Drug Eluting Stents for Malignant Airway Obstruction: A Critical Review of the Literature

Advancements in airway stents: a comprehensive update

PURPOSE OF REVIEW

This review provides an overview of the evolving field of airway stenting (AS), highlighting its relevance in the management of central airway obstruction (CAO). It discusses recent advancements, including 3D-printed silicone stents (3DPSS), metallic stents, biodegradable stents (BS), and drug-eluting stents (DES), which are transforming clinical practice. The review underscores the ongoing challenges in patient selection, stent choice, and long-term management in the context of an evolving landscape.

RECENT FINDINGS

Innovations, particularly 3DPSS, have shown promise in providing patient-specific solutions. These stents offer improved symptom relief, enhanced quality of life, and lower complication rates, especially for complex airway diseases. The use of BS and DES is explored, raising prospects for future applications.

SUMMARY

The evolution of AS reflects a deepening understanding of airway obstructions. Recent innovations, such as 3DPSS, BS, and DES, show considerable promise in addressing the limitations of conventional stents. However, challenges related to complications, patient selection, and long-term management persist, demanding further research. Wide practice variations in the management of AS highlight the need for more clinical data and standardized guidelines. The search for the ideal stent continues, driven by the pursuit of better outcomes for patients with CAO.

Establishing a novel model of malignant airway stenosis in rabbit

Background

Malignant central airway stenosis is a life-threatening condition. However, treatment of malignant airway stenosis remains challenging. There is currently a severe lack of an excellent animal model of malignant airway stenosis to facilitate treatment approaches. This is the first study to establish a rabbit model of malignant airway stenosis for bronchoscopic interventional studies.

Materials and methods

New Zealand White rabbits were used in this study, randomly divided into group A (18 rabbits) and group B (6 rabbits). A VX2 fragment suspension was injected into the submucosal layer of rabbits’ airway by bronchoscopy. Bronchoscopic examinations were performed once a week after VX2 tumor implantation to observe tumor growth and the degree of airway stenosis. Randomly, three rabbits were generally dissected after a weekly bronchoscopic examination in group A. The rabbits that reached grade III airway stenosis underwent stent implantation in group B.

Results

A total of 24 rabbits were successfully implanted with the VX2 fragment suspension in the airway without significant adverse events, and the success rate of the tumor growth was 100%. The degree of airway stenosis reaching grade III took 2 to 3 weeks after implantation of the VX2 tumor. The median survival time of rabbit models without stent implantation and rabbits with stent implantation was 32.5 and 32.0 days, respectively.

Conclusions

The implanting method is safe and effective for the establishment of a rabbit model of malignant airway stenosis. When the tumor grows to 2 to 3 weeks, the rabbit model is available for stent implantation. We recommend the models for more preclinical animal studies on bronchoscopic interventional treatments.

Current practices in the management of central airway obstruction

PURPOSE OF REVIEW

Airway obstruction continues to cause substantial pulmonary morbidity and mortality. We present a review of classic, current, and evolving management techniques, highlighting recently published studies on the topic. Recommendations have historically been primarily based on anecdotal experience, case reports, and retrospective studies, but more solid evidence has emerged in the last decade.

RECENT FINDINGS

Novel endobronchial stents are being developed to mitigate the issues of stent migration, mucus plugging, fracture, and granulation tissue formation. Endobronchial drug delivery has become an active area of translational and clinical research, especially with regards to antineoplastic agents used for malignant airway stenosis. Even classic or updated techniques such as spray cryotherapy, injections of mitomycin-c, and balloon dilation have recently been examined in methodologically sound studies. Finally, recently published data have confirmed that patient breathlessness and quality of life improve significantly with therapeutic airway interventions. A multimodal and multidisciplinary approach to patient care is key to achieving the best outcomes.

SUMMARY

The treatment of central airway stenosis is often multimodal and should focus on patient-centric factors, taking into account risks and benefits of the procedure, operator, and center expertise, and always occur in the context of a multidisciplinary approach. Evidence-based clinical research is increasingly driving patient management.

