Pancreatic neuropathy and neuropathic pain--a comprehensive pathomorphological study of 546 cases

The Role of Surgical Management in Chronic Pancreatitis in Children: A Position Paper From the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition Pancreas Committee

OBJECTIVES

Chronic pancreatitis (CP) is rare in childhood but impactful because of its high disease burden. There is limited literature regarding the management of CP in children, specifically about the various surgical approaches. Herein, we summarize the current pediatric and adult literature and provide recommendations for the surgical management of CP in children.

METHODS

The literature review was performed to include the scope of the problem, indications for operation, conventional surgical options as well as total pancreatectomy with islet autotransplantation, and outcomes following operations for CP.

RESULTS

Surgery is indicated for children with debilitating CP who have failed maximal medical and endoscopic interventions. Surgical management must be tailored to the patient's unique needs, considering the anatomy and morphology of their disease. A conventional surgical approach (eg, drainage operation, partial resection, combination drainage-resection) may be considered in the presence of significant and uniform pancreatic duct dilation or an inflammatory head mass. Total pancreatectomy with islet autotransplantation is the best surgical option in patients with small duct disease. The presence of genetic risk factors often portends a suboptimal outcome following a conventional operation.

CONCLUSIONS

The morphology of disease and the presence of genetic risk factors must be considered while determining the optimal surgical approach for children with CP. Surgical outcomes for CP are variable and depend on the type of intervention. A multidisciplinary team approach is needed to assure that the best possible operation is selected for each patient, their recovery is optimized, and their immediate and long-term postoperative needs are well-met.

Opioid Prescription Is Associated With Increased Survival in Older Adult Patients With Pancreatic Cancer in the United States: A Propensity Score Analysis

PURPOSE

Few studies have assessed the interaction between pain treatment and mortality in pancreatic cancer. The aim of this study was to investigate the association between receipt of opioid prescriptions and survival in adults with pancreatic cancer.

METHODS

The SEER-Medicare linked database was used to identify patients diagnosed with late-stage pancreatic cancer between 2007 and 2015. Kaplan-Meier models were used to assess the association between opioid prescriptions in the year after cancer diagnosis and survival. Cox proportional hazard models were used to determine the association between opioid receipt and survival, adjusting for propensity score and other relevant confounders including cancer-directed therapies and palliative care referral.

RESULTS

A total of 5,770 older adults with pancreatic cancer were identified; 1,678 (29.1%) were prescribed opioids for at least 60 days. Median survival was increased in those with opioid prescriptions (6.0 months) compared with those without (4.0 months, P < .0001). After adjustment for confounders, opioid prescriptions were still associated with improved survival (hazard ratio 0.80; 95% CI, 0.75 to 0.86). On multivariable analysis, opioid prescriptions were associated with older age, female sex, residing in nonmetro areas, and treatment with celiac plexus neurolysis, chemotherapy, and radiation.

CONCLUSION

Receipt of opioid prescriptions is associated with longer survival in patients with pancreatic cancer. This may be due to the impact of cancer-related pain, although further studies are needed to better understand the interaction between pain management, cancer-directed therapies, and systemic factors, such as palliative care, availability of opioids, and clinical practice culture.

HGF/c-Met pathway facilitates the perineural invasion of pancreatic cancer by activating the mTOR/NGF axis

Perineural invasion (PNI) is a pathologic feature of pancreatic cancer and is associated with poor outcomes, metastasis, and recurrence in pancreatic cancer patients. However, the molecular mechanism of PNI remains unclear. The present study aimed to investigate the mechanism that HGF/c-Met pathway facilitates the PNI of pancreatic cancer. In this study, we confirmed that c-Met expression was correlated with PNI in pancreatic cancer tissues. Activating the HGF/c-Met signaling pathway potentiated the expression of nerve growth factor (NGF) to recruit nerves and promote the PNI. Activating the HGF/c-Met signaling pathway also enhanced the migration and invasion ability of cancer cells to facilitate cancer cells invading nerves. Mechanistically, HGF/c-Met signaling pathway can active the mTOR/NGF axis to promote the PNI of pancreatic cancer. Additionally, we found that knocking down c-Met expression inhibited cancer cell migration along the nerve, reduced the damage of the sciatic nerve caused by cancer cells and protected the function of the sciatic nerve in vivo. Taken together, our findings suggest a supportive mechanism of the HGF/c-Met signaling pathway in promoting PNI by activating the mTOR/NGF axis in pancreatic cancer. Blocking the HGF/c-Met signaling pathway may be an effective target for the treatment of PNI.

Sympathetic axonal sprouting induces changes in macrophage populations and protects against pancreatic cancer

Neuronal nerve processes in the tumor microenvironment were highlighted recently. However, the origin of intra-tumoral nerves remains poorly known, in part because of technical difficulties in tracing nerve fibers via conventional histological preparations. Here, we employ three-dimensional (3D) imaging of cleared tissues for a comprehensive analysis of sympathetic innervation in a murine model of pancreatic ductal adenocarcinoma (PDAC). Our results support two independent, but coexisting, mechanisms: passive engulfment of pre-existing sympathetic nerves within tumors plus an active, localized sprouting of axon terminals into non-neoplastic lesions and tumor periphery. Ablation of the innervating sympathetic nerves increases tumor growth and spread. This effect is explained by the observation that sympathectomy increases intratumoral CD163+ macrophage numbers, which contribute to the worse outcome. Altogether, our findings provide insights into the mechanisms by which the sympathetic nervous system exerts cancer-protective properties in a mouse model of PDAC.

Schwann Cells in Digestive System Disorders

Proper functioning of the digestive system is ensured by coordinated action of the central and peripheral nervous systems (PNS). Peripheral innervation of the digestive system can be viewed as intrinsic and extrinsic. The intrinsic portion is mainly composed of the neurons and glia of the enteric nervous system (ENS), while the extrinsic part is formed by sympathetic, parasympathetic, and sensory branches of the PNS. Glial cells are a crucial component of digestive tract innervation, and a great deal of research evidence highlights the important status of ENS glia in health and disease. In this review, we shift the focus a bit and discuss the functions of Schwann cells (SCs), the glial cells of the extrinsic innervation of the digestive system. For more context, we also provide information on the basic findings regarding the function of innervation in disorders of the digestive organs. We find diverse SC roles described particularly in the mouth, the pancreas, and the intestine. We note that most of the scientific evidence concerns the involvement of SCs in cancer progression and pain, but some research identifies stem cell functions and potential for regenerative medicine.

A qualitative investigation of the supportive care experiences of people living with pancreatic and oesophagogastric cancer

Background

Pancreatic and oesophagogastric (OG) cancers have a dismal prognosis and high symptom burden, with supportive care forming an integral component of the care provided to patients. This study aimed to explore the supportive care experiences of patients and caregivers living with pancreatic and OG cancers in order to identify perceived opportunities for improvement.

Methods

Semi-structured individual interviews were conducted with people living with pancreatic and OG cancers, and their caregivers, across Victoria, Australia during 2020. Interviews were thematically analysed to identify common themes.

Results

Forty-one participants were interviewed, including 30 patients and 11 caregivers. Three overarching themes, each with multiple sub-themes, were identified: (i) inadequate support for symptoms and issues across the cancer journey (ii) caregiver’s desire for greater support, and (iii) a multidisciplinary care team is the hallmark of a positive supportive care experience. Generally, those who had access to a cancer care coordinator and/or a palliative care team recounted more positive supportive care experiences.

