Endoscopic fluorescence detection of intraepithelial neoplasia in Barrett's esophagus after oral administration of aminolevulinic acid

Delta-Aminolevulinic Acid-Mediated Photodiagnoses in Surgical Oncology: A Historical Review of Clinical Trials

Fluorescence imaging is an emerging clinical technique for real-time intraoperative visualization of tumors and their boundaries. Though multiple fluorescent contrast agents are available in the basic sciences, few fluorescence agents are available for clinical use. Of the clinical fluorophores, delta aminolevulinic acid (5ALA) is unique for generating visible wavelength tumor-specific fluorescence. In 2017, 5ALA was FDA-approved for glioma surgery in the United States. Additionally, clinical studies suggest this agent may have utility in surgical subspecialties outside of neurosurgery. Data from dermatology, OB/GYN, urology, cardiothoracic surgery, and gastrointestinal surgery show 5ALA is helpful for intraoperative visualization of malignant tissues in multiple organ systems. This review summarizes data from English-language 5ALA clinical trials across surgical subspecialties. Imaging systems, routes of administration, dosing, efficacy, and related side effects are reviewed. We found that modified surgical microscopes and endoscopes are the preferred imaging devices. Systemic dosing across surgical specialties range between 5 and 30 mg/kg bodyweight. Multiple studies discussed potential for skin irritation with sun exposure, however this side effect is infrequently reported. Overall, 5ALA has shown high sensitivity for labeling malignant tissues and providing a means to visualize malignant tissue not apparent with standard operative light sources.

In vitro analysis of photosensitizer accumulation for assessment of applicability of fluorescence diagnosis of squamous cell carcinoma of epidermolysis bullosa patients

Epidermolysis bullosa (EB) is a group of inherited skin disorders characterized by blistering following mechanical trauma. Chronic wounds of EB patients often lead to tumors such as squamous cell carcinoma (SCC). Early diagnosis may prevent its invasive growth--frequently the reason of premature mortality of EB-patients. Early detection of tumors is achieved by fluorescence diagnosis (FD), where photosensitizers localize selectively in tumors and fluoresce upon illumination. Excessive accumulation of photosensitizers in inflamed areas, as occasionally found at chronic wounds and tumors due to inflammatory processes, leads to false-positive results in FD. This study analyzed accumulation kinetics of the photosensitizers hypericin and endogenous protoporphyrin IX (PpIX) in different skin cell lines including the three EB subtypes under normal and proinflammatory conditions (stimulated with TNF-alpha). The aim was to assess the applicability of FD of SCC in EB. All cell lines accumulate hypericin or PpIX mostly increasing with incubation time, but with different kinetics. SCC cells of recessive dystrophic EB (RDEB) accumulate less hypericin or PpIX than nonmalignant RDEB cells. Nevertheless, tumor selectivity in vivo might be existent. Non-EB cell lines are more active concerning photosensitizer enrichment. Proinflammatory conditions of skin cell lines seem to have no major influence on photosensitizer accumulation.

Use of 5-ALA fluorescence guided endoscopic biopsy of a deep-seated primary malignant brain tumor

The introduction of fluorescence-guided resection of primary malignant brain tumors was a milestone in neurosurgery. Deep-seated malignant brain tumors are often not approachable for microsurgical resection. For diagnosis and therapy, new strategies are recommended. The combination of endoscopy and 5-aminolevulinic acid–induced protoporphyrin IX (5-ALA-induced Pp IX) fluorescence–guided procedures supported by neuronavigation seems an interesting option. Here the authors report on a combined approach for 5-ALA fluorescence–guided biopsy in which they use an endoscopy system based on an Xe lamp (excitation approximately λ = 407 nm; dichroic filter system λ = 380–430 nm) to treat a malignant tumor of the thalamus and perform a ventriculostomy and septostomy. The excitation filter and emission filter are adapted to ensure that the remaining visible blue remission is sufficient to superimpose on or suppress the excited red fluorescence of the endogenous fluorochromes. The authors report that the lesion was easily detectable in the fluorescence mode and that biopsy led to histological diagnosis.

