Cancer immunoediting and dioxin-activating aryl hydrocarbon receptor: a missing link in the shift toward tumor immunoescape?

The aryl hydrocarbon receptor (AhR), a member of the PAS protein family, is found in organisms as diverse as Drosophila melano­gaster, nematodes, and mammals. While several reviews have reported that AhR, once activated by agonist ligands, causes long-term effects such as modification of cell growth through cell cycle control, there is also recent evidence of its decisive role in immunosuppression. The most widely studied AhR agonist is 2,3,7,8-tetrachlorodibenzo-p-dioxin, which binds AhR with the highest known affinity, leading to profound suppression of both humoral and cellular immune responses, with praecox thymus involution, consequent thymocyte loss, and induction of T-cell apoptosis. Dioxin-AhR binding causes a decline in the number of dendritic cells and enhances apoptosis following their inappropriate activation. Dioxin-mediated activation of AhR also has a direct influence on the expansion of regula­tory T-cells CD4+CD25+ FoxP3+ (T-regs) and an adverse affect on CD8+ T-cell responses. Dioxin released from industrial and waste incinerators over the last few decades has caused widespread contamination of food, leading to its accumulation in fatty tissue in animals and humans. The elimination half-life of dioxin in humans (7-10 years) may favor the potentially continuous and long-lasting activation of AhR, leading to perpetual immune suppression and facilitating the onset, growth, and diffusion of tumors, especially in young people. In the cancer immunoediting hypoth­esis, which subdivides the relationship between tumor and immune system into three phases: elimination, equilibrium, and escape, it is thought that dioxin accumulation may cause an inevitable shift toward tumor escape

Evaluation of in vivo labelled dendritic cell migration in cancer patients

BACKGROUND: Dendritic Cell (DC) vaccination is a very promising therapeutic strategy in cancer patients. The immunizing ability of DC is critically influenced by their migration activity to lymphatic tissues, where they have the task of priming naïve T-cells. In the present study in vivo DC migration was investigated within the context of a clinical trial of antitumor vaccination. In particular, we compared the migration activity of mature Dendritic Cells (mDC) with that of immature Dendritic Cells (iDC) and also assessed intradermal versus subcutaneous administration. METHODS: DC were labelled with (99m)Tc-HMPAO or (111)In-Oxine, and the presence of labelled DC in regional lymph nodes was evaluated at pre-set times up to a maximum of 72 h after inoculation. Determinations were carried out in 8 patients (7 melanoma and 1 renal cell carcinoma). RESULTS: It was verified that intradermal administration resulted in about a threefold higher migration to lymph nodes than subcutaneous administration, while mDC showed, on average, a six-to eightfold higher migration than iDC. The first DC were detected in lymph nodes 20–60 min after inoculation and the maximum concentration was reached after 48–72 h. CONCLUSIONS: These data obtained in vivo provide preliminary basic information on DC with respect to their antitumor immunization activity. Further research is needed to optimize the therapeutic potential of vaccination with DC

FRET microscopy autologous tumor lysate processing in mature dendritic cell vaccine therapy

Abstract Background: Antigen processing by dendritic cells (DC) exposed to specific stimuli has been well characterized in biological studies. Nonetheless, the question of whether autologous whole tumor lysates (as used in clinical trials) are similarly processed by these cells has not yet been resolved. Methods: In this study, we examined the transfer of peptides from whole tumor lysates to major histocompatibility complex class II molecules (MHC II) in mature dendritic cells (mDC) from a patient with advanced melanoma. Tumor antigenic peptides-MHC II proximity was revealed by F\uf6rster Resonance Energy Transfer (FRET) measurements, which effectively extends the application of fluorescence microscopy to the molecular level (<100?). Tumor lysates were labelled with Alexa-488, as the donor, and mDC MHC II HLA-DR molecules were labelled with Alexa-546-conjugated IgG, as the acceptor. Results: We detected significant energy transfer between donor and acceptor-labelled antibodies against HLA-DR at the membrane surface of mDC. FRET data indicated that fluorescent peptide-loaded MHC II molecules start to accumulate on mDC membranes at 16 hr from the maturation stimulus, steeply increasing at 22 hr with sustained higher FRET detected up to 46 hr. Conclusions: The results obtained imply that the patient mDC correctly processed the tumor specific antigens and their display on the mDC surface may be effective for several days. These observations support the rationale for immunogenic efficacy of autologous tumor lysates

Unexpected High Response Rate to Traditional Therapy after Dendritic Cell-Based Vaccine in Advanced Melanoma: Update of Clinical Outcome and Subgroup Analysis