Tracheal fistula repair with stent placement after failure of reconstruction with muscle tissue. A lung cancer surgery complication

A report a case of a 63 year old male diagnosed with lung cancer adenocarcinoma. The patient had a right paratracheal mass diagnosed with EBUS-TBNA 22G. The patient had surgery, however 7 days after the billau catheter was removed pneumothorax was diagnosed which did not resolved. Bronchoscopy reveled two minor fistulas in the interior wall of the trachea. An additional surgery was performed in order to add muscle patches on the exterior part of the trachea. Unfortunately additional stent placement was placed after a silicon stent since the muscle patches failed. We chose a metallic auto expandable stent since after three months of follow up a small metastatic lesion was observed in the liver. Stent placement is an option for these patients and the right stent has to be placed for each case.

Anti-Cancer Effects of Zotarolimus Combined with 5-Fluorouracil Treatment in HCT-116 Colorectal Cancer-Bearing BALB/c Nude Mice

Zotarolimus is a semi-synthetic derivative of rapamycin and an inhibitor of mammalian target of rapamycin (mTOR) signaling. Currently, zotarolimus is used to prolong the survival time of organ grafts, but it is also a novel immunosuppressive agent with potent anti-proliferative activity. Here, we examine the anti-tumor effect of zotarolimus, alone and in combination with 5-fluorouracil, on HCT-116 colorectal adenocarcinoma cells implanted in BALB/c nude mice. Compared with the control mice, mice treated with zotarolimus or zotarolimus combined with 5-FU showed retarded tumor growth; increased tumor apoptosis through the enhanced expression of cleaved caspase 3 and extracellular signal-regulated kinase (ERK) phosphorylation; reduced inflammation-related factors such as IL-1β, TNF-α, and cyclooxygenase-2 (COX-2) protein; and inhibited metastasis-related factors such as CD44, epidermal growth factor receptor (EGFR), transforming growth factor β (TGF-β), and vascular endothelial growth factor (VEGF). Notably, mice treated with a combination of zotarolimus and 5-FU showed significantly retarded tumor growth, reduced tumor size, and increased tumor inhibition compared with mice treated with 5-FU or zotarolimus alone, indicating a strong synergistic effect. This in vivo study confirms that zotarolimus or zotarolimus combined with 5-FU can be used to retard colorectal adenocarcinoma growth and inhibit tumorigenesis. Our results suggest that zotarolimus may increase the chemo-sensitization of tumor cells. Therefore, zotarolimus alone and zotarolimus combined with 5-FU may be potential anti-tumor agents in the treatment of human colon adenocarcinoma. Future research on zotarolimus may lead to the development of new therapeutic strategies.

Drug delivery to the pediatric upper airway

Pediatric upper airway disorders are frequently life-threatening and require precise assessment and intervention. Targeting these pathologies remains a challenge for clinicians due to the high complexity of pediatric upper airway anatomy and numerous potential etiologies; the most common treatments include systemic delivery of high dose steroids and antibiotics or complex and invasive surgeries. Furthermore, the majority of innovative airway management technologies are only designed and tested for adults, limiting their widespread implementation in the pediatric population. Here, we provide a comprehensive review of the most recent challenges of managing common pediatric upper airway disorders, describe the limitations of current clinical treatments, and elaborate on how to circumvent those limitations via local controlled drug delivery. Furthermore, we propose future advancements in the field of drug-eluting technologies to improve pediatric upper airway management outcomes.

Local drug delivery systems for inflammatory diseases: Status quo, challenges, and opportunities

Inflammation that is not resolved in due course becomes a chronic disease. The treatment of chronic inflammatory diseases involves a long-term use of anti-inflammatory drugs such as corticosteroids and nonsteroidal anti-inflammatory drugs, often accompanied by dose-dependent side effects. Local drug delivery systems have been widely explored to reduce their off-target side effects and the medication frequency, with several products making to the market or in development over the years. However, numerous challenges remain, and drug delivery technology is underutilized in some applications. This review showcases local drug delivery systems in different inflammatory diseases, including the targets well-known to drug delivery scientists (e.g., joints, eyes, and teeth) and other applications with untapped opportunities (e.g., sinus, bladder, and colon). In each section, we start with a brief description of the disease and commonly used therapy, introduce local drug delivery systems currently on the market or in the development stage, focusing on polymeric systems, and discuss the remaining challenges and opportunities in future product development.

