Adenovirus CD40 Ligand Gene Therapy Counteracts Immune Escape Mechanisms in the Tumor Microenvironment

Next-generation CD40 agonists for cancer immunotherapy

INTRODUCTION

There is a need for new therapies that can enhance response rates and broaden the number of cancer indications where immunotherapies provide clinical benefit. CD40 targeting therapies provide an opportunity to meet this need by promoting priming of tumor-specific T cells and reverting the suppressive tumor microenvironment. This is supported by emerging clinical evidence demonstrating the benefits of immunotherapy with CD40 antibodies in combination with standard of care chemotherapy.

AREAS COVERED

This review is focused on the coming wave of next-generation CD40 agonists aiming to improve efficacy and safety, using new approaches and formats beyond monospecific antibodies. Further, the current understanding of the role of different CD40 expressing immune cell populations in the tumor microenvironment is reviewed.

EXPERT OPINION

There are multiple promising next-generation approaches beyond monospecific antibodies targeting CD40 in immuno-oncology. Enhancing efficacy is the most important driver for this development, and approaches that maximize the ability of CD40 to both remodel the tumor microenvironment and boost the anti-tumor T cell response provide great opportunities to benefit cancer patients. Enhanced understanding of the role of different CD40 expressing immune cells in the tumor microenvironment may facilitate more efficient clinical development of these compounds.

Targeted therapies in bladder cancer: signaling pathways, applications, and challenges

Bladder cancer (BC) is one of the most prevalent malignancies in men. Understanding molecular characteristics via studying signaling pathways has made tremendous breakthroughs in BC therapies. Thus, targeted therapies including immune checkpoint inhibitors (ICIs), antibody-drug conjugates (ADCs), and tyrosine kinase inhibitor (TKI) have markedly improved advanced BC outcomes over the last few years. However, the considerable patients still progress after a period of treatment with current therapeutic regimens. Therefore, it is crucial to guide future drug development to improve BC survival, based on the molecular characteristics of BC and clinical outcomes of existing drugs. In this perspective, we summarize the applications and benefits of these targeted drugs and highlight our understanding of mechanisms of low response rates and immune escape of ICIs, ADCs toxicity, and TKI resistance. We also discuss potential solutions to these problems. In addition, we underscore the future drug development of targeting metabolic reprogramming and cancer stem cells (CSCs) with a deep understanding of their signaling pathways features. We expect that finding biomarkers, developing novo drugs and designing clinical trials with precisely selected patients and rationalized drugs will dramatically improve the quality of life and survival of patients with advanced BC.

Analysis of physical activity and plasma levels of soluble CD40 and CD40L in older people with gastrointestinal tract cancer

Regular physical activity prevents and treats cancer patients by assisting and improving the immune system. Co-stimulatory molecules that activate the immune system have been studied in cancer, such as immune checkpoint molecules of the CD40/CD40L pathway. This study aimed to characterize plasma levels of soluble CD40 (sCD40) and CD40 ligand (sCD40L) in older people with gastrointestinal tract (GIT) cancer and associate results with physical activity. This prospective and exploratory cohort study was performed with 24 older people with GIT cancer and 23 healthy elderly individuals as controls. Physical activity level was classified as active or sedentary according to the International Physical Activity Questionnaire-Short Form (IPAQ-SF). Plasma levels of sCD40 and sCD40L were determined using Enzyme-Linked Immunosorbent Assay. Plasma levels of sCD40 were higher, while sCD40L were lower (p = 0.0171) in older people with GIT cancer than controls (p = 0.0038). Regarding physical activity, active older people with GIT cancer presented lower plasma levels of sCD40 and sCD40L than those sedentary with GIT cancer (p = 0.0228 and p = 0.0236), respectively. Our findings suggest that GIT cancer stimulates the immune system in older people, elevates levels of sCD40, and reduces levels of sCD40L. Physical activity may be a protective factor for the immune system of these patients since it acts on sCD40/sCD40L pathway.

Non-stem bladder cancer cell-derived extracellular vesicles promote cancer stem cell survival in response to chemotherapy

BACKGROUND

Chemosenstive non-stem cancer cells (NSCCs) constitute the bulk of tumors and are considered as part of the cancer stem cell (CSC) niche in the tumor microenvironment (TME). Tumor-derived extracellular vesicles (EVs) mediate the communication between tumors and the TME. In this study, we sought to investigate the impacts of EVs released by NSCCs on the maintenance of CSC properties and chemoresistance.

METHODS

We employed murine MB49 bladder cancer (BC) sub-lines representing CSCs and NSCCs as a model system. Chemotherapy drugs were used to treat NSCCs in order to collect conditioned EVs. The impacts of NSCC-derived EVs on CSC progression were evaluated through sphere formation, cytotoxicity, migration, and invasion assays, and by analyzing surface marker expression on these BC cells. Differential proteomic analyses were conducted to identify cargo protein candidates involved in the EV-mediated communication between NSCCs and CSCs.

RESULTS

NSCC-derived EVs contained cargo proteins enriched in proteostasis-related functions, and significantly altered the development of CSCs such that they were more intrinsically chemoresistant, aggressive, and better able to undergo self-renewal.

CONCLUSIONS

We thus identified a novel communication mechanism whereby NSCC-EVs can alter the relative fitness of CSCs to promote disease progression and the acquisition of chemoresistance.

Role of neutrophil extracellular traps in radiation resistance of invasive bladder cancer

Radiation therapy (RT) is used in the management of several cancers; however, tumor radioresistance remains a challenge. Polymorphonuclear neutrophils (PMNs) are recruited to the tumor immune microenvironment (TIME) post-RT and can facilitate tumor progression by forming neutrophil extracellular traps (NETs). Here, we demonstrate a role for NETs as players in tumor radioresistance. Using a syngeneic bladder cancer model, increased NET deposition is observed in the TIME of mice treated with RT and inhibition of NETs improves overall radiation response. In vitro, the protein HMGB1 promotes NET formation through a TLR4-dependent manner and in vivo, inhibition of both HMGB1 and NETs significantly delays tumor growth. Finally, NETs are observed in bladder tumors of patients who did not respond to RT and had persistent disease post-RT, wherein a high tumoral PMN-to-CD8 ratio is associated with worse overall survival. Together, these findings identify NETs as a potential therapeutic target to increase radiation efficacy.

Radioresistance remains a challenge in the treatment of bladder cancer. In this study, the authors show in mice that radiation increases deposits of neutrophil extracellular traps (NETs) via a TLR4-dependent mechanism and that NETs-targeting strategies can improve the response to radiotherapy.

Intratumoral immunostimulatory AdCD40L gene therapy in patients with advanced solid tumors

AdCD40L is a replication-deficient virus carrying the gene for CD40 ligand which has previously been evaluated in patients with urothelial cancer and malignant melanoma. Herein, we present the results of repeated intratumoral injections of AdCD40L in seven patients with metastatic solid cancer. One patient who developed urothelial cancer derived from a renal transplant was treated with repeated injections of AdCD40L alone. The remaining patients suffered from cholangiocarcinoma, kidney, breast, rectal, or ovarian cancer and received AdCD40L repeatedly (4x) in combination with cyclophosphamide. The treatment was safe and generally well-tolerated. Two patients had clinical benefit of the treatment and one of them was accepted for re-treatment. Circulating proinflammatory cytokines were commonly increased after treatment, but save for TNFα, significances were not reached which could be due to the low number of patients. Similar to earlier findings in AdCD40L-treated melanoma patients, IL8 plasma levels were high in the present study. In conclusion, gene therapy by repeated intratumoral AdCD40L injections alone, or in combination with cyclophosphamide, is feasible and safe in patients with solid cancers. The potential of intratumoral CD40L gene transfer as treatment of cancer was illustrated by the clinical improvement in two out of seven patients.