We reviewed the clinical results of a dendritic cell-based phase II clinical vaccine trial in stage IV melanoma and analyzed a patient subgroup treated with standard therapies after stopping vaccination. From 2003 to 2009, 24 metastatic melanoma patients were treated with mature dendritic cells pulsed with autologous tumor lysate and keyhole limpet hemocyanin and low-dose interleukin-2. Overall response (OR) to vaccination was 37.5% with a clinical benefit of 54.1%. All 14 responders showed delayed type hypersensitivity positivity. Median overall survival (OS) was 15 months (95% CI, 8–33). Eleven patients underwent other treatments (3 surgery, 2 biotherapy, 2 radiotherapy, 2 chemotherapy, and 4 biochemotherapy) after stopping vaccination. Of these, 2 patients had a complete response and 5 a partial response, with an OR of 63.6%. Median OS was 34 months (range 16–61). Our results suggest that therapeutic DC vaccination could favor clinical response in patients after more than one line of therapy

Fibrinogen: a novel predictor of responsiveness in metastatic melanoma patients treated with bio-chemotherapy: IMI (italian melanoma inter-group) trial

PURPOSE: To evaluate a panel of pretreatment clinical and laboratory parameters in metastatic melanoma (MM) in order to verify their impact on response and survival in a single prospective multi-institutional phase III study comparing out-patient chemotherapy (CT) vs bioCT. METHODS: A total of 176 patients were randomised to receive CT (cisplatin, dacarbazine, optional carmustine) or bioCT (the same CT followed by subcutaneous IL-2 plus intramuscular α-IFN-2b). Pretreatment total leucocytes, lymphocytes, eosinophyls, C-reactive protein (CRP), lactate dehydrogenase (LDH), erytrosedimentation rate (ESR), and fibrinogen were analyzed. Some clinical parameters (performance status, age, sex, and disease site) were also considered. As we found a positive trend for bio-CT with no statistical significance in OR (25.3% vs 20.2%) and OS (11 Mo vs 9.5 Mo), all analyses are stratified by treatment arm. RESULTS: In univariate analysis, higher value of lymphocytes percentage (P < .0001), lower value of total leucocytes (P=.005), CRP (P=.003), LHD (P < .0001), ESR (P < .027), fibrinogen (P < .0001), and no liver disease were strongly related to a better survival. In a multivariate analysis, using the Cox proportional hazards model, only fibrinogen (P=.004), LDH (P=.009) and liver disease (P=.04) were found to have an independent role on clinical outcome in metastatic melanoma patients. CONCLUSION: Liver disease and higher LDH and fibrinogen levels had an important impact on survival in MM patients. In particular, fibrinogen has been recently reconsidered both for its determinant role in the host hemostatic system, and for its capability to provide protection against NK and LAK-cell-induced lysis. These observations could have some important implications for therapeutic approaches, in particular when immunological strategies are used

The Italian Network for Tumor Biotherapy (NIBIT): Getting together to push the field forward

As for a consolidated tradition, the 5th annual meeting of the Italian Network for Cancer Biotherapy took place in the Certosa of Pontignano, a Tuscan monastery, on September 20–22, 2007. The congress gathered more than 40 Italian leading groups representing academia, biotechnology and pharmaceutical industry. Aim of the meeting was to share new advances in cancer bio-immunotherapy and to promote their swift translation from pre-clinical research to clinical applications. Several topics were covered including: a) molecular and cellular mechanisms of tumor escape; b) therapeutic antibodies and recombinant constructs; c) clinical trials up-date and new programs; d) National Cooperative Networks and their potential interactions; e) old and new times in cancer immunology, an "amarcord". Here, we report the main issues discussed during the meeting

Tolerability of intensified intravenous interferon alfa-2b versus the ECOG 1684 schedule as adjuvant therapy for stage III melanoma: a randomized phase III Italian Melanoma Inter-group trial (IMI – Mel.A.) [ISRCTN75125874]

BACKGROUND: High-dose interferon alfa-2b (IFNalfa-2b), according to the ECOG 1684 schedule, is the only approved adjuvant treatment for stage III melanoma patients by the FDA and EMEA. However, the risk/benefit profile has been questioned limiting its world-wide use. In the late nineties, the Italian Melanoma Inter-group started a spontaneous randomized clinical trial (RCT) to verify if a more intense, but shorter than the ECOG 1684 regimen, could improve survival without increasing the toxicity profile. The safety analysis in the first 169 patients who completed the treatment is here described. METHODS: Stage III melanoma patients were randomized to receive IFNalfa-2b 20 MU/m(2)/d intravenously (IV) 5 days/week × 4 weeks, repeated for three times on weeks 9 to 12, 17 to 20, 25 to 28 (Dose-Dense/Dose-Intense, DD/DI, arm), or IFNalfa-2b 20 MU/m(2)/d IV 5 days/week × 4 weeks followed by 10 MU/m(2 )subcutaneously (SC) three times per week × 48 weeks (High Dose Interferon, HDI, arm). Toxicity was recorded and graded, according to the WHO criteria, as the worst grade that occurred during each cycle. RESULTS: The most common toxicities in both arms were flu-like and gastrointestinal symptoms, leukopenia, liver and neuro-psichiatric morbidities; with regard to severe toxicity, only leukopenia was statistically more frequent in DD/DI arm than in HDI arm (24% vs 9%) (p = 0.0074), yet, this did not cause an increase in the infection risk. Discontinuation of treatment, due to toxicity, was observed in 13 and 17% of the patients in the DD/DI and HDI arm, respectively. The median actual dose intensity delivered in the DD/DI arm (36.4 MU/m(2)/week) was statistically higher than that delivered in the HDI arm (30.7 MU/m(2)/week) (p = 0.003). CONCLUSION: Four cycles of intravenous high-dose IFNalfa-2b can be safely delivered with an increase in the median dose intensity. Efficacy results from this trial are eagerly awaited