Interventional Bronchoscopy

For over 150 years, bronchoscopy, especially flexible bronchoscopy, has been a mainstay for airway inspection, the diagnosis of airway lesions, therapeutic aspiration of airway secretions, and transbronchial biopsy to diagnose parenchymal lung disorders. Its utility for the diagnosis of peripheral pulmonary nodules and therapeutic treatments besides aspiration of airway secretions, however, has been limited. Challenges to the wider use of flexible bronchoscopy have included difficulty in navigating to the lung periphery, the avoidance of vasculature structures when performing diagnostic biopsies, and the ability to biopsy a lesion under direct visualization. The last 10-15 years have seen major advances in thoracic imaging, navigational platforms to direct the bronchoscopist to lung lesions, and the ability to visualize lesions during biopsy. Moreover, multiple new techniques have either become recently available or are currently being investigated to treat a broad range of airway and lung parenchymal diseases, such as asthma, emphysema, and chronic bronchitis, or to alleviate recurrent exacerbations. New bronchoscopic therapies are also being investigated to not only diagnose, but possibly treat, malignant peripheral lung nodules. As a result, flexible bronchoscopy is now able to provide a new and expanding armamentarium of diagnostic and therapeutic tools to treat patients with a variety of lung diseases. This State-of-the-Art review succinctly reviews these techniques and provides clinicians an organized approach to their role in the diagnosis and treatment of a range of lung diseases.

Paclitaxel-eluting silicone airway stent for preventing granulation tissue growth and lung cancer relapse in central airway pathologies

BACKGROUND

Airway stents are used to treat obstructive central airway pathologies including palliation of lung cancer, but face challenges with granulation tissue growth. Paclitaxel is a chemotherapy drug that also suppresses growth of granulation tissue. Yet, side effects arise from administration with toxic solubilizers. By incorporating paclitaxel in silicone stents, delivery of paclitaxel can be localized, and side effects minimized.

METHODS

Paclitaxel was incorporated into Liquid Silicone Rubber (LSR) containing polydimethylsiloxane, either as a powder or solution, prior to curing. Drug release study was compared in vitro at 37°C over 10 days. Drug release was quantified using HPLC, and bronchial cell lines were grown on LSR to investigate drug cytotoxicity, and expression of inflammatory markers, specifically interleukin-6 and interleukin-8.

RESULTS

Release rate of paclitaxel incorporated into silicone rubber was consistent with the Korsmeyer and Weibull models (R² > 0.96). Paclitaxel exposure reduced IL-8 levels in cancer cell lines, whilst no cytotoxic effect was observed in all cell lines at treatment concentration levels (≤ 0.1% (w/v) paclitaxel in silicone).

CONCLUSIONS

Incorporating paclitaxel into a silicone matrix for future use in a tracheobronchial stent was investigated. Drug release from silicone was observed and is a promising avenue for future treatments of central airway pathologies.

Airway stenting: Technological advancements and its role in interventional pulmonology

AS offers rapid and sustained relief of symptoms in most patients treated for malignant or benign CAO and can also be curative in itself in cases of benign tracheobronchial stenosis. In the past 30 years, this field has seen significant progress, from the misuse of vascular non-covered metallic stents to the development of silicone airway stents with an increasingly large panel of shapes and of hybrid, partially or fully covered, SEMS customized to the airways. This study aims to offer an overview on: (i) the respective advantages and drawbacks of these two main categories of devices; (ii) the main indications for AS and the rationale behind the choice of stent in each situation; and (iii) the main promises borne from the progress made in the field in the past few years, including the development of drug-eluting, biodegradable or patient-specific customized AS.