Nuclear Factor-κB Overexpression is Correlated with Poor Outcomes after Multimodality Bladder-Preserving Therapy in Patients with Muscle-Invasive Bladder Cancer

The aim of this study was to investigate prognostic molecular targets for selecting patients with muscle-invasive bladder cancer undergoing bladder-preserving therapy. Pretreatment biopsy samples from patients with muscle-invasive bladder cancer receiving trimodality bladder-preserving therapy were analyzed for expression levels of p53, p16, human epidermal growth factor receptor-2 (Her-2), epidermal growth factor receptor (EGFR), nuclear factor-kappa B (NFκB; p65), E-cadherin, matrix metalloproteinase-9 (MMP9), meiotic recombination 11 homolog (MRE11), programmed death-1 ligand (PD-L1), and mismatch repair proteins (MLH1, PMS2, MSH2, and MSH6) by immunohistochemical (IHC) staining. The correlations between these molecular markers with local progression-free survival (LPFS), distant metastasis-free survival (DMFS), and overall survival (OS) were explored. Biopsy samples from 41 out of 60 patients were evaluated using IHC. Univariate analysis revealed that the high expression of NFκB is associated with significantly worse LPFS, DMFS, and OS, and low expression of p16 is associated with significantly lower LPFS. Upon further multivariate analysis including sex, age, stage, and selected unfavorable factors in the model, NFκB and p16 independently remained significant. The investigational in vitro study demonstrated that irradiation induces up-regulation of NFκB signaling. Irradiated bladder cancer cells showed increased invasion capability and clonogenic survival; inhibition of NFκB signaling by an NFκB inhibitor, SC75741, or RNA interference reversed the observed increases. NFκB expression (p65) is associated with prognostic significance for both LPFS and DMFS in patients treated with bladder-preserving therapy, with consistent impact on cell viability of bladder cancer cells. NFκB may be a putative molecular target to help with outcome stratification.

Temporal changes within the (bladder) tumor microenvironment that accompany the therapeutic effects of the immunocytokine NHS-IL12

BACKGROUND

While significant strides in the treatment of metastatic bladder cancer have been made with immune checkpoint inhibitors, the treatment of carcinoma in situ and non-muscle invasive, non-metastatic (superficial) human urothelial carcinoma, also termed non-muscle invasive bladder cancer (NMIBC), remains intractable with bacillus Calmette-Guerin (BCG) employed as the standard of care. In this study, an immunocytokine, NHS-muIL12, which consists of two molecules of murine IL-12 fused to NHS76, a tumor necrosis-targeting human IgG1, was examined as an immunotherapeutic in an orthotopic MB49^luc bladder tumor model.

METHODS

The antitumor activity of systemic administration of NHS-muIL12 was investigated on MB49^luc tumors, an aggressive, bioluminescent orthotopic bladder cancer model. Temporal studies were carried out on MB49^luc bladder tumors harvested during various time points during NHS-muIL12 treatment and cellular changes associated with the reduction in tumor burden following NHS-muIL12 were determined by flow cytometry. Effects of those changes on the proliferation/activation of lymphoid cells were also determined.

RESULTS

Studies revealed a significant reduction in MB49^luc bladder tumor burden occurring between days 3 and 6 after the third and final systemic administration of NHS-muIL12. Temporal analyses of the MB49^luc bladder tumor microenvironment (TME) initially revealed a large accumulation of myeloid-derived suppressor cells (MDSCs) and macrophages that elicited potent immunosuppression. Immunosuppression was characterized by the inability of CD4⁺ and CD8⁺ T cells to respond to broad-based immune stimulants. NHS-muIL12 administration resulted in temporal-dependent reductions in the number of MDSCs, macrophages and tumor-associated TGF-β, which culminated in a re-ignition of CD4⁺ and CD8⁺ T cells to elicit potent antitumor responses against MB49^luc bladder tumors.

CONCLUSIONS

These findings provide strong evidence that the systemic administration of an immunocytokine consisting of a tumor-targeting Ig through recognition of DNA and DNA-histone complexes coupled to muIL-12 can effectively target the bladder TME; this significantly reduces the myeloid cellular compartment and reverts an immunosuppressive to an immunopermissive TME, ultimately resulting in antitumor effects. These studies provide further rationale for the employment of NHS-IL12 as an immunomodulator and clinical immunotherapeutic for NMIBC.

Enhanced metastatic potential in the MB49 urothelial carcinoma model

Recent data suggest that patients with a basal/stem-like bladder cancer (BC) subtype tend to have metastatic disease, but this is unconfirmed. Here we report the identification of murine MB49 cell line sub-clones with stem-like characteristics in culture. Subcutaneous implantation of S2 and S4 MB49 sub-clones into immunocompetent mice resulted in lung metastases in 50% and 80% of mice respectively, whereas none of the mice implanted with the parental cells developed metastasis. Gene profiling of cells cultured from S2 and S4 primary and metastatic tumors revealed that a panel of genes with basal/stem-like/EMT properties is amplified during metastatic progression. Among them, ITGB1, TWIST1 and KRT6B are consistently up-regulated in metastatic tumors of both MB49 sub-clones. To evaluate clinical relevance, we examined these genes in a human public dataset and found that ITGB1 and KRT6B expression in BC patient tumor samples are positively correlated with tumor grade. Likewise, the expression levels of these three genes are correlated with worse clinical outcomes. This MB49 BC metastatic pre-clinical model provides a unique opportunity to validate and recapitulate results discovered in patient studies and to pursue future mechanistic therapeutic interventions for BC metastasis.

Effectiveness of the combination of vascular targeted photodynamic therapy and anti-cytotoxic T-lymphocyte-associated antigen 4 in a preclinical mouse model of urothelial carcinoma

OBJECTIVE

To investigate the effectiveness of combination treatment of vascular targeted photodynamic therapy and anti-cytotoxic T-lymphocyte-associated antigen 4 immunotherapy in a mouse model of urothelial carcinoma.

METHODS

We used C57BL/6 mice injected with murine bladder 49 cell line. Mice were randomly allocated into four treatment groups: vascular targeted photodynamic therapy only, anti-cytotoxic T-lymphocyte-associated antigen 4 only, combination therapy and control. We carried out three separate experiments that used distinct cohorts of mice: tumor growth and development of lung metastases monitored with bioluminescent imaging (n = 91); survival evaluated with Kaplan-Meier curves (n = 111); and tumor cell population studied with flow cytometry (n = 20). In a fourth experiment, we re-challenged tumors in previously treated mice and compared tumor growth with that of naïve mice.

RESULTS

Combination therapy provided significant benefits over the other three treatment groups: prolonged survival (P < 0.0001), lower tumor signal (P < 0.0001) and decreased lung signal uptake (P ≤ 0.002). We also observed that mice previously treated with vascular targeted photodynamic therapy only or combination therapy did not present tumor growth after re-challenged tumors.

CONCLUSIONS

Combination of vascular targeted photodynamic therapy with anti-cytotoxic T-lymphocyte-associated antigen 4 is an effective therapy in a urothelial carcinoma syngeneic mouse model. The present results suggest this therapy as a potential treatment option for both bladder and upper tract tumors in future clinical trials.

Local angiotensin II contributes to tumor resistance to checkpoint immunotherapy

Background

Current checkpoint immunotherapy has shown potential to control cancer by restoring or activating the immune system. Nevertheless, multiple mechanisms are involved in immunotherapy resistance which limits the clinical benefit of checkpoint inhibitors. An immunosuppressive microenvironment is an important factor mediating the original resistance of tumors to immunotherapy. A previous report by our group has demonstrated that local angiotensin II (AngII) predominantly exists in a tumor hypoxic microenvironment where hypoxic tumour cells produced AngII by a hypoxia-lactate-chymase-dependent mechanism.

