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Until recently, most immunotherapeutic approaches used to fight cancer were ineffective, counteracted by the tumour's ability to evade immune attack. However, extensive research has improved our understanding of tumour immunology and enabled the development of novel treatments that can harness the patient's immune system and prevent immune escape. Over the last few years, through numerous clinical trials and real-world experience, we have accumulated a large amount of evidence regarding the potential for long-term survival with immunotherapy agents in various types of malignancy. The results of these studies have also highlighted a number of recurring observations with immuno-oncology agents, including their potential for clinical application across a broad patient population and for both conventional and unconventional response patterns. Furthermore, given the numerous immune checkpoints that exist and the multiple mechanisms used by tumours to escape the immune system, targeting distinct checkpoint pathways using combination approaches is an attractive therapeutic strategy with the potential to further enhance the antitumour immune response. [ABSTRACT FROM AUTHOR]

The dichotomy of immunology into innate and adaptive immunity has created conceptual barriers in appreciating the intrinsic two-way interaction between immune cells. An emerging body of evidence in various models of immune rejection, including cancer, indicates an indispensable regulation of innate effector functions by adaptive immune cells. This bidirectional cooperativity in innate and adaptive immune functions has broad implications for immune responses in general and for regulating the tumor-associated inflammation that overrides the protective antitumor immunity. Mechanistic understanding of this two-way immune cross-talk could provide insights into novel strategies for designing better immunotherapy approaches against cancer and other diseases that normally defy immune control. [ABSTRACT FROM AUTHOR]

Assesses the immune response to peptide vaccination among melanoma patients in Bethesda, Maryland. Use of real time quantitative polymerase chain reaction assay; Relevance of detecting tumor antigen response in developing cancer vaccines; Implication of the assessment in understanding tumor-host interaction.

A cancer immune signature implicating good prognosis and responsiveness to immunotherapy was described that is observed also in other aspects of immune-mediated, tissue-specific destruction (TSD). Its determinism remains, however, elusive. Based on limited but unique clinical observations, we propose a multifactorial genetic model of human cancer immune responsiveness. [ABSTRACT FROM AUTHOR]

Immune-mediated rejection of human cancer is a relatively rare but well-documented phenomenon. Its rate of occurrence progressively increases from the occasional observation of spontaneous regressions to the high rate of complete remissions observed in response to effective treatments. For two decades, our group has focused its interest in understanding this phenomenon by studying humans following an inductive approach. Sticking to a sequential logic, we dissected the phenomenon by studying to the best of our capability both peripheral and tumor samples and reached the conclusion that immune-mediated cancer rejection is a facet of autoimmunity where the target tissue is the cancer itself. As we are currently defining the strategy to effectively identify the mechanisms leading in individual patients to rejection of their own tumors, we considered useful to summarize the thought process that guided us to our own interpretation of the mechanisms of immune responsiveness. [ABSTRACT FROM AUTHOR]

Plasmacytoid dendritic cells (pDCs) are key components of the innate immune response that are capable of synthesizing and rapidly releasing vast amounts of type I interferons (IFNs), particularly IFN-α. Here we investigated whether pDCs, often regarded as a mere source of IFN, discriminate between various functionally discrete stimuli and to what extent this reflects differences in pDC responses other than IFN- release. To examine the ability of pDCs to differentially respond to various doses of intact and infectious HIV, hepatitis C virus, and H1N1 influenza virus, whole-genome gene expression analysis, enzyme-linked immunosorbent assays, and flow cytometry were used to investigate pDC responses at the transcriptional, protein, and cellular levels. Our data demonstrate that pDCs respond differentially to various viral stimuli with significant changes in gene expression, including those involved in pDC activation, migration, viral endocytosis, survival, or apoptosis. In some cases, the expression of these genes was induced even at levels comparable to that of IFN-α. Interestingly, we also found that depending on the viral entity and the viral titer used for stimulation, induction of IFN-α gene expression and the actual release of IFN-α are not necessarily temporally coordinated. In addition, our data suggest that high-titer influenza A (H1N1) virus infection can stimulate rapid pDC apoptosis. [ABSTRACT FROM AUTHOR]

The authors reflect on the meta-analysis and metagenes regarding the use of CXCL-13 gene as a marker of intratumoral immune response and predictor for chemotherapeutic outcome of breast cancer. Topics include the cancer immunotherapy, response to neoadjuvant chemotherapy, and anti-cytotoxic T lymphocyte-associated protein 4 (CTLA-4) monoclonal antibody (mAb).

