Bioresorbable drug-eluting scaffolds for treatment of vascular disease

ABSTRACT

Introduction: Theoretical advantages of fully bioresorbable scaffold (BRS) stem from transient vessel support without rigid caging. Therefore, it could reduce long-term adverse events associated with the presence of foreign materials.

Areas covered: This article will provide an overview of: drug-eluting BRS for various applications in the treatment of vascular disease; The mechanisms of active agent release from such scaffolds; currently available drug-eluting BRS and their future applications are also discussed.

Expert opinion: The current BRS have been developed in order to achieve optimal vascular patency while providing long-term safety. The clinical efficacy and safety of BRS in coronary treatment have been reported as equal to that of the current metallic drug eluting stents in simple lesions. The application of BRS can potentially be expanded to other vascular beds. The research in bioengineering for the appropriate materials should not only focus on biocompatibility but also should be tailored according to the sites of implantation, which may require different strength and supporting period. The ultimate goal in this field is to develop a biocompatible device that provides equivalent and complementary therapy to other devices, and is able to disappear when the mechanical support and drug delivery are no longer required.     

Chemoembolization and radioembolization

Chemoembolization and radioembolization are at the core of the treatment of patients with hepatocellular carcinoma who cannot receive potentially curative therapies such as transplantation, resection or percutaneous ablation. They differ in the mechanism of action (ischaemia and increase cytotoxic drug exposure for chemoembolization, internal irradiation for radioembolization) and may target different patient populations. Chemoembolization with cytotoxic drug-eluting beads is a more standardized although not necessarily more effective way of performing chemoembolization. Cytoreduction is achieved in most patients but complete tumor ablation may be achieved and lead to extended survival. Grade 1 level of evidence support the use of chemoembolization for the treatment of patients in the early and intermediate stages while grade 2 evidence supports the use of radioembolization for the treatment of patients in intermediate to advanced stages. Selecting the best candidates for both techniques is still a work in progress that ongoing clinical trials are trying to address.     

Drug-eluting stents to prevent stent thrombosis and restenosis

Although first-generation drug-eluting stents (DES) have significantly reduced the risk of in-stent restenosis, they have also increased the long-term risk of stent thrombosis. This safety concern directly triggered the development of new generation DES, with innovations in stent platforms, polymers, and anti-proliferative drugs. Stent platform materials have evolved from stainless steel to cobalt or platinum–chromium alloys with an improved strut design. Drug-carrying polymers have become biocompatible or biodegradable and even polymer-free DES were introduced. New limus-family drugs (such as everolimus, zotarolimus or biolimus) were adopted to enhance stent performances. As a result, these new DES demonstrated superior vascular healing responses on intracoronary imaging studies and lower stent thrombotic events in actual patients. Recently, fully-bioresorbable stents (scaffolds) have been introduced, and expanding their applications. In this article, the important concepts and clinical results of new generation DES and bioresorbable scaffolds are described.     

Meta-Analysis: Therapeutic Effect of Transcatheter Arterial Chemoembolization Combined With Compound Kushen Injection in Hepatocellular Carcinoma

Compound Kushen Injection (CKI) is Sophora Flavescens and Heterosmilacis Japonicae extract. Meta-analysis confirmed that CKI plus transcatheter arterial chemoembolization (TACE) is more superior to TACE alone for unresectable hepatocellular carcinoma (UHCC) patients.