The recent impressive clinical responses to antibody-based immunotherapy have prompted the identification of clinically relevant tumor antigens that can serve as targets in solid tumors. Among them, ...B7-H3, a member of the B7 ligand family, represents an attractive target for antibody-based immunotherapy, it is overexpressed on differentiated malignant cells and cancer-initiating cells, with limited heterogeneity, and high frequency (60% of 25,000 tumor samples) in many different cancer types, but has a limited expression at low level in normal tissues. In nonmalignant tissues, B7-H3 has a predominantly inhibitory role in adaptive immunity, suppressing T-cell activation and proliferation. In malignant tissues, B7-H3 inhibits tumor antigen-specific immune responses, leading to a protumorigenic effect. B7-H3 also has nonimmunologic protumorigenic functions, such as promoting migration and invasion, angiogenesis, chemoresistance, and endothelial-to-mesenchymal transition, as well as affecting tumor cell metabolism. As a result, B7-H3 expression in tumors is associated with poor prognosis. Although experimental B7-H3 silencing reduces cancer cell malignant potential, there has been limited emphasis on the development of B7-H3-blocking antibodies, most likely because the B7-H3 receptor remains unknown. Instead, many antibody-based strategies utilizing distinct effector mechanisms to target B7-H3-expressing cancer cells have been developed. These strategies have demonstrated potent antitumor activity and acceptable safety profiles in preclinical models. Ongoing clinical trials are assessing their safety and efficacy in patients. Identification of the B7-H3 receptor will improve our understanding of its role in tumor immunity, and will suggest rational strategies to develop blocking antibodies, which may enhance the therapeutic efficacy of tumor immunity.
Histopathologic examination reveals that most human tumors are associated with diverse immune cell infiltrates, but the roles of host reactions in disease pathogenesis and prognosis remain to be ...fully clarified. Recent investigations in genetically engineered murine tumor models have uncovered dual functions for immune responses during cancer development and progression. Alterations in tumor cell gene expression profiles and coding sequences may trigger the activation of cytotoxic lymphocytes, which act to restrain tumor growth. In contrast, persistent inflammatory reactions, which may be driven by infection, environmental toxins, or impaired immune regulation, create a microenvironment that fosters tumor cell growth, survival, invasion, and dissemination. The dynamic interplay of these competing responses appears to be a critical event in cancer pathogenesis, with tumor promotion and immune evasion proving dominant in clinically evident disease. Nonetheless, longitudinal studies of patient cohorts have demonstrated that particular histopathologic and genetic signatures of cytotoxic lymphocyte reactions provide important prognostic information. Here, we discuss the dual roles of immunity in cancer development, focusing on gastrointestinal malignancies, given the depth of recent insights into the mechanisms underlying these tumors.
Non-metastatic pancreatic adenocarcinoma (PDAC) is associated with a high rate of recurrence and lethality. In addition, less than half of all patients are able to complete systemic therapy after ...curative-intent pancreatectomy. With its well-known potential benefits, this report highlights the current prospective data relevant to the use of neoadjuvant systemic therapy in resectable PDAC. Recently, there have been numerous reports, many of which consist of long-awaited multi-intuitional trial data evaluating the use of neoadjuvant systemic chemotherapy in non-metastatic PDAC as well as the use of combination chemotherapy regimens in the adjuvant setting. Currently, recommended guidelines for neoadjuvant systemic therapy only exist for borderline-resectable and locally-advanced disease. Given the plethora of new data, there has been a shift in the paradigm of how resectable pancreatic cancer is treated at certain centers across the world. This review highlights the relevant available data from recent sentinel prospective trials and how they relate to the systemic treatment of resectable PDAC in the neoadjuvant setting.
Activation of cellular stress response pathways to maintain metabolic homeostasis is emerging as a critical growth and survival mechanism in many cancers. The pathogenesis of pancreatic ductal ...adenocarcinoma (PDA) requires high levels of autophagy, a conserved self-degradative process. However, the regulatory circuits that activate autophagy and reprogram PDA cell metabolism are unknown. Here we show that autophagy induction in PDA occurs as part of a broader transcriptional program that coordinates activation of lysosome biogenesis and function, and nutrient scavenging, mediated by the MiT/TFE family of transcription factors. In human PDA cells, the MiT/TFE proteins--MITF, TFE3 and TFEB--are decoupled from regulatory mechanisms that control their cytoplasmic retention. Increased nuclear import in turn drives the expression of a coherent network of genes that induce high levels of lysosomal catabolic function essential for PDA growth. Unbiased global metabolite profiling reveals that MiT/TFE-dependent autophagy-lysosome activation is specifically required to maintain intracellular amino acid pools. These results identify the MiT/TFE proteins as master regulators of metabolic reprogramming in pancreatic cancer and demonstrate that transcriptional activation of clearance pathways converging on the lysosome is a novel hallmark of aggressive malignancy.