A Concentric Tube Robot System for Rigid Bronchoscopy: A Feasibility Study on Central Airway Obstruction Removal

New robotic systems have recently emerged to assist with peripheral lung access, but a robotic system for rigid bronchoscopy has yet to be developed. We describe a new robotic system that can deliver thin robotic manipulators through the ports of standard rigid bronchoscopes. The manipulators bend and elongate to provide maneuverability of surgical tools at the endoscope tip, without endoscope motion. We describe an initial feasibility study on the use of this system to bronchoscopically treat a central airway obstruction (CAO). CAO is prevalent and can be life-threatening in patients with large tumors, and conventional rigid bronchoscopic treatments place patients at risk of complications including broken teeth, neck trauma and damage to oropharyngeal structures due to significant forces induced by bronchoscope tilting and manipulation. In this study, we used an ex vivo ovine airway model to demonstrate the ability of a physician using the robotic system to efficiently remove tissue and restore the airway. Pre- and post-operative CT scans showed that the robot was able to reduce the degree of airway obstruction stenosis from 75 to 14% on average for five CAO resections performed in an ex vivo animal model. Using cadaver experiments, we demonstrated the potential of the robotic system to substantially reduce the intraoperative forces applied to the patient's head and neck (from 80.6 to 4.1 N). These preliminary results illustrate that CAO removal is feasible with our new rigid bronchoscopy robot system, and that this approach has the potential to reduce forces applied to the patient due to bronchoscope angulation, and thereby reduce the risk of complications encountered during CAO surgery.

A Design-Based Stereologic Method to Quantify the Tissue Changes Associated with a Novel Drug-Eluting Tracheobronchial Stent

BACKGROUND

Granulation tissue is a common complication of airway stenting, but no published methods can quantify the volume and type of tissue that develops.

OBJECTIVE

To use design-based stereology to quantify changes in tissue volume and type associated with airway stenting.

METHODS

We compared drug-eluting stents (DES) filled with gendine to standard silicone stents in pigs in an assessor-blinded randomized trial. Tracheal stents were placed via rigid bronchoscopy. After 1 month, animals were euthanized and necropsies were performed. Antimicrobial effects of the DES were assessed in trachea tissue samples, on the DES surface, and with residual gel from the DES reservoir. Tracheal thickness was measured using orthogonal intercepts. Design-based stereology was used to quantify the volume density of tissues using a point-counting method. The volume of each tissue was normalized to cartilage volume, which is unaffected by stenting.

RESULTS

Pigs were randomized to DES (n = 36) or control stents (n = 9). The drug was successfully eluted from the DES, and the stent surface showed antibacterial activity. DES and controls did not differ in tissue microbiology, tracheal thickness, or granulation tissue volume. Compared to nonstented controls, stented airways demonstrated a 110% increase in soft-tissue volume (p = 0.005). Submucosal connective tissue (118%; p < 0.0001), epithelium (70%; p < 0.0001), submucosal glands (47%; p = 0.001), and smooth muscle (41%; p < 0.0001) increased in volume.

CONCLUSION

Stenting doubles the volume of soft tissue in the trachea. Design-based stereology can quantify the tissue changes associated with airway stenting.

Investigation of Migration-Preventing Tracheal Stent with High Dose of 5-Fluorouracil or Paclitaxel for Local Drug Delivery

Stent migration is one of the common reasons for the failure of tracheal stent. An antitumor drug/tracheal stent combination can promptly relieve dyspnea caused by tracheal stenosis and locally treat malignant occupying lesion or tumor. To prevent stent migration for more effective treatment, we prepared a migration-preventing nitinol tracheal stent (TS) with a high dose of 5-fluorouracil or paclitaxel (5-FU/TS or PTX/TS) by stent surface coating with a bilayered film, which is composed of a drug-loaded layer containing Carbopol 974P as mucoadhesive matrix and a blank Carbopol 974P layer. The resulting stent had a similar mechanical performance with the nitinol tracheal stent itself. The bilayered film containing 30% PTX (PTX30) could keep adhesion to porcine mucosa for 221.7 ± 11.4 min in PBS at a stirring speed of 150 rpm, and the corresponding PTX30/TS was difficult to be moved in the porcine tracheal lumen with a pulling force less than 0.7 N, indicating its good migration-preventing ability. The migration-preventing ability of the 5-FU/TS or PTX/TS was related to the compositions of bilayered films. The 5-FU release from the 5-FU/TS was dominated by a relaxation mechanism, while the PTX release was mainly controlled by a diffusion mechanism. Moreover, the 5-FU permeation from the 5-FU loaded film through the porcine tracheal mucosa was determined by the 5-FU dissolution, and PTX permeation was limited by the trans-mucosa process. After the deployment of PTX30/TS, inflammatory responses were observed in the rabbit tracheas and gradually alleviated during the follow-up period.

