Efficacy and safety of scheduled early endoscopic ultrasonography-guided ethanol reinjection for patients with pancreatic neuroendocrine tumors: Prospective pilot study

Portuguese Pancreatic Club Perspectives on Endoscopic Ultrasound-Guided and Surgical Treatment of Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors (panNETs) are a group of neoplasms with heterogenous biological and clinical phenotypes. Although historically regarded as rare, the incidence of these tumors has been increasing, mostly owing to improvements in the detection of small, asymptomatic tumors with imaging. The heterogeneity of these lesions creates significant challenges regarding diagnosis, staging, and treatment. Endoscopic ultrasound (EUS) has improved the characterization of pancreatic lesions. Furthermore, EUS nowadays has evolved from a purely diagnostic modality to allow the performance of minimally invasive locoregional therapy for pancreatic focal lesions. The choice of treatment as well as the treatment goals depend on several factors, including tumor secretory status, grading, staging, and patient performance status. Surgery has been the mainstay for the management of these patients, particularly for localized, low-grade, large panNETs >2 cm. Over the last decade, a significant body of evidence has been accumulated evaluating the role of EUS for the ablative therapy of panNETs, namely by the use of chemoablative agents and radiofrequency. Although endoscopic techniques are not routinely recommended by international guidelines, they may be considered for the treatment of smaller lesions in patients who are unwilling or unfit for pancreatic surgery. In this review, we summarize the existing evidence on the interventional techniques for the treatment of patients with panNETs, focusing on the EUS-guided and surgical approaches.

Endoscopic Management of Gastro-Entero-Pancreatic Neuroendocrine Tumours: An Overview of Proposed Resection and Ablation Techniques

A literature search of MEDLINE/PUBMED was conducted with the aim to highlight current endoscopic management of localised gastro-entero-pancreatic NETs. Relevant articles were identified through a manual search, and reference lists were reviewed for additional articles. The results of the research have been displayed in a narrative fashion to illustrate the actual state-of-the-art of endoscopic techniques in the treatment of NETs. Localised NETs of the stomach, duodenum and rectum can benefit from advanced endoscopic resection techniques (e.g., modified endoscopic mucosal resection, endoscopic full thickness resection, endoscopic submucosal dissection) according to centre expertise. Radiofrequency thermal ablation can be proposed as an alternative to surgery in selected patients with localised pancreatic NETs.

EUS-guided interventional therapies for pancreatic diseases

Endoscopic ultrasound (EUS) is an integrated diagnostic technique merging endoscope and ultrasound to examine the digestive system. EUS has emerged as a primary diagnostic method for pancreatic diseases due to its distinctive benefits. Over the past four decades, EUS has undergone a transformation, shifting its role from primarily diagnostic to increasingly therapeutic. Additionally, in recent years, EUS has emerged as an increasingly prominent adjunctive or alternative approach to conventional surgical interventions. This review provides a comprehensive analysis of current technological approaches in the treatment of pancreatic diseases. The dynamic interplay with diverse therapeutic approaches has reinvigorated EUS and shaped its trajectory in the management of pancreatic diseases.

An Overview of Pancreatic Neuroendocrine Tumors and an Update on Endoscopic Techniques for Their Management

The growing importance of advanced endoscopy in the diagnosis and treatment of pancreatic neuroendocrine neoplasms (PanNETs) necessitates a comprehensive understanding of various biochemical markers, genetic testing methods, radiological techniques, and treatment approaches that encompass multiple disciplines within and beyond gastrointestinal oncology. This review aims to highlight key aspects of these topics, with a specific focus on emerging EUS-guided procedures for the management of PanNETs.

Endoscopic Ultrasound-Guided Local Ablative Therapies for the Treatment of Pancreatic Neuroendocrine Tumors and Cystic Lesions: A Review of the Current Literature

Since its emergence as a diagnostic modality in the 1980s, endoscopic ultrasound (EUS) has provided the clinician profound access to gastrointestinal organs to aid in the direct visualization, sampling, and subsequent identification of pancreatic pathology. In recent years, advancements in EUS as an interventional technique have promoted the use of local ablative therapies as a minimally invasive alternative to the surgical management of pancreatic neuroendocrine tumors (pNETs) and pancreatic cystic neoplasms (PCNs), especially for those deemed to be poor operative candidates. EUS-guided local therapies have demonstrated promising efficacy in addressing a spectrum of pancreatic neoplasms, while also balancing local adverse effects on healthy parenchyma. This article serves as a review of the current literature detailing the mechanisms, outcomes, complications, and limitations of EUS-guided local ablative therapies such as chemical ablation and radiofrequency ablation (RFA) for the treatment of pNETs and PCNs, as well as a discussion of future applications of EUS-guided techniques to address a broader scope of pancreatic pathology.

