies (αPD-1, αPD-L1, αTIM-3, αOX40, αCTLA-4, αLAG-3), dendritic cell-based vaccines, and chemokines (CXCR2). There are a substantial number of ongoing clinical trials using two or more of these combination therapies. Preliminary results indicate that these combination therapies are a promising area to focus on for cancer treatments, especially melanoma. The main challenges with the combination of cellular and immunotherapies are adverse events due to toxicities and autoimmunity. Identifying mechanisms for reducing or eliminating these adverse events remains a critical area of research. Many important questions still need to be elucidated in regard to combination cellular therapies and immunotherapies, but with the number of ongoing clinical trials, the future of curative melanoma therapies is promising.

Interferon-Gamma at the Crossroads of Tumor Immune Surveillance or Evasion

Interferon-gamma (IFN-γ) is a pleiotropic molecule with associated antiproliferative, pro-apoptotic and antitumor mechanisms. This effector cytokine, often considered as a major effector of immunity, has been used in the treatment of several diseases, despite its adverse effects. Although broad evidence implicating IFN-γ in tumor immune surveillance, IFN-γ-based therapies undergoing clinical trials have been of limited success. In fact, recent reports suggested that it may also play a protumorigenic role, namely, through IFN-γ signaling insensitivity, downregulation of major histocompatibility complexes, and upregulation of indoleamine 2,3-dioxygenase and of checkpoint inhibitors, as programmed cell-death ligand 1. However, the IFN-γ-mediated responses are still positively associated with patient's survival in several cancers. Consequently, major research efforts are required to understand the immune contexture in which IFN-γ induces its intricate and highly regulated effects in the tumor microenvironment. This review discusses the current knowledge on the pro- and antitumorigenic effects of IFN-γ as part of the complex immune response to cancer, highlighting the relevance to identify IFN-γ responsive patients for the improvement of therapies that exploit associated signaling pathways.

Predictors of Venous Thromboembolism and Early Mortality in Lung Cancer: Results from a Global Prospective Study (CANTARISK)

BACKGROUND

Patients with lung cancer are known to be at increased risk for venous thromboembolism (VTE). Venous thromboembolism is associated with increased risk for early mortality. However, there have been no studies performing a comprehensive assessment of risk factors for VTE or early mortality in lung cancer patients undergoing systemic chemotherapy in a global real-world setting.

MATERIALS AND METHODS

CANTARISK is a prospective, global, noninterventional cohort study including patients with lung cancer initiating a new cancer therapy. Clinical data were collected until 6-month follow-up. The impact of patient-, disease-, and treatment-related factors on the occurrence of VTE and early mortality was evaluated in univariable and multivariable Cox regression analyses. A previously validated VTE risk score (VTE-RS) was also calculated (also known as Khorana score).

RESULTS

Of 1,980 patients with lung cancer who were enrolled from 2011 to 2012, 84% had non-small cell lung cancer. During the first 6 months, 121 patients developed a VTE (6.1%), of which 47% had pulmonary embolism, 46% deep vein thrombosis, 3% catheter-associated thrombosis, and 4% visceral thrombosis. Independent predictors for VTE included female sex, North America location, leg immobilization, and presence of a central venous catheter. The VTE-RS was not significantly associated with VTE in either univariable or multivariable analysis in this population. During the study period, 472 patients died, representing 20%, 24%, 36%, and 25% with VTE-RS 1, 2, ≥3, or unknown, respectively (p < .0001). Significant independent predictors of early mortality include older age, current/former smoking, chronic obstructive pulmonary disease, Eastern Cooperative Oncology Group performance status ≥2, no prior surgery, and metastatic disease, as well as the VTE-RS.

CONCLUSION

In this global, prospective, real-world analysis, several demographic, geographic, and clinical factors are independent risk factors for VTE and early mortality in patients with lung cancer. The VTE-RS represents a significant independent predictor of early mortality but not for VTE in lung cancer in the era of targeted therapy.

IMPLICATIONS FOR PRACTICE

Multiple risk factors for both venous thromboembolism (VTE) and early mortality in patients with lung cancer receiving systemic chemotherapy should guide best practice by better informing clinical evaluation and treatment decision-making. The Khorana risk score is of value in assessing the risk of early all-cause mortality along with other clinical parameters in patients with lung cancer receiving systemic therapy. Further study is needed to fully evaluate the validity of the risk score in predicting the risk of VTE in the modern era of lung cancer therapy.

Surgical immune interventions for solid malignancies

BACKGROUND

The purpose of this study was to systematically review clinically translatable immunotherapeutic agents that are delivered regionally for solid malignancies.

DATA SOURCES

PubMed and ClinicalTrials.gov were searched for published and registered clinical trials, respectively. The search yielded 334 relevant publications, of which 116 articles were included for review after exclusion criteria were applied.

CONCLUSIONS

There has been an increase in the regional administration of cell-based and viral vector-based clinical trials over the last 5 years. Surgical interventions have been developed for intrapleural, intracranial, intraperitoneal, and intratumoral routes of access to enhance the local delivery of these therapies. Multimodality therapies that combine regional immunotherapy with other local and systemic therapies are demonstrating continued growth as the field of immunotherapy continues to expand.

A Validated Risk Score for Venous Thromboembolism Is Predictive of Cancer Progression and Mortality

BACKGROUND

Retrospective studies have suggested an association between cancer-associated venous thromboembolism (VTE) and patient survival. We evaluated a previously validated VTE Clinical Risk Score in also predicting early mortality and cancer progression.

METHODS

A large, nationwide, prospective cohort study of adults with solid tumors or lymphoma initiating chemotherapy was conducted from 2002 to 2006 at 115 U.S. practice sites. Survival and cancer progression were estimated by the method of Kaplan and Meier. Multivariate analysis was based on Cox regression analysis adjusted for major prognostic factors including VTE itself.

