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Francis G Gabriel

Bio: Francis G Gabriel is an academic researcher from Queen Alexandra Hospital. The author has contributed to research in topics: Cisplatin & Chemosensitivity assay. The author has an hindex of 9, co-authored 15 publications receiving 424 citations.

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Journal ArticleDOI
TL;DR: This results indicate that tolerogenic DCs and suppressor T lymphocytes are present in melanoma at all stages of disease progression, and suggest that negative SLN contain immunosuppressive cells and cytokines, due to preconditioning by tolerogenicDCs migrating from the primary melanoma site to the SLN.
Abstract: Cutaneous melanoma is highly immunogenic, yet primary melanomas and metastases develop successfully in otherwise immunocompetent patients. To investigate the local immunosuppressive microenvironment, we examined the presence of suppressor T lymphocytes and tolerising dendritic cells (DCs), the expression of immunosuppressive cytokines (IL-10, TGFβ1 and TGFβ2) and the enzyme indoleamine 2,3-dioxygenase (IDO) using qRT–PCR and immunohistochemistry in primary skin melanomas, negative and positive sentinel lymph nodes (SLN), and lymph nodes with advanced metastases. Our results indicate that tolerogenic DCs and suppressor T lymphocytes are present in melanoma at all stages of disease progression. They express transforming growth factor β receptor 1 (TGFβR1), and are therefore susceptible to TGFβ1 and TGFβ2 specifically expressed by primary melanoma. We found that expression of IDO and interleukin 10 (IL-10) increased with melanoma progression, with the highest concentration in positive SLN. We suggest that negative SLN contain immunosuppressive cells and cytokines, due to preconditioning by tolerogenic DCs migrating from the primary melanoma site to the SLN. In primary melanoma, TGFβ2 is likely to render peripheral DCs tolerogenic, while in lymph nodes IDO and TGFβ1 may have a major effect. This mechanism of tumour-associated immunosuppression may inhibit the immune response to the tumour and may explain the discrepancy between the induction of systemic immunity by anti-melanoma vaccines and their poor performance in the clinic.

133 citations

Journal ArticleDOI
TL;DR: It is suggested that up-regulation of resistance genes or down-regulation in target genes may occur rapidly in human solid tumors, within days of the start of treatment, and that similar changes are present in pre- and post-chemotherapy biopsy material.
Abstract: Tumor resistance to chemotherapy may be present at the beginning of treatment, develop during treatment, or become apparent on re-treatment of the patient. The mechanisms involved are usually inferred from experiments with cell lines, as studies in tumor-derived cells are difficult. Studies of human tumors show that cells adapt to chemotherapy, but it has been largely assumed that clonal selection leads to the resistance of recurrent tumors. Cells derived from 47 tumors of breast, ovarian, esophageal, and colorectal origin and 16 paired esophageal biopsies were exposed to anticancer agents (cisplatin; 5-fluorouracil; epirubicin; doxorubicin; paclitaxel; irinotecan and topotecan) in short-term cell culture (6 days). Real-time quantitative PCR was used to measure up- or down-regulation of 16 different resistance/target genes, and when tissue was available, immunohistochemistry was used to assess the protein levels. In 8/16 paired esophageal biopsies, there was an increase in the expression of multi-drug resistance gene 1 (MDR1) following epirubicin + cisplatin + 5-fluorouracil (ECF) chemotherapy and this was accompanied by increased expression of the MDR-1 encoded protein, P-gp. Following exposure to doxorubicin in vitro, 13/14 breast carcinomas and 9/12 ovarian carcinomas showed >2-fold down-regulation of topoisomerase IIα (TOPOIIα). Exposure to topotecan in vitro, resulted in >4-fold down-regulation of TOPOIIα in 6/7 colorectal tumors and 8/10 ovarian tumors. This study suggests that up-regulation of resistance genes or down-regulation in target genes may occur rapidly in human solid tumors, within days of the start of treatment, and that similar changes are present in pre- and post-chemotherapy biopsy material. The molecular processes used by each tumor appear to be linked to the drug used, but there is also heterogeneity between individual tumors, even those with the same histological type, in the pattern and magnitude of response to the same drugs. Adaptation to chemotherapy may explain why prediction of resistance mechanisms is difficult on the basis of tumor type alone or individual markers, and suggests that more complex predictive methods are required to improve the response rates to chemotherapy.

