Effect of interleukin 12 on tumor induction by 3-methylcholanthrene

Regulatory T cells converted from Th1 cells in tumors suppress cancer immunity via CD39

Regulatory T (Treg) cells are known to impede antitumor immunity, yet the regulatory mechanisms and functional roles of these cells remain poorly understood. In this study, through the characterization of multiple cancer models, we identified a substantial presence of peripherally induced Treg cells in the tumor microenvironment (TME). Depletion of these cells triggered antitumor responses and provided potent therapeutic effects by increasing functional CD8+ T cells. Fate-mapping and transfer experiments revealed that IFN-γ-expressing T helper (Th) 1 cells differentiated into Treg cells in response to TGF-β signaling in tumors. Pseudotime trajectory analysis further revealed the terminal differentiation of Th1-like Treg cells from Th1 cells in the TME. Tumor-resident Treg cells highly expressed T-bet, which was essential for their functions in the TME. Additionally, CD39 was highly expressed by T-bet+ Treg cells in both mouse and human tumors, and was necessary for Treg cell-mediated suppression of CD8+ T cell responses. Our study elucidated the developmental pathway of intratumoral Treg cells and highlighted novel strategies for targeting them in cancer patients.

The IL-23/Th17 pathway inhibitors in the treatment of psoriasis and the risk of skin malignancies: a review

Psoriasis and psoriatic arthritis are chronic inflammatory conditions that constitute a significant global health burden due to their prevalence and impact on quality of life. A deeper comprehension of psoriasis and psoriatic arthritis pathogenesis has recently led to the emergence of novel classes of biologics targeting the IL-23/Th17 pathway. The specific role of interleukin-12, -23, and -17 in cancer as either promoters or inhibitors is under investigation in various studies. Here, we explore the potential role of interleukin-12, -23, and -17 in the development of skin tumours as well as the safety of using their inhibitors in the treatment of psoriasis and psoriatic arthritis, particularly in relation to the risk of melanoma and non-melanoma skin cancer (NMSC) development.

Cancer immunotherapy with enveloped self-amplifying mRNA CARG-2020 that modulates IL-12, IL-17 and PD-L1 pathways to prevent tumor recurrence

Targeting multiple immune mechanisms may overcome therapy resistance and further improve cancer immunotherapy for humans. Here, we describe the application of virus-like vesicles (VLV) for delivery of three immunomodulators alone and in combination, as a promising approach for cancer immunotherapy. VLV vectors were designed to deliver single chain interleukin (IL)-12, short-hairpin RNA (shRNA) targeting programmed death ligand 1 (PD-L1), and a dominant-negative form of IL-17 receptor A (dn-IL17RA) as a single payload or as a combination payload. Intralesional delivery of the VLV vector expressing IL-12 alone, as well as the trivalent vector (designated CARG-2020) eradicated large established tumors. However, only CARG-2020 prevented tumor recurrence and provided long-term survival benefit to the tumor-bearing mice, indicating a benefit of the combined immunomodulation. The abscopal effects of CARG-2020 on the non-injected contralateral tumors, as well as protection from the tumor cell re-challenge, suggest immune-mediated mechanism of protection and establishment of immunological memory. Mechanistically, CARG-2020 potently activates Th1 immune mechanisms and inhibits expression of genes related to T cell exhaustion and cancer-promoting inflammation. The ability of CARG-2020 to prevent tumor recurrence and to provide survival benefit makes it a promising candidate for its development for human cancer immunotherapy.

Cure of syngeneic carcinomas with targeted IL-12 through obligate reprogramming of lymphoid and myeloid immunity

Therapeutic IL-12 has demonstrated the ability to reduce local immune suppression in preclinical models, but clinical development has been limited by severe inflammation-related adverse events with systemic administration. Here, we show that potent immunologic tumor control of established syngeneic carcinomas can be achieved by i.t. administration of a tumor-targeted IL-12 antibody fusion protein (NHS–rmIL-12) using sufficiently low doses to avoid systemic toxicity. Single-cell transcriptomic analysis and ex vivo functional assays of NHS–rmIL-12–treated tumors revealed reinvigoration and enhanced proliferation of exhausted CD8⁺ T lymphocytes, induction of Th1 immunity, and a decrease in Treg number and suppressive capacity. Similarly, myeloid cells transitioned toward inflammatory phenotypes and displayed reduced suppressive capacity. Cell type–specific IL-12 receptor–KO BM chimera studies revealed that therapeutic modulation of both lymphoid and myeloid cells is required for maximum treatment effect and tumor cure. Study of single-cell data sets from human head and neck carcinomas revealed IL-12 receptor expression patterns similar to those observed in murine tumors. These results describing the diverse mechanisms underlying tumor-directed IL-12–induced antitumor immunity provide the preclinical rationale for the clinical study of i.t. NHS–IL-12.

Localized Interleukin-12 for Cancer Immunotherapy

Interleukin-12 (IL-12) is a potent, pro-inflammatory type 1 cytokine that has long been studied as a potential immunotherapy for cancer. Unfortunately, IL-12's remarkable antitumor efficacy in preclinical models has yet to be replicated in humans. Early clinical trials in the mid-1990's showed that systemic delivery of IL-12 incurred dose-limiting toxicities. Nevertheless, IL-12's pleiotropic activity, i.e., its ability to engage multiple effector mechanisms and reverse tumor-induced immunosuppression, continues to entice cancer researchers. The development of strategies which maximize IL-12 delivery to the tumor microenvironment while minimizing systemic exposure are of increasing interest. Diverse IL-12 delivery systems, from immunocytokine fusions to polymeric nanoparticles, have demonstrated robust antitumor immunity with reduced adverse events in preclinical studies. Several localized IL-12 delivery approaches have recently reached the clinical stage with several more at the precipice of translation. Taken together, localized delivery systems are supporting an IL-12 renaissance which may finally allow this potent cytokine to fulfill its considerable clinical potential. This review begins with a brief historical account of cytokine monotherapies and describes how IL-12 went from promising new cure to ostracized black sheep following multiple on-study deaths. The bulk of this comprehensive review focuses on developments in diverse localized delivery strategies for IL-12-based cancer immunotherapies. Advantages and limitations of different delivery technologies are highlighted. Finally, perspectives on how IL-12-based immunotherapies may be utilized for widespread clinical application in the very near future are offered.