Fluorescent molecular imaging and dosimetry tools in photodynamic therapy

Measurement of fluorescence and phosphorescence in vivo is readily used to quantify the concentration of specific species that are relevant to photodynamic therapy. However, the tools to make the data quantitatively accurate vary considerably between different applications. Sampling of the signal can be done with point samples, such as specialized fiber probes or from bulk regions with either imaging or sampling, and then in broad region image-guided manner. Each of these methods is described below, the application to imaging photosensitizer uptake is discussed, and developing methods to image molecular responses to therapy are outlined.

Usefulness of autofluorescence imaging for estimating the extent of gastric neoplastic lesions: a prospective multicenter study

BACKGROUND/AIMS

The aim of this study was to determine whether the margin of early to be detected gastric cancer (EGC) and gastric adenoma is easier to be detected with autofluorescence imaging (AFI) than with white-light endoscopy (WLE).

METHODS

A total of 102 lesions (48 EGCs and 54 gastric adenomas) found in 98 patients were removed endoscopically or surgically. The measured length of each pathology specimen was compared with the lengths estimated using WLE, AFI, and chromoendoscopy.

RESULTS

The lesions could be discriminated from surrounding mucosa by AFI in 86 cases (84.3%). The detection rates were similar for elevated lesions (85.1%) and flat/depressed lesions (82.9%, p=0.770). In terms of histology, the detection rate was slightly higher for adenomas (90.7%) than for cancer (77.1%, p=0.058). The estimated length was shorter than the pathologic length in 31.4% of cases when using WLE and 22.1% of cases when using AFI (p=0.168). The resection range was larger for EMR than for AFI in 24 of 80 cases (30.0%).

CONCLUSIONS

WLE tends to underestimate the size of EGCs, whereas AFI tends to overestimate their size.

Novel imaging modalities in the detection of oesophageal neoplasia

The prognosis of oesophageal neoplasia is dependent on the stage of the disease at the time of detection. Early lesions have an excellent prognosis in contrast to more advanced stages that usually have a dismal prognosis. Therefore, the early detection of these lesions is of the utmost importance. In recent years, several new techniques have been introduced to improve the endoscopic detection of early lesions. The most important improvement, in general, has been the introduction of high-resolution/high-definition endoscopy into daily clinical practice. The value of superimposing techniques such as chromoendoscopy, narrow band imaging and computed virtual chromoendoscopy onto high-resolution/high-definition endoscopy will have to be proven in randomised cross-over trials comparing these techniques with standard techniques. Important future adjuncts to white-light endoscopy serving as 'red-flag' techniques for the detection of early neoplasia may be broad field functional imaging techniques such as video autofluorescence endoscopy. In addition, real-time histopathology during endoscopy has become possible with endocytoscopy and confocal endomicroscopy. The clinical value of these techniques needs to be ascertained in the coming years.

Clinical evaluation of bioadhesive hydrogels for topical delivery of hexylaminolevulinate to Barrett's esophagus

Fluorescence diagnosis following oral administration of 5-aminolevulinic acid (5-ALA) has shown to enable the sensitive visualization of intestinal metaplasia, dysplasia and early carcinoma in Barrett's esophagus. Once being established, this technique will be a potential alternative to today's standard diagnosis, i.e. four-quadrant random biopsies which are taken every 1-2 cm of the esophagus for histopathological analysis. In order to further improve this methodology, topical application of lipophilic 5-ALA esters to the esophagus could be advantageous in terms of fluorescence contrast and fluorescence intensity in the target tissue, adverse side effects, as well as application time. Therefore, the aim of this study was to develop a bioadhesive formulation loaded with hexylaminolevulinate (HAL) targeting the esophageal lining. In the present study, different mucoadhesive gels including poloxamer 407, cross-linked polyacrylic acid, hydroxypropylmethylcellulose, sodium carboxymethylcellulose and chitosan have been evaluated with respect to bioadhesion to the esophagus using an ex vivo rat model and a clinical study on healthy volunteers. In order to visualize the mucoadhesive properties of the formulations, a blue dye was incorporated as contrast agent. Chitosan has shown the best esophageal adhesion both in vitro and in vivo. Furthermore, using the in vitro release profiles from chitosan loaded with 40 mM of HAL, one can estimate that after a residence time of 10 min on the esophageal wall, the amount of HAL delivered to the epithelium will be sufficient to perform fluorescence diagnosis of Barrett's esophagus following swallowing of this formulation.

