CD4+ cytotoxic T cells: an emerging effector arm of anti-tumor immunity

While CD8⁺ cytotoxic T cells have long been considered the primary effector in controlling tumors, the involvement of CD4⁺ "helper" T cells in anti-tumor immunity has been underappreciated. The investigations of intra-tumoral T cells, fueled by the recent advances in genomic technologies, have led to a rethinking of the indirect role of CD4⁺ T cells that have traditionally been described as a "helper". Accumulating evidence from preclinical and clinical studies indicates that CD4⁺ T cells can acquire intrinsic cytotoxic properties and directly kill various types of tumor cells in a major histocompatibility complex classe II (MHC-II)-dependent manner, as opposed to the indirect "helper" function, thus underscoring a potentially critical contribution of CD4⁺ cytotoxic T cells to immune responses against a wide range of tumor types. Here, we discuss the biological properties of anti-tumor CD4⁺ T cells with cytotoxic capability and highlight the emerging observations suggesting their more significant role in anti-tumor immunity than previously appreciated.

CD4+ cytotoxic T cells: an emerging effector arm of anti-tumor immunity

While CD8+ cytotoxic T cells have long been considered the primary effector in controlling tumors, the involvement of CD4+ "helper" T cells in anti-tumor immunity has been underappreciated. The investigations of intra-tumoral T cells, fueled by the recent advances in genomic technologies, have led to a rethinking of the indirect role of CD4+ T cells that have traditionally been described as a "helper". Accumulating evidence from preclinical and clinical studies indicates that CD4+ T cells can acquire intrinsic cytotoxic properties and directly kill various types of tumor cells in a major histocompatibility complex class II (MHC-II)-dependent manner, as opposed to the indirect "helper" function, thus underscoring a potentially critical contribution of CD4+ cytotoxic T cells to immune responses against a wide range of tumor types. Here, we discuss the biological properties of anti-tumor CD4+ T cells with cytotoxic capability and highlight the emerging observations suggesting their more significant role in anti-tumor immunity than previously appreciated. [BMB Reports 2023; 56(3): 140-144].

Does delayed EBV infection contribute to rising childhood cancers?

Childhood cancer is on the rise in high-income countries. Epidemiological studies suggest that reduced exposure to common infections in early life is to blame. However, no specific infection responsible for protection against cancer has been identified, and the underlying mechanisms remain a matter of speculation. Recent findings that Epstein-Barr virus (EBV) can induce antitumor immunity lead us to hypothesize that the delay in EBV infection in such countries might contribute to the increase in childhood cancers.

Facts and Hopes in the Relationship of EBV with Cancer Immunity and Immunotherapy

Epstein-Barr virus (EBV), the first identified human tumor virus, infects and takes up residency in almost every human. However, EBV genome-positive tumors arise in only a tiny minority of infected people, presumably when the virus-carrying tumor cells are able to evade immune surveillance. Traditional views regard viral antigens as the principal targets of host immune surveillance against virus-infected cells. However, recent findings indicate that EBV-infected/-transformed B cells elicit both cytotoxic CD8+ and CD4+ T-cell responses against a wide range of overexpressed cellular antigens known to function as tumor-associated antigens (TAA), in addition to various EBV-encoded antigens. This not only broadens the ways by which the immune system controls EBV infection and prevents it from causing cancers, but also potentially extends immune protection toward EBV-unrelated cancers by targeting shared TAAs. The goal of this review is to incorporate these new findings with literature data and discuss future directions for improved understanding of EBV-induced antitumor immunity, as well as the hopes for rational immune strategies for cancer prevention and therapy.

Abstract A38: Cd70 genetic perturbation limits the development of an effective CD8+ T-cell immune response to Bcl6-driven diffuse large B-cell lymphoma

Multiple immunomodulatory pathways shape the development of anti-tumor immune responses to lymphoid malignancies. We previously defined the recurrent genetic alterations in diffuse large B-cell lymphoma (DLBCL) and identified associated substructure and additional potential genetic bases for immune escape. CD70 was the most commonly perturbed immune response pathway component in our cohort of primary DLBCLs; alterations included inactivating mutations and copy loss. CD70 co-stimulation of CD27+ T cells induces antigen-dependent T-cell expansion and immune surveillance of normal and malignant B cells. Given the frequent co-association of CD70 alterations and BCL6 translocations in our DLBCL patient series, we assessed the consequences of Cd70 deficiency on Bcl6-driven lymphomagenesis in a murine model. We crossed previously generated Cd70 −/- and Bcl6 tg/+ mice to obtain Cd70 −/−; Bcl6 tg/+ animals. In our aging cohorts, Cd70− / −; Bcl6tg/+ mice developed significantly increased numbers of histopathologically confirmed DLBCLs at earlier timepoints, compared to Bcl6 tg/+ animals. Both the Cd70 −/−; Bcl6 tg/+ and Bcl6 tg/+ mice that were euthanized for symptoms exhibited massive splenomegaly and lymphomatous splenic infiltration. None of the wild-type (WT) and Cd70 −/- animals developed lymphoma. To characterize potential differences in anti-tumor responses in Cd70 −/−; Bcl6 tg/+ versus Bcl6 tg/+ mice, we harvested spleens from asymptomatic animals in each cohort at 6, 14 and 18 months (mo). Cd70 −/−; Bcl6 tg/+ mice exhibited significantly earlier onset splenomegaly than Bcl6 tg/+ animals (both in comparison with WT mice). We performed single cell RNA sequencing of splenic cell suspensions from each murine cohort at the above-mentioned predetermined timepoints (6, 14 and 18 mo) and describe genotype-related changes in splenic CD8+ T-cell infiltration in this abstract. Our study revealed an age-related decline in the percentages of naive CD8+ T cells in all genotypes, with more striking and earlier changes in Cd70 −/−; Bcl6 tg/+ animals. Cd70 −/−; Bcl6 tg/+ and Bcl6 tg/+ mice exhibited a selective and significant expansion of CD8+ cytotoxic T cells (CTLs), which expressed Gzmb and Prf1 and the exhaustion markers, Pdcd1, Lag3, Tigit, Tox and Tim3, and exhibited clonal expansion. At 6 mo, prior to splenic enlargement and the development of symptoms, CD8+ CTLs in Cd70 −/−; Bcl6 tg/+ animals expressed significantly higher levels of exhaustion markers than those in Bcl6 tg/+ mice. Consistent with this finding, there was a more limited expansion and a subsequent contraction of these splenic CD8+ CTLs in Cd70 −/−; Bcl6 tg/+ mice, in comparison to Bcl6 tg/+ animals. Taken together, these findings suggest that initial anti-tumor immune responses are less effective in Cd70 −/−; Bcl6 tg/+ mice than in Bcl6 tg/+ animals and highlight the likely importance of CD70/CD27 co-stimulation in CD8+ T-cell response to Bcl6-driven DLBCL.