The utility of 3D-printed airway stents to improve treatment strategies for central airway obstructions

Airway stents are commonly used in the management of patients suffering from central airway obstruction (CAO). CAO may occur directly from airway strictures, obstructing airway cancers, airway fistulas or tracheobronchomalacia, resulting from the weakening and dynamic collapse of the airway wall. Current airway stents are constructed from biocompatible medical-grade silicone or from a nickel-titanium (nitinol) alloy with fixed geometry. The stents are inserted via the mouth during a bronchoscopic procedure. Existing stents have many shortcomings including the development of obstructing granulation tissue in the weeks and months following placement, mucous build up within the stent, and cough. Furthermore, airway stents are expensive and, if improperly sized for a given airway, may be easily dislodged (stent migration). Currently, in Australia, it is estimated that approximately 12,000 patients will develop CAO annually, many of whom will require airway stenting intervention. Of all stenting procedures, the rate of failure is currently reported to be at 22%. With a growing incidence of lung cancer prevalence globally, the need for updating airway stent technology is now greater than ever and personalizing stents using 3D-printing technology may offer the best chance of addressing many of the current limitations in stent design. This review article will assess what represents the gold standard in stent manufacture with regards to treatment of tracheobronchial CAO, the challenges of current airway stents, and outlines the necessity and challenges of incorporating 3D-printing technology into personalizing airway stents today.

New hybrid method for trachea dilatation with rigid and flexible tools

Trachea stenosis is observed either in benign or malignant situations. In cancer malignancy a tumor might obstruct the central airway in three different ways. Again granuloma tissue is usually observed after intubation or stent placement in order to manage a benign malformation of the trachea. In any case there are several tools and techniques that can be used either with surgery or endoscopically to manage such situation. We will focus on a hybrid technique in order to ventilate the patient while performing endoscopic management of granuloma tissue.

Lung cancer induced from chemotherapy a 20 years old case

Lung cancer is diagnosed at a late stage although we have novel diagnostic tools. The association of smoking and other environmental factors are well known. However; there are cases where a malignancy is associated with previous radiation treatment. There is an association between radiotherapy treatment and cancer incidence. We present a case where lung cancer and laryngeal cancer was induced 20 years after radiation therapy of a hogkin lymphoma.

Inhaled Immunotherapy Administration for Lung Cancer; Efficient? Certainly Possible

Lung cancer is still diagnosed at a late stage in most lung cancer patients. Regarding Non-small Cell lung cancer there are novel therapies such as; tyrosine kinase inhibitors and immunotherapy. Currently we have two immunotherapies that can be used either as first-line treatment or second line treatment; pembrolizumab and nivolumab. A third one is being investigated as a combination of immunotherapy; ipilimumab. Aerosol treatment has been investigated for many diseases not only for the lung, but also for systematic diseases. The design of cups was found the most significant factor in producing significant effects. The comparison of cups reveals the design J as the most capable of reducing the droplets at a minimum size of mass median aerodynamic diameter (MMAD) MMAD=1.99. Drug effect comes second in sequence (F=62.04) showing that nivolumab is the most drastic preparation at low particle sizes (1.89), two drugs share an intermediate particle diameter (pembrolizumab and ipilimumab). In total drugs demonstrate a decreasing droplet size: Ipilimumab>Pembrolizumab> Nivolumab.