Associations between hepatocellular carcinoma risk and rs3212227 and rs568408 polymorphisms: a systematic review and meta-analysis

Background

Interleukin-12 (IL-12) is considered to be a risk factor for cancer; however, its role in hepatocellular carcinoma (HCC) remains unknown. This study aimed to explore the impacts of the IL-12 rs3212227 and rs568408 gene polymorphisms on HCC.

Methods

We searched PubMed, Embase, Web of Science, and Chinese Knowledge Infrastructure databases for studies on the associations between HCC and IL-12 rs568408 and rs3212227 polymorphisms published prior to 1 May 2020. The effects of the polymorphisms on HCC susceptibility were presented as odds ratios (ORs) and associated 95% confidence intervals.

Results

Seven studies were ultimately included, including 2375 cases and 3445 controls. The rs3212227 polymorphism was significantly associated with the risk of HCC in both the dominant model (CC+AC vs. AA, OR=1.22) and the allele model (C vs. A, OR=1.12). Combined analysis of rs568408 yielded a significant relative risk for HCC in the dominant (AA+AG vs. GG, OR=1.13), recessive (AA vs. AG+GG, OR=1.72), allele (A vs. G, OR=1.29), heterozygote (AG vs. GG, OR=1.27), and homozygote models (AA vs. GG, OR 1.17).

Conclusion

The IL-12 rs3212227 and rs568408 gene polymorphisms are associated with an increased risk of HCC.

Lipid nanoparticles that deliver IL-12 messenger RNA suppress tumorigenesis in MYC oncogene-driven hepatocellular carcinoma

Interleukin-12 (IL-12) is a promising candidate for cancer immunotherapy because of its ability to activate a number of host immune subsets that recognize and destroy cancer cells. We found that human hepatocellular carcinoma (HCC) patients with higher than median levels of IL-12 have significantly favorable clinical outcomes. Here, we report that a messenger RNA (mRNA) lipid nanoparticle delivering IL-12 (IL-12-LNP) slows down the progression of MYC oncogene-driven HCC. IL-12-LNP was well distributed within the HCC tumor and was not associated with significant animal toxicity. Treatment with IL-12-LNP significantly reduced liver tumor burden measured by dynamic magnetic resonance imaging (MRI), and increased survival of MYC-induced HCC transgenic mice in comparison to control mice. Importantly, IL-12-LNP exhibited no effect on transgenic MYC levels confirming that its therapeutic efficacy was not related to the downregulation of a driver oncogene. IL-12-LNP elicited marked infiltration of activated CD44⁺ CD3⁺ CD4⁺ T helper cells into the tumor, and increased the production of Interferon γ (IFNγ). Collectively, our findings suggest that IL-12-LNP administration may be an effective immunotherapy against HCC.

A Believer's Overview of Cancer Immunosurveillance and Immunotherapy

The field of tumor immunology has grown around the idea that one of the important roles of the immune system is to eliminate cancer. This idea was difficult to reconcile with the accepted notion that the immune system evolved to distinguish self from nonself and therefore tumors derived from self-tissues would not be recognized. Lack of appropriate animal models prevented experimental testing of cancer immunosurveillance. This changed with the realization that the immune system evolved to recognize danger and with the advent of mouse models deficient in one or more immune function, which showed predicted increases in susceptibility to cancer. Simultaneously, technical advances that enabled the study of the human immune system provided data for the existence of tumor-specific T cells and Abs and led to molecular identification of tumor Ags, fully validating the cancer immunosurveillance hypothesis. Immunotherapy designed to strengthen cancer immunosurveillance has achieved unprecedented clinical successes.

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

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

Gold‑manganese oxide nanocomposite suppresses hypoxia and augments pro-inflammatory cytokines in tumor associated macrophages

The tumor microenvironment, essentially hypoxic, is sustained by the hypoxia inducing factor (HIF), released from the pro-tumorigenic tumor associated macrophages (TAMs), functionally identical to the M2 phenotype macrophages. Stability of HIF mainly depends on molecular oxygen and an iron-dependent enzyme prolyl hydroxylase, while its activity may be inhibited by high levels of reactive oxygen species and nitric oxide. The present work showcases a novel approach utilizing the anti-tumorigenic potential of a gold-manganese oxide nanocomposite material in the tumor microenvironment that affects tumor hypoxia, exploring the possibility of restoring the immunoregulatory nature of TAMs from their pro-tumorigenic state. Along with the biochemical markers, ELISA and FACS analyses have also confirmed the potential of these nanoparticles in reverting back the M2 phenotype of TAMs to their classically activated M1 phenotype.

CD4 and CD8 T lymphocyte interplay in controlling tumor growth

The outstanding clinical success of immune checkpoint blockade has revived the interest in underlying mechanisms of the immune system that are capable of eliminating tumors even in advanced stages. In this scenario, CD4 and CD8 T cell responses are part of the cancer immune cycle and both populations significantly influence the clinical outcome. In general, the immune system has evolved several mechanisms to protect the host against cancer. Each of them has to be undermined or evaded during cancer development to enable tumor outgrowth. In this review, we give an overview of T lymphocyte-driven control of tumor growth and discuss the involved tumor-suppressive mechanisms of the immune system, such as senescence surveillance, cancer immunosurveillance, and cancer immunoediting with respect to recent clinical developments of immunotherapies. The main focus is on the currently existing knowledge about the CD4 and CD8 T lymphocyte interplay that mediates the control of tumor growth.

Genetic variants in IL12 influence both hepatitis B virus clearance and HBV-related hepatocellular carcinoma development in a Chinese male population

IL12 plays a major role not only in inducing appropriate immune responses against viral infections (including HBV) but also in the antitumor immune response. This study was conducted to investigate the relationships of genetic variants in IL12 with hepatitis B virus (HBV) clearance and development of HBV-related hepatocellular carcinoma (HCC). We genotyped three single nucleotide polymorphisms (SNPs) of the IL12A (rs568406 and rs2243115) and IL12B (rs3212227) in 395 HBV-positive HCC patients, 293 persistent HBV carriers and 686 subjects with HBV natural clearance from southern China, using the improved multiplex ligase detection reaction (iMLDR) method. Logistic regression analysis adjusted for age, smoking, and alcohol consumption status showed that rs568408 variant genotypes were significantly associated with host HBV-related HCC risk when compared with persistent HBV carriers, and carriers of the GA + AA genotype decreased the HCC risk in comparison with GG carriers (adjusted OR = 0.53, 95 % CI 0.35-0.80, P = 0.002). No relationships between the rs2243115 and rs3212227 SNPs and HCC risk were observed (all P > 0.05). Besides, rs568408 showed an approaching significant effect on susceptibility to HBV persistent infection (adjusted OR = 1.34, 95 % CI 0.99-1.81, P = 0.057 in dominant genetic models). Furthermore, the TG haplotype was observed to be associated with a significantly increased risk of HBV-related HCC (OR = 1.42, 95 % CI 1.10-1.83, P = 0.006), while TA haplotype was associated with a decreased risk of HBV-related HCC (OR = 0.61, 95 % CI 0.45-0.83, P = 0.002). Our results reveal that the IL12A rs568408 variant may be a marker SNP for risk of both HBV clearance and HBV-related HCC development.