Results

Here, using 4T1 and CT26 syngeneic mouse tumor models, we found that local AngII in the tumor microenvironment was involved in immune escape of tumour cells and an AngII signaling blockage sensitized tumours to checkpoint immunotherapy. Furthermore, an AngII signaling blockage reversed the tumor immunosuppressive microenvironment, and inhibition of angiotensinogen (AGT, a precursor of AngII) expression strongly triggered an immune-activating cytokine profile in hypoxic mouse cancer cells. More importantly, AGT silencing combined with a checkpoint blockage generated an abscopal effect in resistant tumors.

Conclusion

Our study demonstrated an important role of local AngII in the formation of a tumor immunosuppressive microenvironment and its blockage may enhance tumor sensitivity to checkpoint immunotherapy. The combination of an AngII signaling blocker and an immune-checkpoint blockage could be a promising strategy to improve tumors responses to current checkpoint immunotherapy.

Electronic supplementary material

The online version of this article (10.1186/s40425-018-0401-3) contains supplementary material, which is available to authorized users.

Tumor-infiltrating immune cell subpopulations influence the oncologic outcome after intravesical Bacillus Calmette-Guérin therapy in bladder cancer

Although Bacillus Calmette-Guérin (BCG) is the most successful immunotherapy for high-risk non-muscle-invasive bladder cancer, approximately 30% of patients are unresponsive to treatment. New biomarkers are important to identify patients who will benefit most from BCG during a worldwide BCG shortage. Local immune cell subsets were measured on formalin-fixed, paraffin-embedded tissue sections of bladder cancer by immunohistochemistry, using monoclonal antibodies to tumor-associated macrophages (TAMs; CD68, CD163), B-lymphocytes (CD20) and T-lymphocyte subsets (CD3, CD4, CD8, GATA3, T-bet, FOXP3 and CD25). Cell densities in the lamina propria without invasion, at the invasive front if present, in the papillary tumor stroma, and in the neoplastic urothelium were calculated. Twenty-nine (72.5%) of 40 patients were classified as BCG responders after a mean follow-up of 35.3 months. A statistically significant association was observed for BCG failure with low density of CD4+ and GATA3+ T-cells, and increased expression of FOXP3+ and CD25+ regulatory T-cells (Tregs) as well as CD68+ and CD163+ TAMs. Survival analysis demonstrated prolonged recurrence-free survival (RFS) in patients with an increased count of CD4+ and GATA3+ T-cells. TAMs, Tregs and T-bet+ T-cells were inversely correlated with RFS. Thus, the tumor microenvironment seems to influence the therapeutic response to BCG, permitting an individualized treatment.

Shaping the Tumor Stroma and Sparking Immune Activation by CD40 and 4-1BB Signaling Induced by an Armed Oncolytic Virus

Purpose: Pancreatic cancer is a severe indication with short expected survival despite surgery and/or combination chemotherapeutics. Checkpoint blockade antibodies are approved for several cancer indications, but pancreatic cancer has remained refractory. However, there are clinical data suggesting that stimulation of the CD40 pathway may be of interest for these patients. Oncolytic viruses armed with immunostimulatory genes represent an interesting approach. Herein, we present LOAd703, a designed adenovirus armed with trimerized CD40L and 4-1BBL that activates the CD40 and 4-1BB pathways, respectively. As many cells in the tumor stroma, including stellate cells and the infiltrating immune cells, express CD40 and some 4-1BB, we hypothesize that LOAd703 activates immunity and simultaneously modulates the biology of the tumor stroma.Experimental Design: Tumor, stellate, endothelial, and immune cells were infected by LOAd703 and investigated by flow cytometry, proteomics, and functional analyses.Results: LOAd703-infected pancreatic cell lines were killed by oncolysis, and the virus was more effective than standard-of-care gemcitabine. In in vivo xenograft models, LOAd703 efficiently reduced established tumors and could be combined with gemcitabine for additional effect. Infected stellate and tumor cells reduced factors that promote tumor growth (Spp-1, Gal-3, HGF, TGFβ and collagen type I), while chemokines were increased. Molecules involved in lymphocyte migration were upregulated on infected endothelial cells. Dendritic cells were robustly stimulated by LOAd703 to produce costimulators, cytokines and chemokines, and such DCs potently expanded both antigen-specific T cells and NK cells.Conclusions: LOAd703 is a potent immune activator that modulates the stroma to support antitumor responses. Clin Cancer Res; 23(19); 5846-57. ©2017 AACR.

Enhanced Mortality to Metastatic Bladder Cancer Cell Line MB49 in Vasoactive Intestinal Peptide Gene Knockout Mice

To identify if the absence of the vasoactive intestinal peptide (VIP) gene enhances susceptibility to death from metastatic bladder cancer, two strains of mice were injected with MB49 murine bladder cancer cells. The growth and spread of the cancer was measured over a period of 4 weeks in C57BL/6 mice and 5 weeks in VIP knockout (KO) mice. A Kaplan-Meier plot was constructed to compare control C57BL/6 mice and C57BL/6 mice with MB49 vs. VIP KO controls and VIP KO mice with MB49. The wild-type (WT) strain (C57BL/6) contained the VIP gene, while the other strain, VIP knockout backcrossed to C57BL/6 (VIP KO) did not and was thus unable to endogenously produce VIP. VIP KO mice had increased mortality compared to C57BL/6 mice at 4 weeks. The number of ulcers between both groups was not statistically significant. In vitro studies indicated that the presence VIP in high doses reduced MB49 cell growth, as well as macrophage inhibitory factor (MIF), a growth factor in bladder cancer cells. These findings support the concept that VIP may attenuate susceptibility to death from bladder cancer, and that it exerts its effect via downregulation of MIF.

Intratumoral Th2 predisposition combines with an increased Th1 functional phenotype in clinical response to intravesical BCG in bladder cancer

Th1-type immunity is considered to be required for efficient response to BCG in bladder cancer, although Th2 predisposition of BCG responders has recently been reported. The aim was to evaluate the relationship of Th1 and Th2 components in 23 patients undergoing BCG treatment. Peripheral blood, serum and urine samples were prospectively collected at baseline, during and after BCG. Th1 (neopterin, tryptophan, kynurenine, kynurenine-to-tryptophan ratio (KTR), IL-12, IFN-γ, soluble TNF-R75 and IL-2Rα) and Th2 (IL-4, IL-10) biomarkers as well as CD4 expression in T helper (Th), effector and regulatory T cells were determined. Local immune cell subsets were measured on formalin-fixed, paraffin-embedded cancer tissue by immunohistochemistry to examine expression of transcription factors that control Th1 (T-bet) and Th2-type (GATA3) immunity. We confirmed a Th2 predisposition with a mean GATA3/T-bet ratio of 5.51. BCG responders showed significantly higher levels of urinary (p = 0.003) and serum neopterin (p = 0.012), kynurenine (p = 0.015), KTR (p = 0.005), IFN-γ (p = 0.005) and IL-12 (p = 0.003) during therapy, whereas levels of IL-10 decreased significantly (p < 0.001) compared to non-responders. GATA3/T-bet ratio correlated positively with serum neopterin (p = 0.008), IFN-γ (p = 0.013) and KTR (p = 0.018) after the first BCG instillation. We observed a significant increase in CD4 expression in the Th cell population (p < 0.05), with only a modest tendency toward higher frequency in responders compared to non-responders (p = 0.303). The combined assessment of GATA3/T-bet ratio, neopterin and KTR may be a useful biomarker in predicting BCG response. Th2-promoting factors such as GATA3 may trigger Th1-type immune responses and thus contribute to the BCG success.