Citation Format: Elisa Mandato, Eleonora Calabretta, Gali Bai, Li Song, Yanbo Sun, Vignesh Shanmugam, Julia Paczkowska, Il-Kyu Choi, Robert Redd, Ming Tang, Lee N Lawton, Donna Neuberg, Scott Rodig, Franziska Michor, Baochun Zhang, Margaret A Shipp. Cd70 genetic perturbation limits the development of an effective CD8+ T-cell immune response to Bcl6-driven diffuse large B-cell lymphoma [abstract]. In: Proceedings of the Third AACR International Meeting: Advances in Malignant Lymphoma: Maximizing the Basic-Translational Interface for Clinical Application; 2022 Jun 23-26; Boston, MA. Philadelphia (PA): AACR; Blood Cancer Discov 2022;3(5_Suppl):Abstract nr A38.

Mechanism of EBV inducing anti-tumour immunity and its therapeutic use

Tumour-associated antigens (TAAs) comprise a large set of non-mutated cellular antigens recognized by T cells in human and murine cancers. Their potential as targets for immunotherapy has been explored for more than two decades¹, yet the origins of TAA-specific T cells remain unclear. While tumour cells may be an important source of TAAs for T cell priming², several recent studies suggest that infection with some viruses, including Epstein-Barr virus and influenza virus can elicit T cell responses against abnormally expressed cellular antigens that function as TAAs^3,4. However, the cellular and molecular basis of such responses remains undefined. Here we show that expression of the Epstein-Barr virus signalling protein LMP1 in B cells provokes T cell responses to multiple TAAs. LMP1 signalling leads to overexpression of many cellular antigens previously shown to be TAAs, their presentation on major histocompatibility complex classes I (MHC-I) and II (MHC-II) (mainly through the endogenous pathway) and the upregulation of costimulatory ligands CD70 and OX40L, thereby inducing potent cytotoxic CD4⁺ and CD8⁺ T cell responses. These findings delineate a mechanism of infection-induced anti-tumour immunity. Furthermore, by ectopically expressing LMP1 in tumour B cells from patients with cancer and thereby enabling them to prime T cells, we develop a general approach for rapid production of autologous cytotoxic CD4⁺ T cells against a wide range of endogenous tumour antigens, such as TAAs and neoantigens, for treating B cell malignancies. This work stresses the need to revisit classical concepts concerning viral and tumour immunity, which will be critical to fully understand the impact of common infections on human health and to improve the rational design of immune approaches to treatment of cancers.

Animal models for dengue vaccine development and testing

Dengue fever is a tropical endemic disease; however, because of climate change, it may become a problem in South Korea in the near future. Research on vaccines for dengue fever and outbreak preparedness are currently insufficient. In addition, because there are no appropriate animal models, controversial results from vaccine efficacy assessments and clinical trials have been reported. Therefore, to study the mechanism of dengue fever and test the immunogenicity of vaccines, an appropriate animal model is urgently needed. In addition to mouse models, more suitable models using animals that can be humanized will need to be constructed. In this report, we look at the current status of model animal construction and discuss which models require further development.

Oncolytic adenovirus expressing relaxin (YDC002) enhances therapeutic efficacy of gemcitabine against pancreatic cancer

Pancreatic cancer is a highly lethal disease for which limited therapeutic options are available. Pancreatic cancer exhibits a pronounced collagen-rich stromal reaction, which induces chemoresistance by inhibiting drug diffusion into the tumor. Complementary treatment with oncolytic virus such as an oncolytic adenovirus expressing relaxin (YDC002) is an innovative treatment option for combating chemoresistant pancreatic cancer. Here, we examined the ability of combined treatment with gemcitabine and YDC002, which degrades extracellular matrix (ECM), to efficiently treat chemoresistant and desmoplastic pancreatic cancer. Gemcitabine alone exhibited similarly low cytotoxicity toward pancreatic cancer cells throughout the concentration range (1-50 μM) used, whereas the combination of YDC002 and a subtherapeutic dose of gemcitabine (0.01-0.05 μM) resulted in potent anticancer effects through effective induction of apoptosis. Importantly, YDC002 combined with gemcitabine significantly attenuated the expression of major ECM components including collagens, fibronectin, and elastin in tumor spheroids and xenograft tumors compared with gemcitabine alone, resulting in potent induction of apoptosis, gemcitabine-mediated cytotoxicity, and an oncolytic effect through degradation of tumor ECM. Our results demonstrate that YDC002 can selectively degrade aberrant ECM and attenuate the ECM-induced chemoresistance observed in desmoplastic pancreatic tumor, resulting in a potent antitumor effect through effective induction of apoptosis.