Interleukin-12 and interleukin-6 gene polymorphisms and risk of bladder cancer in the Iranian population

Interleukin-12 (IL-12) as an antitumor and interleukin-6 (IL-6) as an inflammatory cytokine, are immunomodulatory products that play important roles in responses in cancers and inflammation. We tested the association between two polymorphisms of IL-12(1188A>C; rs3212227) and IL-6 (-174 C>G) and the risk of bladder cancer in 261 patients and 251 healthy individuals. We also investigated the possible association of these SNPs in patients with high-risk jobs and smoking habits with the incidence of bladder cancer. The genotype distributions of IL-6 (-174 C/G) genotype were similar between the cases and the control groups; however, among patients with smoking habits, the association between IL-6 gene polymorphism and incidence of bladder cancer was significant. After a control adjustment for age and sex, the following results were recorded: CC genotype (OR= 2.11, 95%CI=1.56-2.87, p=0.007), GC genotype (OR=2.18, 95%CI=1.16-4.12, p=0.014) and GC+ CC (OR=2.6, 95%CI=1.43-4.47, p=0.011). A significant risk of bladder cancer was observed for the heterozygous genotype (AC) of IL-12 (OR=1.47, 95%CI=1.01-2.14, p=0.045) in all cases, and among smokers (AC) (OR=3.13, 95%CI=1.82-5.37, p=0.00014), combined AC+CC (OR=3.05, 95%CI=1.8-5.18, p=0.000015). Moreover among high risk job patients, there was more than a 3-fold increased risk of cancer in the carriers of IL-12 beta heterozygous (OR=3.7, 95%CI=2.04-6.57, p=0.000056) and combined AC+CC(OR=3.29, 95%CI=1.58-5.86, p=0.00002) genotypes as compared with the AA genotype with low-risk jobs. As a conclusion, this study suggests that IL-12(3'UTR A>C) and IL-6 (-174 C>G) genotypes are significantly associated with an increased risk of bladder cancer in the Iranian population with smoking habits and/or performing high-risk jobs.

Immunomodulatory properties of silver nanoparticles contribute to anticancer strategy for murine fibrosarcoma

The use of nanotechnology in nanoparticle-based cancer therapeutics is gaining impetus due to the unique biophysical properties of nanoparticles at the quantum level. Silver nanoparticles (AgNPs) have been reported as one type of potent therapeutic nanoparticles. The present study is aimed to determine the effect of AgNPs in arresting the growth of a murine fibrosarcoma by a reductive mechanism. Initially, a bioavailability study showed that mouse serum albumin (MSA)-coated AgNPs have enhanced uptake; therefore, toxicity studies of AgNP-MSA at 10 different doses (1-10 mg/kg b.w.) were performed in LACA mice by measuring the complete blood count, lipid profile and histological parameters. The complete blood count, lipid profile and histological parameter results showed that the doses from 2 to 8 mg (IC50: 6.15 mg/kg b.w.) sequentially increased the count of leukocytes, lymphocytes and granulocytes, whereas the 9- and 10-mg doses showed conclusive toxicity. In an antitumor study, the incidence and size of fibrosarcoma were reduced or delayed when murine fibrosarcoma groups were treated by AgNP-MSA. Transmission electron micrographs showed that considerable uptake of AgNP-MSA by the sentinel immune cells associated with tumor tissue and a morphologically buckled structure of the immune cells containing AgNP-MSA. Because the toxicity studies revealed a relationship between AgNPs and immune function, the protumorigenic cytokines TNF-α, IL-6 and IL-1β were also assayed in AgNP-MSA-treated and non-treated fibrosarcoma groups, and these cytokines were found to be downregulated after treatment with AgNP-MSA.

Adenovirally delivered enzyme prodrug therapy with herpes simplex virus-thymidine kinase in composite tissue free flaps shows therapeutic efficacy in rat models of glioma

INTRODUCTION

Free flap gene therapy exploits a novel therapeutic window when viral vectors can be delivered into a flap ex vivo. The authors investigated the therapeutic potential of an adenovirally-delivered thymidine kinase/ganciclovir prodrug system expressed following vector delivery into a free flap.

METHODS

The authors demonstrated direct in vitro cytotoxicity by treating a panel of malignant cell lines with the thymidine kinase/ganciclovir system and demonstrated significant cell kill proportional to the multiplicity of infection of adenoviral vector expressing thymidine kinase. Bystander cytotoxicity was demonstrated using conditioned media from producer cells (expressing adenovirally-delivered thymidine kinase and treated with ganciclovir) to demonstrate cytotoxicity in naive tumor cells. The authors investigated the effect of adenoviral vector expressing thymidine kinase/ganciclovir therapy in vivo, using models of microscopic and macroscopic residual disease in a rodent superficial inferior epigastric artery flap model.

RESULTS

The authors observed retardation of tumor volume growth in both microscopic (p = 0.0004) and macroscopic (p = 0.0005) residual disease models and prolongation of animal survival. Gene expression studies demonstrated that viral genomic material was found predominantly in flap tissues but declined over time.

CONCLUSIONS

The authors describe the utility of virally delivered enzyme/prodrug therapy, using a free flap as a vehicle for delivery. They discuss the merits and limitations of this approach and the unique role of therapeutic free flaps among reconstructive techniques available to the plastic surgeon.

New insights into IL-12-mediated tumor suppression

During the past two decades, interleukin-12 (IL-12) has emerged as one of the most potent cytokines in mediating antitumor activity in a variety of preclinical models. Through pleiotropic effects on different immune cells that form the tumor microenvironment, IL-12 establishes a link between innate and adaptive immunity that involves different immune effector cells and cytokines depending on the type of tumor or the affected tissue. The robust antitumor response exerted by IL-12, however, has not yet been successfully translated into the clinics. The majority of clinical trials involving treatment with IL-12 failed to show sustained antitumor responses and were associated to toxic side effects. Here we discuss the therapeutic effects of IL-12 from preclinical to clinical studies, and will highlight promising strategies to take advantage of the antitumor activity of IL-12 while limiting adverse effects.