Conclusion

Unmet needs are prevalent across the pancreatic and OG cancer journey, with supportive care provided to varying levels of satisfaction. Greater awareness of and access to high-quality multidisciplinary support services is greatly desired by both patients with pancreatic and OG cancer and their caregivers.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-022-07625-y.

Calcium Signalling in Breast Cancer Associated Bone Pain

Calcium (Ca²⁺) is involved as a signalling mediator in a broad variety of physiological processes. Some of the fastest responses in human body like neuronal action potential firing, to the slowest gene transcriptional regulation processes are controlled by pathways involving calcium signalling. Under pathological conditions these mechanisms are also involved in tumoral cells reprogramming, resulting in the altered expression of genes associated with cell proliferation, metastatisation and homing to the secondary metastatic site. On the other hand, calcium exerts a central function in nociception, from cues sensing in distal neurons, to signal modulation and interpretation in the central nervous system leading, in pathological conditions, to hyperalgesia, allodynia and pain chronicization. It is well known the relationship between cancer and pain when tumoral metastatic cells settle in the bones, especially in late breast cancer stage, where they alter the bone micro-environment leading to bone lesions and resulting in pain refractory to the conventional analgesic therapies. The purpose of this review is to address the Ca²⁺ signalling mechanisms involved in cancer cell metastatisation as well as the function of the same signalling tools in pain regulation and transmission. Finally, the possible interactions between these two cells types cohabiting the same Ca²⁺ rich environment will be further explored attempting to highlight new possible therapeutical targets.

Celiac Plexus Neurolysis Is Associated With Decreased Survival in Patients With Pancreatic Cancer: A Propensity Score Analysis

OBJECTIVE

The aim of this study was to investigate survival in patients who received celiac plexus neurolysis (CPN) compared with patients who received opioids.

METHODS

The Surveillance, Epidemiology and End Results-Medicare database was used to identify patients older than 65 years diagnosed with pancreatic cancer between 2007 and 2015. We used claims data to identify patients with a history of CPN and opioid use within 1 year of diagnosis, and other demographic, clinical, and treatment variables. Kaplan-Meier analyses and inverse propensity-weighted adjusted Cox proportional hazard ratios were used to evaluate survival.

RESULTS

We identified 648 patients who underwent CPN (19.0%) compared with 2769 patients who received opioids (81.0%). The median survival and interquartile range for patients who received CPN was 4.0 months (2.0-8.0 months) compared with 7.0 months (3.0-12.0 months) for opioid users (P < 0.0001). After adjusting for confounders and propensity score, the patients who received CPN showed worsened survival (hazard ratio, 1.69; 95% confidence interval, 1.59-1.79).

CONCLUSIONS

Pancreatic cancer patients who underwent CPN had decreased survival compared with opioid users. This suggests that opioid sparing methods to reduce pancreatic cancer pain may actually be harmful. Future prospective studies should investigate whether other opioid sparing therapies impact pancreatic cancer survival.

The impact of nutritional status on pancreatic cancer therapy

INTRODUCTION

Pancreatic Ductal Adenocarcinoma (PDAC) is an aggressive disease with poor outcomes. One of the reasons for the dismal prognosis resides in its impressive ability to alter the nutritional status of patients who develop malnutrition, cachexia, anorexia, and sarcopenia in most cases. The ideal way to measure such changes in PDAC patients, in order to readily identify them and avoid complications or discontinuations of treatment is a relatively unexplored area. In addition, most PDAC patients experience pancreatic exocrine insufficiency (PEI) that contributes to the complex puzzle of malnutrition and that can be treated with Pancreatic Enzyme Replacement Therapy (PERT).

AREAS COVERED

We review current knowledge on the impact of nutritional status on both surgical and medical treatments for PDAC, reporting available data on the causes of malnutrition, characteristics, and advantages of different tools to investigate nutritional status and possible strategies to improve patient outcomes.

EXPERT OPINION

All PDAC patients should receive a careful nutritional assessment at diagnosis, and this should be repeated alongside their treatment path. Screening tools and biochemical variables or scores are associated with prognosis, but bioimpedance vector analysis (BIVA) and radiological assessment of body composition seem more accurate in predicting clinical outcomes and postoperative complications.

Mini review: The role of sensory innervation to subchondral bone in osteoarthritis pain

Osteoarthritis pain is often thought of as a pain driven by nerves that innervate the soft tissues of the joint, but there is emerging evidence for a role for nerves that innervate the underlying bone. In this mini review we cite evidence that subchondral bone lesions are associated with pain in osteoarthritis. We explore recent studies that provide evidence that sensory neurons that innervate bone are nociceptors that signal pain and can be sensitized in osteoarthritis. Finally, we describe neuronal remodeling of sensory and sympathetic nerves in bone and discuss how these processes can contribute to osteoarthritis pain.

Pancreatic QST Differentiates Chronic Pancreatitis Patients into Distinct Pain Phenotypes Independent of Psychiatric Comorbidities

BACKGROUND & AIMS

Quantitative sensory testing (QST) has been previously used to study pain in chronic pancreatitis (CP) but included methods that are not suitable for clinical purposes. The aims of this study were to determine if pancreatic QST (P-QST) can differentiate patients into distinct pain phenotypes and to determine the association of these with their clinical pain and psychiatric comorbidities.

METHODS

A multicenter cross-sectional study was conducted where patients completed validated questionnaires assessing quality of life (QoL), depression and anxiety scores as well as clinical pain symptoms followed by P-QST which included a cold pressor test, repetitive pinprick stimuli and pressure stimulation of the upper abdominal (T10) and control dermatomes. P-QST categorized patients into pain phenotypes based on a previously established nomogram. QoL, clinical pain and psychiatric assessment scores were compared across these groups.

RESULTS

A total of 179 patients were enrolled with a mean age of 54.1±13.6 years among whom 59% were males and 42% had an alcoholic etiology. P-QST showed no hyperalgesia in 91 (51%), segmental hyperalgesia in 50 (28%) and widespread hyperalgesia in 38 (21%) patients. Patients with widespread hyperalgesia had significantly higher pain intensity scores (P = .03) and rates of constant pain (P = .002) as well as decreased QoL (P < .001) and physical functioning (P =.03) in comparison with the other two pain phenotypes. In contrast, psychiatric comorbidities were similar across all groups.

CONCLUSIONS

P-QST may serve as a novel unbiased pain assessment tool in CP as it categorizes patients into distinct pain phenotypes independent of their psychiatric comorbidities.

Evolving pancreatic cancer treatment: From diagnosis to healthcare management

The prognosis of pancreatic ductal adenocarcinoma is still the worst among solid tumors. In this review, a panel of experts addressed the main unanswered questions about the clinical management of this disease, with the aim of providing practical decision support for physicians. On the basis of the evidence available from the literature, the main topics concerning pancreatic cancer are discussed: the diagnosis, as the need for a pathological characterization and the role for germ-line and somatic molecular profiling; the therapeutic management of resectable disease, as the role of upfront surgery or neoadjuvant chemotherapy, the post-operative restaging and the optimal timing foradjuvant chemotherapy, the management of the borderline resectable and locally advanced disease; the metastatic disease and the role of surgery for the management of patients with isolated metastasis and the use of biomarkers of metastatic potential; the role of supportive care and the healthcare management of pancreatic ductal adenocarcinoma.