RESULTS

Of 4,405 patients, 134 (3.0%) died and 330 (7.5%) experienced disease progression during the first 4 months of therapy (median follow-up 75 days). Patients deemed high risk (n = 540, 12.3%) by the Clinical Risk Score had a 120-day mortality rate of 12.7% (adjusted hazard ratio [aHR] 3.00, 95% confidence interval [CI] 1.4-6.3), and intermediate-risk patients (n = 2,665, 60.5%) had a mortality rate of 5.9% (aHR 2.3, 95% CI 1.2-4.4) compared with only 1.4% for low-risk patients (n = 1,200, 27.2%). At 120 days of follow-up, cancer progression occurred in 27.2% of high-risk patients (aHR 2.2, 95% CI 1.4-3.5) and 16.4% of intermediate-risk patients (aHR 1.9, 95% CI 1.3-2.7) compared with only 8.5% of low-risk patients (p < .0001).

CONCLUSION

The Clinical Risk Score, originally developed to predict the occurrence of VTE, is also predictive of early mortality and cancer progression during the first four cycles of outpatient chemotherapy, independent from other major prognostic factors including VTE itself. Ongoing and future studies will help determine the impact of VTE prophylaxis on survival.

IMPLICATIONS FOR PRACTICE

The risk of venous thromboembolism (VTE) is increased in patients receiving cancer chemotherapy. In this article, the authors demonstrate that a popular risk score for VTE in patients with cancer is also associated with the risk of early mortality in this setting. It is important that clinicians evaluate the risk of VTE in patients receiving cancer treatment and discuss the risk and associated symptoms of VTE with patients. Individuals at increased risk should be advised that VTE is a medical emergency and should be urgently diagnosed and appropriately treated to reduce the risk of serious and life-threatening complications.

Adoptive T cell therapy combined with intralesional administrations of TG1042 (adenovirus expressing interferon-γ) in metastatic melanoma patients

Tumor immune escape has recently been shown to be related to the development of an immune tolerance state of the microenvironment. Cytokines activating the immune system such as IFN-γ can be used to reverse the immune escape and thus to potentiate the efficacy of immunotherapy. A clinical study was conducted in 18 stage IIIc/IV melanoma patients treated with tumor-infiltrating lymphocytes (TILs) in combination with intratumoral TG1042 injection (adenovirus expressing IFN-γ). The primary objective was to investigate the safety of treatment. Secondary objectives were to study the clinical response and translational research. The treatment was well tolerated. Among the 13 patients evaluable for tumor response, 38.5% had an overall objective response (OOR = CR + PR) and disease control rate (DCR = CR + PR + S) of 46%. The clinical response of the 37 targeted lesions led to an OOR of 51% and a DCR of 75%. Translational research on predictive markers did not significantly differ between responder and non-responder patients. However, specifically regarding injected lesions, the clinical response correlated with CD3-/CD56+ NK cells which could be activated by TG1042. Further larger studies of this combined immunotherapy are needed to confirm our findings. Intralesional TG1042 combined with antigen-selected TILs should be discussed.

Intratumoral immunotherapy for melanoma

Selection of suitable tumor-associated antigens is a major challenge in the development of effective cancer vaccines. Intratumoral (i.t.) immunotherapy empowers the immune system to mount T cell responses against tumor-associated antigens which are most immunogenic. To mediate systemic tumor regression, i.t. immunotherapy must generate systemic T cell responses that can target distant metastases beyond the initially treated tumor mass. Now that promising preclinical results and some initial success in clinical trials have been obtained, we here review i.t. immunotherapy-related preclinical and clinical studies, their mechanisms of action and future prospects.

Trial watch: DNA vaccines for cancer therapy

The foundation of modern vaccinology dates back to the 1790s, when the English physician Edward Jenner uncovered the tremendous medical potential of prophylactic vaccination. Jenner’s work ignited a wave of nationwide vaccination campaigns abating the incidence of multiple life-threatening infectious diseases and culminating with the eradication of natural smallpox virus, which was definitively certified by the WHO in 1980. The possibility of using vaccines against cancer was first proposed at the end of the 19th century by Paul Ehrlich and William Coley. However, it was not until the 1990s that such a hypothesis began to be intensively investigated, following the realization that the immune system is not completely unresponsive to tumors and that neoplastic cells express immunogenic tumor-associated antigens (TAAs). Nowadays, anticancer vaccines are rapidly moving from the bench to the bedside, and a few prophylactic and therapeutic preparations have already been approved by FDA for use in humans. In this setting, one interesting approach is constituted by DNA vaccines, i.e., TAA-encoding circularized DNA constructs, often of bacterial origin, that are delivered to patients as such or by means of specific vectors, including (but not limited to) liposomal preparations, nanoparticles, bacteria and viruses. The administration of DNA vaccines is most often performed via the intramuscular or subcutaneous route and is expected to cause (1) the endogenous synthesis of the TAA by myocytes and/or resident antigen-presenting cells; (2) the presentation of TAA-derived peptides on the cell surface, in association with MHC class I molecules; and (3) the activation of potentially therapeutic tumor-specific immune responses. In this Trial Watch, we will summarize the results of recent clinical trials that have evaluated/are evaluating DNA vaccines as therapeutic interventions against cancer.

Trial Watch: DNA vaccines for cancer therapy

During the past 2 decades, the possibility that preparations capable of eliciting tumor-specific immune responses would mediate robust therapeutic effects in cancer patients has received renovated interest. In this context, several approaches to vaccinate cancer patients against their own malignancies have been conceived, including the administration of DNA constructs coding for one or more tumor-associated antigens (TAAs). Such DNA-based vaccines conceptually differ from other types of gene therapy in that they are not devised to directly kill cancer cells or sensitize them to the cytotoxic activity of a drug, but rather to elicit a tumor-specific immune response. In spite of an intense wave of preclinical development, the introduction of this immunotherapeutic paradigm into the clinical practice is facing difficulties. Indeed, while most DNA-based anticancer vaccines are well tolerated by cancer patients, they often fail to generate therapeutically relevant clinical responses. In this Trial Watch, we discuss the latest advances on the use of DNA-based vaccines in cancer therapy, discussing the literature that has been produced around this topic during the last 13 months as well as clinical studies that have been launched in the same time frame to assess the actual therapeutic potential of this intervention.