Comparison of serum and tissue levels of trace elements in different models of cervical cancer

Cervical cancer is a leading cause of death by cancer among women worldwide. It is necessary to develop and refine cervical cancer models to more accurately reflect human tumor type. The relevance of cervical cancer to trace element was studied in this paper. By means of quantitative trace element analysis in models and patients with cervical cancer, the tissue and serum levels of trace elements in papillomaviruses-induced cancer models were more similar to that of patients than the levels in models induced by HeLa cell and methylcholanthrene. The results reflect papillomaviruses model most accurately mimic in vivo carcinogenesis of patients with cervical cancer. It will have a superior predictive value over HeLa cell and methylcholanthrene models in pre-clinical trials. The papillomaviruses-induced cervical cancer can provide more reliable models for testing the efficacy of drugs in treating human cancers.

Genetic susceptibility of cervical cancer

Epidemiological and laboratory-based studies have identified infection with one of 15 high-risk human papillomavirus (HPV) types as a necessary but not sufficient cause of cervical cancer. The prevalence of genital HPV infections is high in young women, but most of the infections regress without interventions. Host genetic variations in genes involved in immune response pathways may be related to HPV clearance, and HPV E6/E7 oncoproteins interacting or downstream genes, both coding and non-coding, may contribute to the outcome of high risk HPV infection and cervical cancer. Of specific interest for this review has been the selection of genetic variants in genes involved in the above-referred pathways with a summary of their applications in association studies. Because the supportive and opposing data have been reported in different populations, well-designed international collaborative studies need to be conducted to define the consistency of the associations, paving the way to better define the patients at high risk of developing cervical cancer.

Association of IL27 gene polymorphisms and HBV-related hepatocellular carcinoma risk in a Chinese population

BACKGROUND AND OBJECTIVE

Hepatocellular carcinoma (HCC) is multifactorial, and the genetic background may be a crucial etiologic factor. Interleukin-27 (IL-27) is a novel IL-12 family member which plays an important role in antitumor immunity. Mutations in the IL27 gene may lead to altered cytokine production and/or activity and thus modulate individual's susceptibility to HCC. In this study, we investigated the association between IL27 gene polymorphisms and HBV-related diseases risk in a Chinese population.

METHODS

Studied subjects were divided into four groups: 112 patients with chronic hepatitis B (CHB), 65 patients with hepatitis B virus (HBV)-related liver cirrhosis (LC), 107 patients with HBV-related HCC, and 105 healthy controls. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) strategy and polymerase chain reaction-sequence specific primer (PCR-SSP) strategy were used to detect IL27 gene -964A/G and 2905T/G polymorphisms, respectively. DNA sequencing was used to validate genotype results.

RESULTS

There were no significant differences in the genotype and allele frequencies of IL27 gene polymorphisms between the groups of patients and healthy controls. Furthermore, no association was found between the distributions of the haplotypes and HCC risk.

CONCLUSION

These findings indicate that the genetic variants in IL27 gene may not contribute to HCC development. Further studies with large sample size should be conducted to validate this association.

Macrophages, inflammation, and tumor suppressors: ARF, a new player in the game

The interaction between tumor progression and innate immune system has been well established in the last years. Indeed, several lines of clinical evidence indicate that immune cells such as tumor-associated macrophages (TAMs) interact with tumor cells, favoring growth, angiogenesis, and metastasis of a variety of cancers. In most tumors, TAMs show properties of an alternative polarization phenotype (M2) characterized by the expression of a series of chemokines, cytokines, and proteases that promote immunosuppression, tumor proliferation, and spreading of the cancer cells. Tumor suppressor genes have been traditionally linked to the regulation of cancer progression; however, a growing body of evidence indicates that these genes also play essential roles in the regulation of innate immunity pathways through molecular mechanisms that are still poorly understood. In this paper, we provide an overview of the immunobiology of TAMs as well as what is known about tumor suppressors in the context of immune responses. Recent advances regarding the role of the tumor suppressor ARF as a regulator of inflammation and macrophage polarization are also reviewed.

Single nucleotide polymorphism in the interleukin 12B gene is associated with risk for breast cancer development

We analysed the association of a single nucleotide polymorphism (SNP) in the gene encoding the IL-12 subunit p40 (IL12B, rs3212227, A>C) with breast cancer. The SNPs allelic and genotypic frequencies were compared between patients (n = 191) and healthy (n = 194) women in a case-control study from Croatia. The major allele (A) was associated with susceptibility to breast cancer (P = 0.003; OR = 1.67; 95% CI: 1.17-2.38). Likewise, the minor allele (C) was significantly correlated with protection (P = 0.003; OR = 0.60; 95% CI: 0.42-0.86). At the genotype level, AA homozygosity was significantly associated with predisposition to disease (P = 0.013; OR = 1.68, 95% CI: 1.09-2.59), whereas the minor allele homozygosity (CC) was correlated with protection to disease (P = 0.020, OR = 0.28, 95% CI: 0.09-0.91). The heterozygous genotype showed no significant correlation with disease. The product of the IL12B gene (IL-12 p40) can either form a homodimeric cytokine or be part of two pro-inflammatory (IL-12 and IL-23) cytokines. It is presently unclear whether the major allele is associated with higher or lower protein levels of IL-12 p40 and IL-12 p70, which are critical in inflammation and adaptive immune responses. However, as the A allele is high producer of IL12B (p40) mRNA, these results might imply that higher levels of IL-12 p40 (either as homodimers or joined with one or both of the other two subunits) predispose to breast cancer.