Acetic acid allows effective selection of areas for obtaining biopsy samples in Barrett's esophagus

OBJECTIVE

The aim of this study was to determine whether macroscopic changes resulting from acetic acid application on the surface of columnar-lined esophagus allow regular, nonmagnifying, endoscopic identification of areas presenting dysplasia and/or cancer in Barrett's esophagus.

PATIENTS AND METHODS

A total of 100 patients (mean age, 53 years; range, 27-86 years) under surveillance because of short-segment (n=71) and long-segment (n=29) Barrett's esophagus, with no alterations of columnar-lined esophagus on standard endoscopy, were enrolled. After endoscopic examination, 3% acetic acid was sprayed on columnar-lined esophagus. The subsequent appearance of the mucosa was classified as: (1) Normal pattern: uniform reticulum along the entire columnar-lined esophagus. (2) Abnormal pattern: reticulum presenting areas of rough or irregular appearance. Biopsy samples were obtained from areas of normal and abnormal patterns, and the results of the corresponding histological studies were compared. All endoscopies were performed by the same investigator.

RESULTS

The endoscopic appearance, after acetic acid application, corresponded to a normal pattern in 85% of cases and an abnormal pattern in 15%. The percentage of dysplasia and adenocarcinoma in biopsy specimens was significantly higher in patients with rough or irregular areas (86.7%) than in those with normal uniform reticulum (0%) (P< 0.001). Sensitivity for the identification of areas of dysplasia or adenocarcinoma was 100% (95% confidence interval: 71.7-100%). Specificity was 97.7% (95% confidence interval: 91.2-99.6%).

CONCLUSIONS

This prospective study shows that acetic acid test is useful for standard, nonmagnifying, endoscopic detection of dysplasia and cancer in Barrett's esophagus.

5-Aminolevulinic Acid Derivatives in Photomedicine: Characteristics, Application and Perspectives

The introduction of lipophilic derivatives of the naturally occurring heme precursor 5-aminolevulinic acid (5-ALA) into photomedicine has led to a true revival of this research area. 5-ALA-mediated photodynamic therapy (PDT) and fluorescence photodetection (FD) of neoplastic disease is probably one of the most selective cancer treatments currently known in oncology. To date, this method has been assessed experimentally for the treatment of various medical indications. However, the limited local bioavailability of 5-ALA has widely prevented its use in daily clinical practice. Although researchers were already aware of this drawback early during the development of 5-ALA-mediated PDT, only recently have well-established concepts in pharmaceutical science been adapted to investigate ways to overcome this drawback. Recently, two derivatives of 5-ALA, methylaminolevulinate (MAL) and hexylaminolevulinate (HAL), gained marketing authorization from the regulatory offices in Europe and Australia. MAL is marketed under the trade name Metvix for the treatment of actinic keratosis and difficult-to-treat basal cell carcinoma. HAL has recently been launched under the trade name Hexvix to improve the detection of superficial bladder cancer in Europe. This review will first present the fundamental concepts underlying the use of 5-ALA derivatives in PDT and FD from a chemical, biochemical and pharmaceutical point of view. Experimental evidences from preclinical data on the improvements and limits observed with 5-ALA derivatives will then be introduced. The state-of-the-art from clinical studies with 5-ALA esters will be discussed, with special emphasis placed on the process that led to the development of MAL in dermatology and to HAL in urology. Finally, we will discuss promising medical fields in which use of 5-ALA derivatives might potentially lead to further use of this methodology in photomedicine.