Treatment strategies for combining immunostimulatory oncolytic virus therapeutics with dendritic cell injections

Oncolytic viruses (OVs) are used to treat cancer, as they selectively replicate inside of and lyse tumor cells. The efficacy of this process is limited and new OVs are being designed to mediate tumor cell release of cytokines and co-stimulatory molecules, which attract cytotoxic T cells to target tumor cells, thus increasing the tumor-killing effects of OVs. To further promote treatment efficacy, OVs can be combined with other treatments, such as was done by Huang et al., who showed that combining OV injections with dendritic cell (DC) injections was a more effective treatment than either treatment alone. To further investigate this combination, we built a mathematical model consisting of a system of ordinary differential equations and fit the model to the hierarchical data provided from Huang et al. We used the model to determine the effect of varying doses of OV and DC injections and to test alternative treatment strategies. We found that the DC dose given in Huang et al. was near a bifurcation point and that a slightly larger dose could cause complete eradication of the tumor. Further, the model results suggest that it is more effective to treat a tumor with immunostimulatory oncolytic viruses first and then follow-up with a sequence of DCs than to alternate OV and DC injections. This protocol, which was not considered in the experiments of Huang et al., allows the infection to initially thrive before the immune response is enhanced. Taken together, our work shows how the ordering, temporal spacing, and dosage of OV and DC can be chosen to maximize efficacy and to potentially eliminate tumors altogether.

Quantitative impact of immunomodulation versus oncolysis with cytokine-expressing virus therapeutics

The past century's description of oncolytic virotherapy as a cancer treatment involving specially-engineered viruses that exploit immune deficiencies to selectively lyse cancer cells is no longer adequate. Some of the most promising therapeutic candidates are now being engineered to produce immunostimulatory factors, such as cytokines and co-stimulatory molecules, which, in addition to viral oncolysis, initiate a cytotoxic immune attack against the tumor. This study addresses the combined effects of viral oncolysis and T-cell-mediated oncolysis. We employ a mathematical model of virotherapy that induces release of cytokine IL-12 and co-stimulatory molecule 4-1BB ligand. We found that the model closely matches previously published data, and while viral oncolysis is fundamental in reducing tumor burden, increased stimulation of cytotoxic T cells leads to a short-term reduction in tumor size, but a faster relapse. In addition, we found that combinations of specialist viruses that express either IL-12 or 4-1BBL might initially act more potently against tumors than a generalist virus that simultaneously expresses both, but the advantage is likely not large enough to replace treatment using the generalist virus. Finally, according to our model and its current assumptions, virotherapy appears to be optimizable through targeted design and treatment combinations to substantially improve therapeutic outcomes.

Abstract 298: Overcoming TGF-β-related immunosuppression for cancer immunotherapy by oncolytic adenovirus co-expressing Interleukin-12 and decorin

Interleukin (IL)-12 has been shown to be one of the most promising antitumor cytokines. The major antitumor activities of IL-12 rely on its ability to promote T helper type 1 (Th1) immune responses and CTL responses. However, immune suppression-dominated microenvironments in advanced tumors hinder the effect of IL-12 gene therapy for cancer. Most tumor cells produce large amounts of transforming growth factor-β (TGF-β), which plays crucial roles of tumor-induced immune suppression. The TGF-β inhibits proliferation of immune cells such as T, NK, and dendritic cells, resulting in suppression of antitumor immunity. Moreover, TGF-β is also known to regulate the maintenance and induction of regulatory T (Treg) cells. Thus, it has been hypothesized that inhibiting TGF-β might be an apt strategy for generating more effective cancer immunotherapy. Therefore, to enhance the efficiency of IL-12-mediated cancer immunotherapy, we generated oncolytic adenovirus co-expressing IL-12 and Decorin (hDCN) (RdB/IL12/hDCN) as suitable therapeutic adjuvant to overcome immune suppression by down-regulation of TGF-β through hDCN. Intratumoral administration of RdB/IL12/hDCN promoted enhanced antitumor effects compared with an oncolytic adenovirus expressing IL-12 or hDCN alone (RdB/IL12 or RdB/hDCN, respectively). We showed markedly elevated levels of interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α and IFN-γ secreting cells in RdB/IL12/hDCN-treated tumors. Moreover, Treg in draining lymph nodes (DLNs) dramatically decreased in mice treated with RdB/IL12/hDCN, suggesting an association with the down-regulation of TGF-β in tumor treated with RdB/IL12/hDCN. Consistent with these data, tumor tissue injected with RdB/IL12/hDCN showed increased infiltration of CD4+ T and CD8+ T cells infiltration. Furthermore, hDCN enhanced viral distribution and tumor penetration, leading to improved virus-mediated cancer gene therapy by overcoming the extracellular matrix barrier within tumor masses. Together, these results provide new insight into the ability of hDCN to eliminate immune suppression and demonstrate that adenovirus co-expressing IL-12 and hDCN is a promising therapeutic tool for cancer treatment than adenovirus expressing IL-12 alone.

Note: This abstract was not presented at the meeting.

