Malignant distal biliary obstruction (MDBO) is a prevalent condition observed in individuals with unresectable pancreaticobiliary cancers or metastatic disease.¹ Both conventional insertion of a stent into the bile duct through endoscopic retrograde cholangiopancreatography (ERCP) and endoscopic ultrasound-guided biliary drainage (EUS-GBD) with metal stents are viable endoscopic alternatives. The DRA-MBO trial, which conducted by researchers from Department of Medicine and Therapeutics and Department of Surgery, Faculty of Medicine, the Chinese University of Hong Kong (CU Med), was first to introduce the new procedure, known as EUS-guided choledocho-duodenostomy (ECDS), in Hong Kong.¹ The study’s results reported consistent clinical outcomes between ECDS and ERCP.¹ Moreover, ECDS was associated with a significantly higher technical success rate and shorter procedural time.¹  

The European Society of Gastrointestinal Endoscopy (ESGE) had recommended ERCP and EUS-BD as the first and second options respectively for primary biliary drainage of MDBOs.² However, with the introduction of the lumen-apposing metal stent (LAMS) for ECDS, a previous prospective cohort study involving 19 patients had concluded that ECDS performed with LAMS contributed a total of 79% of patients experiencing improvements in obstructive jaundice within 7 days and a technical success rate of 95% with no incidence of procedure-related adverse events (AEs).³ Hence, the question of whether ECDS could replace ERCP as the standard option for primary biliary drainage was placed into the limelight.¹

The DRA-MBO trial, a double-blinded, multicenter, randomized controlled trial conducted by CU Med, was commenced to compare the treatment outcomes of ECDS and ERCP in primary biliary drainage for patients with unresectable MDBO.¹ A total of 165 adult patients with a bilirubin level of >50μmol/L at diagnosis and radiologically confirmed common bile duct (CBD) obstruction with dilated CBD of ≥12mm in diameter were recruited between 2017 and 2021 and randomized to either receive ECDS with LAMS (n=83) or ERCP with partially covered self-expanding metal stent (CSEMS) (n=82).¹ Patients were then followed up monthly post-operation for 1 year or until clinical symptoms arose.¹ At the end of the study, only 79 patients in the ECDS cohort and 76 patients in the ERCP cohort were included for analysis, with the remaining patients being lost to follow-up or excluded due to receiving neoadjuvant chemotherapy.¹

The primary endpoint of this study was 1-year stent patency rate of the ECDS and ERCP cohorts, where stent dysfunction was defined by the diagnosis of jaundice or cholangitis, with radiological or endoscopically confirmed stent occlusion.¹ Overall, the 1-year stent patency rates of the ECDS and ERCP cohorts were 91.1% and 88.1% respectively, with no significant differences observed (p=0.52).¹ Across the two cohorts, tumor overgrowth was the dominant cause of stent dysfunction.¹ Despite the portion of patients with tumor overgrowth in the ERCP cohort was almost 3-fold of that of the ECDS cohort (9.2 vs. 3.8%), no statistical significance was reached (p=0.21).¹

In terms of secondary endpoints, which involved technical success rate (i.e., accessibility and drainage of CBD), clinical success rate (i.e., >30% drop in bilirubin level within 5 days), incidence of AEs, time to stent dysfunction, reintervention rate and overall survival (OS) of the two cohorts, the clinical outcomes of the ECDS cohort were akin to that of the ERCP cohort.¹ No statistical significance was observed in clinical success rate (93.7% vs. 90.7%; p=0.56), 1-year reintervention rate (p=0.48), 30-day AEs (p=1), 30-day mortality (p=0.53) and OS (p=0.44).¹

Conversely, the ECDS cohort exhibited significantly higher technical success rates (96.2% vs. 76.3%, p<0.001) and shorter median procedural time (10 vs. 25 minutes; p<0.001) compared to the ERCP cohort.¹ These differences may originate from the malignancy-induced edema and friability of the duodenum or the distortion of the ampulla caused by duodenum narrowing or tumor infiltration, elevating the difficulty of performing ERCP.¹  

In summary, the DRA-BMO trial demonstrated the comparable treatment outcomes of ECDS and ERCP, reaffirming ECDS’s advantages in accessibility over ERCP.¹ Hence, ECDS could serve as an alternative option for primary biliary drainage if difficulties for ERCP were anticipated. Further evaluations on procedural cost and quality of life between both techniques are required for a more comprehensive assessment.¹