Early neoplastic and metastatic mammary tumours of transgenic mice detected by 5-aminolevulinic acid-stimulated protoporphyrin IX accumulation

A photodynamic technique for human breast cancer detection founded upon the ability of tumour cells to rapidly accumulate the fluorescent product protoporphyrin IX (PpIX) has been applied to transgenic mouse models of mammary tumorigenesis. A major goal of this investigation was to determine whether mouse mammary tumours are reliable models of human disease in terms of PpIX accumulation, for future mechanistic and therapeutic studies. The haeme substrate 5-aminolevulinic acid (5-ALA) (200 mg kg⁻¹) was administered to mouse strains that develop mammary tumours of various histological subtypes upon expression of the transgenic oncogenes HRAS, Polyoma Virus middle T antigen, or Simian Virus 40 large T antigen in the mammary gland. Early neoplastic lesions, primary tumours and metastases showed consistent and rapid PpIX accumulation compared to the normal surrounding tissues, as evidenced by red fluorescence (635 nm) when the tumours were directly illuminated with blue light (380–440 nm). Detection of mouse mammary tumours at the stage of ductal carcinomain situ by red fluorescence emissions suggests that enhanced PpIX synthesis is a good marker for early tumorigenic processes in the mammary gland. We propose the mouse models provide an ideal experimental system for further investigation of the early diagnostic and therapeutic potential of 5-ALA-stimulated PpIX accumulation in human breast cancer patients.

Endoscopic detection of early upper GI cancers

The detection of early-stage neoplastic lesions in the upper GI tract is associated with improved survival and the potential for complete endoscopic resection that is minimally invasive and less morbid than surgery. Despite technological advances in standard white-light endoscopy, the ability of the endoscopist to reliably detect dysplastic and early cancerous changes in the upper GI tract remains limited. In conditions such as Barrett's oesophagus, practice guidelines recommend periodic endoscopic surveillance with multiple biopsies, a methodology that is hindered by random sampling error, inconsistent histopathological interpretation, and delay in diagnosis. Early detection may be enhanced by several promising diagnostic modalities such as chromoendoscopy, magnification endoscopy, and optical spectroscopic/imaging techniques, as these modalities offer the potential to identify in real-time lesions that are inconspicuous under conventional endoscopy. The combination of novel diagnostic techniques and local endoscopic therapies will provide the endoscopist with much needed tools that can considerably enhance the detection and management of early stage lesions in the upper GI tract.

ALA-induced porphyrin formation and fluorescence in synovitis tissue In-vitro and in vivo studies

The synovial inflammatory process in rheumatoid arthritis (RA) is accompanied by massive tumor-like proliferation and activation of the connective stroma. These abnormal cells actively invade and destroy the peri-articular bone and cartilage at the margins of joints where synovium and bone are attached. There is still a lack of minimally invasive synovectomy methods, which might be suitable for the smaller joints. Unfortunately, these joints are usually involved in the disease. Photodynamic therapy has been evaluated as a possible treatment modality for RA synovitis. The present study describes the differences of 5-aminolevulinic acid (5-ALA) and 5-ALA ester-induced protoporphyrin IX (PpIX) production in cell cultures obtained from patients with RA, osteoarthritis (OA) and human sarcoma cell line (HS 192.T) and in a collagen-induced arthritis model in rats. The incubation of cells with hexyl aminolevulinate (HAL) induced the same amount of fluorescence as 5-ALA and methyl aminolevulinate (MAL) at about a 100-fold lower concentration. Incubation with HAL-induced accumulation of at least twice as much porphyrins in RA- and HS 192.T-cells than 5-ALA and MAL in OA-cells. Similar levels of porphyrins were accumulated in RA and the malignant cells. In vivo, intra-articular application of 5-ALA induced a significant porphyrin accumulation in synovitis tissue as measured by in situ fluorescence spectroscopy. In contrast to our in vitro results and other reports, we could not detect enhanced fluorescence after application of up to 0.1mg HAL.

Barrett metaplasia: reassessment of treatment and follow-up

PURPOSE OF REVIEW

The incidence of esophageal adenocarcinoma continues to rise in the Western world, with a mean 5-year survival of less than 20%. There has therefore been increasing interest in the precursor lesion, Barrett's esophagus. However, adenocarcinoma will not develop in most patients with Barrett's esophagus. This review summarizes the data on the management of Barrett's esophagus that have been published since January 2003.