Citation Format: Eonju Oh, Il-Kyu Choi, June Kyu Hwang, Chae-Ok Yun. Overcoming TGF-β-related immunosuppression for cancer immunotherapy by oncolytic adenovirus co-expressing Interleukin-12 and decorin. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 298. doi:10.1158/1538-7445.AM2015-298

Potent and long-term antiangiogenic efficacy mediated by FP3-expressing oncolytic adenovirus

Various ways to inhibit vascular endothelial growth factor (VEGF), a key facilitator in tumor angiogenesis, are being developed to treat cancer. The soluble VEGF decoy receptor (FP3), due to its high affinity to VEGF, is a highly effective and promising strategy to disrupt VEGF signaling pathway. Despite potential advantage and potent therapeutic efficacy, its employment has been limited by very poor in vivo pharmacokinetic properties. To address this challenge, we designed a novel oncolytic adenovirus (Ad) expressing FP3 (RdB/FP3). To demonstrate the VEGF-specific nature of RdB/FP3, replication-incompetent Ad expressing FP3 (dE1/FP3) was also generated. dE1/FP3 was highly effective in reducing VEGF expression and functionally elicited an antiangiogeneic effect. Furthermore, RdB/FP3 exhibited a potent antitumor effect compared with RdB or recombinant FP3. Consistent with these data, RdB/FP3 was shown to greatly decrease VEGF expression level and vessel density and increase apoptosis in both tumor endothelial and tumor cells, verifying potent suppressive effects of RdB/FP3 on VEGF-mediated tumor angiogenesis in vivo. Importantly, the therapeutic mechanism of antitumor effect mediated by RdB/FP3 is associated with prolonged VEGF silencing efficacy and enhanced oncolysis via cancer cell-specific replication of oncolytic Ad. Taken together, RdB/FP3 provides a new promising therapeutic approach in the treatment of cancer and angiogenesis-related diseases.

Decorin-expressing adenovirus decreases collagen synthesis and upregulates MMP expression in keloid fibroblasts and keloid spheroids

Decorin is a natural transforming growth factor-β1 (TGF-β1) antagonist. Reduced decorin synthesis is associated with dermal scarring, and increased decorin expression appears to reduce scar tissue formation. To investigate the therapeutic potential of decorin for keloids, human dermal fibroblasts (HDFs) and keloid-derived fibroblasts (KFs) were transduced with decorin-expressing adenovirus (dE1-RGD/GFP/DCN), and we examined the therapeutic potential of decorin-expressing Ad for treating pathologic skin fibrosis. Decorin expression was examined by immunofluorescence assay on keloid tissues. HDFs and KFs were transduced with dE1-RGD/GFP/DCN or control virus, and protein levels of decorin, epidermal growth factor receptor (EGFR) and secreted TGF-β1 were assessed by Western blotting and ELISA. And type I and III collagen, and matrix metalloproteinase-1 (MMP-1) and matrix metalloproteinase-3 (MMP-3) mRNA levels were measured by real-time RT-PCR. Additionally, we immunohistochemically investigated the expression levels of the major extracellular matrix (ECM) proteins in keloid spheroids transduced with dE1-RGD/GFP/DCN. Lower decorin expression was observed in the keloid region compared to adjacent normal tissues. After treatment with dE1-RGD/GFP/DCN, secreted TGF-β1 and EGFR protein expressions were decreased in TGF-β1-treated HDFs and KFs. Also, type I and III collagen mRNA levels were decreased, and the expression of MMP-1 and MMP-3 mRNA was strongly upregulated. In addition, the expression of type I and III collagen, fibronectin and elastin was significantly reduced in dE1-RGD/GFP/DCN-transduced keloid spheroids. These results support the utility of decorin-expressing adenovirus to reduce collagen synthesis in KFs and keloid spheroid, which may be highly beneficial in treating keloids.

Identification and functional characterization of nuclear mortalin in human carcinogenesis

The Hsp70 family protein mortalin is an essential chaperone that is frequently enriched in cancer cells and exists in various subcellular sites, including the mitochondrion, plasma membrane, endoplasmic reticulum, and cytosol. Although the molecular mechanisms underlying its multiple subcellular localizations are not yet clear, their functional significance has been revealed by several studies. In this study, we examined the nuclear fractions of human cells and found that the malignantly transformed cells have more mortalin than the normal cells. We then generated a mortalin mutant that lacked a mitochondrial targeting signal peptide. It was largely localized in the nucleus, and, hence, is called nuclear mortalin (mot-N). Functional characterization of mot-N revealed that it efficiently protects cancer cells against endogenous and exogenous oxidative stress. Furthermore, compared with the full-length mortalin overexpressing cancer cells, mot-N derivatives showed increased malignant properties, including higher proliferation rate, colony forming efficacy, motility, and tumor forming capacity both in in vitro and in vivo assays. We demonstrate that mot-N promotes carcinogenesis and cancer cell metastasis by inactivation of tumor suppressor protein p53 functions and by interaction and functional activation of telomerase and heterogeneous ribonucleoprotein K (hnRNP-K) proteins.

Treatment of necrotising fasciitis using glycerol-preserved skin allografts for temporary wound coverage

Allografts of human skin have been used for both temporary and permanent wound coverage. They are useful as temporary bridges for the critically ill patient who is not allowed to receive definite wound coverage, or for wound bed preparation before permanent grafting. Glycerol-preserved skin allografts have several benefits including good adherence to the wound bed, water vapour transport, antimicrobial characteristics, low toxicity and antigenicity, ease of application and removal, a long shelf-life, and minimal storage requirements. We achieved lower limb salvage using a glycerol-preserved skin allograft for temporary wound coverage in the treatment of necrotising fasciitis.