Adenovirus-mediated delivery of the human IFN-γ gene potentiates the cytotoxicity of daunorubicin against leukemic cells through downregulation of the α4β1 integrin/ILK/apoptosis pathway

The recurrence of acute myeloid leukemia (AML) is primarily attributed to drug resistance and minimal residual disease. In addition, adhesion of hematopoietic tumor cells to bone marrow extracellular matrix via β1 integrins (α4β1 and α5β1) is crucial in this process. In the current study, the viability and antiapoptotic ability of U937 cells exposed to daunorubicin (DNR) were shown to be enhanced when cocultured with the mesenchymal stem cells (MSCs) or MSCs transduced with a recombinant adeno-LacZ vector (MSCs-LacZ), followed by upregulation of the adhesion rate of leukemic cells. Notably, cell viability, antiapoptotic and adhesive ability were reversed when U937 cells were cocultured with the MSCs transduced with a recombinant adeno-IFN-γ vector (MSCs-IFN-γ). Transwell assay showed that cell-cell contact is essential for the protective effects of unmodified MSC and the antitumor effects of IFN-γ-expressing MSCs. Western blot analysis and caspase activity assay results indicated that the α4β1 integrin/ILK/apoptosis pathway contributes to the combination effects of DNR and MSCs-IFN-γ, which was further confirmed by the results of the α4β1 integrin siRNA experiments. Thus, gene-modified MSCs expressing IFN-γ may enhance the cytotoxicity of DNR against leukemic cells through downregulation of the α4β1 pathway and may present a novel promising therapeutic strategy for AML.

Adenovirus-Based Vectors for the Development of Prophylactic and Therapeutic Vaccines

Emerging and reemerging infectious diseases as well as cancer pose great global health impacts on the society. Vaccines have emerged as effective treatments to prevent or reduce the burdens of already developed diseases. This is achieved by means of activating various components of the immune system to generate systemic inflammatory reactions targeting infectious agents or diseased cells for control/elimination. DNA virus-based genetic vaccines gained significant attention in the past decades owing to the development of DNA manipulation technologies, which allowed engineering of recombinant viral vectors encoding sequences for foreign antigens or their immunogenic epitopes as well as various immunomodulatory molecules. Despite tremendous progress in the past 50 years, many hurdles still remain for achieving the full clinical potential of viral-vectored vaccines. This chapter will present the evolution of vaccines from “live” or “attenuated” first-generation agents to recombinant DNA and viral-vectored vaccines. Particular emphasis will be given to human adenovirus (Ad) for the development of prophylactic and therapeutic vaccines. Ad biological properties related to vaccine development will be highlighted along with their advantages and potential hurdles to be overcome. In particular, we will discuss (1) genetic modifications in the Ad capsid protein to reduce the intrinsic viral immunogenicity, (2) antigen capsid incorporation for effective presentation of foreign antigens to the immune system, (3) modification of the hexon and fiber capsid proteins for Ad liver de-targeting and selective retargeting to cancer cells, (4) Ad-based vaccines carrying “arming” transgenes with immunostimulatory functions as immune adjuvants, and (5) oncolytic Ad vectors as a new therapeutic approach against cancer. Finally, the combination of adenoviral vectors with other non-adenoviral vector systems, the prime/boost strategy of immunization, clinical trials involving Ad-based vaccines, and the perspectives for the field development will be discussed.

Gene immunotherapy of chronic lymphocytic leukemia: a phase I study of intranodally injected adenovirus expressing a chimeric CD154 molecule

New therapies for chronic lymphocytic leukemia (CLL) are needed, particularly those that can eradicate residual disease and elicit anti-CLL immune responses. CD40 ligation on CLL cells, which can be achieved using adenovirus encoding chimeric CD154 (Ad-ISF35), enhances their ability to function as antigen-presenting cells and increases their sensitivity to clearance by immune-effector mechanisms. In this study, we report the results of a first-in-man phase I trial of intranodal direct injection (IDI) of Ad-ISF35 in patients with CLL to evaluate toxicity, safety, and tolerability. Fifteen patients received a single IDI of 1 × 10(10) to 33 × 10(10) Ad-ISF35 viral particles (vp), with a defined maximum tolerated dose as 1 × 10(11) vp. Although the most common adverse events were transient grade 1 to 2 pain at the injection site and flu-like symptoms following IDI, some patients receiving the highest dose had transient, asymptomatic grade 3 to 4 hypophosphatemia, neutropenia, or transaminitis. Increased expression of death receptor, immune costimulatory molecules, and Ad-ISF35 vector DNA was detected in circulating CLL cells. Notably, we also observed preliminary clinical responses, including reductions in leukemia cell counts, lymphadenopathy, and splenomegaly. Six patients did not require additional therapy for more than 6 months, and three achieved a partial remission. In conclusion, Ad-ISF35 IDI was safely delivered in patients with CLLs and induced systemic biologic and clinical responses. These results provide the rationale for phase II studies in CLLs, lymphomas, and CD40-expressing solid tumors.

