Regulatory T Cells in Pancreatic Cancer: Of Mice and Men.

Regulatory T cells (Treg) are one of the major immunosuppressive cell subsets in the pancreatic tumor microenvironment. Tregs influence tumor growth by acting either directly on cancer cells or via the inhibition of effector immune cells. Treg cells mechanisms form a partially redundant network with other immunosuppressive cells such as myeloid-derived suppressor cells (MDSC) that confer robustness to tumor immunosuppression and resistance to immunotherapy. The results obtained in preclinical studies where after Treg depletion, MDSCs concomitantly decreased in early tumors whereas an inverse association was seen in advanced PCa, urge a comprehensive analysis of the immunosuppressive profile of PCa throughout tumorigenesis. One relevant context to analyse these complex compensatory mechanisms may be the tumors of patients who underwent neoTx. Here, we observed a parallel decrease in the numbers of both intratumoral Tregs and MDSC after neoTx even in locally advanced PCa. NeoTx also led to decreased amounts of αSMA+ myofibroblastic cancer-associated fibroblasts (myCAF) and increased proportions of CD8+ cytotoxic T lymphocytes in the tumor. In order to understand these dynamics and to uncover stage-specific actional strategies involving Tregs, pre-clinical models that allow the administration of neoTx to different stages of PCa may be a very useful platform.

Molecular Profiling in Pancreatic Cancer: Current Role and Its Impact on Primary Surgery.

Background: The advent of next-generation sequencing technologies has enabled the identification of molecular subtypes of pancreatic ductal adenocarcinoma (PDAC) with different biological traits and clinically targetable features. Summary: Although current chemotherapy trials are currently exploiting this knowledge, these molecular subtypes have not yet sufficiently caught the attention of surgeons. In fact, integration of these molecular subtypes into the timing of surgery can in theory improve patient outcome. Here, we present the molecular subtypes of PDAC from the surgeon's perspective and a clinically applicable algorithm that integrates the molecular subtyping of PDAC preoperatively into the decision of primary surgery versus neoadjuvant therapy. Furthermore, we point out the potential of "tailored" (in addition to conventional) neoadjuvant treatment for exploiting the molecular subtypes of PDAC. Key Messages: We believe that for surgeons, the preoperative knowledge on the subtype of PDAC can properly guide in deciding between upfront surgery versus neoadjuvant treatment for improving patient outcome.

Innervated mouse pancreas organoids as an ex vivo model to study pancreatic neuropathy in pancreatic cancer.

Pancreatic cancer is characterized by bi-directional interactions between pancreatic cancer cells and stromal cells including neural cells. The absence of neural cells in pancreatic organoids limits the investigation of cell- cell interaction and tumor innervation. This protocol describes how to generate innervated wild type (WT) and Kras+/LSLG12D Trp53fl/f lp48+/Cre (KPC) murine pancreatic organoids. To specifically investigate neurogenesis, organoids are co-cultured with iPSCs-derived neural crest cells, while co-culture with dorsal root ganglia explants is used for comparing organoids with mature neurons. For complete details on the use and execution of this protocol, please refer to Huch et al. (2013), Boj et al. (2015), and Demir et al. (2014).

Future directions in preclinical and translational cancer neuroscience research.

Recent advances in cancer neuroscience necessitate the systematic analysis of neural influences in cancer as potential therapeutic targets in oncology. Here, we outline recommendations for future preclinical and translational research in this field.

Future directions of neoadjuvant therapy in pancreatic cancer.

Neoadjuvant therapy with conventional chemotherapies have visibly improved the prognosis of locally advanced pancreatic cancer (PCa). However, molecular targeted therapies that have provided durable responses in other tumor entities, have not yet found access into neoadjuvant therapy of PCa. In fact, due to the presence of the tumor burden serving as an antigen source for T cell priming, neoadjuvant chemotherapy may unleash a more potent antitumoral immune response than adjuvant or palliative chemotherapy.

Neoadjuvant therapy in pancreatic cancer: what is the true oncological benefit?