Interleukin-12B rs3212227 polymorphism and cancer risk: a meta-analysis

IL-12 plays a very important role in the development and progress of cancer. IL-12B rs3212227 polymorphism has been reported and many studies have focused on the role of this polymorphism in various cancers. However, the association between IL-12B rs3212227 polymorphism and cancer risk remains controversial. Therefore, we performed a systematic meta-analysis to estimate the overall cancer risk associated with this gene polymorphism and to quantify any potential between-study heterogeneity. PubMed and Embase databases were searched for case-control studies published up to April 1, 2012 that investigated IL-12B rs3212227 polymorphism and cancer risk. Odds ratios (OR) with 95 % confidence intervals (95 % CI) were used to access the strength of this association. Heterogeneity among articles and publication bias were also verified. Ten studies with 2,954 cancer patients and 3,276 healthy controls were included. This meta-analysis showed that there was a significant association between IL-12B rs3212227 polymorphism and overall cancer risk (CC/AC vs AA: OR = 1.32, 95 % CI = 1.06-1.63). When stratified by cancer type, we found a significant increased risk in cervical and nasopharyngeal cancer (OR = 1.34, 95 % CI = 1.04-1.73; OR = 2.03, 95 % CI = 1.57-2.63, respectively). In the stratified analysis, we also observed a similar association in population-based studies (OR = 1.34, 95 % CI = 1.00-1.80), Asian populations (OR = 1.33, 95 % CI = 1.06-1.67) and European populations (OR = 1.54, 95 % CI = 1.04-2.28). According to the results of our meta-analysis, IL-12B rs3212227 polymorphism probably is associated with a high risk of cancer.

Interleukin-12: clinical usage and molecular markers of cancer susceptibility

The last decade has seen the emergence of immunomodulators as therapeutic agents in cancer treatment. Interleukins (ILs) are a category of small cell-signaling molecules that organize communication and interaction between immune cells and therefore they could be used as perfect immunomodulators. IL-12 is a promising candidate for cancer immunotherapy since it plays a major role in development of antitumor immune response. Numerous studies report that IL-12 promotes an effective destruction of cancer cells both in vivo and in vitro. In addition, IL-12 has anti-angiogenic activity and it is able to dramatically decrease tumor-supportive activities of tumor-associated macrophages. The first part of the review is devoted to immunobiology of IL-12. Signaling pathways of IL-12 as well as clinical trials of this cytokine are discussed. The second part of the review is concerned on the inherited variations in IL-12A and IL-12B genes that could modulate cancer susceptibility, and as a consequence, possess predictive, therapeutic, or prognostic significance. It is known that functional single nucleotide polymorphisms (SNPs) in IL-12A and IL-12B genes may dramatically affect on protein expression level, or alter its functions, which may lead to immune disorders, autoimmune diseases, and eventually contribute to cancer occurrence. The list of genetic polymorphisms for further investigations might include the following: IL-12B_+1188A/C (rs3212227), IL-12A_+277G/A (rs568408), IL-12A_-798T/A (rs582054), IL-12A_-504T/G (rs190533), IL-12A_-1148T/C (rs2243123), and IL-12B_+16974 A/C. Perhaps, some of these SNPs may become an attractive target for oncogenomics and possibly could be used in programs of early cancer diagnosis as well as cancer prevention in the nearest future.

Multifaceted tumor stromal fibroblasts

Tumors are highly complex tissues composed of neoplastic cells and different kinds of stromal cells. Tumor stromal cells, especially fibroblasts, play important roles during the multistep development of tumors. In this review, the two-faced characteristics of tumor stromal fibroblasts are discussed in the light of our current knowledge. For one thing, fibroblasts act as an "inflammation regulator" by secretion of cytokines and regulation of tumor immunity; for another, they act as a "damage healer" for cure of wounds by remodeling extracellular matrix or taking a part in the "foreign body reaction". Since the properties of fibroblasts are complicated, both aspects of fibroblasts for tumor development should be considered carefully in clinical studies to target cancer-associated fibroblasts.

The antitumor effects of adenoviral-mediated, intratumoral delivery of interleukin 23 require endogenous IL-12

Interleukin (IL)-23 is a member of the IL-12 family of heterodimeric cytokines, comprised of p19 and p40 subunits, which exhibits immunostimulatory properties similar to IL-12. We have demonstrated previously that adenoviral-mediated, intratumoral delivery of IL-23 (Ad.IL-23) was able to induce systemic antitumor immunity. Here we demonstrate that Ad.IL-23 requires endogenous IL-12 for conferring an antitumor effect after adenoviral-mediated, intratumoral delivery. In contrast, Ad.IL-12 does not require IL-23 for its antitumor effects although endogenous IL-23 appears important for induction of systemic antitumor immunity by IL-12. However, despite the requirement for endogenous IL-12, co-delivery of IL-23 and IL-12 does not provide even an additive local or systemic antitumor effect, regardless of the dose. We further demonstrate that although the use of a single-chain IL-23 (scIL-23) results in higher level of expression and a more pronounced IL-23-mediated antitumor effect, there is still no synergy with IL-12. These results demonstrate that although significant antitumor effects are achieved by intratumoral injection of adenovirus expressing either scIL-23 or IL-12 alone and that IL-23 requires endogenous IL-12 for maximum antitumor benefit, the combined use of these cytokines provides no additive or synergistic effect.

A DNA vaccine against ERBB2 impairs chemical carcinogenesis in random-bred hamsters

Vaccines against oncoantigens halt early neoplastic lesions in several cancer-prone, genetically engineered mouse models, whereas their ability to prevent chemical carcinogenesis has not been explored. This is a significant issue, as exposure to chemical mutagens is responsible for a substantial percentage of cancers worldwide. Here, we show that the archetypal oncoantigen ERBB2 is transiently overexpressed in Syrian hamsters during the early stages of 7,12-dimethylbenz[α]anthracene (DMBA)-induced oral carcinogenesis. Repeated DNA vaccinations against ERBB2 significantly reduce the number, size, and severity of oral lesions in a manner directly proportional to the anti-ERBB2 antibody response. These results support the prospects of vaccines as a fresh strategy in the management of individuals at risk for exposure to defined carcinogenic agents.

Increased expression of nonmuscle myosin IIs is associated with 3MC-induced mouse tumor

Administration of the chemical carcinogen, 3-methylcholanthrene (3MC), in the hind leg induces the progressive formation of tumors in mice within 110 days. Previous reports suggest that transformation of muscle cells to atypical cells is one of the causes of tumor formation. Molecular events that lead to transformation of normal cells to atypical cells are not well understood. Here, we investigate the effect of 3MC on the expression of nonmuscle myosin IIs (NM IIs) which are known to be involved in cell migration, division and adhesion. Mass spectroscopy analysis reveals that tumor tissue contains 64.5% NM II-A, 34% II-B and only 1.5% II-C of total NM IIs, whereas these three isoforms of NM IIs are undetectable by mass spectroscopy in normal tissue associated with the tumor (NTAT) from the hind leg. Quantification of heavy chain mRNAs of NM II suggests that tumor tissue contains 25.7-fold and 19.03-fold more of NM II-A and II-B, respectively, compared with NTAT. Unlike NM II-B, which is detected only after tumor formation, II-A is detectable as early as day 7 after a second dose of 3MC. Immunofluorescence confocal microscopy reveals that fibroblast cells which are sparsely distributed in normal tissue are densely populated but of atypical shape in the tumor. These findings suggest that transformation of fibroblasts or non-fibroblast cells to atypical, cancerous cells is associated with increased levels of NM II-A and NM II-B expression in the 3MC-induced tumor mouse model. 3MC-induced transformation is further demonstrated in C2C12 myotubes.