IL-18 inhibits growth of murine orthotopic prostate carcinomas via both adaptive and innate immune mechanisms

Interleukin(IL)-18 is a pleiotrophic cytokine with functions in immune modulation, angiogenesis and bone metabolism. In this study, the potential of IL-18 as an immunotherapy for prostate cancer (PCa) was examined using the murine model of prostate carcinoma, RM1 and a bone metastatic variant RM1(BM)/B4H7-luc. RM1 and RM1(BM)/B4H7-luc cells were stably transfected to express bioactive IL-18. These cells were implanted into syngeneic immunocompetent mice, with or without an IL-18-neutralising antibody (αIL-18, SK113AE4). IL-18 significantly inhibited the growth of both subcutaneous and orthotopic RM1 tumors and the IL-18 neutralizing antibody abrogated the tumor growth-inhibition. In vivo neutralization of interferon-gamma (IFN-γ) completely eliminated the anti-tumor effects of IL-18 confirming an essential role of IFN-γ as a down-stream mediator of the anti-tumor activity of IL-18. Tumors from mice in which IL-18 and/or IFN-γ was neutralized contained significantly fewer CD4⁺ and CD8⁺ T cells than those with functional IL-18. The essential role of adaptive immunity was demonstrated as tumors grew more rapidly in RAG1^−/− mice or in mice depleted of CD4⁺ and/or CD8⁺ cells than in normal mice. The tumors in RAG1^−/− mice were also significantly smaller when IL-18 was present, indicating that innate immune mechanisms are involved. IL-18 also induced an increase in tumor infiltration of macrophages and neutrophils but not NK cells. In other experiments, direct injection of recombinant IL-18 into established tumors also inhibited tumor growth, which was associated with an increase in intratumoral macrophages, but not T cells. These results suggest that local IL-18 in the tumor environment can significantly potentiate anti-tumor immunity in the prostate and clearly demonstrate that this effect is mediated by innate and adaptive immune mechanisms.

Re-inventing intratumoral immunotherapy for melanoma

Immunotherapeutics have been applied intratumorally to manage accessible lesions and to induce systemic immunity in malignant melanoma. Intratumoral bacillus Calmette-Guérin (BCG) has been used for 40 years, and intratumoral BCG, IL-2, IFN-α and imiquimod are recommended as treatment options for patients with in-transit melanoma metastases. Regression of cutaneous metastases can be achieved. Subcutaneous metastases are more refractory, and regression of uninjected, visceral metastases is infrequent. Other microbial products, cytokines, chemicals, immune cells, antibody and viral and plasmid vectors expressing immunologically active molecules have been tested. Antitumor activity has not been demonstrated to be superior to that of intratumoral BCG. There are few controlled trials, and whether survival is impacted with any approach has not yet been established. The immunotherapeutics applied and the intratumoral administration procedure itself can activate responses that are immune inhibitory. More rigorous clinical testing and improved understanding and modulation of regulatory immune responses are necessary.

Development of viral vectors for gene therapy for chronic pain

Chronic pain is a major health concern that affects millions of people. There are no adequate long-term therapies for chronic pain sufferers, leading to significant cost for both society and the individual. The most commonly used therapy for chronic pain is the application of opioid analgesics and nonsteroidal anti-inflammatory drugs, but these drugs can lead to addiction and may cause side effects. Further studies of the mechanisms of chronic pain have opened the way for development of new treatment strategies, one of which is gene therapy. The key to gene therapy is selecting safe and highly efficient gene delivery systems that can deliver therapeutic genes to overexpress or suppress relevant targets in specific cell types. Here we review several promising viral vectors that could be applied in gene transfer for the treatment of chronic pain and further discuss the possible mechanisms of genes of interest that could be delivered with viral vectors for the treatment of chronic pain.

Transformation of SV40-immortalized human uroepithelial cells by 3-methylcholanthrene increases IFN- and Large T Antigen-induced transcripts

BACKGROUND

Simian Virus 40 (SV40) immortalization followed by treatment of cells with 3-methylcholanthrene (3-MC) has been used to elicit tumors in athymic mice. 3-MC carcinogenesis has been thoroughly studied, however gene-level interactions between 3-MC and SV40 that could have produced the observed tumors have not been explored. The commercially-available human uroepithelial cell lines were either SV40-immortalized (HUC) or SV40-immortalized and then 3-MC-transformed (HUC-TC).

RESULTS

To characterize the SV40 - 3MC interaction, we compared human gene expression in these cell lines using a human cancer array and confirmed selected changes by RT-PCR. Many viral Large T Antigen (Tag) expression-related changes occurred in HUC-TC, and it is concluded that SV40 and 3-MC may act synergistically to transform cells. Changes noted in IFP 9-27, 2'-5' OAS, IF 56, MxA and MxAB were typical of those that occur in response to viral exposure and are part of the innate immune response. Because interferon is crucial to innate immune host defenses and many gene changes were interferon-related, we explored cellular growth responses to exogenous IFN-gamma and found that treatment impeded growth in tumor, but not immortalized HUC on days 4 - 7. Cellular metabolism however, was inhibited in both cell types. We conclude that IFN-gamma metabolic responses were functional in both cell lines, but IFN-gamma anti-proliferative responses functioned only in tumor cells.

CONCLUSIONS

Synergism of SV40 with 3-MC or other environmental carcinogens may be of concern as SV40 is now endemic in 2-5.9% of the U.S. population. In addition, SV40-immortalization is a generally-accepted method used in many research materials, but the possibility of off-target effects in studies carried out using these cells has not been considered. We hope that our work will stimulate further study of this important phenomenon.

Clinical Use of Interferon-gamma

Interferon gamma (IFN-gamma), a pleotropic cytokine, has been shown to be important to the function of virtually all immune cells and both innate and adaptive immune responses. In 1986, early clinical trials of this cytokine began to evaluate its therapeutic potential. The initial studies focused on the tolerability and pharmacology of IFN-gamma and systematically determined its antitumor and anti-infection activities. In the 20-plus years since those first trials, IFN-gamma has been used in a wide variety of clinical indications, which are reviewed in this article.