133 citations

Journal ArticleDOI
TL;DR: Genes predicted to be involved in known mechanisms drug sensitivity and resistance correlate well with in vitro chemosensitivity and may allow the definition of predictive signatures to guide individualized chemotherapy in lung cancer.
Abstract: Background: NSCLC exhibits considerable heterogeneity in its sensitivity to chemotherapy and similar heterogeneity is noted in vitro in a variety of model systems. This study has tested the hypothesis that the molecular basis of the observed in vitro chemosensitivity of NSCLC lies within the known resistance mechanisms inherent to these patients' tumors. Methods: The chemosensitivity of a series of 49 NSCLC tumors was assessed using the ATP-based tumor chemosensitivity assay (ATP-TCA) and compared with quantitative expression of resistance genes measured by RT-PCR in a Taqman Array™ following extraction of RNA from formalin-fixed paraffin-embedded (FFPE) tissue. Results: There was considerable heterogeneity between tumors within the ATP-TCA, and while this showed no direct correlation with individual gene expression, there was strong correlation of multi-gene signatures for many of the single agents and combinations tested. For instance, docetaxel activity showed some dependence on the expression of drug pumps, while cisplatin activity showed some dependence on DNA repair enzyme expression. Activity of both drugs was influenced more strongly still by the expression of anti- and pro-apoptotic genes by the tumor for both docetaxel and cisplatin. The doublet combinations of cisplatin with gemcitabine and cisplatin with docetaxel showed gene expression signatures incorporating resistance mechanisms for both agents. Conclusion: Genes predicted to be involved in known mechanisms drug sensitivity and resistance correlate well with in vitro chemosensitivity and may allow the definition of predictive signatures to guide individualized chemotherapy in lung cancer.

37 citations

Journal ArticleDOI
TL;DR: Intraoperative assessment of SLNs in breast cancer using a molecular assay is a safe, acceptable and accurate technique that allows a reduction in the frequency of delayed axillary clearance surgery.
Abstract: Background Accurate intraoperative sentinel lymph node (SLN) assessment enables axillary clearance to be completed immediately in node-positive breast cancer patients. This article reports a study of the introduction of intraoperative molecular SLN analysis in routine clinical practice in the Portsmouth Breast Care Centre. Design There was prospective analysis of 254 consecutive patients who underwent SLN biopsy in a single centre. Nodes were sectioned at 2 mm intervals and alternate slices were analysed using a CE-marked assay for mammaglobin (MG) and cytokeratin 19 (CK19). Remaining slices of node were sent for histological analysis, which included CK19 immunohistochemistry. While the assay was being carried out, the surgeon performed the breast tumour resection. The cost per patient was estimated retrospectively and the cost effects on the hospital and primary care trust for a typical service were also estimated. Results A total of 491 SLNs from 254 patients were evaluated. The intraoperative assay showed positivity of SLNs for metastatic cells in 78 patients. There was 100% detection of macrometastases within sentinel nodes analysed by GeneSearch. Overall concordance between histological status, including micrometastases and GeneSearch analysis, was 95% (sensitivity 96%, specificity 95%). The cost per procedure was increased for wide local excision with SLN biopsy and intraoperative assessment compared with other models, but fewer procedures were carried out. Conclusion Intraoperative assessment of SLNs in breast cancer using a molecular assay is a safe, acceptable and accurate technique that allows a reduction in the frequency of delayed axillary clearance surgery. Take-up of this method may be hampered by perverse incentives operating within healthcare funding.