Comparison of EUS-guided ablation and surgical resection for nonfunctioning small pancreatic neuroendocrine tumors: a propensity score-matching study

BACKGROUND AND AIMS

Treatment strategies for small pancreatic neuroendocrine tumors (PNETs) <2 cm in size are still under debate. The feasibility and safety of EUS-guided ethanol ablation (EUS-EA) have been demonstrated. However, sample sizes in previous studies were small with no comparative studies on surgery. Therefore, we aimed to compare the safety and long-term outcomes of EUS-EA with those of surgery for the management of nonfunctioning small PNETs.

METHODS

We retrospectively reviewed patients with PNETs who were managed by EUS-EA (from 2011 to 2018) and surgery (from 2000 to 2018) at Asan Medical Center. Propensity score matching (PSM) was performed to increase comparability. The primary outcome was early and late major adverse events (Clavien-Dindo grade ≥III) after treatment. Secondary outcomes were 10-year overall (OS) and disease-specific survival (DSS) rates, length of hospital stay, and development of endocrine pancreatic insufficiency.

RESULTS

Of all patients, 97 and 188 patients were included in the EUS-EA and surgery groups, respectively. PSM created 89 matched pairs. EUS-EA was associated with a significantly lower rate of early major adverse events (0% vs 11.2%, P = .003). Late major adverse events occurred more frequently after surgery, with no significant difference between groups (3.4% vs 10.1%, P = .07). Both treatment modalities showed comparable 10-year OS and DSS rates. The length of hospital stay was significantly shorter in the EUS-EA group (4 days vs 14.1 days, P < .001), and endocrine pancreatic insufficiency was less common after EUS-EA than after surgery (33.3% vs 48.6%, P = .121).

CONCLUSIONS

EUS-EA had fewer adverse events and a shorter hospital stay with similar OS and DSS rates compared with surgery, suggesting that EUS-EA may be a preferred alternative to surgical resection in selected patients with nonfunctioning small PNETs.

Current status of the role of endoscopy in evaluation and management of gastrointestinal and pancreatic neuroendocrine tumors

The incidence of gastroenteropancreatic neuroendocrine tumors (GEP-NETs) has increased over the last several decades. In general, NETs are slow-growing neoplasms and the data on the natural history is still evolving. The availability and improved utilization of advanced imaging modalities have allowed the selection of cases suitable for endotherapy. In this regard, endoscopic ultrasound (EUS) has emerged as a central imaging modality to assess the depth of infiltration in gastroduodenal as well as rectal NETs. Enhanced EUS modalities, including contrast-enhanced EUS and EUS elastography, reliably differentiate pancreatic neuroendocrine tumors (PNETs) from adenocarcinomas and may enable prediction of aggressive PNETs. With recent developments in therapeutic endoscopy, a large proportion of GEP-NETs can be safely managed endoscopically. Endoscopic resection techniques, including endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD), allow the safe removal of gastroduodenal and rectal NETs. Recent data indicate that modified EMR techniques may be superior to conventional EMR with regard to histologically complete resection. Device-assisted endoscopic full thickness resection is emerging as a safe and effective technique for upper gastrointestinal as well as rectal NETs. In selected cases with PNETs, who are otherwise unfit for surgery, EUS-guided ablation is increasingly being recognized as a safe treatment option. This review focusses on evidence-based approaches to endoscopic evaluation and the management of GEP-NETs with special emphasis on recent advancements.

Endoscopic ablation therapy for the pancreatic neoplasms

Recently, endoscopic ultrasound (EUS)-guided ablation therapy has been reported as a less invasive therapy for patients with pancreatic neoplasms. Some ablation techniques, including injective ablation (using ethanol or other ablative agents), radiofrequency ablation (RFA), photodynamic therapy, and laser ablation, have been described in the literature. Among these, injective ablation and RFA are more frequently used for treating pancreatic neoplasms. Few studies have evaluated the effectiveness of EUS-guided ethanol ablation (EUS-EA) for potentially malignant solid neoplasms (neuroendocrine neoplasms or solid pseudopapillary neoplasms) and have reported a complete response (CR) rate of 60-80%. In addition, the CR rate after EUS-RFA for these lesions has been reported to be 55-100%, with no additional procedure-related adverse events (AEs). Regarding the amelioration of the symptoms of an insulinoma, the success rates of both the therapies were found to be excellent. Regarding complete tumor ablation, EUS-RFA appeared to be superior to EUS-EA. Although EUS-RFA has been reported as a safe treatment for pancreatic cancers, its effectiveness remains inadequate. Some studies have examined the effectiveness of EUS-guided injection ablation therapy for pancreatic cystic neoplasms (PCNs) and have reported CR rates that range from 35% to 79%. Alcohol-free chemotherapeutic agent ablation appears to be effective, with a low risk of AEs. However, studies on the effectiveness of EUS-RFA for PCNs are limited. In the future, EUS-guided ablation therapy could become a more widely used approach for potentially malignant and malignant pancreatic lesions.