Post-Obstructive Pneumonia in Patients with Cancer: A Review

Published literature on post-obstructive pneumonia is difficult to find and consists mainly of case reports or small case series. This entity is encountered most often in patients with advanced lung malignancy but is also occasionally seen in patients with community-acquired pneumonia (CAP). There are substantial differences in the manifestations, treatment, and outcomes of post-obstructive pneumonia in these two settings. When obstruction is present in patients with CAP, it is almost always secondary to an underlying pulmonary malignancy. In fact, the observation of an obstructive component in patients with CAP leads to the detection of primary or metastatic lung cancer in more than 50% of such individuals. Post-obstructive pneumonia in patients with advanced lung malignancy is far more common (~ 50% of patients) and is associated with substantial morbidity and mortality. The management of these patients is very challenging and involves multiple disciplines including medical oncology, pulmonary medicine, infectious diseases, intervention radiology, surgery, and intensive care teams. The administration of broad-spectrum antibiotic regimens is generally required. Refractory or recurrent infections despite the administration of appropriate antimicrobial therapy are the norm. Frequent and prolonged antibiotic administration leads to the development of resistant microflora. Complications such as lung abscess, empyema, and local fistula formation develop often. Relief of obstruction generally produces only temporary symptomatic improvement.

A new mode of ventilation for interventional pulmonology. A case with EBUS-TBNA and debulking

Lung cancer is still underdiagnosed mainly due to lack of symptoms. Most patients are diagnosed in a late stage where unfortunately only systematic therapy can be applied. Fortunately in the last five years several novel therapies and combinations have emerged. However; in certain situations local therapeutics modalities have to be applied in order to solve emergency problems as in the case that we will present. Convex-EBUS probe was used along with a novel method of ventilation which keeps PCO₂ concentration satisfyingly low.

Malignant central airway obstruction

This review comprehensively describes recent advances in the management of malignant central airway obstruction (CAO). Malignant CAO can be a dramatic and devastating manifestation of primary lung cancer or metastatic disease. A variety of diagnostic modalities are available to provide valuable information to plan a therapeutic intervention. Clinical heterogeneity in the presentation of malignant CAO provides opportunities to adapt and utilize endoscopic technology and tools in many ways. Mechanical debulking, thermal tools, cryotherapy and airway stents are methods and instruments used to rapidly restore airway patency. Delayed bronchoscopic methods, such as photodynamic therapy (PDT) and brachytherapy can also be utilized in specific non-emergent situations to establish airway patency. Although data regarding the success and complications of therapeutic interventions are retrospective and characterized by clinical and outcome measure variability, the symptoms of malignant CAO can often be successfully palliated. Assessment of risks and benefits of interventions in each individual patient during the decision-making process forms the critical foundation of the management of malignant CAO.

Innovative use of a Montgomery cannula in the bronchoscopic management of tracheal stenosis and failed tracheostomy decannulation

Background

Endoprosthesis are being used in the everyday clinical practice either as a permanent solution or transient. They can be used in both benign and malignant situations.

Case presentation

We report a case in which a temporary Montgomery cannula is used in conjunction with therapeutic bronchoscopy to manage a patient with failed tracheostomy decannulation secondary to a distal complex tracheal stenosis.

Conclusions

This innovative use of the Montgomery cannula allowed for successful management of the patient's tracheal stenosis and subsequent tracheostomy tube decannulation.

A retrograde y-stenting of the trachea for treatment of mediastinal fistula in an unusual situation

INTRODUCTION

Stents have been used for quite some time for the treatment of benign and malignant airway stenosis. Silicon stents are preferred for benign situations, whereas metallic self-expanding stents are preferred for malignant comorbidities.