Generation of human dendritic cells that simultaneously secrete IL-12 and have migratory capacity by adenoviral gene transfer of hCD40L in combination with IFN-gamma

Dendritic cells (DCs) are professional antigen presenting cells and have key functions in the initiation of immune responses. Hence, antigen-loaded DCs have become important tools for active-specific immunotherapy. In addition to defining strategies for antigen loading, effective T-cell activation by DCs will depend on vaccination protocols that facilitate DC migration to secondary lymphoid tissues and expression of costimulatory molecules and cytokines. Adenoviral gene transfer has been successfully implemented for genetic antigen loading of DCs. In this study, we exploit an adenoviral vector encoding human CD40 ligand (CD40L), Ad5hCD40L, to establish DCs that feature both migration potential and prolonged secretion of the key T-helper 1 cytokine interleukin-12p70 (IL-12p70). Transduction of human monocyte-derived DCs with Ad5hCD40L resulted in efficient CD40L expression, which was detected only intracellularly, and in secretion of IL-12p70. Addition of recombinant interferon (IFN)-gamma shortly after DC transduction substantially increased IL-12p70 secretion. Maturation of DCs was achieved with a standard cytokine maturation cocktail (MC) containing prostaglandin E2 which, however, abolished IL-12p70 secretion by Ad5hCD40L-transduced cells in the absence of IFN-gamma. Only DCs treated with Ad5hCD40L, MC, and IFN-gamma migrated efficiently towards CCL19 and continued to secrete IL-12p70. Finally, DCs transduced with both Ad5hCD40L and an adenoviral vector encoding the melanoma antigen MelanA/MART-1 and treated with MC and IFN-gamma efficiently primed naive autologous CD8+ T cells into antigen-specific cytotoxic T lymphocyte. This strategy to generate DCs that exert both migration capacity and prolonged IL-12p70 secretion after intracellular CD40L expression and IFN-gamma treatment has the potential to further improve current DC vaccination protocols.

Effects of methyl-beta-cyclodextrin treatment on secretion profile of interferon-beta and zonula occuludin-1 architecture in Madin-Darby canine kidney cell monolayers

The interferon (IFN) is a paradigm of secretory protein. However, it has been poorly understood how its secretion is regulated in polarized epithelial cells. Recently, we had shown that exogenous IFNs transiently expressed in polarized monolayers were predominantly secreted to the side on which gene transfection had been performed, while stably expressed IFNs were secreted almost equally to the both cell sides. Since those modes of secretion did not affect each other, epithelial cell layers seemed to have at least two protein sorting/secretion pathways, one for transient expression and the other for stable expression, for identical secretory proteins. Furthermore, this dual secretion profile seemed to be mediated by distinct post-trans Golgi network vesicles, suggesting the involvement of lipid rafts in the sorting multiplicity. To address this issue, here we studied the effects of cholesterol depletion with methyl-beta-cyclodextrin (MbetaCD) on the secretion profile of IFN-beta exogenously expressed in Madin-Darby canine kidney (MDCK) cells. The MbetaCD-treatment, however, did not affect the profile in either transient or stable expression, although the architecture of zonula occuludin-1, which links to the tight junction, was substantially disrupted by the treatment. Further analysis of Triton X-100-insoluble cell extracts by sucrose density centrifugation demonstrated that IFN-beta was not apparently associated with lipid rafts in either transient or stable expression. These results suggest that lipid rafts may not be crucially involved in the regulation of secretion polarity of IFN-beta in the epithelial cells.

Adenoviral vector-based strategies for cancer therapy

Definitive treatment of cancer has eluded scientists for decades. Current therapeutic modalities like surgery, chemotherapy, radiotherapy and receptor-targeted antibodies have varied degree of success and generally have moderate to severe side effects. Gene therapy is one of the novel and promising approaches for therapeutic intervention of cancer. Viral vectors in general and adenoviral (Ad) vectors in particular are efficient natural gene delivery systems and are one of the obvious choices for cancer gene therapy. Clinical and preclinical findings with a wide variety of approaches like tumor suppressor and suicide gene therapy, oncolysis, immunotherapy, anti-angiogenesis and RNA interference using Ad vectors have been quite promising, but there are still many hurdles to overcome. Shortcomings like increased immunogenicity, prevalence of preexisting anti-Ad immunity in human population and lack of specific targeting limit the clinical usefulness of Ad vectors. In recent years, extensive research efforts have been made to overcome these limitations through a variety of approaches including the use of conditionally-replicating Ad and specific targeting of tumor cells. In this review, we discuss the potential strengths and limitations of Ad vectors for cancer therapy.

Langerhans cells and dendritic cells are cytotoxic towards HPV16 E6 and E7 expressing target cells

Dendritic cells (DC) can be cytotoxic towards tumor cells by means of TNF family molecules expressed on the cell surface of activated DCs. Tumor cells expressing appropriate receptors are killed by DC, generating a source of antigen to be presented to the immune system. It has not been investigated whether Langerhans cells (LC) are selectively cytotoxic to tumor cells. This is of particular interest for epithelial tumor cells that physically interact with LC in vivo. Among epithelial tumors, the oncogenic process of cervical tumors is relatively well defined by their Human Papillomavirus (HPV) mediated etiology. To study whether HPV16 E6 and E7 expressions, otherwise observed in cervical tumor cells, can sensitize normal cervical epithelial cells to DC and LC mediated killing, the E6 and E7 genes were introduced by retroviral transfection, and cells were subsequently used as targets in cytotoxicity assays. Expression of cytotoxic molecules by effector cells was measured in response to the pro-inflammatory cytokine IFN-gamma; cytotoxicity was established and concomitant expression of receptor molecules was assessed on target cells. A correlation between the shrinkage of HPV16 E6 and E7+ tumors versus DC and LC infiltration was evaluated in a murine model of cervical cancer. DC and LC proved to be equally cytotoxic towards E6 and E7 expressing cervical epithelial cells. IFN-gamma induced TRAIL expression by DC and LC, and inhibition of TRAIL partially blocked cytotoxic effects. Expression of TRAIL decoy receptors was reduced following introduction of E6 and E7 into host cells. Shrinkage of HPV16 E6 and E7 expressing tumors correlated with infiltration by S100+ DC and LC, co-localizing with apoptotic mouse tumor cells. In conclusion, DC and LC mediated killing may be exploitable for anti-tumor treatment.