Strategies to increase drug penetration in solid tumors

Despite significant improvement in modalities for treatment of cancer that led to a longer survival period, the death rate of patients with solid tumors has not changed during the last decades. Emerging studies have identified several physical barriers that limit the therapeutic efficacy of cancer therapeutic agents such as monoclonal antibodies, chemotherapeutic agents, anti-tumor immune cells, and gene therapeutics. Most solid tumors are of epithelial origin and, although malignant cells are de-differentiated, they maintain intercellular junctions, a key feature of epithelial cells, both in the primary tumor as well as in metastatic lesions. Furthermore, nests of malignant epithelial tumor cells are shielded by layers of extracellular matrix (ECM) proteins (e.g., collagen, elastin, fibronectin, laminin) whereby tumor vasculature rarely penetrates into the tumor nests. In this chapter, we will review potential strategies to modulate the ECM and epithelial junctions to enhance the intratumoral diffusion and/or to remove physical masking of target receptors on malignant cells. We will focus on peptides that bind to the junction protein desmoglein 2 and trigger intracellular signaling, resulting in the transient opening of intercellular junctions. Intravenous injection of these junction openers increased the efficacy and safety of therapies with monoclonal antibodies, chemotherapeutics, and T cells in mouse tumor models and was safe in non-human primates. Furthermore, we will summarize approaches to transiently degrade ECM proteins or downregulate their expression. Among these approaches is the intratumoral expression of relaxin or decorin after adenovirus- or stem cell-mediated gene transfer. We will provide examples that relaxin-based approaches increase the anti-tumor efficacy of oncolytic viruses, monoclonal antibodies, and T cells.

Oncolytic adenovirus expressing IL-23 and p35 elicits IFN-γ- and TNF-α-co-producing T cell-mediated antitumor immunity

Cytokine immunogene therapy is a promising strategy for cancer treatment. Interleukin (IL)-12 boosts potent antitumor immunity by inducing T helper 1 cell differentiation and stimulating cytotoxic T lymphocyte and natural killer cell cytotoxicity. IL-23 has been proposed to have similar but not overlapping functions with IL-12 in inducing Th1 cell differentiation and antitumor immunity. However, the therapeutic effects of intratumoral co-expression of IL-12 and IL-23 in a cancer model have yet to be investigated. Therefore, we investigated for the first time an effective cancer immunogene therapy of syngeneic tumors via intratumoral inoculation of oncolytic adenovirus co-expressing IL-23 and p35, RdB/IL23/p35. Intratumoral administration of RdB/IL23/p35 elicited strong antitumor effects and increased survival in a murine B16-F10 syngeneic tumor model. The levels of IL-12, IL-23, interferon-γ (IFN-γ), and tumor necrosis factor-α (TNF-α) were elevated in RdB/IL23/p35-treated tumors. Moreover, the proportion of regulatory T cells was markedly decreased in mice treated with RdB/IL23/p35. Consistent with these data, mice injected with RdB/IL23/p35 showed massive infiltration of CD4⁺ and CD8⁺ T cells into the tumor as well as enhanced induction of tumor-specific immunity. Importantly, therapeutic mechanism of antitumor immunity mediated by RdB/IL23/p35 is associated with the generation and recruitment of IFN-γ- and TNF-α-co-producing T cells in tumor microenvironment. These results provide a new insight into therapeutic mechanisms of IL-12 plus IL-23 and provide a potential clinical cancer immunotherapeutic agent for improved antitumor immunity.

Ex vivo expansion of highly cytotoxic human NK cells by cocultivation with irradiated tumor cells for adoptive immunotherapy

Adoptive natural killer (NK) cell therapy may offer an effective treatment regimen for cancer patients whose disease is refractory to conventional therapy. NK cells can kill a wide range of tumor cells by patterned recognition of target ligands. We hypothesized that tumor targets sensitive to NK lysis would drive vigorous expansion of NK cells from human peripheral blood mononuclear cells (PBMC). Here, we provide the basis for developing a novel ex vivo expansion process. By screening class I-negative or -mismatched tumor cell lines we identified a Jurkat T-lymphoblast subline termed KL-1, which was highly effective in specifically expanding NK cells. KL-1 addition to PBMC cultures achieved approximately 100-fold expansion of NK cells with nearly 90% purity, accompanied by reciprocal inhibition of T-cell growth. Marked elevations in expression of activation receptors, natural cytotoxicity receptors (NKp30, NKp44), and adhesion molecules (CD11a, ICAM-1) were associated with high tumor-lytic capacity, in both in vitro and in vivo models. KL-1-mediated expansion of NK cells was contact dependent and required interactions with CD16, the Fcγ receptor on NK cells, with ligands that are expressed on B cells. Indeed, B-cell depletion during culture abrogated selective NK cell expansion, while addition of EBV-transformed B cells further augmented NK expansion to approximately 740-fold. Together, our studies define a novel method for efficient activation of human NK cells that employs KL-1-lysed tumor cells and cocultured B cells, which drive a robust expansion of potent antitumor effector cells that will be useful for clinical evaluation.

Abstract 4393: Optimizing DC vaccination by combination with oncolytic adenovirus coexpressing IL-12 and GM-CSF

Dendritic cell (DC)-based vaccination is a promising strategy for cancer immunotherapy. However, clinical trials have indicated that immunosuppressive microenvironments induced by tumors profoundly suppress antitumor immunity and inhibit vaccine efficacy, resulting in insufficient reduction of tumor burdens. To overcome these obstacles and enhance the efficiency of DC vaccination, we generated IL-12- and GM-CSF-coexpressing oncolytic adenovirus (Ad-αB7/IL12/GMCSF) as suitable therapeutic adjuvant to eliminate immune suppression and promote DC function. By treating tumors with Ad-αB7/IL12/GMCSF prior to DC vaccination, DCs elicited greater antitumor effects than in response to either treatment alone. DC migration to draining lymph nodes (DLNs) dramatically increased in mice treated with the combination therapy. This result was associated with upregulation of CCL21+ lymphatics in tumors treated with Ad-αB7/IL12/GMCSF. Moreover, the proportion of CD4+CD25+ T cells and VEGF expression was decreased in mice treated with the combination therapy. Furthermore, combination therapy using immature DCs also showed effective antitumor effects when combined with Ad-αB7/IL12/GMCSF. The combination therapy had a remarkable therapeutic efficacy on large tumors. Taken together, oncolytic adenovirus coexpressing IL-12 and GM-CSF in combination with DC vaccination has synergistic antitumor effects and can act as a potent adjuvant for promoting and optimizing DC vaccination.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4393. doi:1538-7445.AM2012-4393