Activation of myeloid and endothelial cells by CD40L gene therapy supports T-cell expansion and migration into the tumor microenvironment

CD40 is an interesting target in cancer immunotherapy due to its ability to stimulate T-helper 1 immunity via maturation of dendritic cells and to drive M2 to M1 macrophage differentiation. Pancreatic cancer has a high M2 content that has shown responsive to anti-CD40 agonist therapy and CD40 may thus be a suitable target for immune activation in these patients. In this study, a novel oncolytic adenovirus armed with a trimerized membrane-bound extracellular CD40L (TMZ-CD40L) was evaluated as a treatment of pancreatic cancer. Further, the CD40L mechanisms of action were elucidated in cancer models. The results demonstrated that the virus transferring TMZ-CD40L had oncolytic capacity in pancreatic cancer cells and could control tumor progression. TMZ-CD40L was a potent stimulator of human myeloid cells and T-cell responses. Further, CD40L-mediated stimulation increased tumor-infiltrating T cells in vivo, which may be due to a direct activation of endothelial cells to upregulate receptors for lymphocyte attachment and transmigration. In conclusion, CD40L-mediated gene therapy is an interesting concept for the treatment of tumors with high levels of M2 macrophages, such as pancreatic cancer, and an oncolytic virus as carrier of CD40L may further boost tumor killing and immune activation.

Interdependent IL-7 and IFN-γ signalling in T-cell controls tumour eradication by combined α-CTLA-4+α-PD-1 therapy

Combination therapy with α-CTLA-4 and α-PD-1 has shown significant clinical responses in different types of cancer. However, the underlying mechanisms remain elusive. Here, combining detailed analysis of human tumour samples with preclinical tumour models, we report that concomitant blockade of CTLA-4 and PD-1 improves anti-tumour immune responses and synergistically eradicates tumour. Mechanistically, combination therapy relies on the interdependence between IL-7 and IFN-γ signalling in T cells, as lack of either pathway abrogates the immune-boosting and therapeutic effects of combination therapy. Combination treatment increases IL-7Rα expression on tumour-infiltrating T cells in an IFN-γ/IFN-γR signalling-dependent manner, which may serve as a potential biomarker for clinical trials with immune checkpoint blockade. Our data suggest that combining immune checkpoint blockade with IL-7 signalling could be an effective modality to improve immunotherapeutic efficacy. Taken together, we conclude that combination therapy potently reverses immunosuppression and eradicates tumours via an intricate interplay between IFN-γ/IFN-γR and IL-7/IL-7R pathways.

CAR T-Cell Therapy: The Role of Physical Barriers and Immunosuppression in Lymphoma

Chimeric antigen receptor (CAR) T-cells have shown remarkable results in patients with B-cell leukemia and lymphoma. However, while CAR T-cells have shown complete responses in a majority of patients with acute lymphoblastic leukemia (ALL), lymphomas are more difficult to treat. Different CAR designs and conditioning protocols seem to affect the persistence of patient responses. However, factors that determine if patients receiving the same CARs will respond or not remain obscure. In Sweden, a phase I/IIa trial using third-generation CAR T-cells is ongoing in which we intend to compare tumor biology and immunology, in each patient, to treatment response. CAR T-cell therapy is a powerful tool to add to the treatment options for this patient group but we need to perform the necessary basic research on the multifactorial mechanisms of action to give patients the best possible option of survival. Such studies are also crucial to expand the success of CAR T-cells beyond CD19+ B-cell malignancy. This review will focus on possible barriers of treating lymphoma to define factors that need to be investigated to develop the next generation of CAR T-cell therapy.

Immunostimulatory Gene Therapy Using Oncolytic Viruses as Vehicles

Immunostimulatory gene therapy has been developed during the past twenty years. The aim of immunostimulatory gene therapy is to tilt the suppressive tumor microenvironment to promote anti-tumor immunity. Hence, like a Trojan horse, the gene vehicle can carry warriors and weapons into enemy territory to combat the tumor from within. The most promising immune stimulators are those activating and sustaining Th1 responses, but even if potent effects were seen in preclinical models, many clinical trials failed to show objective responses in cancer patients. However, with new tools to control ongoing immunosuppression in cancer patients, immunostimulatory gene therapy is now emerging as an interesting option. In parallel, oncolytic viruses have been shown to be safe in patients. To prolong immune stimulation and to increase efficacy, these two fields are now merging and oncolytic viruses are armed with immunostimulatory transgenes. These novel agents are racing towards approval as established cancer immunotherapeutics.

CD14-expressing cancer cells establish the inflammatory and proliferative tumor microenvironment in bladder cancer

Nonresolving chronic inflammation at the neoplastic site is consistently associated with promoting tumor progression and poor patient outcomes. However, many aspects behind the mechanisms that establish this tumor-promoting inflammatory microenvironment remain undefined. Using bladder cancer (BC) as a model, we found that CD14-high cancer cells express higher levels of numerous inflammation mediators and form larger tumors compared with CD14-low cells. CD14 antigen is a glycosyl-phosphatidylinositol (GPI)-linked glycoprotein and has been shown to be critically important in the signaling pathways of Toll-like receptor (TLR). CD14 expression in this BC subpopulation of cancer cells is required for increased cytokine production and increased tumor growth. Furthermore, tumors formed by CD14-high cells are more highly vascularized with higher myeloid cell infiltration. Inflammatory factors produced by CD14-high BC cells recruit and polarize monocytes and macrophages to acquire immune-suppressive characteristics. In contrast, CD14-low BC cells have a higher baseline cell division rate than CD14-high cells. Importantly, CD14-high cells produce factors that further increase the proliferation of CD14-low cells. Collectively, we demonstrate that CD14-high BC cells may orchestrate tumor-promoting inflammation and drive tumor cell proliferation to promote tumor growth.

Novel therapeutic approaches for recurrent nonmuscle invasive bladder cancer

This article summarizes strategies being investigated in patients with nonmuscle invasive bladder cancer. Progress has been made toward improving the delivery method of intravesical agents. Intravesical therapy is limited by the amount of time that the agent remains in contact with the bladder. Bladder cancer is considered to be responsive to immune therapy. Thus, many novel approaches are immune-based therapies and include cancer vaccines, use of Bacillus Calmette-Guérin (BCG) subcomponents, and checkpoint inhibitors. Finally, access to bladder mucosa via direct catheterization into the bladder via the urethra has enabled unique strategies for delivery of cancer therapy including viral- or plasmid-based gene therapy.

Enhanced therapeutic anti-tumor immunity induced by co-administration of 5-fluorouracil and adenovirus expressing CD40 ligand

Bystander immune activation by chemotherapy has recently gained extensive interest and provided support for the clinical use of chemotherapeutic agents in combination with immune enhancers. The CD40 ligand (CD40L; CD154) is a potent regulator of the anti-tumor immune response and recombinant adenovirus (RAd)-mediated CD40L gene therapy has been effective in various cancer models and in man. In this study we have assessed the combined effect of local RAd-CD40L and 5-fluorouracil (5-FU) administration on a syngeneic MB49 mouse bladder tumor model. Whereas MB49 cells implanted into immunocompetent mice responded poorly to RAd-CD40L or 5-FU alone, administration of both agents dramatically decreased tumor growth, increased survival of the mice and induced systemic MB49-specific immunity. This combination treatment was ineffective in athymic nude mice, highlighting an important role for T cell mediated anti-tumor immunity for full efficacy. 5-FU up-regulated the expression of Fas and immunogenic cell death markers in MB49 cells and cytotoxic T lymphocytes from mice receiving RAd-CD40L immunotherapy efficiently lysed 5-FU treated MB49 cells in a Fas ligand-dependent manner. Furthermore, local RAd-CD40L and 5-FU administration induced a shift of myeloid-derived suppressor cell phenotype into a less suppressive population. Collectively, these data suggest that RAd-CD40L gene therapy is a promising adjuvant treatment to 5-FU for the management of bladder cancer.