36 citations

Journal ArticleDOI
TL;DR: Data suggest that melanoma chemosensitivity is influenced by known resistance mechanisms, including susceptibility to apoptosis, which may increase understanding of the mechanisms underlying chemos sensitivity to drugs active against melanoma and provide signatures with predictive value.
Abstract: Background Chemotherapy benefits relatively few patients with cutaneous melanoma. The assessment of tumour chemosensitivity by the ATP-based tumour chemosensitivity assay (ATP-TCA) has shown strong correlation with outcome in cutaneous melanoma, but requires fresh tissue and dedicated laboratory facilities. Aim To examine whether the results of the ATP-TCA correlate with the expression of genes known to be involved in resistance to chemotherapy, based on the hypothesis that the molecular basis of chemosensitivity lies within known drug resistance mechanisms. Method The chemosensitivity of 47 cutaneous melanomas was assessed using the ATP-TCA and correlated with quantitative expression of 93 resistance genes measured by quantitative reverse transcriptase PCR (qRT-PCR) in a Taqman Array after extraction of total RNA from formalin-fixed paraffin-embedded tissue. Results Drugs susceptible to particular resistance mechanisms showed good correlation with genes linked to these mechanisms using signatures of up to 17 genes. Comparison of these signatures for DTIC, treosulfan and cisplatin showed several genes in common. HSP70 , at least one human epidermal growth factor receptor, genes involved in apoptosis ( IAP2 , PTEN ) and DNA repair ( ERCC1 , XPA , XRCC1 , XRCC6 ) were present for these agents, as well as genes involved in the regulation of proliferation ( Ki67 , p21, p27). The combinations tested included genes represented in the single agent signatures. Conclusions These data suggest that melanoma chemosensitivity is influenced by known resistance mechanisms, including susceptibility to apoptosis. Use of a candidate gene approach may increase understanding of the mechanisms underlying chemosensitivity to drugs active against melanoma and provide signatures with predictive value.

27 citations


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TL;DR: This Review will explore how tumour-associated mutations detectable in the blood can be used in the clinic after diagnosis, including the assessment of prognosis, early detection of disease recurrence, and as surrogates for traditional biopsies with the purpose of predicting response to treatments and the development of acquired resistance.
Abstract: Cancer is associated with mutated genes, and analysis of tumour-linked genetic alterations is increasingly used for diagnostic, prognostic and treatment purposes. The genetic profile of solid tumours is currently obtained from surgical or biopsy specimens; however, the latter procedure cannot always be performed routinely owing to its invasive nature. Information acquired from a single biopsy provides a spatially and temporally limited snap-shot of a tumour and might fail to reflect its heterogeneity. Tumour cells release circulating free DNA (cfDNA) into the blood, but the majority of circulating DNA is often not of cancerous origin, and detection of cancer-associated alleles in the blood has long been impossible to achieve. Technological advances have overcome these restrictions, making it possible to identify both genetic and epigenetic aberrations. A liquid biopsy, or blood sample, can provide the genetic landscape of all cancerous lesions (primary and metastases) as well as offering the opportunity to systematically track genomic evolution. This Review will explore how tumour-associated mutations detectable in the blood can be used in the clinic after diagnosis, including the assessment of prognosis, early detection of disease recurrence, and as surrogates for traditional biopsies with the purpose of predicting response to treatments and the development of acquired resistance.

1,424 citations

Journal ArticleDOI
TL;DR: In lung cancer, flattening of dose-response curves at higher doses suggests that efficacy is limited by exhaustion of something required for cell killing, and several clinical observations suggest epigenetic events may play a major role in resistance.
Abstract: While cisplatin and carboplatin are active versus most common cancers, epithelial malignancies are incurable when metastatic. Even if an initial response occurs, acquired resistance due to mutations and epigenetic events limits efficacy. Resistance may be due to excess of a resistance factor, to saturation of factors required for tumor cell killing, or to mutation or alteration of a factor required for tumor cell killing. Platinum resistance could arise from decreased tumor blood flow, extracellular conditions, reduced platinum uptake, increased efflux, intracellular detoxification by glutathione, etc., decreased binding (e.g., due to high intracellular pH), DNA repair, decreased mismatch repair, defective apoptosis, antiapoptotic factors, effects of several signaling pathways, or presence of quiescent non-cycling cells. In lung cancer, flattening of dose-response curves at higher doses suggests that efficacy is limited by exhaustion of something required for cell killing, and several clinical observations suggest epigenetic events may play a major role in resistance.