Negative regulation-resistant p53 variant enhances oncolytic adenoviral gene therapy

Intact p53 function is essential for responsiveness to cancer therapy. However, p53 activity is attenuated by the proto-oncoprotein Mdm2, the adenovirus protein E1B 55kD, and the p53 C-terminal domain. To confer resistance to Mdm2, E1B 55kD, and C-terminal negative regulation, we generated a p53 variant (p53VPΔ30) by deleting the N-terminal and C-terminal regions of wild-type p53 and inserting the transcriptional activation domain of herpes simplex virus VP16 protein. The oncolytic adenovirus vector Ad-mΔ19 expressing p53VPΔ30 (Ad-mΔ19/p53VPΔ30) showed greater cytotoxicity than Ad-mΔ19 expressing wild-type p53 or other p53 variants in human cancer cell lines. We found that Ad-mΔ19/p53VPΔ30 induced apoptosis through accumulation of p53VPΔ30, regardless of endogenous p53 and Mdm2 status. Moreover, Ad-mΔ19/p53VPΔ30 showed a greater antitumor effect and increased survival rates of mice with U343 brain cancer xenografts that expressed wild-type p53 and high Mdm2 levels. To our knowledge, this is the first study reporting a p53 variant modified at the N terminus and C terminus that shows resistance to degradation by Mdm2 and E1B 55kD, as well as negative regulation by the p53 C terminus, without decreased trans-activation activity. Taken together, these results indicate that Ad-mΔ19/p53VPΔ30 shows potential for improving p53-mediated cancer gene therapy.

Adenovirus-relaxin gene therapy for keloids: implication for reversing pathological fibrosis

BACKGROUND

Keloids or hypertrophic scars are pathological proliferations of the dermal skin layer resulting from excessive collagen deposition. Because the hormone relaxin (RLX) inhibits collagen synthesis and expression in stimulated fibroblasts, an adenovirus expressing RLX (dE1-RGD/lacZ/RLX) was generated.

OBJECTIVES

To investigate the effect of RLX-expressing adenovirus on expression of various extracellular matrix (ECM) components in primary keloid spheroids.

METHODS

The expression levels of type I and III collagen, fibronectin and elastin were investigated by immunohistochemistry in primary keloid spheroids transduced with the RLX-expressing adenovirus.

RESULTS

Immunohistochemical analysis showed that expression of major ECM components (e.g. type I and III collagen, elastin and fibronectin) was markedly reduced in primary keloid spheroids transduced with dE1-RGD/lacZ/RLX.

CONCLUSIONS

These results suggest that the antifibrotic effect of RLX-expressing adenovirus may have therapeutic effects on keloids by reversing pathological fibrosis and preventing keloid recurrence after surgical excision.

Combination of radiotherapy and adenovirus-mediated p53 gene therapy for MDM2-overexpressing hepatocellular carcinoma

The p53 gene plays a determinant role in radiation-induced cell death and its protein product is negatively regulated by MDM2. We investigated whether adenovirus-mediated modified p53 gene transfer, which blocks p53-MDM2 binding, is effective for radiation-induced cell death in hepatocellular carcinoma (HCC) at different MDM2 cellular levels. Human hepatocellular carcinoma cell lines expressing MDM2 at low levels (Huh7) and high levels (SK-Hep1) were used. Ad-p53 and Ad-p53vp are replication-deficient adenoviral vectors containing human wild-type or modified p53, respectively. The anti-tumor effect was highest for Ad-p53 + radiotherapy (RT) in the low-level MDM2 cells, whereas this effect was highest for Ad-p53vp + RT in the MDM2-overexpressing cells. In Huh-7 cells, Ad-p53 + RT decreased cell viability (32%) in vitro and inhibited tumor growth (enhancement factor, 1.86) in vivo. Additionally, p21 expression and apoptosis were increased. In contrast, in SK-Hep1 cells, Ad-p53vp + RT showed decreased cell viability (51%) in vitro and inhibition of tumor growth (enhancement factor, 3.07) in vivo. Caspase-3 expression and apoptosis were also increased. Adenovirus-expressing modified p53, which blocks p53-MDM2 binding, was effective in killing tumor cells overexpressing MDM2. Furthermore, the combination strategy for disruption of the p53-MDM2 interaction with RT demonstrated enhanced anti-tumor effects both in vitro and in vivo.

MicroRNA-296 is enriched in cancer cells and downregulates p21WAF1 mRNA expression via interaction with its 3' untranslated region

MicroRNAs (miRNAs) are a class of noncoding small RNAs that act as negative regulators of gene expression. To identify miRNAs that may regulate human cell immortalization and carcinogenesis, we performed comparative miRNA array profiling of human normal and SV40-T antigen immortalized cells. We found that miR-296 was upregulated in immortalized cells that also had activation of telomerase. By an independent experiment on genomic analysis of cancer cells we found that chromosome region (20q13.32), where miR-296 is located, was amplified in 28/36 cell lines, and most of these showed enriched miR-296 expression. Overexpression of miR-296 in human cancer cells, with and without telomerase activity, had no effect on their telomerase function. Instead, it suppressed p53 function that is frequently downregulated during human cell immortalization and carcinogenesis. By monitoring the activity of a luciferase reporter connected to p53 and p21^WAF1 (p21) untranslated regions (UTRs), we demonstrate that miR-296 interacts with the p21-3′UTR, and the Hu binding site of p21-3′UTR was identified as a potential miR-296 target site. We demonstrate for the first time that miR-296 is frequently upregulated during immortalization of human cells and contributes to carcinogenesis by downregulation of p53-p21^WAF1 pathway.