Endoscopic ultrasound guided interventions in the management of pancreatic cancer

There has been a growing interest in developing endoscopic ultrasound (EUS)-guided interventions for pancreatic cancer, some of which have become standard of care. There are two main factors that drive these advancements to facilitate treatment of patients with pancreatic cancer, ranging from direct locoregional therapy to palliation of symptoms related to inoperable pancreatic cancer. Firstly, an upper EUS has the capability to access the entire pancreas–lesions in the pancreatic head and uncinate process can be accessed from the duodenum, and lesions in the pancreatic body and tail can be accessed from the stomach. Secondly, there has been a robust development of devices that allow through-the-needle interventions, such as placement of fiducial markers, brachytherapy, intratumoral injection, gastroenterostomy creation, and ablation. While these techniques are rapidly emerging, data from a multicenter randomized controlled trial for some procedures are awaited prior to their adoption in clinical settings.

EUS-guided radiofrequency and ethanol ablation for pancreatic neuroendocrine tumors: A systematic review and meta-analysis

EUS-guided radiofrequency ablation (RFA) and ethanol ablation (EA) for pancreatic neuroendocrine tumors (PNETs) have recently been reported with good outcomes. We performed a systematic review and meta-analysis to evaluate the comparative effectiveness and safety of EUS-RFA and EUS-EA in the treatment of PNETs. A comprehensive search of multiple databases (through October 2020) was performed to identify studies that reported outcomes of EUS-RFA and EUS-EA of PNETs. Outcomes assessed included clinical success, technical success, and adverse events (AEs). A total of 181 (100 EUS-RFA, 81 EUS-EA) patients (60.7 ± 9.2 years) with 204 (113 EUS-RFA, 91 EUS-EA) PNETs (mean size 15.1 ± 4.7 mm) were included from 20 studies. There was no significant difference in the rates of technical success (94.4% [95% confidence interval (CI): 88.5–97.3, I² = 0] vs. 96.7% [95% CI: 90.8–98.8, I² = 0]; P = 0.42), clinical success (85.2% (95% CI: 75.9–91.4, I² = 0) vs. 82.2% [95% CI: 68.2–90.8, I² = 10.1]; P = 0.65), and AEs (14.1% [95% CI: 7.1–26.3, I² = 0] vs. 11.5% [95% CI: 4.7–25.4, I² = 63.5]; P = 0.7) between EUS-RFA and EUS-EA, respectively. The most common AE was pancreatitis with the rate of 7.8% and 7.6% (P = 0.95) for EUS-RFA and EUS-EA, respectively. On meta-regression, the location of PNETs in head/neck of pancreas (P = 0.03) was a positive predictor of clinical success for EUS-RFA. EUS-RFA and EUS-EA have similar effectiveness and safety for PNETs ablation. Head/neck location of PNETs was a positive predictor for clinical success after EUS-RFA.

In situ vaccination using unique TLR9 ligand K3-SPG induces long-lasting systemic immune response and synergizes with systemic and local immunotherapy

Although checkpoint inhibitors (CPIs) have changed the paradigm of cancer therapy, low response rates and serious systemic adverse events remain challenging. In situ vaccine (ISV), intratumoral injection of immunomodulators that stimulate innate immunity at the tumor site, allows for the development of vaccines in patients themselves. K3-SPG, a second-generation nanoparticulate Toll-like receptor 9 (TLR9) ligand consisting of K-type CpG oligodeoxynucleotide (ODN) wrapped with SPG (schizophyllan), integrates the best of conventional CpG ODNs, making it an ideal cancer immunotherapy adjuvant. Focusing on clinical feasibility for pancreaticobiliary and gastrointestinal cancers, we investigated the antitumor activity of K3-SPG-ISV in preclinical models of pancreatic ductal adenocarcinoma (PDAC) and colorectal cancer (CRC). K3-SPG-ISV suppressed tumor growth more potently than K3-ISV or K3-SPG intravenous injections, prolonged survival, and enhanced the antitumor effect of CPIs. Notably, in PDAC model, K3-SPG-ISV alone induced systemic antitumor effect and immunological memory. ISV combination of K3-SPG and agonistic CD40 antibody further enhanced the antitumor effect. Our results imply that K3-SPG-based ISV can be applied as monotherapy or combined with CPIs to improve their response rate or, conversely, with CPI-free local immunotherapy to avoid CPI-related adverse events. In either strategy, the potency of K3-SPG-based ISV would provide the rationale for its clinical application to puncturable pancreaticobiliary and gastrointestinal malignancies.