CD40L gene therapy tilts the myeloid cell profile and promotes infiltration of activated T lymphocytes

CD40 ligand (CD40L) is a potent stimulator of tumor immunity via its activation of dendritic cells, which in turn initiate T-cell activation. However, T cells are inhibited by suppressive myeloid cells, which constitute an important part of immune evasion. We hypothesized that CD40L may revert the function of suppressive myeloid cells to generate a T-cell stimulatory environment, and this was investigated in the murine bladder cancer model MB49/C57BL/6. Upon intratumoral adenoviral CD40L (AdCD40L) gene therapy, the infiltration of CD11b(+)Gr-1(+) cells was significantly reduced, whereas activated T cells were increased. In vitro, CD40L-expressing MB49 cells tilted the myeloid subpopulations in favor of granulocytic CD11b(+)Gr-1(high) myeloid cells instead of monocytic CD11b(+)Gr-1(int/low) myeloid cells. Further, the level of macrophages in splenocyte co-cultures with MB49 cells was evaluated. In cultures with MB49 cells expressing CD40L, the overall level of macrophages was reduced and the remaining cells were differentiated into M1-like cells. Hence, these data support that CD40L tilts myeloid immune cell populations in favor of anti-tumor immunity (M1) instead of immunosuppression (CD11b(+)Gr-1(int/low) and M2), and this was accompanied by an increased level of activated T cells in the tumor tissue.

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.

Is cancer gene therapy an empty suit?

Gene therapy as a treatment for cancer is regarded as high in promise, but low in delivery, a deficiency that has become more obvious with ever-increasing reports of the successful correction of monogenic disorders by this approach. We review the commercial and scientific obstacles that have led to these delays and describe how they are progressively being overcome. Recent and striking successes and correspondingly increased commercial involvement suggest that gene transfer could finally become a powerful method for development of safe and effective cancer therapeutic drugs.

AdCD40L--crossing the valley of death?

CD40-mediated cancer therapy has been under development since it became clear that CD40 plays a profound role in the stimulation of adaptive immune responses. Further, CD40 signaling on tumor cells may lead to growth arrest or even apoptosis that improves therapy outcome. The therapeutic window is appealing since the immune system is selective and normal cells do not apoptose upon CD40 signaling. AdCD40L is an adenoviral-based immunostimulatory gene therapy under evaluation for its efficacy to treat cancer. Because of its nature, the adenoviral backbone will stimulate TLRs while CD40L potentiates the shifts toward Th1 type of immunity. AdCD40L has shown efficacy in various murine models, and safety studies have been performed on dog patients and in human clinical trials. AdCD40L has been used for both ex vivo gene modification of tumor cell vaccines as well as for direct intratumoral injections. Lately, an oncolytic vector has been used to further increase the eradication of solid tumors that as a consequence further boosts the release of tumor antigens and creates danger signaling in the tumor micro milieu. This review discusses the currently unfolding mechanisms of action of AdCD40L gene therapy and its possibilities to reach clinical care.

CAR/FoxP3-engineered T regulatory cells target the CNS and suppress EAE upon intranasal delivery

BACKGROUND

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS). In the murine experimental autoimmune encephalomyelitis (EAE) model of MS, T regulatory (Treg) cell therapy has proved to be beneficial, but generation of stable CNS-targeting Tregs needs further development. Here, we propose gene engineering to achieve CNS-targeting Tregs from naïve CD4 cells and demonstrate their efficacy in the EAE model.

METHODS

CD4+ T cells were modified utilizing a lentiviral vector system to express a chimeric antigen receptor (CAR) targeting myelin oligodendrocyte glycoprotein (MOG) in trans with the murine FoxP3 gene that drives Treg differentiation. The cells were evaluated in vitro for suppressive capacity and in C57BL/6 mice to treat EAE. Cells were administered by intranasal (i.n.) cell delivery.

RESULTS

The engineered Tregs demonstrated suppressive capacity in vitro and could efficiently access various regions in the brain via i.n cell delivery. Clinical score 3 EAE mice were treated and the engineered Tregs suppressed ongoing encephalomyelitis as demonstrated by reduced disease symptoms as well as decreased IL-12 and IFNgamma mRNAs in brain tissue. Immunohistochemical markers for myelination (MBP) and reactive astrogliosis (GFAP) confirmed recovery in mice treated with engineered Tregs compared to controls. Symptom-free mice were rechallenged with a second EAE-inducing inoculum but remained healthy, demonstrating the sustained effect of engineered Tregs.

CONCLUSION

CNS-targeting Tregs delivered i.n. localized to the CNS and efficiently suppressed ongoing inflammation leading to diminished disease symptoms.

CD40 stimulates a "feed-forward" NF-κB-driven molecular pathway that regulates IFN-β expression in carcinoma cells

IFN-β and the CD40L (CD154) share important roles in the antiviral and antitumor immune responses. In this study, we show that CD40 receptor occupancy results in IFN-β upregulation through an unconventional "feed-forward" mechanism, which is orchestrated by canonical NF-κB and involves the sequential de novo synthesis of IFN regulatory factor (IRF)1 and Viperin (RSAD2), an IRF1 target. RelA (p65) NF-κB, IRF1, and Viperin-dependent IRF7 binding to the IFN-β promoter largely controls its activity. However, full activation of IFN-β also requires the parallel engagement of noncanonical NF-κB2 signaling leading to p52 recruitment to the IFN-β promoter. These data define a novel link between CD40 signaling and IFN-β expression and provide a telling example of how signal propagation can be exploited to ensure efficient regulation of gene expression.

Immune response is an important aspect of the antitumor effect produced by a CD40L-encoding oncolytic adenovirus

Oncolytic adenovirus is an attractive platform for immunotherapy because virus replication is highly immunogenic and not subject to tolerance. Although oncolysis releases tumor epitopes and provides costimulatory danger signals, arming the virus with immunostimulatory molecules can further improve efficacy. CD40 ligand (CD40L, CD154) induces apoptosis of tumor cells and triggers several immune mechanisms, including a T-helper type 1 (T(H)1) response, which leads to activation of cytotoxic T cells and reduction of immunosuppression. In this study, we constructed a novel oncolytic adenovirus, Ad5/3-hTERT-E1A-hCD40L, which features a chimeric Ad5/3 capsid for enhanced tumor transduction, a human telomerase reverse transcriptase (hTERT) promoter for tumor selectivity, and human CD40L for increased efficacy. Ad5/3-hTERT-E1A-hCD40L significantly inhibited tumor growth in vivo via oncolytic and apoptotic effects, and (Ad5/3-hTERT-E1A-hCD40L)-mediated oncolysis resulted in enhanced calreticulin exposure and HMGB1 and ATP release, which were suggestive of immunogenicity. In two syngeneic mouse models, murine CD40L induced recruitment and activation of antigen-presenting cells, leading to increased interleukin-12 production in splenocytes. This effect was associated with induction of the T(H)1 cytokines IFN-γ, RANTES, and TNF-α. Tumors treated with Ad5/3-CMV-mCD40L also displayed an enhanced presence of macrophages and cytotoxic CD8(+) T cells but not B cells. Together, our findings show that adenoviruses coding for CD40L mediate multiple antitumor effects including oncolysis, apoptosis, induction of T-cell responses, and upregulation of T(H)1 cytokines.

The HDAC inhibitor FK228 enhances adenoviral transgene expression by a transduction-independent mechanism but does not increase adenovirus replication

The histone deacetylase inhibitor FK228 has previously been shown to enhance adenoviral transgene expression when cells are pre-incubated with the drug. Upregulation of the coxsackie adenovirus receptor (CAR), leading to increased viral transduction, has been proposed as the main mechanism. In the present study, we found that the highest increase in transgene expression was achieved when non-toxic concentrations of FK228 were added immediately after transduction, demonstrating that the main effect by which FK228 enhances transgene expression is transduction-independent. FK228 had positive effects both on Ad5 and Ad5/f35 vectors with a variety of transgenes and promoters, indicating that FK228 works mainly by increasing transgene expression at the transcriptional level. In some cases, the effects were dramatic, as demonstrated by an increase in CD40L expression by FK228 from 0.3% to 62% when the murine prostate cancer cell line TRAMP-C2 was transduced with Ad[CD40L]. One unexpected finding was that FK228 decreased the transgene expression of an adenoviral vector with the prostate cell-specific PPT promoter in the human prostate adenocarcinoma cell lines LNCaP and PC-346C. This is probably a consequence of alteration of the adenocarcinoma cell lines towards a neuroendocrine differentiation after FK228 treatment. The observations in this study indicate that FK228 enhances adenoviral therapy by a transduction-independent mechanism. Furthermore, since histone deacetylase inhibitors may affect the differentiation of cells, it is important to keep in mind that the activity and specificity of tissue- and tumor-specific promoters may also be affected.