579 citations

Journal ArticleDOI
TL;DR: Indoleamine 2,3-dioxygenase suppresses infiltration and accumulation of tumor-reactive T cells in the context of anti–CTLA-4 immunotherapy and attenuates the anti-tumor efficacy.
Abstract: The cytotoxic T lymphocyte antigen-4 (CTLA-4)–blocking antibody ipilimumab results in durable responses in metastatic melanoma, though therapeutic benefit has been limited to a fraction of patients. This calls for identification of resistance mechanisms and development of combinatorial strategies. Here, we examine the inhibitory role of indoleamine 2,3-dioxygenase (IDO) on the antitumor efficacy of CTLA-4 blockade. In IDO knockout mice treated with anti–CTLA-4 antibody, we demonstrate a striking delay in B16 melanoma tumor growth and increased overall survival when compared with wild-type mice. This was also observed with antibodies targeting PD-1–PD-L1 and GITR. To highlight the therapeutic relevance of these findings, we show that CTLA-4 blockade strongly synergizes with IDO inhibitors to mediate rejection of both IDO-expressing and nonexpressing poorly immunogenic tumors, emphasizing the importance of the inhibitory role of both tumor- and host-derived IDO. This effect was T cell dependent, leading to enhanced infiltration of tumor-specific effector T cells and a marked increase in the effector-to-regulatory T cell ratios in the tumors. Overall, these data demonstrate the immunosuppressive role of IDO in the context of immunotherapies targeting immune checkpoints and provide a strong incentive to clinically explore combination therapies using IDO inhibitors irrespective of IDO expression by the tumor cells.

563 citations

Journal ArticleDOI
TL;DR: Interleukin‐10 is a cytokine with broad anti‐inflammatory properties by its suppression of both macrophage and dendritic cell function, including antigen‐presenting cell function and the production of proinflammatory cytokines, which shows great potential as adjuvants in preventative or therapeutic vaccines against chronic infection or cancer.
Abstract: Summary: Interleukin-10 (IL-10) is a cytokine with broad anti-inflammatory properties by its suppression of both macrophage and dendritic cell function, including antigen-presenting cell function and the production of proinflammatory cytokines. This can result subsequently in the feedback regulation of both T-helper 1 (Th1)-type and Th2-type responses. This review discusses the potential use of IL-10 or agents that induce IL-10 as potential anti-inflammatory therapies in inflammatory diseases. Although IL-10-deficient mice develop colitis in the presence of normal gut flora and clear certain intracellular pathogens more efficiently, this is often accompanied by immunopathology, which can be lethal to the host. This reinforces the anti-inflammatory properties of IL-10, although it should be noted that as discussed below, IL-10 can also promote B-cell and other immune responses under particular settings. A penalty of its role to limit the immune and inflammatory responses to pathogens and prevent damage to the host is that high or dysregulated levels of IL-10 may result in chronic infection. Thus, antagonists of IL-10 show great potential as adjuvants in preventative or therapeutic vaccines against chronic infection or cancer. This article reviews basic published studies on IL-10, which may lead to potential uses of IL-10 or its antagonists in human disease.

423 citations

Journal ArticleDOI
TL;DR: In this article, the authors reviewed several studies that correlate IDO expression in human cancer samples and tumor-draining lymph nodes, with relevant clinical or immunologic parameters, and concluded that increased IDOexpression correlates with diverse tumor progression parameters and shorter patient survival.
Abstract: Indoleamine 2,3-dioxygenase (IDO) is a tryptophan-catabolizing enzyme with immune-regulating activities in many contexts, such as fetal protection, allograft protection, and cancer progression. Clinical trials are currently evaluating IDO inhibition with 1-methyltryptophan in cancer immunotherapy. However, the exact role of tryptophan catabolism by IDO in human cancers remains poorly understood. Here, we review several studies that correlate IDO expression in human cancer samples and tumor-draining lymph nodes, with relevant clinical or immunologic parameters. IDO expression in various histologic cancer types seems to decrease tumor infiltration of immune cells and to increase the proportion of regulatory T lymphocytes in the infiltrate. The impact of IDO on different immune cell infiltration leads to the conclusion that IDO negatively regulates the recruitment of antitumor immune cells. In addition, increased IDO expression correlates with diverse tumor progression parameters and shorter patient survival. In summary, in the vast majority of the reported studies, IDO expression is correlated with a less favorable prognosis. As we may see results from the first clinical trials with 1-methyltryptophan in years to come, this review brings together IDO studies from human studies and aims to help appreciate outcomes from current and future trials. Consequently, IDO inhibition seems a promising approach for cancer immunotherapy.

327 citations