BACKGROUND: Neoadjuvant therapies (neoTx) have revolutionized the treatment of borderline resectable (BR) and locally advanced (LA) pancreatic cancer (PCa) by significantly increasing the rate of R0 resections, which remains the only curative strategy for these patients. However, there is still room for improvement of neoTx in PCa. PURPOSE: Here, we aimed to critically analyze the benefits of neoTx in LA and BR PCa and its potential use on patients with resectable PCa. We also explored the feasibility of arterial resection (AR) to increase surgical radicality and the incorporation of immunotherapy to optimize neoadjuvant approaches in PCa. CONCLUSION: For early stage, i.e., resectable, PCa, there is not enough scientific evidence for routinely recommending neoTx. For LA and BR PCa, optimization of neoadjuvant therapy necessitates more sophisticated complex surgical resections, machine learning and radiomic approaches, integration of immunotherapy due to the high antigen load, standardized histopathological assessment, and improved multidisciplinary communication.

Neoadjuvant Therapy Remodels the Pancreatic Cancer Microenvironment via Depletion of Protumorigenic Immune Cells.

PURPOSE: Neoadjuvant therapy (neoTx) has dramatically improved the prognosis of patients with locally advanced and borderline resectable pancreatic ductal adenocarcinoma, yet its mechanisms of action on tumor cells and the tumor microenvironment are still unknown. Here, we aimed to characterize the multiple facets of neoTx-induced alterations in the pancreatic cancer microenvironment. EXPERIMENTAL DESIGN: We performed the currently most comprehensive histopathologic analysis of desmoplasia, angiogenesis, neural invasion, and immune cell infiltration at the tumor-host interface of pancreatic cancer after neoTx (n = 37) versus after primary resection (n = 37) through quantitative IHC and double immunofluorescence using automated and software-based quantification algorithms. RESULTS: We demonstrate that, independently of the applied pretreatment, neoadjuvant regimes are able to reverse the immunosuppressive behavior of malignant cells on pancreatic cancer microenvironment. Here, neoTx-driven selective depletion of regulatory T cells and myeloid-derived suppressor cells was associated with enrichment of antitumor immune cells in the peritumoral niche, decreased stromal activation, and less neural invasion. Importantly, the degree of this antitumor immune remodeling correlates to the degree of histopathologic response to neoTx. Survival analysis revealed that the tumor proliferation rate together with the activation of the stroma and the intratumoral infiltration with CD4+ T cells and natural killer cells constitute as independent prognostic factors for neoadjuvantly treated pancreatic cancer. CONCLUSIONS: NeoTx is not only cytotoxic but has pleiotropic, beneficial effects on all cellular and noncellular components of pancreatic cancer. Combinational approaches including immunotherapy may unleash long-term and more effective antitumor responses and improve prognosis of pancreatic cancer.

Targeting nNOS ameliorates the severe neuropathic pain due to chronic pancreatitis.

BACKGROUND: Pain due to pancreatic cancer/PCa or chronic pancreatitis/CP, is notoriously resistant to the strongest pain medications. Here, we aimed at deciphering the specific molecular mediators of pain at surgical-stage pancreatic disease and to discover novel translational targets. METHODS: We performed a systematic, quantitative analysis of the neurotransmitter/neuroenzmye profile within intrapancreatic nerves of CP and PCa patients. Ex vivo neuronal cultures treated with human pancreatic extracts, conditional genetically engineered knockout mouse models of PCa and CP, and the cerulein-induced CP model were employed to explore the therapeutic potential of the identified targets. FINDINGS: We identified a unique enrichment of neuronal nitric-oxide-synthase (nNOS) in the pancreatic nerves of CP patients with increasing pain severity. Employment of ex vivo neuronal cultures treated with pancreatic tissue extracts of CP patients, and brain-derived-neurotrophic-factor-deficient (BDNF+/-) mice revealed neuronal enrichment of nNOS to be a consequence of BDNF loss in the progressively destroyed pancreatic tissue. Mechanistically, nNOS upregulation in sensory neurons was induced by tryptase secreted from perineural mast cells. In a head-to-head comparison of several genetically induced, painless mouse models of PCa (KPC, KC mice) or CP (Ptf1a-Cre;Atg5fl/fl) against the hypersecretion/cerulein-induced, painful CP mouse model, we show that a similar nNOS enrichment is present in the painful cerulein-CP model, but absent in painless genetic models. Consequently, mice afflicted with painful cerulein-induced CP could be significantly relieved upon treatment with the specific nNOS inhibitor NPLA. INTERPRETATION: We propose nNOS inhibition as a novel strategy to treat the unbearable pain in CP. FUND: Deutsche Forschungsgemeinschaft/DFG (DE2428/3-1 and 3-2).