Study protocol for endoscopic ultrasonography-guided ethanol injection therapy for patients with pancreatic neuroendocrine neoplasm: a multicentre prospective study

INTRODUCTION

The management of small pancreatic neuroendocrine neoplasms (PNENs) remains controversial. The standard treatment for PNENs is surgical resection; however, invasiveness of surgical procedure remains higher and the incidence of postoperative adverse events is still high. Recently, the efficacy and safety of endoscopic ultrasonography (EUS)-guided ethanol injection for small PNENs has been preliminarily demonstrated. Thus, a multicentre prospective study is being conducted to evaluate the efficacy and safety of EUS-guided ethanol injection therapy for small PNENs.

METHODS AND ANALYSIS

The major eligibility criteria are the presence of pathologically diagnosed grade (G) 1 tumour, a tumour size of ≤15 mm and non-functional PNEN or insulinoma. For treatment, we will use a 25-gauge needle and pure ethanol. Contrast-enhanced CT (CE-CT) will be performed on postoperative day 3-5, and if enhanced areas of the tumour are still apparent, an additional session is scheduled during the same hospitalisation period. We set the total amount of ethanol per session to 2 mL. To evaluate the efficacy and safety, CE-CT will be performed at 1 and 6 months after treatment. The primary endpoint is the percentage of subjects who achieved all of the following evaluated points. Efficacy will be evaluated based on the achievement of complete ablation (defined as no enhanced area within the tumour on CE-CT) at 1 and 6 months. Safety will be evaluated based on the avoidance of severe adverse events within 1 month after treatment, continuing severe pancreatic fistula at 1 month after treatment and the incidence and/or exacerbation of diabetes mellitus at 6 months after treatment.

ETHICS AND DISSEMINATION

This protocol has been approved by Okayama University Certified Review Board (approval number. CRB19-007). The results will be submitted to peer-reviewed journals and will be presented at international conferences.

TRIAL REGISTRATION NUMBER

jRCTs061200016.

EUS-guided ablation of pancreatic neoplasms

Ablative therapies for locoregional treatment of pancreatic neoplastic lesions developed over the last decade to be applied during surgery are now becoming also available to be utilized under endoscopic ultrasound (EUS) guidance. The advantage of this approach is clear because of the close proximity of the EUS transducer to the target lesion, coupled with developments of specifically designed ablation devices, making the procedure minimally invasive, and potentially sparing patients from the morbidity of this method when performed surgically. EUS-guided ablative techniques that have been applied to pancreatic neoplastic cysts, pancreatic functional and non-functional neuroendocrine neoplasms and pancreatic ductal adenocarcinoma include ethanol injection, radiofrequency ablation (RFA), a combination of bipolar RFA and cryoablation, laser therapy (LT) and photodynamic therapy (PDT). Up to now, most of these procedures have been applied to patients at high surgical risk or who refused surgery. However, more studies evaluating some of these treatments also in selected patients not at surgical risk are becoming available. These studies will pave the road to apply this therapeutic approach to a more extensive number of patients, alone or in association with other therapies, such as immunomodulating drugs. The present manuscript will critically review the available evidence in the field of EUS-guided local ablative treatment of solid and cystic pancreatic neoplasms.

Interventional endoscopic ultrasound for pancreatic neuroendocrine neoplasms

The proximity of the endoscopic ultrasound (EUS) transducer to the pancreas and the possibility to place needles or other accessories into a target located adjacent to the wall of the GI tract have encouraged researchers to develop various EUS-guided local treatments directed towards pancreatic neuroendocrine neoplasms (PanNENs). The use of pre-operative EUS-guided tattooing or fiducial marker placement to facilitate intraoperative tumor localization has proven effective in reducing operative time of laparoscopic surgeries. To reduce the mortality and morbidity rates of surgical resection, which is presently the mainstay treatment of PanNENs. EUS-guided loco-regional treatments, such as injection of alcohol and radiofrequency ablation have been proposed and results are hitherto promising. The present paper summarizes currently available data in the field of EUS-guided interventions to pancreatic neuroendocrine tumors, as well as possible future applications.