The use of biodegradable stents in malignant oesophageal strictures for the treatment of dysphagia before neoadjuvant treatment or radical radiotherapy: a feasibility study

Biodegradable PTX-PLGA-coated magnesium stent for benign esophageal stricture: An experimental study

Biodegradable stents can degrade step by step and thereby avoid secondary removal by endoscopic procedures in contrast to metal stents. Herein, a biodegradable composite stent, a magnesium (Mg)-based braided stent with a surface coating of poly (lactic-co-glycolic acid) (PLGA) containing paclitaxel (PTX), was designed and tested. By adding this drug-loaded polymer coating, the radial force of the stent increased from 33 Newton (N) to 83 N. PTX was continuously released as the stent degraded, and the in vitro cumulative drug release in phosphate-buffered saline for 28 days was 115 ± 13.5 μg/mL at pH = 7.4 and 176 ± 12 μg/mL at pH = 4.0. There was no statistically significant difference in the viability of fibroblasts of stent extracts with different concentration gradients (P > 0.05), while the PTX-loaded stents effectively promoted fibroblast apoptosis. In the animal experiment, the stents were able to maintain esophageal patency during the 3-week follow-up and to reduce the infiltration of inflammatory cells and the amount of fibrous tissue. These results showed that the PTX-PLGA-coated Mg stent has the potential to be a safe and effective approach for benign esophageal stricture. STATEMENT OF SIGNIFICANCE: We designed a biodegradable composite stent, having poly (lactic-co-glycolic acid) (PLGA) containing paclitaxel (PTX) coated the surface of the magnesium (Mg)-based braided stent. We evaluated in vitro and in vivo characteristics of the Mg esophageal stent having a PLGA coating plus a variable concentration of PTX in comparison with the absence of PTX PLGA coating. The PTX PLGA stents exerted higher radial force than stents without coating, degraded more quickly in an acid medium, and effectively promoted fibroblast apoptosis in vitro experiments. In a rabbit model of caustic-induced esophageal stricture, there was an increased lumen and decreased inflammation of the esophageal wall in the animals stented with PTX-PLGA versus the sham group, indicating a potential approach for benign esophageal stricture.

Futuristic Developments and Applications in Endoluminal Stenting

Endoscopic stenting is a well-established option for the treatment of malignant obstruction, temporary management of benign strictures, and sealing transmural defects, as well as drainage of pancreatic fluid collections and biliary obstruction. In recent years, in addition to expansion in indications for endoscopic stenting, considerable strides have been made in stent technology, and several types of devices with advanced designs and materials are continuously being developed. In this review, we discuss the important developments in stent designs and novel indications for endoluminal and transluminal stenting. Our discussion specifically focuses on (i) biodegradable as well as (ii) irradiating and drug-eluting stents for esophageal, gastroduodenal, biliary, and colonic indications, (iii) endoscopic stenting in inflammatory bowel disease, and (iv) lumen-apposing metal stent.

A Phase II Study of Biodegradable Stents Plus Palliative Radiotherapy in Oesophageal Cancer

AIMS

Self-expanding metal stents provide rapid improvement of dysphagia in oesophageal cancer but are associated with complications. The aim of the present study was to test the effectiveness of an alternative treatment of combining biodegradable stents with radiotherapy.

MATERIALS AND METHODS

A Simon two-stage single-arm prospective phase II trial design was used to determine the efficacy of biodegradable stents plus radiotherapy in patients with dysphagia caused by oesophagus cancer who were unsuitable for radical treatment. Fourteen patients were recruited and data from 12 were included in the final analyses.

RESULTS

Five of 12 patients met the primary end point: one stent-related patient death; four further interventions for dysphagia within 16 weeks of stenting (41.7%, 95% confidence interval 15.2-72.3%). The median time to a 10-point deterioration of quality of life was 2.7 weeks. Nine patients died within 52 weeks of registration. The median time to death from any cause was 15.0 weeks (95% confidence interval 9.6-not reached).

CONCLUSION

The high re-intervention observed, which met the pre-defined early stopping criteria, meant that the suggested alternative treatment was not sufficiently effective to be considered for a larger scale trial design. Further work is needed to define the place of biodegradable stents in the management of malignant oesophageal strictures.