Cell-based immunotherapies are among the most promising approaches for developing effective and targeted immune response. However, their clinical usefulness and the evaluation of their efficacy rely heavily on complex quality control assessment. Therefore, rapid systematic methods are urgently needed for the in-depth characterization of relevant factors affecting newly developed cell product consistency and the identification of reliable markers for quality control. Using dendritic cells (DCs) as a model, we present a strategy to comprehensively characterize manufactured cellular products in order to define factors affecting their variability, quality and function. After generating clinical grade human monocyte-derived mature DCs (mDCs), we tested by gene expression profiling the degrees of product consistency related to the manufacturing process and variability due to intra- and interdonor factors, and how each factor affects single gene variation. Then, by calculating for each gene an index of variation we selected candidate markers for identity testing, and defined a set of genes that may be useful comparability and potency markers. Subsequently, we confirmed the observed gene index of variation in a larger clinical data set. In conclusion, using high-throughput technology we developed a method for the characterization of cellular therapies and the discovery of novel candidate quality assurance markers. [ABSTRACT FROM AUTHOR]

Ex vivo production of highly stimulator mature dendritic cells (DCs) for cellular therapy has been used to treat different pathological conditions with the aim of inducing a specific immune response. In the last decade, several protocols have been developed to mature monocyte-derived DCs: each one has led to the generation of DCs showing different phenotypes and stimulatory abilities, but it is not yet known which one is the best for inducing effective immune responses. We grouped several different maturation protocols according to the downstream pathways they activated and reviewed the shared features at a transcriptomic level to reveal the potential of DCs matured by each protocol to develop Th-polarized immune responses. [ABSTRACT FROM AUTHOR]

Background: Type-1 T cells are critical for effective anti-tumor immune responses. The recently discovered microRNAs (miRs) are a large family of small regulatory RNAs that control diverse aspects of cell function, including immune regulation. We identified miRs differentially regulated between type-1 and type-2 T cells, and determined how the expression of such miRs is regulated. Methods: We performed miR microarray analyses on in vitro differentiated murine T helper type-1 (Th1) and T helper type-2 (Th2) cells to identify differentially expressed miRs. We used quantitative RT-PCR to confirm the differential expression levels. We also used WST-1, ELISA, and flow cytometry to evaluate the survival, function and phenotype of cells, respectively. We employed mice transgenic for the identified miRs to determine the biological impact of miR-17-92 expression in T cells. Results: Our initial miR microarray analyses revealed that the miR-17-92 cluster is one of the most significantly over-expressed miR in murine Th1 cells when compared with Th2 cells. RT-PCR confirmed that the miR-17-92 cluster expression was consistently higher in Th1 cells than Th2 cells. Disruption of the IL-4 signaling through either IL-4 neutralizing antibody or knockout of signal transducer and activator of transcription (STAT)6 reversed the miR- 17-92 cluster suppression in Th2 cells. Furthermore, T cells from tumor bearing mice and glioma patients had decreased levels of miR-17-92 when compared with cells from non-tumor bearing counterparts. CD4+ T cells derived from miR-17-92 transgenic mice demonstrated superior type-1 phenotype with increased IFN-γ production and very late antigen (VLA)-4 expression when compared with counterparts derived from wild type mice. Human Jurkat T cells ectopically expressing increased levels of miR-17-92 cluster members demonstrated increased IL-2 production and resistance to activation-induced cell death (AICD). Conclusion: The type-2-skewing tumor microenvironment induces the down-regulation of miR-17-92 expression in T cells, thereby diminishing the persistence of tumor-specific T cells and tumor control. Genetic engineering of T cells to express miR-17-92 may represent a promising approach for cancer immunotherapy. [ABSTRACT FROM AUTHOR]