Eukaryotic initiation factor 2 signaling behind neural invasion linked with lymphatic and vascular invasion in pancreatic cancer

Perineural invasion (PNI) is a typical poor prognostic factor in pancreatic ductal adenocarcinoma (PDAC). The mechanisms linking PNI to poor prognosis remain unclear. This study aimed to clarify what changes occurred alongside PNI in PDAC. A 128-patient cohort undergoing surgery for early-stage PDAC was evaluated. Subdivided into two groups, according to pathological state, a pancreatic nerve invasion (ne) score of less than three (from none to moderate invasion) was designated as the low-grade ne group. The high-grade (marked invasion) ne group (74 cases, 57.8%) showed a higher incidence of lymphatic metastasis (P = 0.002), a higher incidence of early recurrence (P = 0.004), decreased RFS (P < 0.001), and decreased DSS (P < 0.001). The severity of lymphatic (r = 0.440, P = 0.042) and venous (r = 0.610, P = 0.002) invasions was positively correlated with the ne score. Tumors having abundant stroma often displayed severe ne. Proteomics identified eukaryotic initiation factor 2 (EIF2) signaling as the most significantly enriched pathway in high-grade ne PDAC. Additionally, EIF2 signaling-related ribosome proteins decreased according to severity. Results showed that PNI is linked with lymphatic and vascular invasion in early-stage PDAC. Furthermore, the dysregulation of proteostasis and ribosome biogenesis can yield a difference in PNI severity.

The role of extracorporeal shock wave lithotripsy in the treatment of chronic pancreatitis

Pain is the most frequent symptom in chronic pancreatitis (CP) and has an important impact on quality of life. One of its major pathophysiological mechanisms is ductal hypertension, caused by main pancreatic duct stones and/or strictures. In this article, we focus on extracorporeal shock wave lithotripsy (ESWL) as a treatment for main pancreatic duct stones, which have been reported in >50% of CP patients. ESWL uses acoustic pulses to generate compressive stress on the stones, resulting in their gradual fragmentation. In patients with radiopaque obstructive main pancreatic duct (MPD) stones larger than 5 mm, located in the pancreas head or body, ESWL improves ductal clearance, thereby relieving pain and improving quality of life. In case of insufficient ductal clearance or the presence of an MPD stricture, ESWL can be followed by endoscopic retrograde cholangiopancreatography (ERCP) to increase success rate. Alternatively, direct pancreaticoscopy with intracorporeal lithotripsy or surgery can be performed.

[Conservative or surgical treatment of chronic pancreatitis?]

The cardinal symptom of chronic pancreatitis is severe belt-like upper abdominal pain, which requires immediate and adequate treatment. Furthermore, advanced stage chronic pancreatitis is often associated with complications, such as pancreatic pseudocysts, pancreatic duct stones and stenosis as well as biliary stenosis. The various endoscopic and surgical treatment options for chronic pancreatitis patients have been controversially discussed for decades. The new German S3 guidelines on pancreatitis now clearly define the best treatment options depending on the indications for treatment. For the treatment of pain in chronic pancreatitis it has been known for a long time that a surgical intervention is superior to endoscopic intervention concerning long-term pain relief. The recently published ESCAPE study has further underlined this by showing that early surgical intervention was superior to a step-up approach with initial endoscopic treatment. For the treatment of pancreatic pain, an initial endoscopic treatment attempt is therefore justified for short-term pain relief but in the midterm and long term, surgical intervention is the treatment of choice. In contrast, pancreatic pseudocysts, solitary proximally situated pancreatic duct stones and benign biliary strictures (except in calcifying pancreatitis) can nowadays generally be managed endoscopically. For distal pancreatic duct stones and symptomatic pancreatic duct stenosis surgical treatment is again the method of choice. This review article discusses these indication-related procedures in detail and explains them in relation to the recently published S3 guidelines on pancreatitis of the German Society for Gastroenterology, Digestive and Metabolic Diseases (DGVS).

Perineural Invasion and Associated Pain Transmission in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) is one of the cancers with the highest incidence of perineural invasion (PNI), which often indicates a poor prognosis. Aggressive tumor cells invade nerves, causing neurogenic inflammation; the tumor microenvironment also induces nerves to undergo a series of structural and functional reprogramming. In turn, neurons and the surrounding glial cells promote the development of pancreatic cancer through autocrine and/or paracrine signaling. In addition, hyperalgesia in PDAC patients implies alterations of pain transmission in the peripheral and central nervous systems. Currently, the studies on this topic are relatively limited. This review will elaborate on the mechanisms of tumor-neural interactions and its possible relationship with pain from several aspects that have been focused on in recent years.

Roles of the nervous system in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC), with its extremely poor prognosis, presents a substantial health problem worldwide. Outcomes have improved thanks to progress in surgical technique, chemotherapy, pre-/postoperative management, and centralization of patient care to high-volume centers. However, our goals are yet to be met. Recently, exome sequencing using PDAC surgical specimens has demonstrated that the most frequently altered genes were the axon guidance genes, indicating involvement of the nervous system in PDAC carcinogenesis. Moreover, perineural invasion has been widely identified as one poor prognostic factor. The combination of innovative technologies and extensive clinician experience with the nervous system come together here to create a new treatment option. However, evidence has emerged that suggests that the relationship between cancer and nerves in PDAC, the underlying mechanism, is not fully understood. In an attempt to tackle this lethal cancer, this review summarizes the anatomy and physiology of the pancreas and discusses the role of the nervous system in the pathophysiology of PDAC.

The Roles of Magnetic Resonance-Guided Focused Ultrasound in Pain Relief in Patients With Bone Metastases: A Systemic Review and Meta-Analysis

Objective

Cancer pain, the most common skeleton-related event of bone metastases, significantly disturbs patients' life. MRI-guided focused ultrasound (MRgFUS) is a therapeutic option to relieve pain; however, its efficacy and safety have not been fully explored. Therefore, we aim to conduct a meta-analysis on studies reporting MRgFUS for patients with bone metastases.

Methods

Randomized controlled trials (RCT) and non-RCTs on MRgFUS treatment for patients with bone metastases were collected using PubMed, MEDLINE In-Process (US National Library of Medicine), National Institutes of Health (US National Library of Medicine), Embase (Elsevier), Web of Science, CINAHL, and the Cochrane Library between August 2007 and September 2019. Data on quantitative pain assessment before/after MRgFUS, response rate, and complication were extracted and analyzed.

Results

Fifteen eligible studies with 362 patients were selected in this meta-analysis. The average pain score was 6.74 (95% CI: 6.30-7.18) at baseline, 4.15 (95% CI: 3.31-4.99) at 0-1 week, 3.09 (95% CI: 2.46-3.72) at 1-5 weeks, and 2.28 (95% CI: 1.37-3.19) at 5-14 weeks. Compared with baseline, the pain improvement at 0-1 week was 2.54 (95% CI: 1.92-3.16, p < 0.01), at 1-5 weeks was 3.56 (95% CI: 3.11-4.02, p < 0.01), and at 5-14 weeks was 4.22 (95% CI: 3.68-4.76, p < 0.01). Change from baseline in OMEDD at 2 weeks after treatment was -15.11 (95% CI: -34.73, 4.50), at 1 month after treatment was -10.87 (95% CI: -26.32, 4.58), and at 3 months after treatment was -5.53 (95% CI: -20.44, 9.38). The overall CR rate was 0.36 (95% CI: 0.24-0.48), PR rate was 0.47 (95% CI: 0.36-0.58), and NR rate was 0.23 (95% CI: 0.13-0.34). Among 14 studies including 352 patients, 93 (26.4%) patients with minor complications and 5 (1.42%) patients with major complications were recorded.