Use of esophageal stents to relieve dysphagia during neoadjuvant therapy prior to esophageal resection: a systematic review

Esophageal cancer stenting offers symptomatic relief for patients suffering from dysphagia. There are limited data to support their use to relieve dysphagia and improve nutrition during neoadjuvant therapy with some concern that they may negatively impact oncological outcomes. The aim of this systematic review was to quantify the impact of esophageal stents on outcomes prior to resection with curative intent. A literature search was performed using Embase, Medline, PubMed, PubMed Central, the Cochrane library for articles pertaining to esophageal stent use prior to or during neoadjuvant chemotherapy or chemoradiotherapy in patients planned for curative esophagectomy. Data extracted included basic demographics, clinical, nutritional and oncologic outcomes. A total of 9 studies involving 465 patients were included. Esophageal stent use resulted in a significant improvement in mean dysphagia scores in the immediate post stent period but failed to demonstrate any positive changes in weight, body mass index (BMI) or albumin. Only 33% of stented patients ultimately progressed to potential curative surgical resection and stents were associated with reduced R0 resection rates and lower overall survival. This systematic review shows that, although esophageal stenting is associated with improvements in dysphagia during neoadjuvant therapy, their effect on improving patient nutritional status is less clear and they may be associated with poorer long-term oncological outcomes. Stents should be used with caution in patients who are being considered for potentially curative resection of esophageal malignancies and other strategies of nutritional supplementation should be considered.

A bridging stent to surgery in patients with esophageal and gastroesophageal junction cancer has a dramatic negative impact on patient survival: A retrospective cohort study through data acquired from a prospectively maintained national database

This study aimed to assess the impact of esophageal stenting on postoperative complications and survival in patients with obstructing esophageal and gastroesophageal junction (GEJ) cancer. All patients treated without neoadjuvant therapy that had an R0-resection performed for esophageal and GEJ cancer between January 2003 and December 2010 were identified from a prospectively maintained database. Data on stenting, postoperative mortality, morbidity, recurrence-free survival, complications, and length of hospital stay were collected. Kaplan-Meier plots for survival and recurrence-free survival curves were constructed for R0 resected patients. Data were compared between the stent and no-stent group by nonparametric tests. Two hundred seventy three consecutive R0 resected patients with esophageal or GEJ cancer were identified. Of these patients, 63 had a stent as a bridge to surgery. The male/female ratio was 2.64 (198/75) with a median age in the stent group (SG) of 65.1 versus 64.3 in the no stent group (NSG). Patients were comparable with respect to gender, age, smoking, TNM-classification, oncological treatment, hospital stay, tumor location, and histology. The median survival in the SG was 11.6 months compared with 21.3 months for patients treated without a bridging stent (P < 0.001). There were no statistically significant differences in 30-day mortality between the two groups, but NSG patients exhibited a significantly better two-year survival (P = 0.017). The median recurrence-free survival was 9.1 months for the SG compared with 15.2 months for the NSG. The use of a stent as a bridging procedure to surgery in patients treated without neaoadjuvant therapy for an esophageal or GEJ cancer that later underwent R0 resection decreased the two year survival and the recurrence-free survival.

Biodegradable esophageal stents in benign and malignant strictures - a single center experience

BACKGROUND AND STUDY AIMS

Biodegradable (BD) esophageal stents were recently developed mainly for refractory benign strictures, but experience and available literature are limited.

PATIENTS AND METHODS

This was a retrospective observational study. All patients who had BD stents inserted due to refractory benign esophageal strictures or malignant strictures, or were awaiting radical radiotherapy/chemotherapy or neo-adjuvant therapy and esophagectomy between March 2011 and July 2015 were included.

RESULTS

Stent placement was successful in all patients. Ten patients with benign strictures (3 male, median age 80.5 years, IQR: 68.75 - 89.5) were followed-up for a median of 171.5 weeks (IQR: 24 - 177.25). The interval between dilatations prior to the first BD stent placement (median: 34.25 days, IQR: 23.06 - 48.29) was significantly shorter than the interval between the first BD stent placement and the first intervention required (median: 149.5 days, IQR: 94.25 - 209.5) and this difference was statistically significant (P = 0.012). Ten patients with esophageal cancer (8 male, median age: 69 years, IQR: 59.25 - 80.75) were included and they were followed up for a median of 36 weeks (IQR: 26 - 58). Only 1 completed radical radiotherapy successfully, but developed refractory post-radiotherapy stricture. No one proceeded to esophagectomy and 50 % required a self-expanding metal stent (SEMS) at a median of 134 days (IQR: 100 - 263) following stent placement.