Proproliferative functions of Drosophila small mitochondrial heat shock protein 22 in human cells

Aging is a complex process accompanied by a decreased capacity of cells to cope with random damages induced by reactive oxygen species, the natural by-products of energy metabolism, leading to protein aggregation in various components of the cell. Chaperones are important players in the aging process as they prevent protein misfolding and aggregation. Small chaperones, such as small heat shock proteins, are involved in the refolding and/or disposal of protein aggregates, a feature of many age-associated diseases. In Drosophila melanogaster, mitochondrial Hsp22 (DmHsp22), is localized in the mitochondrial matrix and is preferentially up-regulated during aging. Its overexpression results in an extension of life span (>30%) (Morrow, G., Samson, M., Michaud, S., and Tanguay, R. M. (2004) FASEB J. 18, 598-599 and Morrow, G., Battistini, S., Zhang, P., and Tanguay, R. M. (2004) J. Biol. Chem. 279, 43382-43385). Long lived flies expressing Hsp22 also have an increased resistance to oxidative stress and maintain locomotor activity longer. In the present study, the cross-species effects of Hsp22 expression were tested. DmHsp22 was found to be functionally active in human cells. It extended the life span of normal fibroblasts, slowing the aging process as evidenced by a lower level of the senescence associated beta-galactosidase. DmHsp22 expression in human cancer cells increased their malignant properties including anchorage-independent growth, tumor formation in nude mice, and resistance to a variety of anticancer drugs. We report that the DmHsp22 interacts and inactivates wild type tumor suppressor protein p53, which may be one possible way of its functioning in human cells.

PPAR-gamma ligand promotes the growth of APC-mutated HT-29 human colon cancer cells in vitro and in vivo

PPAR-gamma has been known to induce suppression, differentiation and reversal of malignant changes in colon cancer in vitro. However, there are several reports that PPAR-gamma ligands enhance colon polyp development in APCmin mice in vivo. These contradictory results have not yet been thoroughly explained. To explain the contradictory results, we analyzed the effects of different concentrations of the PPAR-gamma agonist, 15-deoxy-D12, 14-prostaglandin (15-d Delta PGJ2) and pioglitazone, on APC gene-mutated colon cancer cell lines (HT-29). We measured cell growth and suppression by cell count and MTT assay and analyzed the expression of beta-catenin and c-Myc protein by Western blot. In addition, we inoculated HT-29 cells into APCmin mice to compare tumor size. High concentrations (10-100 microM/L 15-d Delta PGJ2 and pioglitazone) of PPAR-gamma ligand suppressed growth, while low concentrations (0.01-1 microM/L 15-d Delta PGJ2 and pioglitazone) of PPAR-gamma ligand promoted growth. In particular, the effects of 0.1 microM/L 15-d Delta PGJ2 and pioglitazone on cell growth were statistically significant (P = 0.003, P = 0.001, respectively). Tumor growth was associated with an increase in beta-catenin and c-Myc expression. The growth of xenograft tumors was greater in PPAR-gamma ligand-treated mice than in control mice (control vs day 14: P = 0.024, control vs day 28: P = 0.007). The expression of beta-catenin and c-Myc protein were also elevated in PPAR-gamma-treated mouse tissues. PPAR-gamma ligand can promote the growth of APC-mutated HT-29 colon cancer cells in vitro and in vivo. In addition, the tumor promoting effect seems to be associated with an increase in beta-catenin and c-Myc expression. We think that well-controlled clinical trials should be conducted to confirm our results and to verify clinical applications.

A phase II study of biweekly dose-intensified oral capecitabine plus irinotecan (bXELIRI) for patients with advanced or metastatic gastric cancer

Capecitabine, a prodrug of 5-FU, has been reported to generate maximal tumour activity at tumour sites and/or to improve drug tolerability as compared with 5-FU infusion, and it has also been demonstrated to act synergistically with irinotecan against some solid cancers. A previous study concluded that dose-intensified biweekly capecitabine seems to be more effective at increasing both response rate and progression-free survival time than conventional dose and schedule of capecitabine in colon cancer. We conducted this study to ascertain the efficacy and toxicity of dose-intensified biweekly capecitabine and irinotecan combination chemotherapy in chemotherapy-naïve advanced or metastatic gastric cancer patients. Patients were treated with irinotecan 130 mg m⁻² intravenously for 90 min on days 1 and 15. Capecitabine at 3500 mg m⁻² day⁻¹, divided into two sessions per day, was administered for seven consecutive days from days 1 and 15, and followed by a 7-day drug-free period, respectively. Fifty-five eligible patients were enrolled in this study from November 2003 to April 2006. There were 22 women and 33 men: median patient age was 54 years (range: 27–81). A total of 200 treatment cycles were administered at a median number of four per patient (range: 1–9). Intent-to-treatment analysis showed that one patient achieved complete response (1.8%), 23 partial response (41.8%), 15 stable disease (27.3%), 10 progressive disease (18.2%) and 6 were non-evaluable (10.9%). The overall response rate was 43.6% (95% confidence interval: 30.2–56.9). The common grade 3–4 toxicities were neutropenia in 12 (21.8%), nausea/vomiting in 3 (5.4%) and diarrhea in 4 (7.2%) patients. Median time to progression was 5 months (range: 0.5–11 months), median survival duration was 11 months (range: 0.5–45 months) and median response duration was 6 months (range: 0.5–9 months). Biweekly dose-intensified capecitabine and irinotecan combination chemotherapy was active for the treatment of advanced or metastatic gastric cancers with a tolerable safety profile.