The concept of using replicating oncolytic viruses in cancer therapy dates to the beginning of the twentieth century. However, in the last few years, an increasing number of pre-clinical and clinical trials have been carried out with promising preliminarily results. Novel, indeed, is the suggestion that viral oncolytic therapy might not operate exclusively through an oncolysis-mediated process but additionally requires the “assistance” of the host’s immune system. Originally, the host’s immune response was believed to play a predominant obstructive role against viral replication, hence limiting the anti-tumor efficacy of viral vectors. Recent data, however, suggest that the immune response may also play a key role in promoting tumor destruction in association with the oncolytic process. In fact, immune effector pathways activated during oncolytic virus-induced tumor rejection seem to follow a similar pattern to those observed when the broader phenomenon of immune-mediated tissue-specific rejection occurs in other immune-related pathologies. We recently formulated the “Immunologic Constant of Rejection” hypothesis, emphasizing commonalties in transcriptional patterns observed when tissue-destruction occurs: whether with a favorable outcome, such as in tumor rejection and pathogen clearance; or a destructive one, such as in allograft rejection or autoimmunity. Here, we propose that a similar mechanism induces clearance of virally infected tumors and that such a mechanism is primarily dependent on innate immune functions. [ABSTRACT FROM AUTHOR]

There is mounting evidence describing the immunosuppressive role of bulky metastatic disease, thus countering the therapeutic effects of tumor vaccine. Therefore, adjuvant immunotherapy may have a better impact on clinical outcome. In this phase II clinical trial, we aimed to test the feasibility of using a specific mutant ras peptide vaccine as an adjuvant immunotherapy in pancreatic and colorectal cancer patients. Twelve patients with no evidence of disease (NED), five pancreatic and seven colorectal cancer patients were vaccinated subcutaneously with 13-mer mutant ras peptide, corresponding to their tumor’s ras mutation. Vaccinations were given every 4 weeks, up to a total of six vaccines. No serious acute or delayed systemic side effects were seen. We detected specific immune responses to the relevant mutant ras peptide by measuring IFN-gamma mRNA expression by quantitative real-time PCR. Five out of eleven patients showed a positive immune response. Furthermore, the five pancreatic cancer patients have shown a mean disease-free survival (DFS) of 35.2+ months and a mean overall survival (OS) of 44.4+ months. The seven colorectal cancer patients have shown a mean disease-free survival (DFS) of 27.2+ months and a mean overall survival (OS) of 41.5+ months. In this study, we found that it is feasible to use mutant ras vaccine in the adjuvant setting. This vaccine is safe, can induce specific immune responses, and it appears to have a positive outcome in overall survival. Therefore, we believe that such an approach warrants further investigation in combination with other therapies. [ABSTRACT FROM AUTHOR]

We recently compared the HCV polyprotein to the human proteome in order to test whether amino acid sequences unique to the virus could represent immunodominant epitopic determinants of the human humoral immune response against HCV. We identified a relatively limited number of HCV fragments with no/low similarity to the human host that represented exclusive HCV motifs. In this study, the peptides corresponding to low/zero similarity sequences were synthesized and assayed with HCV-infected sera. With different patterns, the synthetic HCV peptides corresponding to low/zero similarity sequences were found to be immunoreactive. In particular, the HCV E1 (315–323) HRMAWDMMM, HCV E2/NS1 (547–555) NWFGCTWMN, and HCV NS5 (2638–2646) YDTRCFDST sequences were immunodominant in the HCV-infected cohort under study. These three peptides correspond to sequences that are endowed with low-similarity to the human proteome, are highly conserved among various HCV strains, and have, potentially, a scarce susceptibility to proteolytic attacks. These data may be of help in defining the multiple factors which concur in the modulation of the human immune response against HCV, eventually providing information for the design of effective anti-HCV vaccines. [ABSTRACT FROM AUTHOR]