PATIENT AND METHODS

In general, stents can be placed in different approach directions, although in pulmonary medicine it is logical to apply only antegrade techniques - until now. A 63-year-old patient, 168 cm height and 53 kg weight on referral, suffered chronical diseases. The patient was diagnosed with a papillary thyroid carcinoma in 1989, which was treated by resection and radiotherapy. In the following years, she developed a stenosis of the esophagus. The decision to try endobronchial stenting was made upon the plan to close that fistula with a pedicled omentum majus replacement through the diaphragmal opening of the esophagus. This surgical plastic needed an abutment and a secured continuous airway replacement above the tracheostoma level. A Freitag stent (FS), 11 cm in length (110-25-40) and an inner diameter of 13 mm, was placed successfully retrograde into the trachea and completely bridged the big fistula. Unfortunately the patient passed away due to pulmonary infections after several weeks.

DISCUSSION

In this case report, a successful but unusual case of retrograde stent placement of a modified FS is presented.

Second-line afatinib administration in an elderly patient with squamous cell carcinoma

Introduction

The majority of cases of lung cancer are still diagnosed at a late stage. At this stage, palliative therapeutic options including nonspecific cytotoxic drugs, targeted therapy, or immunotherapy can be utilized. In 2016, immunotherapy was approved in Europe for squamous cell carcinoma and adenocarcinoma. Moreover, afatinib was also approved as second-line therapy for squamous cell carcinoma.

Case report

This article presents a case of a 76-year-old male with squamous cell carcinoma who received nab-paclitaxel as first-line therapy, and his treatment was switched to the tyrosine kinase inhibitor afatinib (40 mg) after disease progression with left lung atelectasis. After receiving afatinib for only 28 days, the atelectasis resolved. No adverse effects were observed from the afatinib therapy.

Discussion

In this case, afatinib 40 mg proved to be an effective alternative treatment for an elderly patient. Treatment choice should be based on the performance status of the patient, cost-effectiveness, and drug treatment guidelines.

Paclitaxel Drug-eluting Tracheal Stent Could Reduce Granulation Tissue Formation in a Canine Model

Background:

Currently available silicone and metallic stents for tracheal stenosis are associated with many problems. Granulation proliferation is one of the main complications. The present study aimed to evaluate the efficacy of paclitaxel drug-eluting tracheal stent in reducing granulation tissue formation in a canine model, as well as the pharmacokinetic features and safety profiles of the coated drug.

Methods:

Eight beagles were randomly divided into a control group (bare-metal stent group, n = 4) and an experimental group (paclitaxel-eluting stent group, n = 4). The observation period was 5 months. One beagle in both groups was sacrificed at the end of the 1^st and 3^rd months, respectively. The last two beagles in both groups were sacrificed at the end of 5^th month. The proliferation of granulation tissue and changes in tracheal mucosa were compared between the two groups. Blood routine and liver and kidney function were monitored to evaluate the safety of the paclitaxel-eluting stent. The elution method and high-performance liquid chromatography were used to characterize the rate of in vivo release of paclitaxel from the stent.

Results:

Compared with the control group, the proliferation of granulation tissue in the experimental group was significantly reduced. The drug release of paclitaxel-eluting stent was the fastest in the 1^st month after implantation (up to 70.9%). Then, the release slowed down gradually. By the 5^th month, the release reached up to 98.5%. During the observation period, a high concentration of the drug in the trachea (in the stented and adjacent unstented areas) and lung tissue was not noted, and the blood test showed no side effect.

Conclusions:

The paclitaxel-eluting stent could safely reduce the granulation tissue formation after stent implantation in vivo, suggesting that the paclitaxel-eluting tracheal stent might be considered for potential use in humans in the future.

Gefitinib/gefitinib microspheres loaded polyurethane constructs as drug-eluting stent coating