Improving adenovirus based gene transfer: strategies to accomplish immune evasion

Adenovirus (Ad) based gene transfer vectors continue to be the platform of choice for an increasing number of clinical trials worldwide. In fact, within the last five years, the number of clinical trials that utilize Ad based vectors has doubled, indicating growing enthusiasm for the numerous positive characteristics of this gene transfer platform. For example, Ad vectors can be easily and relatively inexpensively produced to high titers in a cGMP compliant manner, can be stably stored and transported, and have a broad applicability for a wide range of clinical conditions, including both gene therapy and vaccine applications. Ad vector based gene transfer will become more useful as strategies to counteract innate and/or pre-existing adaptive immune responses to Ads are developed and confirmed to be efficacious. The approaches attempting to overcome these limitations can be divided into two broad categories: pre-emptive immune modulation of the host, and selective modification of the Ad vector itself. The first category of methods includes the use of immunosuppressive drugs or specific compounds to block important immune pathways, which are known to be induced by Ads. The second category comprises several innovative strategies inclusive of: (1) Ad-capsid-display of specific inhibitors or ligands; (2) covalent modifications of the entire Ad vector capsid moiety; (3) the use of tissue specific promoters and local administration routes; (4) the use of genome modified Ads; and (5) the development of chimeric or alternative serotype Ads. This review article will focus on both the promise and the limitations of each of these immune evasion strategies, and in the process delineate future directions in developing safer and more efficacious Ad-based gene transfer strategies.

Local AdCD40L gene therapy is effective for disseminated murine experimental cancer by breaking T-cell tolerance and inducing tumor cell growth inhibition

CD40 ligand (CD40L) is one of the most potent stimulators of Th1-type immunity through its maturation of dendritic cells that, in turn, stimulate effector cells such as T cells and NK cells. Lately, CD40-mediated cell growth inhibition and apoptosis have been in focus for the development of novel cancer treatment regiments, including recombinant soluble CD40L or CD40-stimulating antibodies. In this study, intravesical CD40L gene transfer through adenoviral vectors (AdCD40L) was used to treat an aggressive model of disseminated bladder cancer (MB49/C57BL/6). Three weekly AdCD40L vector instillations increased overall survival of tumor-bearing mice (mean 18.5 d, control mice 13 d). Furthermore, bladder tumors were eradicated (2 of 10) simultaneously as lung metastases (6 of 10) were cleared. FoxP3 levels were similar in the tumors of AdCD40L-treated mice and control mice but the tumor-infiltrating effector T cells in AdCD40L-treated mice were cytotoxic (CD107a+) in contrast to those in control-treated tumors. Furthermore, AdCD40L gene therapy could induce cell growth inhibition and cell death in the MB49 tumor cells in vitro and in vivo. However, this effect was not potent enough to cure growing tumors in immunodeficient mice. In conclusion, AdCD40L gene therapy is potent for disseminated cancer both by activation of T cells and controlling tumor cell growth and viability.

AdCD40L immunogene therapy for bladder carcinoma--the first phase I/IIa trial

PURPOSE

Immunotherapy with Bacillus Calmette-Guerin (BCG) instillation is recommended for high-risk, non-muscle invasive bladder cancer. Bacillus Calmette-Guerin is not effective in advanced tumors, and better alternatives are warranted. Immunostimulating gene therapy with adenoviral vectors expressing CD40 ligand (AdCD40L) has shown efficacy in tumor models. CD40 ligand stimulates systemic immunity and may be effective in local and invasive human disease.

EXPERIMENTAL DESIGN

Patients with invasive bladder cancer scheduled for cystectomy or patients with T(a) tumors were enrolled in a phase I/IIa trial. Patients were treated with three cycles of intrabladder Clorpactin WCS-90 prewash, followed by AdCD40L instillation 1 week apart. Safety, gene transfer, immune effects, and antitumor responses were monitored.

RESULTS

All eight recruited patients were treated as scheduled, and therapy was well tolerated. The main adverse effect was transient local pain during prewash. Postoperatively, urinary tract infections and one case of late septicemia with elevated potassium were reported. No adverse events were ascribed to vector therapy. Gene transfer was detected in biopsies, and bladders were heavily infiltrated with T cells. The effector marker IFN-gamma increased in biopsies, whereas levels of circulating T regulatory cells were reduced. Histologic evaluation indicated that AdCD40L therapy reduced the load of malignant cells.

CONCLUSIONS

To our knowledge, this is the first report on immunogene therapy in bladder cancer and the first using AdCD40L in vivo. Local AdCD40L gene therapy was safe, boosted immune activation, and should be further evaluated as a single or an adjuvant therapy for urothelial malignancies.

Immunogene therapy against colon cancer metastasis using an adenovirus vector expressing CD40 ligand

BACKGROUND

Colon cancer is one of the most common cancers worldwide, and liver metastasis is a poor prognostic factor for all types of digestive cancers, including colon cancer. We studied CD40 ligand (CD40L)-mediated immunogene therapy for metastatic liver cancer in rats.

METHODS

We studied whether in vitro infection of a rat colon cancer cell line (RCN9) with an adenoviral-vector that expresses the CD40L (AxCAmCD40L) induced CD40L expression. In vivo to confirm the antitumor effect induced by AxCAmCD40L, the tumor cells that had been transduced by AxCAmCD40L were implanted into the subcutaneous tissues of syngenic rats (prevention model) or AxCAmCD40L was injected into the tumor tissues of the rats (treatment model). Furthermore, immune cells including NK cells, cytotoxic T cells, and tumor-specific antibodies induced by AxCAmCD40L were examined.

RESULTS

Immunogene therapy using AxCAmCD40L suppressed the tumor growth strongly or reduced tumor size in the prevention model and treatment model. NK cells, cytotoxic T cells, and tumor-specific antibodies contributed to this antitumor effect in both groups.

CONCLUSION

These observations suggest that CD40L-mediated immunogene therapy for metastatic colon cancer in the liver and lungs is effective and is mediated by the activation of both the cellular and humoral immune systems.

Overexpression and interactions of interleukin-10, transforming growth factor beta, and vascular endothelial growth factor in esophageal squamous cell carcinoma

BACKGROUND

Sharing the role of immune suppression, interleukin-10 (IL-10), transforming growth factor beta (TGF-beta), and vascular endothelial growth factor (VEGF) are critical genes in several aspects of tumorigenesis. To elucidate the role of these cytokines in esophageal squamous cell carcinoma (ESCC), their relative mRNA expression in tumoral tissue compared with corresponding tumor-free tissue was evaluated.

METHODS

A total of 49 patients with histologically confirmed ESCC were included in the study prior to any therapeutic interventions. Quantitative analysis of the mRNA expression was performed by real-time reverse transcription-polymerase chain reaction and the clinicopathologic associations were assessed.

RESULTS

The mRNA of IL-10, VEGF, and TGF-beta was frequently overexpressed in 53.2%, 44.9%, and 37.5% of ESCC patients, respectively. TGF-beta was significantly co-expressed with IL-10 and with VEGF. Although VEGF was not independently associated with increased tumor size (p = 0.065), concomitant overexpression of VEGF with TGF-beta was significantly correlated with increased size of the tumor (p < 0.05).