Immune responses against tumor-associated antigens rely on efficient epitope presentation. The melanoma-associated antigen (Ag) gp100 contains HLA-A*0201 ligands that are characterized by low to medium binding affinity, among which gp100209-217 is the most prominent (Kawakami et al., J Immunol 154:3961–3968, 1995). While this epitope is a natural T-cell target, it primes with low-efficiency T-cell responses during immunization. A modified gp100 epitope, gp100209-217T210M, that contains a Thr to Met substitution at position 2 of the antigenic nonamer is characterized by high binding affinity for HLA-A*0201 and elicits strong and clinically effective T-cell responses. This higher affinity is believed to represent the sole reason for enhanced immunogenicity. Contrasting with this observation is the unpredictable relationship between affinity and immunogenicity observed in other antigen systems. In addition, we noted a striking difference between the capability of endogenously processed gp100209-217 and gp100209-217T210M to induce T-cell responses in an in vitro model. Therefore, we questioned whether factors other than HLA-affinity might play a role in determining the immunogenicity of these epitopes. In the present study, we evaluated the in vitro proteasomal cleavages of 23meric precursor peptides encompassing the native sequence (gp100201-223) or the modified sequence (gp100201-223T210M). Here we show that the standard proteasome liberates the C-termini of both antigenic peptides but not the N-termini. Quantitative analysis of the digestion products revealed that more of the fragments displaying the final C-termini were produced from the wild-type precursor. However, a stronger TCR engagement was observed when fractions of digested gp100201-223T210M were used to activate an HLA-A*0201–expressing target T-cell clone. This difference was also found using separately produced, synthetic nonamers. In conclusion, the high binding affinity of gp100209-217T210M seems to compensate for possible differences in proteasomal cleavage at the biological level. Since the final antigenic nonamer is not directly produced by the proteasome, additional further factors may influence the antigenic peptide availability, such as post-proteasomal processing and intracellular peptide transport. [ABSTRACT FROM AUTHOR]

Human metastatic cutaneous melanoma has gained a well deserved reputation for its immune responsiveness. The reason(s) remain(s) unknown. We attempted previously to characterize several variables that may affect the relationship between tumor and host immune cells but, taken one at the time, none yielded a convincing explanation. With explorative purposes, high-throughput technology was applied here to portray transcriptional characteristics unique to metastatic cutaneous melanoma that may or may not be relevant to its immunogenic potential. Several functional signatures could be identified descriptive of immune or other biological functions. In addition, the transcriptional profile of metastatic melanoma was compared with that of primary renal cell cancers (RCC) identifying several genes co-coordinately expressed by the two tumor types. Since RCC is another immune responsive tumor, commonalities between RCC and melanoma may help untangle the enigma of their potential immune responsiveness. This purely descriptive study provides, therefore, a map for the investigation of metastatic melanoma in future clinical trials and at the same time may invite consideration of novel therapeutic targets. [ABSTRACT FROM AUTHOR]

Metastatic melanoma represents a challenging clinical situation and, until relatively recently, there was an absence of effective treatment options. However, in 2011, the advanced melanoma treatment landscape was revolutionised with the approval of the anti-cytotoxic T-lymphocyte-associated protein-4 checkpoint inhibitor ipilimumab and the selective BRAF kinase inhibitor vemurafenib, both of which significantly improved overall survival. Since then, availability of new immunotherapies, especially the anti-programmed death-1 checkpoint inhibitors, as well as other targeted therapies, have further improved outcomes for patients with advanced melanoma. Seven years on from the first approval of these novel therapies, evidence for the use of various immune-based and targeted approaches is continuing to increase at a rapid rate. Improved understanding of the tumour microenvironment and tumour immuno-evasion strategies has resulted in different approaches to target and harness the immune response. These new immune-based approaches offer the opportunity for various approaches with distinct modes of action being used in combination with one another, as well as combined with other treatment modalities such as targeted therapy, electrochemotherapy and surgery. The increasing number of treatment options that are now available has resulted in a growing need to identify which patients will derive most benefit from which treatments. Much research is now focused on the identification of biomarkers that can be utilised to help select patients for treatment. These and other recent advances in the management of melanoma were the focus of discussions at the third Melanoma Bridge meeting (30 November-2 December, 2017, Naples, Italy), which is summarised in this report. [ABSTRACT FROM AUTHOR]