Conclusion

This meta-analysis identifies MRgFUS as a reliable therapeutic option to relieve cancer pain for patients with metastatic bone tumors with controllable related complications.

Drug Repurposing, an Attractive Strategy in Pancreatic Cancer Treatment: Preclinical and Clinical Updates

Pancreatic cancer (PC) is one of the deadliest malignancies worldwide, since patients rarely display symptoms until an advanced and unresectable stage of the disease. Current chemotherapy options are unsatisfactory and there is an urgent need for more effective and less toxic drugs to improve the dismal PC therapy. Repurposing of non-oncology drugs in PC treatment represents a very promising therapeutic option and different compounds are currently being considered as candidates for repurposing in the treatment of this tumor. In this review, we provide an update on some of the most promising FDA-approved, non-oncology, repurposed drug candidates that show prominent clinical and preclinical data in pancreatic cancer. We also focus on proposed mechanisms of action and known molecular targets that they modulate in PC. Furthermore, we provide an explorative bioinformatic analysis, which suggests that some of the PC repurposed drug candidates have additional, unexplored, oncology-relevant targets. Finally, we discuss recent developments regarding the immunomodulatory role displayed by some of these drugs, which may expand their potential application in synergy with approved anticancer immunomodulatory agents that are mostly ineffective as single agents in PC.

Pancreatic Pain-Knowledge Gaps and Research Opportunities in Children and Adults: Summary of a National Institute of Diabetes and Digestive and Kidney Diseases Workshop

ABSTRACT

A workshop was sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases to focus on research gaps and opportunities in pancreatic pain. The event was held on July 21, 2021, and structured into 4 sessions: (1) pathophysiology; (2) biomarkers, mediators, and pharmacology of pain; (3) pain assessment; and (4) pain treatment challenges and opportunities. The current state of knowledge was reviewed; many knowledge gaps and research needs were identified that require further investigation. Common themes included the need to better understand the underlying mechanisms of pain in pancreatic diseases, the relationship of visceral neural pathways and central pain centers, the role of behavioral factors and disorders on the perception of pain, and differences in pain perception and processes in children when compared with adults. In addition, the role of genetic risk factors for pain and the mechanisms and role of placebos in pain treatment were discussed. Methods of pain assessment including quantitative sensory testing were examined, as well as the process of central sensitization of pain. Finally, newer approaches to pain management including cognitive behavioral therapy, nerve stimulation, experimental (nonopioid) drugs, and cannabinoid compounds were covered.

Cellular and molecular mechanisms of perineural invasion of pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignant disease with a unique tumor microenvironment surrounded by an interlaced network of cancer and noncancerous cells. Recent works have revealed that the dynamic interaction between cancer cells and neuronal cells leads to perineural invasion (PNI), a clinical pathological feature of PDAC. The formation and function of PNI are dually regulated by molecular (e.g., involving neurotrophins, cytokines, chemokines, and neurotransmitters), metabolic (e.g., serine metabolism), and cellular mechanisms (e.g., involving Schwann cells, stromal cells, T cells, and macrophages). Such integrated mechanisms of PNI not only support tumor development, growth, invasion, and metastasis but also mediate the formation of pain, all of which are closely related to poor disease prognosis in PDAC. This review details the modulation, signaling pathways, detection, and clinical relevance of PNI and highlights the opportunities for further exploration that may benefit PDAC patients.

A phase I study of the safety and activity of K-001 in patients with advanced pancreatic ductal adenocarcinoma

Background

Pancreatic ductal adenocarcinoma (PDAC) is a deadly disease that lack of effective therapeutic drugs. K-001 is an oral antitumor drug made from active ingredients of marine microorganisms. The current study aimed to evaluate safety and antitumor activity of K-001 in patients with advanced PDAC.

Methods

In this phase I, open-label trial, patients with advanced PDAC were recruited to a dose-escalation study in a standard 3 + 3 design. K-001 was administered twice daily in four-week cycles, and dose escalation from 1350 mg to 2160 mg was evaluated twice daily. Physical examination and laboratory tests were done at screening and then weekly. The safety, dose-limiting toxicity (DLT), and maximum tolerated dose (MTD) of K-001 were assessed while tumor response was estimated by Response Evaluation Criteria in Solid Tumor (RECIST).

Results

Eighteen patients with advanced PDAC were screened, and twelve eligible patients were analyzed in the study. No DLT was observed. Totally, 47 adverse events (AEs) presented, and 14 drug-related AEs were reported in 7 patients, including 8 grade 1 events (57.1%) and 6 grade 2 events (42.9%). There was no grade 3 or 4 drug-related AE. In these 14 drug-related AEs, the most frequent ones were dyspepsia (21.4%), followed by flatulence, constipation, and hemorrhoid bleeding (above 10% of each). Among all 12 patients, 10 patients (83.3%) maintained stable disease (SD), and 2 patients (16.7%) had progressive disease (PD). The objective response rate (ORR) was 0% and the disease control rate (DCR) was 83.3%.

Conclusions

K-001 manifests satisfactory safety and tolerability, as well as meaningful antitumor activity in advanced PDAC patients. Further evaluation of K-001 in phase II/III appears warranted.

Trial registration

NCT02720666. Registered 28 Match 2016 - Retrospectively registered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08375-6.

Pancreas Cancer-Associated Pain Management

Pain is highly prevalent in patients with pancreas cancer and contributes to the morbidity of the disease. Pain may be due to pancreatic enzyme insufficiency, obstruction, and/or a direct mass effect on nerves in the celiac plexus. Proper supportive care to decrease pain is an important aspect of the overall management of these patients. There are limited data specific to the management of pain caused by pancreatic cancer. Here we review the literature and offer recommendations regarding multiple modalities available to treat pain in these patients. The dissemination and adoption of these best supportive care practices can improve quantity and quality of life for patients with pancreatic cancer. IMPLICATIONS FOR PRACTICE: Pain management is important to improve the quality of life and survival of a patient with cancer. The pathophysiology of pain in pancreas cancer is complex and multifactorial. Despite tumor response to chemotherapy, a sizeable percentage of patients are at risk for ongoing cancer-related pain and its comorbid consequences. Accordingly, the management of pain in patients with pancreas cancer can be challenging and often requires a multifaceted approach.

Morphologic Factors Predict Pain Relief Following Pancreatic Head Resection in Chronic Pancreatitis Description of the Chronic Pancreatitis Pain Relief (CPPR) Score

OBJECTIVE

This study analyzes the clinicopathologic findings and their impact on outcome of patients so as to identify which patients benefit most from surgical treatment in chronic pancreatitis, especially in regard to pain relief.

SUMMARY BACKGROUND DATA

The predominant symptom of chronic pancreatitis is chronic pain resulting in reduced quality of life. It is well known that the main reason for development of the disease is abuse of alcohol and nicotine, but only little data on factors influencing outcome are available.

