Nitinol stents loaded with a high dose of antitumor 5-fluorouracil or paclitaxel: esophageal tissue responses in a porcine model

Background A poor prognosis associated with esophageal cancer leads to surgical resection not suitable for most patients. Nitinol stents loaded with 50% 5-fluorouracil (5-FU) or paclitaxel (PTX), functioning both as a stent and local chemotherapy, could provide a new therapy modality for these patients. Objective To investigate esophageal tissue responses to nitinol stents loaded with 50% 5-FU or PTX implanted in the esophagus of healthy pigs. Design Twenty-three healthy Bama mini-pigs were randomly divided into 4 groups for stent implantation: group A (PTX stent, n = 13), group B (5-FU stent, n = 8), group C (blank film–covered stent, n = 1), and group D (bare stent, n = 1). Tissue responses were observed by endoscopy or pathologic analyses, and 5-FU or PTX concentrations were measured in the esophagus at the stent implantation site at different time points. Setting Animal laboratory. Interventions Endoscopic placement of esophagus stent. Main Outcome Measurements Endoscopic examination, histology, and drug concentration analysis. Results In general, the esophageal tissue responses varied according to different parts of 5-FU or PTX stent (middle part [drug-containing part] and bare ends [drug-free part]). Severe tissue responses at the bare ends of the stent included inflammation, ulceration, and granulation. However, the tissue responses were greatly reduced in the middle part of the stent. The drug concentrations in the esophagus that had contact with the 5-FU stent or PTX stent were very high, especially for the first period after implantation, which did not cause obvious tissue damage. Limitation Some subjects had incomplete follow-up because of unexpected deaths and stent migration. Conclusion The nitinol stents loaded with 50% 5-FU or PTX did not cause severe esophageal tissue responses, although there was a large concentration of the drug in these tissues.