Therapeutic biliary stents: applications and opportunities

ABSTRACT

Introduction

Biliary stents are used to optimize ductal patency and enable bile flow in the management of obstruction or injury related to biliary tract tumors, strictures, stones, or leaks. Although direct therapeutic applications of biliary stents are less well developed, stents can be used to deliver drugs, radioisotopes, and photodynamic therapy.

Areas covered

This report provides an in-depth overview of the clinical indications, and therapeutic utility of biliary stents. Unique considerations for the design of biliary stents are described. The properties and functionalities of materials used for stents such as metal alloys, plastic polymers, or biodegradable materials are described, and opportunities for design of future stents are outlined. Current and potential applications of stents for therapeutic applications for biliary tract diseases are described.

Expert Opinion

Therapeutic biliary stents could be used to minimize inflammation, prevent stricture formation, reduce infections, or provide localized anti-cancer therapy for biliary tract cancers. Stents could be transformed into therapeutic platforms using advanced materials, 3D printing, nanotechnology, and artificial intelligence. Whilst clinical study and validation will be required for adoption, future advances in stent design and materials are expected to expand the use of therapeutic biliary stents for the treatment of biliary tract disorders.

KEYWORDS:

• Therapeutic biliary stents
• biliary stent design
• malignant biliary obstruction
• localized disease control
• Biliary strictures

Article highlights

• Biliary stents can be used not only to restore bile duct patency, but also to directly deliver therapeutic agents such as drugs, for the treatment of biliary tract diseases.

• The use of biliary stents as therapeutic devices for benign or malignat biliary tract disorders is under-utilized.

• Unique considerations for the design of biliary stents include the anatomy of the biliary tract, the composition and properties of bile, the dynamics of bile flow and the kinetics of degradation in bile.

• Drug-eluting biliary stents have shown promise in clinical studies for improving outcomes in malignant biliary obstruction compared to standard stents.

• Stents have been used to facilitate intrabiliary brachytherapy using iodine-125 seeds, or to enable photodynamic therapy, improving patency and survival in patients with malignant biliary obstruction.

• Emerging approaches to therapeutic biliary stent design include the use of 3D printing, nanoparticle coatings, and the incorporation of drugs or therapeutic agents directly into biodegradable stent materials.

Abbreviations

CI, confidence interval; cSEMS, covered self-expanding metal stents; DES, drug-eluting stent; EUS, endoscopic ultrasound; MBO, malignant biliary obstruction; MHS, malignant hilar stricture; MOJ, malignant obstructive jaundice; OR, odds ratio; pcSEMS, partially covered self-expanding metal stents; PS, plastic stents; PS, photosensitizer; SEMS, self-expanding metal stents; uSEMS, uncovered self-expanding metal stents.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Reviewers disclosure

Peer reviewers on this manuscript have no relevant financial relationships or otherwise to disclose.

Acknowledgments

Support for this study was provided by the James C and Sarah K Kennedy Deanship and Alfred D and Audrey M Petersen Professorship at Mayo Clinic to Dr. Tushar Patel. We are grateful for the contributions of all participants in the treatment trials reviewed and the members of the Patel Lab for their insights.

Additional information

Funding

This paper was not funded.