METHODS

One thousand one hundred forty-six consecutive patients who underwent surgery for chronic pancreatitis were included. Clinicopathologic data, including morphology of the pancreas in preoperative diagnostics and the histopathologic results, were evaluated. A long-term follow-up including Quality of Life and pain scores was performed. Additionally, we describe the novel Chronic Pancreatitis Pain Relief Score (CPPR-Score) as a tool for prediction of pain relief.

RESULTS

Overall the rate of pain relief was 79.8% after surgery. The presence of an inflammatory mass in the pancreatic head larger than 4 cm (P < 0.001), presence of a dilated main pancreatic duct of over 4 mm (P < 0.001), histopathologically detected severe calcifications (P = 0.001) and severe fibrosis (P < 0.001) as well as ethanol induced disease (P < 0.001) found to be strong independent prognostic factors for pain relief. The CPPR-Score (0-5 points) proved to be a very good predictive score for pain-relief (P < 0.001).

CONCLUSIONS

The rate of pain relief after surgical treatment in chronic pancreatitis is high and the commonly used procedures can be performed with acceptable morbidity and mortality. The Chronic Pancreatitis Pain Relief Score allows identifying patients who will benefit most from surgery.

Tumor innervation and clinical outcome in pancreatic cancer

Pancreatic cancer is a highly aggressive malignancy characterized by poor survival, recurrence after surgery and resistance to therapy. Nerves infiltrate the microenvironment of pancreatic cancers and contribute to tumor progression, however the clinicopathological significance of tumor innervation is unclear. In this study, the presence of nerves and their cross-sectional size were quantified by immunohistochemistry for the neuronal markers S-100, PGP9.5 and GAP-43 in a series of 99 pancreatic cancer cases versus 71 normal adjacent pancreatic tissues. A trend was observed between the presence of nerves in the tumor microenvironment of pancreatic cancer and worse overall patient survival (HR = 1.8, 95% CI 0.77-4.28, p = 0.08). The size of nerves, as measured by cross-sectional area, were significantly higher in pancreatic cancer than in the normal adjacent tissue (p = 0.002) and larger nerves were directly associated with worse patient survival (HR = 0.41, 95% CI 0.19-0.87, p = 0.04). In conclusion, this study suggests that the presence and size of nerves within the pancreatic cancer microenvironment are associated with tumor aggressiveness.

CD74 promotes perineural invasion of cancer cells and mediates neuroplasticity via the AKT/EGR-1/GDNF axis in pancreatic ductal adenocarcinoma

Perineural invasion (PNI) is a common feature of pancreatic ductal adenocarcinoma (PDAC) and is one of the important causes of local recurrence in resected pancreatic cancer, but the molecular mechanism remains largely unexplored. Here, we used immunohistochemistry staining to determine the expression of CD74. Then the in vivo PNI model, in vitro neuroplasticity assay, cell proliferation assay, wound healing and Transwell-based invasion assay were performed to examine the function of CD74 in pancreatic cancer cell lines. ChIP assay and Luciferase reporter assay were used to illustrate the mechanism underlying CD74 induced GDNF expression. We confirmed that the expression level of CD74 was an independent predictor of PNI and poor prognosis for PDAC. Moreover, we found that upregulation of CD74 on PDAC enhanced its migration and invasive capabilities and potentiated the secretion of neurotrophic factor GDNF to promote the neuroplasticity. Mechanistically, CD74 promoted GDNF production via the AKT/EGR-1/GDNF axis in PDAC. Taken together, our findings suggest a supportive role of CD74 in the PNI of PDAC, and deepen our understanding of how cancer cells promote neuroplasticity in the microenvironment of PDAC.

GPRC5A: An emerging prognostic biomarker for predicting malignancy of Pancreatic Cancer based on bioinformatics analysis

Background: Pancreatic cancer (PaCa) is a highly lethal malignancy. The treatment options for PaCa lack efficacy. The study aimed to explore the molecular biomarkers for predicting survival of PaCa and identify the potential carcinogenic mechanisms of the selected gene. Methods: Based on public databases of PaCa, differentially expressed genes (DEGs) were identified using Networkanalyst. Survival analyses were exerted on GEPIA. Oncomine and The Human Protein Atlas were used for verifying the expression on mRNA and protein levels. Enrichment analyses were generated on Metascape and gene set enrichment analysis (GSEA). Univariate analyses were performed to determine the clinical factors associated with the expression of GPRC5A. Results: GPRC5A was identified as the most valuable gene in predicting survival of PaCa patients. Patients with high expression of GPRC5A showed larger tumor size, higher TNM stages, higher tumor grade, and more positive resection margin. In mutant KRAS, TP53, CDKN2A and SMAD4 group, the expression of GPRC5A was higher than non-mutant group. Mechanistically, GPRC5A may promote metastasis of PaCa mainly via regulating epithelial-mesenchymal transition (EMT) and neuroactive ligand-receptor interaction. Conclusion: GPRC5A may act as an oncogene in the progression of PaCa and could be a prognostic biomarker in predicting survival of PaCa.

Combinatorial sympathetic and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) blockades inhibit the murine melanoma growth by targeting infiltrating T cells

Background

Failure of the proliferation and infiltration of tumor-specific T cells in tumor site has been considered as one of important reasons induce the inefficiencies of immune checkpoint therapies in advanced cancers. Therefore, we aimed to demonstrate how combinatorial sympathetic and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) blockade affects the tumor growth of melanoma-bearing mice and potential mechanisms.

Methods

Tumor growth was measured and the infiltrating immune cell populations were observed with flow cytometry in B16-F10 melanoma-bearing mice treated with combined sympathetic and immune checkpoint blockade, using anti-CTLA-4 antibodies. The expression of adrenergic receptors was investigated in human peripheral blood mononuclear cells and their subpopulations, and the proliferation of T cell subsets was detected when stimulated by norepinephrine and its antagonists.

Results

B16-F10 tumor growth was associated with infiltrating CD8⁺ T cells. Combinatorial sympathetic and CTLA-4 blockade inhibited tumor growth and enhanced CD8⁺ infiltration. Meanwhile, all β1, β2 and β3 adrenergic receptors were found to be expressed in human peripheral blood mononuclear cells, activated T cells, monocytes, and monocyte-induced dendritic cells. β2-adrenergic receptors were expressed in most CD4⁺ T cells with increased expression in activated CD8⁺ T cells. Moreover, norepinephrine was able to prevent CD4⁺ T cell proliferation and β2-adrenergic receptor antagonists could reverse the inhibition of CD4⁺, but not CD8⁺ cell proliferation.

Conclusions

We conclude that the combination of sympathetic and CTLA-4 inhibitors is more effective for inhibiting melanoma progression than a single treatment and might enhance the infiltration of T cells in the tumor site, offering a novel therapeutic approach for immune checkpoint targeting.

Nerve fibers in the tumor microenvironment in neurotropic cancer-pancreatic cancer and cholangiocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) and cholangiocarcinoma (CCA) are both deadly cancers and they share many biological features besides their close anatomical location. One of the main histological features is neurotropism, which results in frequent perineural invasion. The underlying mechanism of cancer cells favoring growth by and through the nerve fibers is not fully understood. In this review, we provide knowledge of these cancers with frequent perineural invasion. We discuss nerve fiber crosstalk with the main different components of the tumor microenvironment (TME), the immune cells, and the fibroblasts. Also, we discuss the crosstalk between the nerve fibers and the cancer. We highlight the shared signaling pathways of the mechanisms behind perineural invasion in PDAC and CCA. Hereby we have focussed on signaling neurotransmitters and neuropeptides which may be a target for future therapies. Furthermore, we have summarized retrospective results of the previous literature about nerve fibers in PDAC and CCA patients. We provide our point of view in the potential for nerve fibers to be used as powerful biomarker for prognosis, as a tool to stratify patients for therapy or as a target in a (combination) therapy. Taking the presence of nerves into account can potentially change the field of personalized care in these neurotropic cancers.