CONCLUSIONS

Overexpression of IL-10, TGF-beta, and VEGF plays an important role in ESCC and consequently leads to the frequent event of immune evasion in ESCC. TGF-beta is concomitantly overexpressed with IL-10 and with VEGF in ESCC. A stimulatory signal from TGF-beta to VEGF is necessary for VEGF to promote tumor progression.

The Janus faces of CD40 in cancer

CD40 is a TNF receptor family member that is widely recognized for its prominent role in immune regulation and homeostasis. Expression of CD40 is not restricted to normal lymphoid cells but is also evident in the majority of haemopoietic and epithelial malignancies where it has been implicated in oncogenic events. Accumulating evidence, however, suggests that the CD40 pathway can be exploited for cancer therapy by virtue of its ability to stimulate the host anti-tumor immune response, normalize the tumor microenvironment and directly suppress the growth of CD40-positive tumors. Here, we provide an overview of the multifaceted functions of the CD40 pathway in cancer and its emerging role in the treatment of malignancy.

A novel immunotherapy for superficial bladder cancer by intravesical immobilization of GM-CSF

In situ gene therapy with granulocyte-macrophage colony-stimulating factor (GM-CSF) was demonstrated to successfully inhibit tumour cell growth in a mouse orthotopic bladder cancer model, but suffered from several disadvantages, such as limited efficiency for gene delivery, low expression efficiency of the transgene and the safety concern resulting from viral vector. In order to address the limits, a novel immunotherapy was developed attentively through immobilization of streptavidin-tagged bioactive GM-CSF on the biotinylated mucosal surface of bladder wall on the basis of both the unique property of streptavidin (SA) to bind rapidly and almost irreversibly to any biotin-linked molecule and the outstanding ability of biotin to be incorporated easily into the proteins on the cell surface. The mouse orthotopic model of MB49 bladder cancer was used to evaluate the feasibility and efficacy of the novel immunotherapy performed twice a week for 3 weeks. Briefly, 1 day after intravesical implantation of 1 x 10(6) MB49 tumour cells in C57BL/6 mouse, 100 microl of 1 mg/ml NHS-PEO4-biotin was instilled and allowed to incubate in the bladder for 30 min., followed by intravesical instillation of 100 microl of 0.15 mg/ml SA-GM-CSF bifunctional fusion protein and incubation for 1 hr. SA-GM-CSF fusion protein was shown to be immobilized efficiently and durably on the biotinylated mucosal surface of bladder wall. The bladder cancer incidence was dramatically decreased from 100% in the control group to 37.5% in the SA-GM-CSF group. Importantly, 70% of the SA-GM-CSF-cured mice were protected against a second intravesical wild-type MB49 tumour challenge, indicating that an effective anti-tumour immunity was generated against MB49 bladder cancer. Thus, the novel immunotherapy may be an attractive therapeutic alternative and should be evaluated in bladder cancer patients.

Adenovirus delivery of human CD40 ligand gene confers direct therapeutic effects on carcinomas

CD40, a tumor necrosis factor receptor family member, is an emerging target for cancer therapy being best appreciated as an important regulator of the anti-tumor immune response. In this study, we report the development of a replication-defective recombinant adenovirus (RAd) vector expressing human CD40 ligand (RAd-hCD40L) and show that sustained engagement of the CD40 pathway in malignant cells results in direct anti-proliferative and pro-apoptotic effects. Thus, transduction of CD40-positive bladder, cervical and ovarian carcinoma cell lines with RAd-hCD40L potently inhibits their proliferation in vitro, whereas CD40-negative lines remain unresponsive. RAd-hCD40L is also found to be superior to recombinant CD40L in inducing carcinoma cell death and in amplifying the cytotoxic effects of the chemotherapeutic agents 5-fluorouracil, cis-platin and mitomycin C. Soluble CD40L is produced by RAd-hCD40L transduced carcinoma cells but unlike other soluble tumor necrosis factor family ligands, it does not interfere with the death-promoting activity of its membrane-bound form. In a mouse xenograft tumor model bearing a human bladder carcinoma, intratumoral delivery of RAd-hCD40L suppresses cancer growth. These findings highlight the potential of exploiting the CD40 pathway in carcinomas using CD40L gene transfer alone or in combination with other modalities for cancer therapy. Our results have also broader implications in understanding the multifaceted anti-tumor activities of the CD40 pathway in carcinomas, which thus offer an attractive option for future clinical application.

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.

Efficient adenovector CD40 ligand immunotherapy of canine malignant melanoma

Cutaneous canine melanomas are usually benign in contrast to human malignant melanoma. However, the canine oropharyngeal, uveal, and mucocutaneous neoplasms are aggressive and have metastatic potential. Surgery and to a lesser extent radiotherapy and chemotherapy are widely adopted treatments but are seldom curative in advanced stages. The similarities between human and canine melanoma make spontaneous canine melanoma an excellent disease model for exploring novel therapies. Herein, we report the first 2 adenovector CD40L immunogene (AdCD40L) treatments of aggressive canine malignant melanoma. Case no. 1 was an advanced stage III oral melanoma that was cured from malignant melanoma with 2 intratumor AdCD40L injections before cytoreductive surgery. After treatment, the tumor tissue was infiltrated with T lymphocytes and B lymphocytes suggesting immune activation. This dog survived 401 days after the first round of gene therapy and was free of melanoma at autopsy. Case no. 2 had a conjunctival malignant melanoma with a rapid progression. This case was treated with 6 AdCD40L injections over 60 days. One hundred and twenty days after start of gene therapy and 60 days after the last injection, the tumor had regressed dramatically, and the dog had a minimal tumor mass and no signs of progression or metastasis. Our results indicate that AdCD40L immunogene therapy is beneficial in canine malignant melanoma and could be considered for human malignant melanoma as well.

CD40 induces antigen transporter and immunoproteasome gene expression in carcinomas via the coordinated action of NF-kappaB and of NF-kappaB-mediated de novo synthesis of IRF-1

Cancer cells may evade immune surveillance as a result of defective antigen processing and presentation. In this study, we demonstrate that CD40 ligation overcomes this defect through the coordinated action of the transcription factors NF-kappaB and interferon regulatory factor 1 (IRF-1). We show that unlike interferon signaling, which triggers the STAT1-mediated transcriptional activation of IRF-1, the ligation of CD40 in carcinomas induces the rapid upregulation of IRF-1 in a STAT1-independent but NF-kappaB-dependent manner. The transcriptional activation of IRF-1 is controlled largely by the recruitment of p65 (RelA) NF-kappaB to the IRF-1 promoter following the engagement of a TAK1/IkappaB kinase beta/IkappaBalpha signaling pathway downstream of CD40. NF-kappaB and de novo-synthesized IRF-1 converge to regulate the expression of genes involved in antigen processing and transport, as evident from the sequential recruitment of NF-kappaB and IRF-1 to the promoters of the genes encoding transporter for antigen processing 1 (TAP1), TAP2, tapasin, and low-molecular-mass polypeptides LMP2 and LMP10. Moreover, the RNA interference-mediated knockdown of IRF-1 reduced, whereas the inhibition of NF-kappaB abolished, the effects of CD40 on TAP1 and LMP2 upregulation in carcinoma cells. Collectively, these data reveal a novel "feed-forward" mechanism induced by NF-kappaB which ensures that acutely synthesized IRF-1 operates in concert with NF-kappaB to amplify the immunoproteasome and antigen-processing functions of CD40.

Alpha-fetoprotein and other tumour-associated antigens for immunotherapy of hepatocellular cancer

BACKGROUND

Hepatocellular carcinoma (HCC) is a leading cause of cancer death, with few treatment options for advanced disease.

OBJECTIVES

Here, we review the aetiology of HCC and focus on recent data on tumour-associated antigens (TAA) for HCC, their functions and potential use as immunological targets for immune-based therapy for HCC. In addition, we examine some aspects of antigen presentation within the liver.