Targeted delivery of murine IFN-gamma using a recombinant fowlpox virus: NK cell recruitment to regional lymph nodes and priming of tumor-specific host immunity

Interferon-gamma (IFN-gamma) is a proinflammatory cytokine that also acts as a potent immunomodulatory agent. In this study, a replication-deficient recombinant avian (fowlpox) virus was engineered to express the murine IFN-gamma gene (rF-MuIFN-gamma) with the rationale of delivering concentrated levels of the cytokine to a local tissue microenvironment. Subcutaneous (s.c.) rF-MuIFN-gamma administration resulted in IFN-gamma production that (1) was restricted to the tissue microenvironment of the injection site and (2) was biologically active, as evidenced by a significant increase of class I MHC expression levels in s.c. growing tumors following rF-MuIFN-gamma administration. Infection of a highly tumorigenic murine cell line, MC38, with rF-MuIFN-gamma functioned as an effective tumor cell-based vaccine by protecting mice from the formation of primary tumors and from subsequent tumor challenge. The cell-based vaccine was completely ineffective if mice were vaccinated with MC38 cells either pretreated with rIFN-gamma or infected with the wild-type fowlpox virus (FP-WT). Analysis of the regional lymph nodes draining the site of injection of the rF-MuIFN-gamma-based tumor cell vaccine revealed the presence of tumor-specific cell lysis (CTL) as well as a significant amount of lysis directed at natural killer (NK)-sensitive YAC-1 cells. Flow cytometric analyses coupled with functional assays confirmed the sustained presence of NK1.1(+) cells within those draining lymph nodes for up to 5 days after rF-MuIFN-gamma injection. Mice treated with NK cell-depleting antibodies prior to the injection of the rF-MuIFN-gamma-infected MC38 tumor cells were not protected from primary tumor growth; analysis of the lymph nodes draining the injection site in NK-depleted mice revealed an accompanying loss of the tumor-specific CTL activity. The findings provide evidence that NK cells, known for their contributions to host innate immunity, also provide immunoregulatory signals required for the development of an adaptive immune response, which, in turn, protected vaccinated mice against tumor growth.

Minicircle-IFNgamma induces antiproliferative and antitumoral effects in human nasopharyngeal carcinoma

PURPOSE

The aims of this work were to investigate the antitumor effect of IFNgamma gene transfer on human nasopharyngeal carcinoma (NPC) and to assess the potential of minicircle vector for antitumor gene therapy.

EXPERIMENTAL DESIGN

We developed a recombinant minicircle vector carrying the human IFNgamma gene and evaluated the effects of minicircle-mediated IFNgamma gene transfer on NPC cell lines in vitro and on xenografts in vivo.

RESULTS

Relative to p2PhiC31-IFNgamma, minicircle-mediated IFNgamma gene transfer in vitro resulted in 19- to 102-fold greater IFNgamma expression levels in transfected cells (293, NIH 3T3, CNE-1, CNE-2, and C666-1) and inhibited the growth of CNE-1, CNE-2, and C666-1 cells more efficiently, reducing relative growth rates to 7.1 +/- 1.6%, 2.7 +/- 1.0%, and 6.1 +/- 1.6%, respectively. Flow cytometry and caspase-3 activity assays suggested that the antiproliferative effects of IFNgamma gene transfer on NPC cell lines could be attributed to G(0)-G(1) arrest and apoptosis. Minicircle-mediated intratumoral IFNgamma expression in vivo was 11 to 14 times higher than p2PhiC31-IFNgamma in CNE-2- and C666-1-xenografted mice and lasted for 21 days. Compared with p2PhiC31-IFNgamma treatment, minicircle-IFNgamma treatment significantly increased survival and achieved inhibition rates of 77.5% and 83%, respectively.

CONCLUSIONS

Our data indicate that IFNgamma gene transfer exerts antiproliferative effects on NPC cells in vitro and leads to a profound antitumor effect in vivo. Minicircle-IFNgamma is more efficient than corresponding conventional plasmids due to its capability of mediating long-lasting high levels of IFNgamma gene expression. Therefore, minicircle-mediated IFNgamma gene transfer is a promising novel approach in the treatment of NPC.

An inventory of shedding data from clinical gene therapy trials

Viruses are the most commonly used vectors for clinical gene therapy. The risk of dissemination of a viral vector into the environment via excreta from the treated patient, a phenomenon called shedding, is a major safety concern for the environment. Despite the significant number of clinical gene therapy trials that have been conducted worldwide, there is currently no overview of actual shedding data available. In this article, an inventory of shedding data obtained from a total of 100 publications on clinical gene therapy trials using retroviral, adenoviral, adeno-associated viral and pox viral vectors is presented. In addition, the experimental set-up for shedding analysis including the assays used and biological materials tested is summarized. The collected data based on the analysis of 1619 patients in total demonstrate that shedding of these vectors occurs in practice, mainly determined by the type of vector and the route of vector administration. Due to the use of non-quantitative assays, the lack of information on assay sensitivity in most publications, and the fact that assay sensitivity is expressed in various ways, general conclusions cannot be made as to the level of vector shedding. The evaluation of the potential impact and consequences of the observations is complicated by the high degree of variety in the experimental design of shedding analysis between trials. This inventory can be supportive to clinical gene therapy investigators for the establishment of an evidence-based risk assessment to be included in a clinical protocol application, as well as to national regulatory authorities for the ongoing development of regulatory guidelines regarding gene therapy.

Adhesion molecules in cutaneous immunity

Skin serves a vital role, providing protection from the broad array of pathogens present in our environment. In addition to the passive barrier functions of the skin, mammals have evolved a robust and versatile surveillance and rapid response system for recognition and elimination of invading organisms. This immune surveillance network directs the movement of immune cells, regulating homeostatic populations of immune cells in the skin, as well as recruitment to sites of inflammation. In this review, we discuss current understanding of the regulation and function of adhesion molecules in cutaneous immune surveillance and their relevance to the immunopathology of inflammatory skin disease.