One of the complications of bronchotracheal cancer is obstruction of the upper airways. Local tumor resection in combination with an airway stent can suppress intraluminal tumor (re)growth. We have investigated a novel drug-eluting stent coating for local release of the anticancer drug gefitinib. A polyurethane (PU) sandwich construct was prepared by a spray coating method in which gefitinib was embedded between a PU support layer of 200μm and a PU top layer of 50-200μm. Gefitinib was either embedded in the construct as small crystals or as gefitinib-loaded poly(lactic-co-glycolic acid) (PLGA) microspheres (MSP). The drug was incorporated in the PU constructs with high recovery (83-93%), and the spray coating procedure did not affect the morphologies of the embedded microspheres as demonstrated by scanning electron microscopy (SEM), confocal laser scanning microscopy and fluorescence microscopy analysis. PU constructs loaded with gefitinib crystals released the drug for 7-21days and showed diffusion based release kinetics. Importantly, directional release of the drug towards the top layer, which is supposed to face the tumor mass, was controlled by the thicknesses of the PU top layer. PU constructs loaded with gefitinib microspheres released the drug in a sustained manner for >6months indicating that drug release from the microspheres became the rate limiting step. In conclusion, the sandwich structure of drug-loaded PLGA microspheres in PU coating is a promising coating for airway stents that release anticancer drugs locally for a prolonged time.

Techniques of endoscopic airway tumor treatment

Interventional bronchoscopy has a predominant role in the management of both early and advanced-stage airway tumors. Given the very poor prognosis of lung cancer, there is a need for new tools to improve early detection and bronchoscopic treatment of endo-bronchial precancerous lesions. In more advanced stages, interventional bronchoscopy plays an important role, as nearly a third of lung cancers lead to proximal airway obstruction. This will cause great discomfort or even life-threatening symptoms related to local extension, such as dyspnea, post-obstructive pneumonia, and hemoptysis. Surgery for very locally advanced disease is only effective for a limited number of patients and the effects of conventional antitumor therapies, like radiation therapy or chemotherapy, are inconstant and are too delayed in a palliative context. In this review, we aim to provide pulmonologists with an exhaustive technical overview of (I) the bronchoscopic management of benign endobronchial lesions; (II) the bronchoscopic management of malignant tumors, including the curative treatment of localized lesions and palliative management of malignant proximal airway stenosis; and (III) descriptions of the emerging endoscopic techniques used to treat peripheral lung tumors.

Central airway tumors: interventional bronchoscopy in diagnosis and management

The diagnosis of central airway tumors is usually challenging because of the vague presentations. Advances in visualization technology in bronchoscopy aid early detection of bronchial lesion. Cryotechnology has great impact on endobronchial lesion sampling and provides better diagnostic yield. Airway tumor involvements result in significant alteration in life quality and lead to poor life expectancy. Timely and efficiently use ablation techniques by heat or cold energy provide symptoms relief for central airway obstruction. Prostheses implantation is effective in maintaining airway patency after ablative procedure or external compression. Combined interventional bronchoscopy modalities and other adjunctive therapies have improvement in quality of life and further benefit in survival. This review aims to provide a diagnostic approach to central airway tumors and an overview of currently available techniques of interventional bronchoscopy in managing symptomatic central airway obstruction.

Survival and Quality of Life Benefit after Endoscopic Management of Malignant Central Airway Obstruction

Background: Although interventional management of malignant central airway obstruction (mCAO) is well established, its impact on survival and quality of life (QoL) has not been extensively studied.

Aim: We prospectively assessed survival, QoL and dyspnea (using validated EORTC questionnaire) in patients with mCAO 1 day before interventional bronchoscopy, 1 week after and every following month, in comparison to patients who declined this approach.

Material/Patients/Methods: 36 patients underwent extensive interventional bronchoscopic management as indicated, whereas 12 declined. All patients received full chemotherapy and radiotherapy as indicated. Patients of the 2 groups were matched for age, comorbidities, type of malignancy and level of obstruction. Follow up time was 8.0±8.7 (range 1-38) months.

Results: Mean survival for intervention and control group was 10±9 and 4±3 months respectively (p=0.04). QoL improved significantly in intervention group patients up to the 6^th month (p<0.05) not deteriorating for those surviving up to 12 months. Dyspnea decreased in patients of the intervention group 1 month post procedure remaining reduced for survivors over the 12th month. Patients of the control group had worse QoL and dyspnea in all time points.

Conclusions: Interventional management of patients with mCAO, may achieve prolonged survival with sustained significant improvement of QoL and dyspnea.