Symptom Management in Pancreatic Cancer

OPINION STATEMENT

Despite extensive research that has identified new risk factors, genetic mutations, and therapeutic options, pancreatic ductal adenocarcinoma continues to be a leading cause of cancer related death. Patients with pancreatic cancer, along with their clinicians, must balance realistic hope alongside a life-threatening diagnosis. As the search for treatments to reduce the morbidity and mortality continues, symptom management and quality of life remain the focus of our efforts. In addition to side effects of cancer-directed therapy, patients are at risk for malnutrition, pain, and fatigue. These factors are often overlooked in practice, so a multidisciplinary team is critical in optimizing the care of patients.

Indirect cholinergic activation slows down pancreatic cancer growth and tumor-associated inflammation

Background

Nerve-cancer interactions are increasingly recognized to be of paramount importance for the emergence and progression of pancreatic cancer (PCa). Here, we investigated the role of indirect cholinergic activation on PCa progression through inhibition of acetylcholinesterase (AChE) via clinically available AChE-inhibitors, i.e. physostigmine and pyridostigmine.

Methods

We applied immunohistochemistry, immunoblotting, MTT-viability, invasion, flow-cytometric-cell-cycle-assays, phospho-kinase arrays, multiplex ELISA and xenografted mice to assess the impact of AChE inhibition on PCa cell growth and invasiveness, and tumor-associated inflammation. Survival analyses were performed in a novel genetically-induced, surgically-resectable mouse model of PCa under adjuvant treatment with gemcitabine+/−physostigmine/pyridostigmine (n = 30 mice). Human PCa specimens (n = 39) were analyzed for the impact of cancer AChE expression on tumor stage and survival.

Results

We discovered a strong expression of AChE in cancer cells of human PCa specimens. Inhibition of this cancer-cell-intrinsic AChE via pyridostigmine and physostigmine, or administration of acetylcholine (ACh), diminished PCa cell viability and invasion in vitro and in vivo via suppression of pERK signaling, and reduced tumor-associated macrophage (TAM) infiltration and serum pro-inflammatory cytokine levels. In the novel genetically-induced, surgically-resectable PCa mouse model, adjuvant co-therapy with AChE blockers had no impact on survival. Accordingly, survival of resected PCa patients did not differ based on tumor AChE expression levels. Patients with higher-stage PCa also exhibited loss of the ACh-synthesizing enzyme, choline-acetyltransferase (ChAT), in their nerves.

Conclusion

For future clinical trials of PCa, direct cholinergic stimulation of the muscarinic signaling, rather than indirect activation via AChE blockade, may be a more effective strategy.

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.

Neurons Release Serine to Support mRNA Translation in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) tumors have a nutrient-poor, desmoplastic, and highly innervated tumor microenvironment. Although neurons can release stimulatory factors to accelerate PDAC tumorigenesis, the metabolic contribution of peripheral axons has not been explored. We found that peripheral axons release serine (Ser) to support the growth of exogenous Ser (exSer)-dependent PDAC cells during Ser/Gly (glycine) deprivation. Ser deprivation resulted in ribosomal stalling on two of the six Ser codons, TCC and TCT, and allowed the selective translation and secretion of nerve growth factor (NGF) by PDAC cells to promote tumor innervation. Consistent with this, exSer-dependent PDAC tumors grew slower and displayed enhanced innervation in mice on a Ser/Gly-free diet. Blockade of compensatory neuronal innervation using LOXO-101, a Trk-NGF inhibitor, further decreased PDAC tumor growth. Our data indicate that axonal-cancer metabolic crosstalk is a critical adaptation to support PDAC growth in nutrient poor environments.

Localisation analysis of nerves in the mouse pancreas reveals the sites of highest nerve density and nociceptive innervation

BACKGROUND

Neuropathy and neuro-inflammation drive the severe pain and disease progression in human chronic pancreatitis and pancreatic cancer. Mice, especially genetically induced-mouse models, have been increasingly utilized in mechanistic research on pancreatic neuropathy, but the normal "peripheral neurobiology" of the mouse pancreas has not yet been critically compared to human pancreas.

METHODS

We introduced a standardized tissue-harvesting technique that preserves the anatomic orientation of the mouse pancreas and allows complete sectioning in an anterior to posterior fashion. We applied immunohistochemistry and quantitative colorimetry of all nerves from the whole organ for studying pancreatic neuro-anatomy.

KEY RESULTS

Nerves in the mouse pancreas appeared as "clusters" of nerve trunks in contrast to singly distributed nerve trunks in the human pancreas. Nerve trunks in the mouse pancreas were exclusively found around intrapancreatic blood vessels, and around lymphoid structures. The majority of nerve trunks were located in the pancreatic head (0.15 ± 0.08% of tissue area) and the anterior/front surface of the corpus/body (0.17 ± 0.27%), thus significantly more than in the tail (0.02 ± 0.02%, P = .006). Nerves in the tail included a higher proportion of nociceptive fibers, but the absolute majority, ie, ca. 70%, of all nociceptive fibers, were localized in the head. Mice heterozygous for Bdnf knockout allele (Bdnf^+/- ) exhibited enrichment of nitrergic nerve fibers specifically in the head and corpus.

CONCLUSIONS & INFERENCES

Neuro-anatomy of the "mesenteric type" mouse pancreas is highly different from the "compact" human pancreas. Studies that aim at reproducing human pancreatic neuro-phenomena in mouse models should pay diligent attention to these anatomic differences.

Cancer-associated fibroblasts in therapeutic resistance of pancreatic cancer: Present situation, predicaments, and perspectives

Pancreatic cancer is highly lethal, and the most effective treatment is curative resection followed by chemotherapy. Unfortunately, chemoresistance is an extremely common occurrence, and novel treatment modalities, such as immunotherapy and molecular targeted therapy, have shown limited success in clinical practice. Pancreatic cancer is characterized by an abundant stromal compartment. Cancer-associated fibroblasts (CAFs) and the extracellular matrix they deposit account for a large portion of the pancreatic tumor stroma. CAFs interact directly and indirectly with pancreatic cancer cells and can compromise the effects of, and even promote tumorigenic responses to, various treatment approaches. To eliminate these adverse effects, CAFs depletion strategies were developed. Instead of the anticipated antitumor effects of CAFs depletion, more aggressive tumor phenotypes were occasionally observed. The failure of universal stromal depletion led to the investigation of CAFs heterogeneity that forms the foundation for stromal remodeling and normalization. This review analyzes the role of CAFs in therapeutic resistance of pancreatic cancer and discusses potential CAFs-targeting strategies basing on the diverse biological functions of CAFs, thus to improve the outcome of pancreatic cancer treatment.