T-Cell Distribution and Adhesion Receptor Expression in Metastatic Melanoma

PURPOSE

Metastatic malignant melanoma is a devastating disease with a poor prognosis. Recent therapeutic trials have focused on immunotherapy to induce development of endogenous antitumor immune responses. To date, such protocols have shown success in activation of tumor-specific CTL but no overall improvement in survival. To kill tumor, antigen-specific CTL must efficiently target and enter tumor tissue. The purpose of this study was to examine the pathway of leukocyte migration to metastatic melanoma.

EXPERIMENTAL DESIGN

Peripheral blood and metastatic melanoma tissues (n = 65) were evaluated for expression of adhesion molecules using immunohistochemistry of tumor sections and flow cytometry of tumor-associated and peripheral blood CTL and compared with healthy controls. CTL expressing T-cell receptors for the melanoma antigen MART-1 were identified in a subset of samples by reactivity with HLA-A2 tetramers loaded with MART-1 peptide.

RESULTS

Results show that the majority of metastatic melanoma samples examined do not express the vascular adhesion receptors E-selectin (CD62E), P-selectin (CD62P), and intercellular adhesion molecule-1 (CD54) on vessels within the tumor boundaries. Strong adhesion receptor expression was noted on vessels within adjacent tissue. Tumor-associated T lymphocytes accumulate preferentially in these adjacent areas and are not enriched for skin- or lymph node-homing receptor phenotype.

CONCLUSION

Expression of leukocyte homing receptors is dysregulated on the vasculature of metastatic melanoma. This results in a block to recruitment of activated tumor-specific CTL to melanoma metastases and is a likely factor limiting the effectiveness of current immunotherapy protocols.

Cytokine gene transfer for cancer therapy

The possibility of inducing a strong immune response to impair tumor growth by ectopically expressing cytokines, followed by the generation of an antitumor memory raised great hopes and enthusiasm as a therapeutic approach. However, the efficacy of this strategy on established tumor models appeared low and the initial results in the clinics were disappointing. Recently, new evidence indicates that cytokine gene combination or the combined use of cytokine genes with additional gene therapy approaches induces a synergistic effect supporting the use of cytokine gene therapy to improve the clinical outcome for cancer patients.

Angiogenesis meets immunology: Cytokine gene therapy of cancer

Delivery of cytokine genes at the tumor site in pre-clinical models has been shown to recruit host inflammatory cells followed by inhibition of tumor growth. This local effect is often accompanied by systemic protection mediated by the immune system, mainly by CD8(+) T and NK cells. On this basis, cytokine gene-transduced tumor cells have widely been used as vaccines in clinical trials, which have shown good safety profiles and some local responses but substantial lack of systemic efficacy. Are these findings the end of the story? Possibly not, if major improvements will be attained in the coming years. These should be directed at the level of gene selection and delivery, in order to identify the optimal cytokine and achieve efficient and durable cytokine expression, and at the level of improving immune stimulation, i.e. by co-administration of co-stimulatory molecules including B7 and CD40, or boosting the expression of tumor antigens or MHC class I molecules. Interestingly, some of the cytokines which have shown encouraging anti-tumor activity, including IFNs, IL-4, IL-12 and TNF-alpha, are endowed with anti-angiogenic or vasculotoxic effects, which may significantly contribute to local tumor control. Therapeutic exploitation of this property may result in the design of novel approaches which, by maximizing immune-stimulating and anti-angiogenic effects, could possibly lead to starvation of established tumors in patients.

Recent clinical progress in virus-based therapies for cancer

As our knowledge of the molecular basis of cancer expands, viral vectors have been increasingly studied as potential antitumour therapeutic agents. With their ability to invade and replicate within target cells, viruses have been utilised as oncolytic agents to directly lyse tumour cells. Viruses can also deliver their genetic payload into infected cells, allowing for the repair of defective tumour suppressor genes, disruption of oncogenic pathways, and production of cytokines that activate the immune system. Finally, viruses encoding tumour-associated antigens can infect dendritic cells, triggering the development of a tumour-specific immune response. The ability to engineer viruses with high levels of tumour specificity and efficient rates of infection has enhanced the safety profile of these agents, allowing for the development of viable therapeutic options that have been examined in the clinic, either alone or in conjunction with more conventional therapies. This review highlights the principles underlying virus-based therapies for cancer, with an emphasis on recent developments from the clinic.

Viral Vaccines for Cancer Immunotherapy

The understanding that tumor cells can be recognized and eliminated by the immune system has led to intense interest in the development of cancer vaccines. Viruses are naturally occurring agents that cause human disease but have the potential to prevent disease when attenuated forms or subunits are used as vaccines before exposure. A large number of viruses have been engineered as attenuated vaccines for the expression of tumor antigens, immunomodulatory molecules, and as vehicles for direct destruction of tumor cells or expression of highly specific gene products. This article focuses on the major viruses that are under development as cancer vaccines, including the poxviruses, adenoviruses, adeno-associated viruses, herpesviruses, retroviruses, and lentiviruses. The biology supporting these viruses as vaccines is reviewed and clinical progress is reported.