Effect of Acute Maximal Exercise on Circulating Levels of Interleukin-12 during Ramadan Fasting

PURPOSE

The purpose of this study was to examine the effects of Ramadan fasting on circulating levels of interleukin-12 (IL-12) after a brief maximal exercise.

METHODS

NINE SUBJECTS PERFORMED A WINGATE TEST ON THREE DIFFERENT OCCASIONS: (i) the first week of Ramadan (1WR), (ii) the fourth week of Ramadan (4WR), and (iii) three weeks after Ramadan (AR). Blood samples were taken before, immediately and 60 min after the exercise. Plasma concentrations of IL-12 were measured using enzyme-linked immunosorbent assay. Variance analysis revealed no significant effect of Ramadan on P(peak) and P(mean) during the three testing periods.

RESULTS

Considering the effect of Ramadan on plasma concentrations of IL-12, analysis of the variance revealed a significant Ramadan effect (F((2,) (16))=66.27; P < 0.001) as well as a significant time effect (F((2,) (16))= 120.66; P < 0.001). However, no significant (Ramadan × time) of test interaction (F((4,) (32))=2.40; P>0.05). For all measures, IL-12 levels were lower during 1WR and 4WR in comparison with AR (P < 0.05). Considering the exercise effects, IL-12 levels measured immediately after the exercise were significantly higher than those measured before and at 60 minutes after the exercise (P < 0.001).

CONCLUSIONS

These results suggest that an acute intense exercise-induced IL-12 response is modified by daytime fasting and modifications in sleep schedule during Ramadan.

Genetic susceptibility of cervical cancer

Epidemiological and laboratory-based studies have identified infection with one of 15 high-risk human papillomavirus (HPV) types as a necessary but not sufficient cause of cervical cancer. The prevalence of genital HPV infections is high in young women, but most of the infections regress without interventions. Host genetic variations in genes involved in immune response pathways may be related to HPV clearance, and HPV E6/E7 oncoproteins interacting or downstream genes, both coding and non-coding, may contribute to the outcome of high risk HPV infection and cervical cancer. Of specific interest for this review has been the selection of genetic variants in genes involved in the above-referred pathways with a summary of their applications in association studies. Because the supportive and opposing data have been reported in different populations, well-designed international collaborative studies need to be conducted to define the consistency of the associations, paving the way to better define the patients at high risk of developing cervical cancer.

Anti-TIM3 antibody promotes T cell IFN-γ-mediated antitumor immunity and suppresses established tumors

Strategies to activate and rescue exhausted tumor-specific T cells, including the use of monoclonal antibodies (mAb) that block the negative costimulatory receptors CTLA-4 and PD-1 are proving very effective, but TIM3 has been relatively neglected as a target. Here we report an extensive characterization of the therapeutic activity and mechanism of action of an anti-mouse TIM3 mAb against experimental and carcinogen-induced tumors. For the first time we specifically define the mechanism of antitumor action of anti-TIM3 requiring IFN-γ producing CD8(+) T cells and CD4(+) T cells, and a higher ratio of tumor infiltrating CD8(+):CD4(+) T cells correlating with therapeutic success. Interestingly, in some models, anti-TIM3 appeared to be effective sometime before the appearance and accumulation of significant TIM3(+)PD-1(+) T cell populations in tumor bearing mice. Anti-TIM3 displayed modest prophylactic and therapeutic activity against a small fraction of carcinogen-induced sarcomas, but comparative and combination studies of anti-TIM3 with anti-CTLA-4 and anti-PD-1 against experimental and carcinogen-induced tumors suggested that these agents might be well-tolerated and very effective in combination.

Cancer-preventing attributes of probiotics: an update

Cancer is a serious global public health problem. Cancer incidence and mortality have been steadily rising throughout the past century in most places of the world. There are several epidemiological evidences that support a protective role of probiotics against cancer. Lactic acid bacteria and their probioactive cellular substances exert many beneficial effects in the gastrointestinal tract, and also release various enzymes into the intestinal lumen and exert potential synergistic (LAB) effects on digestion and alleviate symptoms of intestinal malabsorption. Consumption of fermented dairy products with LAB may elicit anti-tumor effects. These effects are attributed to the inhibition of mutagenic activity, the decrease in several enzymes implicated in the generation of carcinogens, mutagens, or tumor-promoting agents, suppression of tumors, and epidemiology correlating dietary regimes and cancer. Specific cellular components in lactic acid bacteria seem to induce strong adjuvant effects including modulation of cell-mediated immune responses, activation of the reticulo-endothelial system, augmentation of cytokine pathways, and regulation of interleukins and tumor necrosis factors. Studies on the effect of probiotic consumption on cancer appear promising, since recent in vitro and in vivo studies have indicated that probiotic bacteria might reduce the risk, incidence and number of tumors of the colon, liver and bladder. The protective effect against cancer development may be ascribed to binding of mutagens by intestinal bacteria, may suppress the growth of bacteria that convert procarcinogens into carcinogens, thereby reducing the amount of carcinogens in the intestine, reduction of the enzymes beta-glucuronidase and beta-glucosidase and deconjugation of bile acids, or merely by enhancing the immune system of the host. There are isolated reports citing that administration of LAB results in increased activity of anti-oxidative enzymes or by modulating circulatory oxidative stress that protects cells against carcinogen-induced damage. These include glutathione-S-transferase, glutathione, glutathione reductase, glutathione peroxidase, superoxide dismutase and catalase. However, there is no direct experimental evidence for cancer suppression in human subjects as a result of the consumption of probiotic cultures in fermented or unfermented dairy products, but there is a wealth of indirect evidence based largely on laboratory studies.