Microenvironmental Determinants of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) belongs to the most lethal solid tumors in humans. A histological hallmark feature of PDAC is the pronounced tumor microenvironment (TME) that dynamically evolves during tumor progression. The TME consists of different non-neoplastic cells such as cancer-associated fibroblasts, immune cells, endothelial cells, and neurons. Furthermore, abundant extracellular matrix components such as collagen and hyaluronic acid as well as matricellular proteins create a highly dynamic and hypovascular TME with multiple biochemical and physical interactions among the various cellular and acellular components that promote tumor progression and therapeutic resistance. In recent years, intensive research efforts have resulted in a significantly improved understanding of the biology and pathophysiology of the TME in PDAC, and novel stroma-targeted approaches are emerging that may help to improve the devastating prognosis of PDAC patients. However, none of anti-stromal therapies has been approved in patients so far, and there is still a large discrepancy between multiple successful preclinical results and subsequent failure in clinical trials. Furthermore, recent findings suggest that parts of the TME may also possess tumor-restraining properties rendering tailored therapies even more challenging.

The quality of pain management in pancreatic cancer: A prospective multi-center study

BACKGROUND/OBJECTIVES

Pancreatic ductal adenocarcinoma (PDAC) is frequently associated with severe pain. Given the almost inevitably fatal nature of the disease, pain control is crucial. However, data on quality of pain management in PDAC is scarce.

METHODS

This is a multi-center, prospective study to evaluate the quality of pain management in PDAC. Insufficient pain treatment (undertreatment) was prevalent if there was an incongruence between the patients level of pain and the potency of analgesic drug therapy. Determinants of pain and undertreatment were identified using multivariable logistic regression.

RESULTS

139 patients with histologically confirmed PDAC were analyzed. The prevalence of pain was 63%, with approximately one third of the patients grading their pain as moderate to severe. Palliative stage (OR: 3.37, 95%CI: 1.23-9.21, p = 0.018) and localization of the primary tumor in the body or tail (OR: 2.57, 95%CI: 1.05-6.31, p = 0.039) were independent determinants of pain. Of those reporting pain, 60% were undertreated and in 89% pain interfered with activities and emotions. Age ≥ 70 years (OR: 3.20, 95%CI: 1.09-9.41, p = 0.035) was an independent predictor of undertreatment. Patients with longer-known PDAC ( ≥ 30 days) showed improved pain management compared to new cases (OR: 0.19, 95%CI: 0.05-0.81, p = 0.025). Treatment by gastroenterologists (OR: 0.22, 95%CI: 0.05-0.89, p = 0.034) was associated with less undertreatment.

CONCLUSIONS

The results show a high proportion of PDAC patients with pain, pain interference and undertreatment, whose characteristics could help to identify patients at risk in the future. Several changes in the management of cancer-related pain are necessary to overcome barriers to optimal treatment.

Chronic pancreatitis

Chronic pancreatitis is a multifactorial, fibroinflammatory syndrome in which repetitive episodes of pancreatic inflammation lead to extensive fibrotic tissue replacement, resulting in chronic pain, exocrine and endocrine pancreatic insufficiency, reduced quality of life, and a shorter life expectancy. The incidence and prevalence of chronic pancreatitis is rising and no curative treatment is available. Using novel diagnostic algorithms, definitive chronic pancreatitis can be diagnosed by imaging criteria alone, whereas probable chronic pancreatitis requires clinical features and imaging criteria. Criteria for the diagnosis of early chronic pancreatitis are still under discussion and need prospective validation in clinical trials. Cross-sectional imaging should be used first; endoscopic ultrasound is needed only when CT or MRI are inconclusive or to plan therapeutic interventions. Management of chronic pancreatitis requires an interdisciplinary approach including primary care practitioners, gastroenterologists, surgeons, radiologists, pain specialists, and nutritional therapists. Patients with chronic pancreatitis should be seen at least once a year and re-evaluated for causal risk factors, symptom control, and complications such as malnutrition, pancreatic exocrine insufficiency, and diabetes; refer to a specialised centre if symptoms are poorly controlled or there is risk of deterioration. Scoring systems to monitor disease progression have been developed and validated internationally. Interventional treatments for pain or cholestasis should be done by specialists only, and early discussion of treatment approaches should include all medical disciplines involved in care. Throughout this Seminar, we address research needs such as staging of pancreatitis, aspects of malnutrition and pain, and cancer surveillance, to help improve the care of patients.

CXCL10 and CCL21 Promote Migration of Pancreatic Cancer Cells Toward Sensory Neurons and Neural Remodeling in Tumors in Mice, Associated With Pain in Patients

BACKGROUND & AIMS

Pancreatic ductal adenocarcinoma (PDAC) is frequently accompanied by excruciating pain, which has been associated with attraction of cancer cells and their invasion of intrapancreatic sensory nerves. Neutralization of the chemokine CCL2 reduced cancer-associated pain in a clinical trial, but there have been no systematic analyses of the highly diverse chemokine families and their receptors in PDAC.

METHODS

We performed an open, unbiased RNA-interference screen of mammalian chemokines in co-cultures of mouse PDAC cells (K8484) and mouse peripheral sensory neurons, and confirmed findings in studies of DT8082 PDAC cells. We studied the effects of chemokines on migration of PDAC cell lines. Orthotopic tumors were grown from K8484 cells in mice, and mice were given injections of neutralizing antibodies against chemokines, antagonists, or control antibodies. We analyzed abdominal mechanical hypersensitivity and collected tumors and analyzed them by histology and immunohistochemistry to assess neural remodeling. We collected PDAC samples and information on pain levels from 74 patients undergoing resection and measured levels of CXCR3 and CCR7 by immunohistochemistry and immunoblotting.

RESULTS

Knockdown of 9 chemokines in DRG neurons significantly reduced migration of PDAC cells towards sensory neurons. Sensory neuron-derived CCL21 and CXCL10 promoted migration of PDAC cells via their receptors CCR7 and CXCR3, respectively, which were expressed by cells in orthotopic tumors and PDAC specimens from patients. Neutralization of CCL21 or CXCL10, or their receptors, in mice with orthotopic tumors significantly reduced nociceptive hypersensitivity and nerve fiber hypertrophy and improved behavioral parameters without affecting tumor infiltration by T cells or neutrophils. Increased levels of CXCR3 and CCR7 in human PDAC specimens were associated with increased frequency of cancer-associated pain, determined from patient questionnaires.

CONCLUSIONS

In an unbiased screen of chemokines, we identified CCL21 and CXCL10 as proteins that promote migration of pancreatic cancer cells toward sensory neurons. Inhibition of these chemokines or their receptors reduce hypersensitivity in mice with orthotopic tumors, and patients with PDACs with high levels of the chemokine receptors of CXCR3 and CCR7 had increased frequency of cancer-associated pain.

Clinically Actionable Strategies for Studying Neural Influences in Cancer

Neuro-glial activation is a recently identified hallmark of growing cancers. Targeting tumor hyperinnervation in preclinical and small clinical trials has yielded promising antitumor effects, highlighting the need of systematic analysis of neural influences in cancer (NIC). Here, we outline the strategies translating these findings from bench to the clinic.

Celiac Plexus Block After Stereotactic Body Radiotherapy Improves Pain Relief in Locally Advanced Pancreatic Cancer

Purpose

This study evaluated the analgesic effect of stereotactic body radiotherapy (SBRT) in combination with celiac plexus block (CPB), relative to SBRT alone, in locally advanced pancreatic cancer (LAPC) patients.

Patients and Methods

We reviewed medical records of all patients with LAPC, who received SBRT between 1 January 2017 to 31 August 2019 at our center. The average numeric rating scale (NRS) of ≥3 was used in all patients at admission. We recorded average and worst NRS in a 24-hour period, and daily narcotic doses before SBRT, followed by weekly for 1 month and monthly for 3 months.