CONCLUSIONS

BD stents were successfully deployed in both benign and malignant strictures. They offered a prolonged dilatation-free interval in benign strictures, yet in the majority of patients, strictures recurred. In malignant strictures, stent patency was similar to that of benign strictures, which suggests a potential value in ensuring adequate oral intake during oncologic therapy. In our cohort, however, use of stents did not contribute to improved outcome.

Fabrication of a Delaying Biodegradable Magnesium Alloy-Based Esophageal Stent via Coating Elastic Polymer

Esophageal stent implantation can relieve esophageal stenosis and obstructions in benign esophageal strictures, and magnesium alloy stents are a good candidate because of biodegradation and biological safety. However, biodegradable esophageal stents show a poor corrosion resistance and a quick loss of mechanical support in vivo. In this study, we chose the elastic and biodegradable mixed polymer of Poly(ε-caprolactone) (PCL) and poly(trimethylene carbonate) (PTMC) as the coated membrane on magnesium alloy stents for fabricating a fully biodegradable esophageal stent, which showed an ability to delay the degradation time and maintain mechanical performance in the long term. After 48 repeated compressions, the mechanical testing demonstrated that the PCL-PTMC-coated magnesium stents possess good flexibility and elasticity, and could provide enough support against lesion compression when used in vivo. According to the in vitro degradation evaluation, the PCL-PTMC membrane coated on magnesium was a good material combination for biodegradable stents. During the in vivo evaluation, the proliferation of the smooth muscle cells showed no signs of cell toxicity. Histological examination revealed the inflammation scores at four weeks in the magnesium-(PCL-PTMC) stent group were similar to those in the control group (p > 0.05). The α-smooth muscle actin layer in the media was thinner in the magnesium-(PCL-PTMC) stent group than in the control group (p < 0.05). Both the epithelial and smooth muscle cell layers were significantly thinner in the magnesium-(PCL-PTMC) stent group than in the control group. The stent insertion was feasible and provided reliable support for at least four weeks, without causing severe injury or collagen deposition. Thus, this stent provides a new stent for the treatment of benign esophageal stricture and a novel research path in the development of temporary stents in other cases of benign stricture.

Polymeric Biodegradable Stent Insertion in the Esophagus

Esophageal stent insertion has been used as a well-accepted and effective alternative to manage and improve the quality of life for patients diagnosed with esophageal diseases and disorders. Current stents are either permanent or temporary and are fabricated from either metal or plastic. The partially covered self-expanding metal stent (SEMS) has a firm anchoring effect and prevent stent migration, however, the hyperplastic tissue reaction cause stent restenosis and make it difficult to remove. A fully covered SEMS and self-expanding plastic stent (SEPS) reduced reactive hyperplasia but has a high migration rate. The main advantage that polymeric biodegradable stents (BDSs) have over metal or plastic stents is that removal is not require and reduce the need for repeated stent insertion. But the slightly lower radial force of BDS may be its main shortcoming and a post-implant problem. Thus, strengthening support of BDS is a content of the research in the future. BDSs are often temporarily effective in esophageal stricture to relieve dysphagia. In the future, it can be expect that biodegradable drug-eluting stents (DES) will be available to treat benign esophageal stricture, perforations or leaks with additional use as palliative modalities for treating malignant esophageal stricture, as the bridge to surgery or to maintain luminal patency during neoadjuvant chemoradiation.

Biodegradable stents for the treatment of bowel strictures in Crohn's disease: technical results and challenges

BACKGROUND AND STUDY AIMS

In patients with Crohn's disease, the idea of biodegradable stents for treatment of bowel strictures with limited effect of endoscopic balloon dilation is tempting and initial results have been promising. The aim of this study was to evaluate the technical and clinical success of biodegradable stents for treatment of inflamed Crohn's strictures refractory to endoscopic balloon dilatation.

PATIENTS AND METHODS

Consecutive patients treated with biodegradable stents due to Crohn's disease and inflamed bowel strictures refractory to endoscopic balloon dilatation were included. Technical and clinical success were evaluated.

RESULTS

Six patients were included in the study. Technical success was obtained in five patients (83 %). Clinical success was limited to one patient (20 %); failure was observed due to mucosal overgrowth (n = 2), stent migration (n = 1), and stent collapse (n = 1).

CONCLUSIONS

In Crohn's disease, it is technically feasible to treat bowel strictures with biodegradable stents. However, we have stopped using biodegradable stents due to lack of clinical success and side effects such as mucosal overgrowth and stent collapse.