RECENT FINDINGS

The control of reflux symptoms significantly improves quality of life, and surgical antireflux therapy may gradually cause regression of the Barrett segment compared with proton pump inhibitor therapy. The data substantiate the claim that the cancer risk in Barrett esophagus is lower than had hitherto been suggested. The risk factors for progression include increasing age and length of segment, macroscopic inflammatory changes, loss of heterozygosity over several genetic loci, and increased proliferation status. The extent of high-grade dysplasia may not accurately predict cancer development, and continued surveillance, rather than intervention, for such patients may decrease the chances of curative treatment. Long-term follow-up data are beginning to accumulate for nonsurgical treatment strategies. Chemoprevention trials are under way to evaluate the role of acid suppression and nonsteroidal anti-inflammatory drugs and their derivatives.

SUMMARY

At this time, endoscopic surveillance and surgical management remain the mainstay, but continued research efforts should enable risk stratification and cancer prevention in the future.

Hexaminolevulinate-induced fluorescence endoscopy in patients with rectal adenoma and cancer: a pilot study

BACKGROUND

Fluorescence endoscopy is a promising new method for detection and treatment of premalignant and malignant lesions. The aim of this pilot study was to investigate the feasibility of hexaminolevulinate-based photodetection of rectal adenoma and cancer, including safety, dose finding, and efficacy.

METHODS

Ten patients with known rectal adenoma or cancer were sensitized by instillation of 3.2 mM of hexaminolevulinate as an enema. Fluorescence endoscopy was performed after retention of the enema for 30 to 60 minutes, followed by a rest time of up to 30 minutes before endoscopy. Biopsy specimens were taken from fluorescent and non-fluorescent areas and fluorescence microscopy studies were performed to assess the distribution of protoporphyrin IX fluorescence in different tissue layers. Adverse events were reported by direct questioning of all patients; skin photosensitivity, changes in biochemical tests of liver function, blood pressure and heart rate, and the occurrence of GI symptoms (nausea, vomiting) were recorded for 5 patients.

OBSERVATIONS

Hexaminolevulinate-induced fluorescence endoscopy produced selective fluorescence of all rectal adenomas with intraepithelial neoplasia. For rectal cancer, there was only weak fluorescence or none at all. No hexaminolevulinate-induced side effect was observed. In two patients, fluorescence differentiated adenomas and hyperplastic polyps.

CONCLUSIONS

Hexaminolevulinate-based fluorescence endoscopy (3.2 mM administered as an enema) in patients with rectal cancer and adenoma was well tolerated and produced no significant skin sensitivity or other side effects. The optimal duration of application is 30 to 45 minutes, with a rest time of 30 minutes. Selective fluorescence of adenoma with intraepithelial neoplasia suggests that hexaminolevulinate-based fluorescence endoscopy may be useful for detection of premalignant lesions.

Detection and staging of esophageal cancers

PURPOSE OF REVIEW

Technology for detection and staging of esophageal cancer has made significant strides advances in the past 2 years. These advances have led to the enhanced selection of appropriate treatments for esophageal cancer. Cancers that are discovered at an early stage can be treated with endoscopic therapy, whereas advanced cancers are primarily treated with chemotherapy and radiation.

RECENT FINDINGS

Detection of esophageal cancer can be enhanced by two major mechanisms: one is by enhancing the lesion, which has typically been done using vital dyes and the other is by changing the method of imaging of the lesion, which has been accomplished by the use of several technologies including fluorescence and optical coherence tomography. Neither of these techniques has been proven, but some investigators have been able to use them to enhance cancer detection. Similar technologies have been applied to staging esophageal cancer. The optical imaging devices also have the potential to stage mucosa-based malignancy. The use of positron emission tomography has been the most recent development that may have application for advanced cancer. Endoscopic ultrasonography has also been improved in resolution and ability to perform fine needle aspiration. The most significant development for staging early cancers is mucosal resection. Finally, by using mucosal resection techniques, the depth of tumor invasion can be established by histology, which allows gastroenterologists to treat early cancers with greater confidence regarding rates of metastatic disease.

SUMMARY

Early detection of esophageal cancer can be enhanced by the use of vital dyes for mucosal staining, but the advancement of novel optical diagnostic strategies may be more suitable for clinical use. The primary advantage of these new staging methods is to clearly identify early stage cancer that potentially can be treated without traditional surgical resection techniques. More advanced cancers can be staged with positron emission tomography, but definitive studies demonstrating its role are still lacking.