Risk factors for adverse outcomes at various phases of endoscopic ultrasound-guided treatment of pancreatic fluid collections: Data from a multi-institutional consortium

WONDER-02: plastic stent vs. lumen-apposing metal stent for endoscopic ultrasound-guided drainage of pancreatic pseudocysts-study protocol for a multicentre randomised non-inferiority trial

BACKGROUND

Endoscopic ultrasound (EUS)-guided transluminal drainage has become a first-line treatment modality for symptomatic pancreatic pseudocysts. Despite the increasing popularity of lumen-apposing metal stents (LAMSs), plastic stents may resolve non-necrotic fluid collections effectively with lower costs and no LAMS-specific adverse events. To date, there has been a paucity of data on the appropriate stent type in this setting. This trial aims to assess the non-inferiority of plastic stents to a LAMS for the initial EUS-guided drainage of pseudocysts.

METHODS

The WONDER-02 trial is a multicentre, open-label, non-inferiority, randomised controlled trial, which will enrol pancreatic pseudocyst patients requiring EUS-guided treatment in 26 centres in Japan. This trial plans to enrol 80 patients who will be randomised at a 1:1 ratio to receive either plastic stents or a LAMS (40 patients per arm). In the plastic stent group, EUS-guided drainage will be performed using two 7-Fr double pigtail stents. In the LAMS group, the treatment will be performed in the same way except for LAMS use. The step-up treatment will be performed via endoscopic and/or percutaneous procedures at the trial investigator's discretion. The primary endpoint is clinical success, which is defined as a decrease in a pseudocyst size to ≤ 2 cm and an improvement in inflammatory indicators (i.e. body temperature, white blood cell count, and serum C-reactive protein). Secondary endpoints include technical success, adverse events including mortality, pseudocyst recurrence, and medical costs.

DISCUSSION

The WONDER-02 trial will investigate the efficacy and safety of plastic stents compared to a LAMS in EUS-guided treatment of symptomatic pancreatic pseudocysts with a particular focus on the non-inferior efficacy of plastic stents. The findings will help establish a new treatment algorithm for this population.

TRIAL REGISTRATION

ClinicalTrials.gov NCT06133023 registered on 9 November 2023. UMIN000052647 registered on 30 October 2023. jRCT1032230444 registered on 7 November 2023.

Controversies in endoscopic ultrasonography-guided management of walled-off necrosis

Walled-off necrosis (WON) develops as local complications after acute necrotizing pancreatitis. Although less invasive interventions such as endoscopic ultrasonography (EUS)-guided drainage and endoscopic necrosectomy are selected over surgical interventions, delayed and step-up interventions are still preferred to avoid procedure-related adverse events. However, there is a controversy about the appropriate timing of drainage and subsequent necrosectomy. The advent of large-caliber lumen-apposing metal stents has also brought about potential advantages of proactive interventions, which still needs investigation in future trials. When step-up interventions of necrosectomy and additional drainage are necessary, a structured or protocoled approach for WON has been reported to improve safety and effectiveness of endoscopic and/or percutaneous treatment, but has not been standardized yet. Finally, long-term outcomes such as recurrence of WON, pancreatic endocrine, and exocrine function are increasingly investigated in association with disconnected pancreatic duct syndrome. In this review we discuss current evidence and controversy on EUS-guided management of WON.