IL-12 initiates tumor rejection via lymphoid tissue-inducer cells bearing the natural cytotoxicity receptor NKp46

The potent tumoricidal activity of interleukin 12 (IL-12) is thought to be mediated by the activation and polarization of natural killer (NK) cells and T helper type 1 (T(H)1) cells, respectively. By systematic analysis of the IL-12-induced immune response to subcutaneous melanoma (B16), we found that tumor suppression was mediated independently of T lymphocytes or NK cells. IL-12 initiated local antitumor immunity by stimulating a subset of NKp46(+) lymphoid tissue-inducer (LTi) cells dependent on the transcription factor RORγt. The presence of these NKp46(+) LTi cells induced upregulation of adhesion molecules in the tumor vasculature and resulted in more leukocyte invasion. Thus, this innate cell type is responsive to IL-12 and is a powerful mediator of tumor suppression.

In silico modeling and in vivo efficacy of cancer-preventive vaccinations

Cancer vaccine feasibility would benefit from reducing the number and duration of vaccinations without diminishing efficacy. However, the duration of in vivo studies and the huge number of possible variations in vaccination protocols have discouraged their optimization. In this study, we employed an established mouse model of preventive vaccination using HER-2/neu transgenic mice (BALB-neuT) to validate in silico-designed protocols that reduce the number of vaccinations and optimize efficacy. With biological training, the in silico model captured the overall in vivo behavior and highlighted certain critical issues. First, although vaccinations could be reduced in number without sacrificing efficacy, the intensity of early vaccinations was a key determinant of long-term tumor prevention needed for predictive utility in the model. Second, after vaccinations ended, older mice exhibited more rapid tumor onset and sharper decline in antibody levels than young mice, emphasizing immune aging as a key variable in models of vaccine protocols for elderly individuals. Long-term studies confirmed predictions of in silico modeling in which an immune plateau phase, once reached, could be maintained with a reduced number of vaccinations. Furthermore, that rapid priming in young mice is required for long-term antitumor protection, and that the accuracy of mathematical modeling of early immune responses is critical. Finally, that the design and modeling of cancer vaccines and vaccination protocols must take into account the progressive aging of the immune system, by striving to boost immune responses in elderly hosts. Our results show that an integrated in vivo-in silico approach could improve both mathematical and biological models of cancer immunoprevention.

The management of ductal intraepithelial neoplasia (DIN): open controversies and guidelines of the Istituto Europeo di Oncologia (IEO), Milan, Italy

The management of ductal intraepithelial neoplasia (DIN) has substantially changed over the past 30 years, as its incidence has increased (from 2-3% to more than 20%), mainly due to the widespread use of mammography screening. This article describes not only the more widespread theoretical concepts on DIN but also the differences in the practical applications of the theory between different countries, different oncology specialists, and different cancer centers. Papers related to the international multicentre-randomized trials and retrospective studies were analyzed. We include articles and papers published between 1993 and 2010 related to patients with DIN, and abstracts and reports from MEDLINE and other sources were indentified. The standard of care for DIN consists of (a) breast conservative surgery (mastectomy is still indicated in large lesions--masses or microcalcifications--in about 30% of cases); (b) radiotherapy (RT) after conservative surgery, and (c) medical treatment in estrogen receptors-positive patients. However, most studies have shown significant differences between theory and practical application. Moreover, there are differences regarding (a) the indications of sentinel lymph node biopsy, (b) the definition and identification of low-risk DIN subgroups that can avoid RT and tamoxifen, and (c) the research into new alternative drugs in adjuvant medical therapy. A general agreement on the best management of DIN does not exist as yet. New large trials are needed in order to define the best management of DIN patients which is (in most respects) still complex and controversial.

IL12 polymorphisms, HBV infection and risk of hepatocellular carcinoma in a high-risk Chinese population

To investigate the association between the potentially functional polymorphisms in IL12A and IL12B, HBV infection and risk of hepatocellular carcinoma in a Chinese population, we genotyped three polymorphisms, rs568408 (3'UTR G>A), rs2243115 (5'UTR T>G) in IL12A and rs3212227 (3'UTR A>C) in IL12B in a case-control study of 869 hepatocellular carcinoma (HCC) cases and 891 cancer-free controls. We found that the IL12A rs568408 GA/AA variant genotypes were associated with a significantly increased risk of HCC (adjusted odds ratio (OR) = 1.53, 95% confidence interval (CI) = 1.17-2.00), compared with the wild-type GG homozygote. In the stratified analyses, the increased risk of HCC associated with rs568408 GA/AA was more evident in patients who were negative for HBsAg (adjusted OR = 1.71, 95% CI = 1.23-2.39). However, no significant associations between IL12A rs2243115 T/G, IL12B rs3212227 A/C and risk of HCC were observed. Our findings indicate that IL12A rs568408 may contribute to the risk of HCC and modify HCC risk associated with HBV infection.

Lymphocytes in cancer development: polarization towards pro-tumor immunity

The classic view that the role of immune cells in cancer is primarily one of tumor rejection has been supplanted by a more complex view of leukocytes having both pro- and anti-tumor properties. This shift is due to the now well recognized capabilities of several myeloid cell types that foster pro-tumor programming of premalignant tissue, as well as the discovery that subsets of leukocytes also suppress development and effector functions of lymphocytes important for mediating anti-tumor immunity. In this review, we focus on the underappreciated role that T lymphocytes play in promoting tumor development. This includes, in addition to the role of T regulatory cells, a role for natural killer T cells and CD4(+) T helper cells in suppressing anti-tumor immunity and promoting cancer growth and metastasis.

Adenoviral-mediated, intratumor gene transfer of interleukin 23 induces a therapeutic antitumor response

Interleukin 23 (IL-23) is a member of the IL-12 family of heterodimeric cytokines, composed of p19 and p40 subunits, which exhibits immunostimulatory properties similar to IL-12. IL-23 has been shown to possess potent antitumor activities in several establishment models of cancer and a few therapeutic models, but the efficacy of local, adenoviral-mediated expression of IL-23 in established tumors has yet to be investigated. Here we have examined the antitumor activity of adenovirally delivered IL-23 in a day-7 MCA205 murine fibrosarcoma tumor model. Three intratumoral injections of adenovirus expressing IL-23 (Ad.IL-23) significantly increased animal survival and resulted in complete rejection of 40% of tumors, with subsequent generation of protective immunity and MCA205-specific cytotoxic T lymphocytes. In addition, we have shown that the antitumor activity of IL-23 is independent of IL-17, perforin and Fas ligand, but dependent on interferon-gamma, CD4(+) and CD8(+) T cells. These results demonstrate that direct intratumoral injection of adenovirus expressing IL-23 results in enhanced survival, tumor eradication and generation of protective immunity by generation of a Th1-type immune response.