Background The objective of this study was to identify trends in the diagnosis and treatment of cystic neoplasms of the pancreas using a retrospective review of patients from a surgical database at ...an academic referral center during a 33-year period. Methods Patient characteristics, including demographics, pathology, and survival, were analyzed over 5 time periods between 1978 and 2011. Results A total of 851 consecutive patients underwent resection for a cystic neoplasm of the pancreas during a 33-year period. Sixty-five percent of patients were female, and mean age was 60 years. The most common pathologic diagnoses were intraductal papillary mucinous neoplasm (38%), mucinous cystic neoplasm (23%), serous cystadenoma (16%), and cystic neuroendocrine neoplasm (7%). There was a stepwise increase in the number of resections across time periods (67 between 1978 and 1989; 376 between 2005 and 2011), with a parallel increase in the proportion of incidentally discovered lesions (22% to 50%). Diagnosis of intraductal papillary mucinous neoplasm was very uncommon in the first 2 time periods (before the first recognition of intraductal papillary mucinous neoplasm as a distinct entity) but predominated in the last 2 (41% and 49%), and cystic neuroendocrine neoplasms, which constituted 3% of the cystic neoplasms in the first time-period, now comprise more than 8% of pancreatic cystic neoplasms. The proportion of malignant neoplasms decreased over time (41% between 1978 and 1989; 12% between 2005 and 2011), reflecting probably the earlier diagnosis and treatment of premalignant neoplasms. Although operative mortality was minimal (4/849, 0.5%), the postoperative complication rate was 38%. Overall 5-year survival for all mucinous lesions was 87%. Conclusion Cystic neoplasms of the pancreas are being diagnosed and treated with increasing frequency. At present, most are incidentally discovered intraductal papillary mucinous neoplasms.
Circulating tumor cells (CTCs) are shed from primary tumors into the bloodstream, mediating the hematogenous spread of cancer to distant organs. To define their composition, we compared genome-wide ...expression profiles of CTCs with matched primary tumors in a mouse model of pancreatic cancer, isolating individual CTCs using epitope-independent microfluidic capture, followed by single-cell RNA sequencing. CTCs clustered separately from primary tumors and tumor-derived cell lines, showing low-proliferative signatures, enrichment for the stem-cell-associated gene Aldh1a2, biphenotypic expression of epithelial and mesenchymal markers, and expression of Igfbp5, a gene transcript enriched at the epithelial-stromal interface. Mouse as well as human pancreatic CTCs exhibit a very high expression of stromal-derived extracellular matrix (ECM) proteins, including SPARC, whose knockdown in cancer cells suppresses cell migration and invasiveness. The aberrant expression by CTCs of stromal ECM genes points to their contribution of microenvironmental signals for the spread of cancer to distant organs.
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•Pancreatic CTCs can be enriched with antigen-agnostic microfluidic technology•Single-cell RNA sequencing of pancreatic CTCs reveals three distinct CTC populations•Extracellular matrix genes are highly expressed in mouse and human CTCs•The extracellular matrix protein SPARC contributes to pancreatic tumor metastasis
Circulating tumor cells (CTCs) are enriched for the precursors of metastasis, but their composition has not been fully defined. Ting et al. have utilized a microfluidic device to perform single-cell RNA sequencing of pancreatic CTCs, identifying three distinct populations that suggest multiple paths in the metastatic cascade. Extracellular matrix gene expression in particular was highly enriched in CTCs, pointing to a contribution to distal spread of cancer.
Most pancreatic neuroendocrine tumors (PNETs) do not produce excess hormones and are therefore considered 'non-functional'
. As clinical behaviors vary widely and distant metastases are eventually ...lethal
, biological classifications might guide treatment. Using enhancer maps to infer gene regulatory programs, we find that non-functional PNETs fall into two major subtypes, with epigenomes and transcriptomes that partially resemble islet α- and β-cells. Transcription factors ARX and PDX1 specify these normal cells, respectively
, and 84% of 142 non-functional PNETs expressed one or the other factor, occasionally both. Among 103 cases, distant relapses occurred almost exclusively in patients with ARX
PDX1
tumors and, within this subtype, in cases with alternative lengthening of telomeres. These markedly different outcomes belied similar clinical presentations and histology and, in one cohort, occurred irrespective of MEN1 mutation. This robust molecular stratification provides insight into cell lineage correlates of non-functional PNETs, accurately predicts disease course and can inform postoperative clinical decisions.
The presence of growth-induced solid stresses in tumors has been suspected for some time, but these stresses were largely estimated using mathematical models. Solid stresses can deform the ...surrounding tissues and compress intratumoral lymphatic and blood vessels. Compression of lymphatic vessels elevates interstitial fluid pressure, whereas compression of blood vessels reduces blood flow. Reduced blood flow, in turn, leads to hypoxia, which promotes tumor progression, immunosuppression, inflammation, invasion, and metastasis and lowers the efficacy of chemo-, radio-, and immunotherapies. Thus, strategies designed to alleviate solid stress have the potential to improve cancer treatment. However, a lack of methods for measuring solid stress has hindered the development of solid stress-alleviating drugs. Here, we present a simple technique to estimate the growth-induced solid stress accumulated within animal and human tumors, and we show that this stress can be reduced by depleting cancer cells, fibroblasts, collagen, and/or hyaluronan, resulting in improved tumor perfusion. Furthermore, we show that therapeutic depletion of carcinoma-associated fibroblasts with an inhibitor of the sonic hedgehog pathway reduces solid stress, decompresses blood and lymphatic vessels, and increases perfusion. In addition to providing insights into the mechanopathology of tumors, our approach can serve as a rapid screen for stress-reducing and perfusion-enhancing drugs.
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