Enhanced antitumor effect of oncolytic adenovirus expressing interleukin-12 and B7-1 in an immunocompetent murine model

PURPOSE

We investigated whether an armed viral platform, where lytic property of a viral infection is coupled to viral-mediated delivery of therapeutic genes, could increase the therapeutic potential of a viral-based therapy.

EXPERIMENTAL DESIGN

We generated interleukin (IL)-12-expressing oncolytic adenovirus (YKL-IL-12) and IL-12- and B7-1-expressing (YKL-IL12/B7) oncolytic adenovirus. Therapeutic efficacy of these newly engineered adenoviruses was then evaluated in vivo using an immunocompetent mouse bearing murine melanoma B16-F10 tumors. Overall survival was assessed with the Kaplan-Meier method. The induction of immune cell cytotoxicity was assessed by CTL assay, IFN-gamma enzyme-linked immunospot assay, and immunohistochemical studies.

RESULTS

YKL-IL12/B7 oncolytic adenovirus, expressing both IL-12 and B7-1, showed a higher incidence of complete tumor regression compared with the analogous oncolytic adenovirus, YKL-1, or IL-12-expressing, YKL-IL12. Significant survival advantage was also seen in response to YKL-IL12/B7. Moreover, IL-12 and IFN-gamma levels produced in tumors treated with YKL-IL12/B7 was significantly greater than those treated with YKL-IL12. The enhanced survival advantage was mediated by the induction of immune cell cytotoxicity. In agreement with these results, massive infiltration of CD4(+) and CD8(+) T cells into tissues surrounding the necrotic area of the tumor was observed following in situ delivery of YKL-IL12/B7.

CONCLUSION

Combination of oncolysis and the enhancement of antitumor immune response by oncolytic adenovirus expressing both IL-12 and B7-1 elicits potent antitumor effect and survival advantage.

Docetaxel (Taxotere), cisplatin, UFT, and leucovorin combination chemotherapy in advanced gastric cancer

We conducted this study to ascertain the efficacy and toxicity of docetaxel and cisplatin combined with oral UFT and leucovorin as a first-line treatment for patients with advanced gastric cancer. In all, 52 patients received courses of docetaxel 60 mg m(-2) intravenously (i.v.) for 1 h and then cisplatin 75 mg m(-2) i.v. for 2 h on day 1. Oral UFT at 400-600 mg day(-1), as determined by body surface area, and leucovorin at 75 mg day(-1) were administered for 21 consecutive days from day 1, and this was followed by a 7-day drug-free interval. A total of 225 courses were administered, and the median number of courses per patient was four. Four complete responses (7.7%) and 22 partial responses (42.3%) were achieved, giving an overall response rate of 50% (95% Confidence Interval: 36.4-63.6%). The major toxicity was neutropenia, which reached grade 3/4 in 36 patients (69.3%). Grade 3/4 nausea and vomiting was observed in 12 patients (23.1%). Median time to progression was 22 weeks (4 to 156+ weeks), median survival duration was 48 weeks (4 to 156+ weeks), and median response duration was 24 weeks (6-152 weeks). We conclude that docetaxel, cisplatin, oral UFT, and leucovorin combination chemotherapy is effective and tolerable for the treatment of advanced gastric cancer.

Effects of 5-fluorouracil and leucovorin in the treatment of pancreatic-biliary tract adenocarcinomas

Adenocarcinomas of the pancreas and biliary tract are highly malignant neoplasms, which are found in the advanced stage. Chemotherapy commonly plays a palliative role in the treatment of pancreatic and biliary tract cancers. 5-Fluorouracil (5-FU) is the most widely studied single agent; the response rate of 5-FU is only 20%. Recently, some reports presented interesting results, in which 5-FU, modulated with levofolinic acid (leucovorin), was active in patients with colorectal cancer. In relation, we performed a phase II study of 5-FU, modulated with leucovorin, in patients affected by advanced pancreatic or biliary tract cancer. Fifty-one patients with nonresectable carcinomas of the pancreas or biliary tract admitted to Korea University Hospital between May 1995 and December 1998 were included in this study. Chemotherapy consisted of leucovorin 25 mg/m2/day by 2-hour intravenous infusion, followed by 5-FU 375 mg/m2/day by bolus intravenous infusion, from day I to day 5. The treatment was repeated every 3 to 4 weeks. A total of 51 eligible patients with advanced adenocarcinoma of the pancreas or biliary tract were enrolled. Of 23 enrolled patients with pancreatic adenocarcinoma, one patient showed complete remission with a survival duration of 13 months (response duration was 9 months). Three patients had partial responses (PRs) with survival times of 6, 12, and 15 months, respectively. The overall response rate was 17.4% (95% confidence interval [CI], 7.2%-36.2%). The median time of overall survival was 6 months (range: 1-15 months). Of 28 enrolled patients with biliary tract cancer, complete responses were observed in 2 patients (7.1%) with survival time of 14 and 16 months, respectively. Seven patients had PRs with a median survival of 8 months. The overall response rate was 32.1% (95% CI, 20.3%-57.5%). The median time of overall survival was 6 months (range: 1-16 months). The most prominent toxicity was mucositis. Hematologic toxicity was less severe. 5-Fluorouracil in modulation with intravenous leucovorin is well tolerated by patients with stage IV pancreatic adenocarcinoma or biliary tract cancer. Although the response rate for patients with pancreatic adenocarcinoma is not better than that achieved using 5-FU monochemotherapy, the 32.1% overall response rate achieved in patients with biliary tract cancer suggests that 5-FU modulation with leucovorin is active in biliary tract cancer.