Cancer immunotherapy

Recent scientific advances have expanded our understanding of the immune system and its response to malignant cells. The clinical goal of tumour immunotherapy is to provide either passive or active immunity against malignancies by harnessing the immune system to target tumours. Monoclonal antibodies, cytokines, cellular immunotherapy, and vaccines have increasingly become successful therapeutic agents for the treatment of solid and haematological cancers in preclinical models, clinical trials, and practice. In this article, we review recent advances in the immunotherapy of cancer, focusing on new strategies and future perspectives as well as on clinical trials attempting to enhance the efficacy of immunotherapeutic modalities and translate this knowledge into effective cancer therapies.

A critical analysis of the tumour immunosurveillance controversy for 3-MCA-induced sarcomas

The cancer immunoediting hypothesis has gained significant footing over the past decade as a result of work performed using sarcomas induced by 3-methylcholanthrene (3-MCA) in mice. Despite the progress made by several groups in establishing evidence for the three phases of immunoediting (elimination, equilibrium and escape), there continues to be active controversy on the nature of interaction between spontaneously formed tumour cells and the immune system during the early phases of tumourigenesis. At the root of this controversy is conflicting and unresolved evidence spanning back to the 1970s regarding the incidence and frequency of 3-MCA-induced sarcomas in immunocompetent mice as compared to immunodeficient mice. In this mini review we provide a critical analysis of both sides of this controversy.

IFN-gamma-dependent type 1 immunity is crucial for immunosurveillance against squamous cell carcinoma in a novel mouse carcinogenesis model

3-Methylcholanthrene (MCA)-induced sarcomas have been used as conventional tools for investigating immunosurveillance against tumor development. However, MCA-induced sarcoma is not always an ideal model for the study of the human cancer system because carcinomas and not sarcomas are the dominant types of human cancers. To resolve this problem, we established a novel and simple method to induce mouse squamous cell carcinomas (SCCs). As well known, the subcutaneous injection of MCA caused the formation of sarcomas at 100% incidence. However, we here first succeeded at inducing SCC at 60% of incidence within 2 months by a single intra-dermal injection of MCA. Using this primary SCC model, we demonstrated the critical role of interferon (IFN)-gamma-dependent type 1 immunity in immunosurveillance against SCC from the following results: (i) The incidence of SCC was accelerated in IFN-gamma-deficient mice compared with that in wild-type mice; (ii) In vivo injection of CpG-oligodeoxynucleotides (CpG-ODN) caused a marked reduction in the incidence of SCC in parallel with the activation of type 1-dependent antitumor immunity and (iii) The antitumor activity of CpG-ODN was significantly decreased in IFN-gamma-deficient mice. Thus, our established MCA-induced mouse SCC model could be a powerful tool for evaluating immunosurveillance mechanisms during the development of SCC and might result in a novel strategy to address immunosurveillance mechanisms of human cancer.

Relationship between the in vitro response of dendritic cells to Lactobacillus and prevention of tumorigenesis in the mouse

BACKGROUND

Some strains of lactobacilli stimulate immune cells, yet little is known about their potency in cancer prevention. We have previously reported that Lactobacillus casei Shirota (LcS) suppresses murine tumorigenesis through immune modulation. In this study, differences were compared among six representative strains of lactobacilli in regard to their ability to stimulate bone marrow cell-derived dendritic cells (BMDCs) in vitro and tumor suppression in vivo.

METHODS

BM-DCs were cocultured with a Lactobacillus strain in vitro, and the interleukin (IL)-12 released into the culture supernatant was measured by enzyme-linked immunosorbent assay. Tumors were chemically induced by a single subcutaneous injection of 3-methylcholanthrene (MC) in BALB/c mice. The test diets containing Lactobacillus were given from the day of the MC injection, and the tumor incidences were monitored. Peyer's patches were dissected from Lactobacillus-fed mice, and the status of c-Src, a regulator of DCs, in Peyer's patch cells was examined by Western blotting.

RESULTS

In the coculture system, L. fermentum FERM P-13857 and LcS potently elicited IL-12 production. LcS but not the other strains of lactobacilli showed tumor suppression. The inactive form of c-Src, phosphorylated at Tyr527, was dominantly detected in Peyer's patches resected from L. fermentum FERM P-13857-fed mice compared with LcS-fed mice.

CONCLUSIONS

The responses of DCs may be associated with tumor suppression by an ingested Lactobacillus strain.

Tumor immunoediting and immunosculpting pathways to cancer progression

Recent studies have suggested that a natural function of the immune system is to respond and destroy aberrant, dysfunctional cells by a process called immunosurveillance. These studies also suggest that the tumors that arise despite immunosurveillance have been immunosculpted by the immune system. The purported abilities of tumors to induce immune tolerance and suppression, the increased pathogenic behavior of the tumor cells following exposure to immune effectors and the loss of immunogenicity (i.e. immunoediting) often observed in advanced stage tumors could be the result of immunosculpting. In some cases, these immunosculpting features may be permanent and irreversible. However, in other cases, reversible epigenetic mechanisms may underlie the immune resistant tumor phenotype. Regardless, these immune-induced alterations could contribute to cancer pathogenesis. Understanding the mechanisms by which tumors evade immunity will be important for disease prevention and therapeutics.

Challenges and prospects of immunotherapy as cancer treatment

The concept of cancer immunotherapy stems from the proposed function of the immune system, called immunosurveillance, to protect against growing tumors. Due to genetic aberrations, tumor cells display an altered repertoire of MHC-associated peptides that can lead to the activation of immune cells able to eliminate the transformed cells. In some instances, under the pressure of the immune system, both the tumor and its microenvironment are shaped and immune-resistant tumor variants are selected initiating the process of cancer immunoediting. This can impair not only host-generated immunosurveillance, but also attempts to harness the immune response for therapeutic purposes, namely immunotherapy. Rather than being an exhaustive review of the different approaches of cancer immunotherapy, the focus of this review is to provide the reader with future challenges of the field by proposing 'second generation' immunotherapy approaches that take into account immunosubversive mechanisms adopted by tumor cells. After an introduction on the process of immunosurveillance and immunoescape we will analyze why current immunotherapy approaches have not fulfilled their promise and will finish by summarizing what are the challenges for future approaches.