Immune gene-viral therapy with triplex efficacy mediated by oncolytic adenovirus carrying an interferon-gamma gene yields efficient antitumor activity in immunodeficient and immunocompetent mice

Among numerous gene therapeutic strategies for cancer treatment, gene transfer by conditionally replicative adenovirus (CRAd) of interferon-gamma (IFN-gamma) may be useful because of the possibility that it will yield IFN-gamma-mediated antiangiogenesis, immune responses, and CRAd-mediated oncolysis. In this study, we constructed a human TERT promoter-mediated oncolytic adenovirus targeting telomerase-positive cancers and armed with a mouse or human IFN-gamma gene to generate novel immune gene-viral therapeutic systems, CNHK300-mIFN-gamma and CNHK300-hIFN-gamma, respectively. The systems can specifically target, replicate in, and lyse cancer cells, while sparing normal cells. The advantage of these systems is that the number of transgene copies and their expression increase markedly via viral replication within infected cancer cells, and replicated viral progeny can then infect additional cancer cells within the tumor mass. CNHK300-mIFN-gamma induced regression of xenografts in liver cancer models in both immunodeficient and immunocompetent mice by triplex mechanisms including selective oncolysis, antiangiogenesis, and immune responses. We conclude that combining immune gene therapy and oncolytic virotherapy can enhance antitumor efficacy as a result of synergism between CRAd oncolysis and transgene composite antitumor responses.

Adenovirus as vehicle for anticancer genetic immunotherapy

Adenoviruses (Ads) are in the forefront of genetic immunization methods being developed against cancer. Their ability to elicit an effective immune response against tumor-associated antigens has been demonstrated in many model systems. Several clinical trials, which use Ad as vehicle for immunization, are already in progress. Preclinical studies have also demonstrated the efficacy of combining Ad-mediated immunization with adjuvants such as chemotherapeutic agents and cytokines. Issues related to sero-prevalence and safety of Ads, however, continue to pose a challenge and need to be addressed.

Phase I study of the intratumoral administration of recombinant canarypox viruses expressing B7.1 and interleukin 12 in patients with metastatic melanoma

The objective of this study was to evaluate the safety and activity of the intratumoral administration of the immune costimulatory molecule, B7.1, encoded by a vector derived from the canarypox virus, ALVAC (ALVAC-B7.1), alone and with the intratumoral injection of ALVAC encoding the immune-stimulatory cytokine, interleukin 12 (ALVAC-IL-12). Fourteen patients with metastatic melanoma who had s.c. nodules received intratumoral injections on days 1, 4, 8, and 11. Nine patients were given escalating doses of up to 25 x 10(8) plaque-forming units of ALVAC-B7.1. Five patients were given 25 x 10(8) plaque-forming units of ALVAC-B7.1 combined with ALVAC-IL-12 50% tissue culture infective dose of 2 x 10(6). Toxicity was mild to moderate and consisted of inflammatory reactions at the injection site and fever, chills, myalgia, and fatigue. Higher levels of B7.1 mRNA were observed in ALVAC-B7.1-injected tumors compared with saline-injected control tumors. Higher levels of intratumoral vascular endothelial growth factor and IL-10, cytokines with immune suppressive activities, were also observed in ALVAC-B7.1- and ALVAC-IL-12-injected tumors compared with saline-injected controls. Serum levels of vascular endothelial growth factor increased at day 18 and returned to baseline at day 43. All patients developed antibody to ALVAC. Intratumoral IL-12 and IFN-gamma mRNA decreased. Changes in serum IL-12 and IFN-gamma levels were not observed. Tumor regressions were not observed. The intratumoral injections of ALVAC-B7.1 and ALVAC-IL-12 were well tolerated at these dose levels and at this schedule and resulted in measurable biological response. This response included the production of factors that may suppress the antitumor immunologic activity of these vectors.

Current strategies in cancer gene therapy

Cancer gene therapy is the most studied application of gene therapy. Many genetic alterations are involved in the transformation of a normal cell into a neoplastic one. The two main gene groups involved in cancer development are oncogenes and tumor suppressor genes. While the latter eliminates cancerous cells via apoptosis, the former enhances cell proliferation. Therefore, apoptotic genes and anti-oncogenes are widely used in cancer gene therapy. In addition to oncogenes and tumor suppressor genes, chemotherapy and gene therapy can be combined through suicide gene strategy. A suicide gene encodes for a non-mammalian enzyme; this enzyme is used to convert a non-toxic prodrug into its active cytotoxic metabolite within the cancerous cells. Tumor suppressor genes, anti-oncogenes and suicide genes target cancer cells on the molecular level. On the other hand, cancer is immunogenic in nature; therefore, it can also be targeted on the immunological level. Boosting the immune response against cancerous cells is usually achieved via genes encoding for cytokines. Interleukin-12 gene, for example, is one of the most studied cytokine genes for cancer gene therapy applications. DNA vaccines are also used after conventional treatments to eliminate remnant malignant cells. All these therapeutic strategies and other strategies namely anti-angiogenesis and drug resistant genes are briefly reviewed and highlighted in this article.

Turning tumor cells in situ into T-helper cell-stimulating, MHC class II tumor epitope-presenters: immuno-curing and immuno-consolidation

Immunological control or cure of tumors depends on initiating a robust T helper cell response to MHC class II epitopes of tumor-associated antigens. T helper cells regulate the potency of cytotoxic T lymphocyte and antibody responses. We have developed a novel approach to stimulate T helper cells by converting tumor cells into MHC class II molecule-positive, antigen presenting cells. Furthermore, using antisense methods, we suppress expression of the Ii protein, that normally blocks the antigenic peptide binding site of MHC class II molecules during synthesis in the endoplasmic reticulum. In such gene-engineered tumor cells, the MHC class II molecules pick up antigenic peptides, which have been transported into the endoplasmic reticulum for binding to MHC class I molecules. All nucleated cells create such "surveys of self" to detect viral or malignant transformation. Our method extends that survey of self to MHC class II endogenous tumor-associated antigens. Simultaneous presentation of tumor antigens by both MHC class I and II generates a robust and long-lasting antitumor immune response. Injecting murine tumors with genes, which induce MHC class II molecules and suppress Ii protein, cures a significant number of animals with renal and prostate tumors. We have developed analogous human gene vectors that are suitable for most patients and cancers, because they are monomorphic and active in all HLA-DR alleles. We review our findings, and analyze remaining issues for preclinical study and the design of clinical trials.