Defining the Critical Hurdles in Cancer Immunotherapy

ABSTRACT: Scientific discoveries that provide strong evidence of antitumor effects in preclinical models often encounter significant delays before being tested in patients with cancer. While some of these delays have a scientific basis, others do not. We need to do better. Innovative strategies need to move into early stage clinical trials as quickly as it is safe, and if successful, these therapies should efficiently obtain regulatory approval and widespread clinical application. In late 2009 and 2010 the Society for Immunotherapy of Cancer (SITC), convened an "Immunotherapy Summit" with representatives from immunotherapy organizations representing Europe, Japan, China and North America to discuss collaborations to improve development and delivery of cancer immunotherapy. One of the concepts raised by SITC and defined as critical by all parties was the need to identify hurdles that impede effective translation of cancer immunotherapy. With consensus on these hurdles, international working groups could be developed to make recommendations vetted by the participating organizations. These recommendations could then be considered by regulatory bodies, governmental and private funding agencies, pharmaceutical companies and academic institutions to facilitate changes necessary to accelerate clinical translation of novel immune-based cancer therapies. The critical hurdles identified by representatives of the collaborating organizations, now organized as the World Immunotherapy Council, are presented and discussed in this report. Some of the identified hurdles impede all investigators, others hinder investigators only in certain regions or institutions or are more relevant to specific types of immunotherapy or first-in-humans studies. Each of these hurdles can significantly delay clinical translation of promising advances in immunotherapy yet be overcome to improve outcomes of patients with cancer

Defining the critical hurdles in cancer immunotherapy

Scientific discoveries that provide strong evidence of antitumor effects in preclinical models often encounter significant delays before being tested in patients with cancer. While some of these delays have a scientific basis, others do not. We need to do better. Innovative strategies need to move into early stage clinical trials as quickly as it is safe, and if successful, these therapies should efficiently obtain regulatory approval and widespread clinical application. In late 2009 and 2010 the Society for Immunotherapy of Cancer (SITC), convened an "Immunotherapy Summit" with representatives from immunotherapy organizations representing Europe, Japan, China and North America to discuss collaborations to improve development and delivery of cancer immunotherapy. One of the concepts raised by SITC and defined as critical by all parties was the need to identify hurdles that impede effective translation of cancer immunotherapy. With consensus on these hurdles, international working groups could be developed to make recommendations vetted by the participating organizations. These recommendations could then be considered by regulatory bodies, governmental and private funding agencies, pharmaceutical companies and academic institutions to facilitate changes necessary to accelerate clinical translation of novel immune-based cancer therapies. The critical hurdles identified by representatives of the collaborating organizations, now organized as the World Immunotherapy Council, are presented and discussed in this report. Some of the identified hurdles impede all investigators; others hinder investigators only in certain regions or institutions or are more relevant to specific types of immunotherapy or first-in-humans studies. Each of these hurdles can significantly delay clinical translation of promising advances in immunotherapy yet if overcome, have the potential to improve outcomes of patients with cancer

Cancer immunoediting and dioxin-activating aryl hydrocarbon receptor: a missing link in the shift toward tumor immunoescape?

The aryl hydrocarbon receptor (AhR), a member of the PAS protein family, is found in organisms as diverse as Drosophila melano­gaster, nematodes, and mammals. While several reviews have reported that AhR, once activated by agonist ligands, causes long-term effects such as modification of cell growth through cell cycle control, there is also recent evidence of its decisive role in immunosuppression. The most widely studied AhR agonist is 2,3,7,8-tetrachlorodibenzo-p-dioxin, which binds AhR with the highest known affinity, leading to profound suppression of both humoral and cellular immune responses, with praecox thymus involution, consequent thymocyte loss, and induction of T-cell apoptosis. Dioxin-AhR binding causes a decline in the number of dendritic cells and enhances apoptosis following their inappropriate activation. Dioxin-mediated activation of AhR also has a direct influence on the expansion of regula­tory T-cells CD4+CD25+ FoxP3+ (T-regs) and an adverse affect on CD8+ T-cell responses. Dioxin released from industrial and waste incinerators over the last few decades has caused widespread contamination of food, leading to its accumulation in fatty tissue in animals and humans. The elimination half-life of dioxin in humans (7-10 years) may favor the potentially continuous and long-lasting activation of AhR, leading to perpetual immune suppression and facilitating the onset, growth, and diffusion of tumors, especially in young people. In the cancer immunoediting hypoth­esis, which subdivides the relationship between tumor and immune system into three phases: elimination, equilibrium, and escape, it is thought that dioxin accumulation may cause an inevitable shift toward tumor escape