RESULTS/CONCLUSIONS

alpha-Fetoprotein (AFP) has been investigated for many years as a TAA, and has been tested in recent clinical trials. More recently, additional TAA have been identified and new therapeutic approaches have been investigated which may be testable clinically in this difficult disease setting.

CpG therapy is superior to BCG in an orthotopic bladder cancer model and generates CD4+ T-cell immunity

Bacillus Calmette Guérin (BCG) immunotherapy has been successful in extending tumor remission in bladder cancer, the fifth most common cancer in men. However, relapses are frequent and some patients develop resistance to BCG. CpGs were previously demonstrated to be effective in the murine MB49 model. In this paper, we modeled a more aggressive orthotopic bladder cancer than previously studied. Moreover, we compared standard BCG immunotherapy side-by-side with the Toll-like receptor-9 agonist CpG. MB49 tumor-bearing mice were treated with BCG or CpG and survival as well as tumor progression were observed over time. Urine, blood, and tumors were collected and analyzed. Mice were rechallenged and evaluated for tumor-specific immunity. In this study, CpGs induced a complete response of large aggressive orthotopic MB49 bladder tumors, resulting in tumor-specific systemic immunity. Further, data indicated that this potent antitumor effect required T cells. A comparison of CpGs and BCG in both a highly and less aggressive orthotopic tumor model, and in a subcutaneous tumor model, demonstrated that CpGs were superior to BCG. In the orthotopic model, BCG induced a local cytokine storm during treatment initiation whereas CpG affected a more refined cytokine pattern over time. Increased levels of cytokines in serum correlated with enhanced survival in the subcutaneous model. Further, immune cell depletion studies demonstrated that CpG-induced protective immunity was CD4+ T-cell dependent. Taken together, our data suggest that CpGs are superior to BCG for bladder cancer immunotherapy. Thus, this potent new drug may be an attractive therapeutic alternative and should be evaluated in bladder cancer patients.

Expression-targeted gene therapy for the treatment of transitional cell carcinoma

Targeted gene delivery for induced apoptosis of transitional cell carcinomas was carried out in vivo in mice via utilization of the murine cyclooxygenase type 2 (Cox-2) promoter (Tis10). MB49 cells, which constitutively overexpress Cox-2 like numerous other carcinomas, selectively expressed delivered genes that utilized this transcriptional control element. The products of the delivered genes were artificially inducible forms of caspases 3 and 9, which remained inactive until a chemical inducer of dimerization was later injected intraperitoneally. The genes were delivered intravesically as plasmids complexed with poly(ethylenimine). Significant improvements, in the form of reduced bladder mass, reduced tumor volume, anti-angiogenesis and inhibition of tumor growth were seen versus untreated or unactivated controls. In some instances, tumors were seen to go into complete remission. There were no apparent bystander effects associated with the treatments. This targeted gene therapy regimen could have wide applicability to numerous cancers due to constitutive overexpression of Cox-2.

CD8+ T cells against multiple tumor-associated antigens in peripheral blood of midgut carcinoid patients

PURPOSE

The aim of the study was to identify immunogenic HLA-A*0201-binding epitopes derived from a number of classical midgut carcinoid-associated proteins. CD8(+) T cells recognizing tumor-associated antigen (TAA) epitopes are of great interest for the establishment of immunotherapy as a novel treatment for this type of malignancy.

EXPERIMENTAL DESIGN

Midgut carcinoid tumor specimens were microdissected and expression levels of potential TAAs were investigated by quantitative real time PCR. HLA-A*0201-binding motifs were selected using HLA peptide binding prediction algorithms and stabilization of HLA-A*0201 was verified using TAP-deficient T2 cells. Peripheral blood of midgut carcinoid patients was analyzed for peptide epitope recognition and the feasibility of generating peptide-reactive CD8(+) T cells in healthy blood donors was examined by an in vitro stimulation protocol using mature DCs. Activation of patient and healthy donor CD8(+) T cells was analyzed by intracellular flow cytometry staining of interferon gamma.

RESULTS

Chromogranin A (CGA), tryptophan hydroxylase 1 (TPH-1), vesicular monoamine transporter 1 (VMAT-1), caudal type homeobox transcription factor 2 (CDX-2), and islet autoantigen 2 (IA-2) are properly expressed by midgut carcinoid tumor cells, with CGA mRNA expressed to greatest level. Midgut carcinoid patients have increased frequencies of peripheral blood CD8(+) T cells recognizing a pool of HLA-A*0201 peptides derived from these proteins compared to healthy age-matched individuals. Activated peptide-specific CD8(+) T cells could also be generated in healthy blood donors by in vitro stimulation.

CONCLUSION

We have identified a number of immunogenic midgut carcinoid-associated peptide epitopes recognized by CD8(+) T cells. We show that midgut carcinoid patients display immune recognition of their tumors. Memory CD8(+) T cells in patient blood are of great interest when pursuing an immunotherapeutic treatment strategy.

Adeno-associated virus mediated gene transfer into lung cancer cells promoting CD40 ligand-based immunotherapy

Expression of the CD40 ligand (CD40L) on tumors can activate host immune systems and produce antitumor effects against the tumors. To deliver the CD40L gene efficiently, we evaluated the efficiency of transduction of different serotypes of adeno-associated virus (AAV) vectors in lung cancer A549 cells and compared the transduction efficiency of a conventional AAV vector with that of self-complementary AAV (scAAV) vectors as well. We determined that serotype AAV2/5 transduced A549 cells much more efficiently than serotypes AAV2/1, AAV2/2, AAV2/6, AAV2/7, AAV2/8, AAV2/9 and AAV2/10. And the transduction efficiency of scAAV2/5 was significantly higher than conventional AAV2/5. Furthermore, pre-treatment with carboplatin, which is a chemotherapeutic agent used in lung cancer chemotherapy, substantially increased AAV-mediated transgene expression. The scAAV2/5 vectors encoding human CD40L were used to tranduce CD40L into A549 cells, which were then co-cultivated with immature human dendritic cells (DCs). Interleukin 12 (IL-12) that was released was measured in the culture supernatant. Specificity of the immunostimulatory effect of CD40L was confirmed by blocking with a monoclonal antibody binding to human CD40L. The in vivo antitumor activity was evaluated in BALB/c nude mice bearing A549 lung cancer. scAAV2/5-CD40L showed significant inhibitory effects on the growth of transplanted tumor cells as compared with control group. These studies suggest that recombinant AAV2/5-CD40L may provide an effective form of therapy for lung cancer.

RE. Template-driven gene selection procedure

The hierarchical clustering and statistical techniques usually used to analyse microarray data do not inherently represent the underlying biology. Herein, a hybrid approach involving characteristics of both supervised and unsupervised learning is presented. This approach is based on template matching in which the interaction of the variables of inherent malignancy and the ability to express the malignant phenotype are modelled. Immortalised normal urothelial cells and bladder cancer cells of different malignancy were grown in conventional two-dimensional tissue culture and in three dimensions on extracellular matrices (ECMs) that were either permissive or restrictive for expression of the malignant phenotype. The transcriptome represents the effects of two variables--inherent malignancy and the modulatory effect of ECM. By assigning values to each of the biological variables of inherent malignancy and the ability to express the malignant phenotype, a template was constructed, which encapsulated the interaction between them. Gene expression correlating both positively and negatively with the template was observed, but when iterative correlations were carried out, the different models for the template converged on the same actual template. A subset of 21 genes was identified, which correlated with two a priori models or an optimised model above the 95% confidence limits identified in a bootstrap resampling with 5000 permutations of the data set. The correlation coefficients of expression of several genes were > 0.8. Analysis of upstream transcriptional regulatory elements (TREs) confirmed that these genes were not a randomly selected set of genes. Several TREs were identified as significantly over-expressed in the sample of 20 genes for which TREs were identified, and the high correlations of several genes were consistent with transcriptional co-regulation. The authors suggest that the template method can be used to identify a unique set of genes for further investigation.