Results

A total of 23 patients in the SBRT group and 12 under SBRT+CPB who met the inclusion criteria were enrolled. All patients in the SBRT+CPB group received CPB within 10 days after SBRT. Pain intensity and narcotic consumption were comparable in both groups at initial assessment. However, a significant decrease (P < 0.05) in average NRS was recorded in the SBRT+CPB group relative to SBRT at 2, 3 and 4 weeks after SBRT. A comparison of daily narcotic consumption with baseline values showed a significant decrease in the SBRT+CPB group at 3 and 4 weeks after SBRT (P < 0.05), while no significant differences were observed in the SBRT group.

Conclusion

CPB after SBRT appears to be an effective therapeutic option in patients with LAPC and warrants further evaluation with increased number of patients in prospective clinical trials.

A Novel Role of Interleukin 13 Receptor alpha2 in Perineural Invasion and its Association with Poor Prognosis of Patients with Pancreatic Ductal Adenocarcinoma

Perineural invasion (PNI) is one of the major pathological characteristics of pancreatic ductal adeno-carcinoma (PDAC), which is mediated by invading cancer cells into nerve cells. Herein, we identify the overexpression of Interleukin-13 Receptor alpha2 (IL-13Rα2) in the PNI from 236 PDAC samples by studying its expression at the protein levels by immunohistochemistry (IHC) and the RNA level by in situ hybridization (ISH). We observe that ≥75% samples overexpressed IL-13Rα2 by IHC and ISH in grade 2 and 3 tumors, while ≥64% stage II and III tumors overexpressed IL-13Rα2 (≥2+). Interestingly, ≥36 % peripancreatic neural plexus (PL) and ≥70% nerve endings (Ne) among PNI in PDAC samples showed higher levels of IL-13Rα2 (≥2+). IL-13Rα2 +ve PL and Ne subjects survived significantly less than IL-13Rα2 –ve subjects, suggesting that IL-13Rα2 may have a unique role as a biomarker of PNI-aggressiveness. Importantly, IL-13Rα2 may be a therapeutic target for intervention, which might not only prolong patient survival but also help alleviate pain attributed to perineural invasion. Our study uncovers a novel role of IL-13Rα2 in PNI as a key factor of the disease severity, thus revealing a therapeutically targetable option for PDAC and to facilitate PNI-associated pain management.

Pathogenesis and Treatment of Pancreatic Cancer Related Pain

Pancreatic cancer is often diagnosed due to the patient seeking medical attention for abdominal pain. It is among the most painful cancers, with pain severity strongly correlating with prognosis. Perineural invasion is a prominent feature of pancreatic cancer and often the first route of metastasis resulting in neuropathic pain. While surgical pain is present, it is generally short-lived; chemo- and radio-therapy associated side effect pain is often longer lasting and more difficult to manage. Treatment-induced mucositis in response to chemotherapy occurs throughout the GI tract resulting in infection-prone ulcers on the lip, buccal mucosa, palate or tongue. Cisplatin treatment is associated with axonal neuropathy in the dorsal root ganglion, although other large sensory fibers can be affected. Opioid-induced hyperalgesia can also emerge in patients. Along with traditional means to address pain, neurolytic celiac plexus block of afferent nociceptive fibers has been reported to be effective in 74% of patients. Moreover, as cancer treatments become more effective and result in improved survival, treatment-related side effects become more prevalent. Here, pancreatic cancer and treatment associated pain are reviewed along with current treatment strategies. Potential future therapeutic strategies to target the pathophysiology underlying pancreatic cancer and pain induction are also presented.

The Neural Regulation of Cancer

The nervous system is intimately involved in physiological processes from development and growth to tissue homeostasis and repair throughout the body. It logically follows that the nervous system has the potential to play analogous roles in the context of cancer. Progress toward understanding the crucial role of the nervous system in cancer has accelerated in recent years, but much remains to be learned. Here, we highlight rapidly evolving concepts in this burgeoning research space and consider next steps toward understanding and therapeutically targeting the neural regulation of cancer.

Tenascin C in the Tumor-Nerve Microenvironment Enhances Perineural Invasion and Correlates With Locoregional Recurrence in Pancreatic Ductal Adenocarcinoma

OBJECTIVES

Perineural invasion is common in pancreatic ductal adenocarcinoma (PDAC) and worsens the postoperative prognosis. Tenascin C (TNC), an extracellular matrix glycoprotein, modulates tumor progression. We evaluated the functional roles of TNC, especially in perineural invasion of PDAC.

METHODS

We examined immunohistochemical TNC expression in 78 resected PDAC specimens. The relationships between TNC expression and clinicopathological features were retrospectively analyzed. Interactions between cancer cells and nerves with TNC supplementation were investigated using an in vitro coculture model with PDAC cell line and mouse dorsal root ganglion (DRG).

RESULTS

Tenascin C expression was predominant in perineural sites at the invasive tumor front. High perineural TNC expression in 30 patients (38%) was associated with perineural invasion, pathological T stage ≥3, and postoperative locoregional recurrence. High TNC expression was independently associated with postoperative, poor recurrence-free survival by multivariate analysis. In the in vitro coculture model, a TNC-rich matrix enhanced both PDAC cell colony extensions toward nerves and DRG axonal outgrowth toward cancer cell colonies, whereas TNC did not affect axonal outgrowth or cancer cell proliferation in separately cultured DRG and PDAC cells.

CONCLUSIONS

Strong perineural TNC expression indicated poor prognosis with locoregional recurrence. The neurotropism of TNC-induced PDAC suggests that TNC is a potential PDAC therapeutic target.

Perineural Invasion Reprograms the Immune Microenvironment through Cholinergic Signaling in Pancreatic Ductal Adenocarcinoma

Perineural invasion is a common feature of pancreatic ductal adenocarcinoma (PDAC). Here, we investigated the effect of perineural invasion on the microenvironment and how this affects PDAC progression. Transcriptome expression profiles of PDAC tissues with different perineural invasion status were compared, and the intratumoral T-cell density and levels of neurotransmitters in these tissues were assessed. Perineural invasion was associated with impaired immune responses characterized by decreased CD8⁺ T and Th1 cells, and increased Th2 cells. Acetylcholine levels were elevated in severe perineural invasion. Acetylcholine impaired the ability of PDAC cells to recruit CD8⁺ T cells via HDAC1-mediated suppression of CCL5. Moreover, acetylcholine directly inhibited IFNγ production by CD8⁺ T cells in a dose-dependent manner and favored Th2 over Th1 differentiation. Furthermore, hyperactivation of cholinergic signaling enhanced tumor growth by suppressing the intratumoral T-cell response in an orthotopic PDAC model. Conversely, blocking perineural invasion with bilateral subdiaphragmatic vagotomy in tumor-bearing mice was associated with an increase in CD8⁺ T cells, an elevated Th1/Th2 ratio, and improved survival. In conclusion, perineural invasion-triggered cholinergic signaling favors tumor growth by promoting an immune-suppressive microenvironment characterized by impaired CD8⁺ T-cell infiltration and a reduced Th1/Th2 ratio. SIGNIFICANCE: These findings provide a promising therapeutic strategy to modulate the immunosuppressive microenvironment of pancreatic ductal adenocarcinoma with severe perineural invasion.