Photodynamic therapy for cholangiocarcinoma

Advances in research and application of photodynamic therapy in cholangiocarcinoma (Review)

Cholangiocarcinoma (CCA) is a disease characterized by insidious clinical manifestations and challenging to diagnose. Patients are usually diagnosed at an advanced stage and miss the opportunity for radical surgery. Therefore, effective palliative therapy is the main treatment approach for unresectable CCA. Current common palliative treatments include biliary drainage, chemotherapy, radiotherapy, targeted therapy and immunotherapy. However, these treatments only offer limited improvement in quality of life and survival. Photodynamic therapy (PDT) is a novel local treatment method that is considered a safe tumor ablation method for numerous cancers. It has shown good efficacy in various studies of CCA and is expected to become an important treatment for CCA. In the present study, the mechanisms of PDT in the treatment of CCA were systematically explored and the progress in the research of photosensitizers was discussed. The current study focused on the various PDT protocols and their therapeutic effects in CCA, with the objective of providing a new horizon for future research and clinical applications of PDT in the treatment of CCA.

Endoscopic palliation of malignant biliary obstruction

Malignant biliary obstruction often presents with challenges requiring the endoscopist to assess the location of the lesion, the staging of the disease, the eventual resectability and patient preferences in term of biliary decompression. This review will focus on the different modalities available in order to offer the most appropriate palliation, such as conventional endoscopic retrograde cholangiopancreatography, endoscopic ultrasound guided biliary drainage as well as ablative therapies including photodynamic therapy or radiofrequency ablation.

One-Step Aqueous Synthesis of Anionic and Cationic AgInS2 Quantum Dots and Their Utility in Improving the Efficacy of ALA-Based Photodynamic Therapy

Silver–indium–sulfide quantum dots (AIS QDs) have potential applications in many areas, including biomedicine. Their lack of regulated heavy metals, unlike many commercialized QDs, stands out as an advantage, but the necessity for alloyed or core–shell structures and related costly and sophisticated processes for the production of stable and high quantum yield aqueous AIS QDs are the current challenges. The present study demonstrates the one-step aqueous synthesis of simple AgInS₂ QD compositions utilizing for the first time either a polyethyleneimine/2-mercaptopropionic acid (AIS-PEI/2MPA) mixture or only 2-mercaptopropionic acid (AIS-2MPA) as the stabilizing molecules, providing a AgInS₂ portfolio consisting of cationic and anionic AIS QDs, respectively, and tuneable emission. Small AIS QDs with long-term stability and high quantum yields (19–23%) were achieved at a molar ratio of Ag/In/S 1/10/10 in water without any dopant or a semiconductor shell. The theranostic potential of these cationic and anionic AIS QDs was also evaluated in vitro. Non-toxic doses were determined, and fluorescence imaging potential was demonstrated. More importantly, these QDs were electrostatically loaded with zwitterionic 5-aminolevulinic acid (ALA) as a prodrug to enhance the tumor availability of ALA and to improve ALA-induced porphyrin photodynamic therapy (PDT). This is the first study investigating the influence of nanoparticle charge on ALA binding, release, and therapeutic efficacy. Surface charge was found to be more critical in cellular internalization and dark toxicity rather than drug loading and release. Both QDs provided enhanced ALA release at acidic pH but protected the prodrug at physiological pH, which is critical for tumor delivery of ALA, which suffers from low bioavailability. The PDT efficacy of the ALA-loaded AIS QDs was tested in 2D monolayers and 3D constructs of HT29 and SW480 human colon adenocarcinoma cancer cell lines. The incorporation of ALA delivery by the AIS QDs, which on their own do not cause phototoxicity, elicited significant cell death due to enhanced light-induced ROS generation and apoptotic/necrotic cell death, reducing the IC50 for ALA dramatically to about 0.1 and 0.01 mM in anionic and cationic AIS QDs, respectively. Combined with simple synthetic methods, the strong intracellular photoluminescence of AIS QDs, good biocompatibility of especially the anionic AIS QDs, and the ability to act as drug carriers for effective PDT signify that the AIS QDs, in particular AIS-2MPA, are highly promising theranostic QDs.

Use of the ALA-loaded cationic and anionic AIS QDs for visible light PDT coupled with QD-based optical imaging in the medical imaging window was studied.

Ablative therapies of the biliary tree

Cholangiocarcinoma, a malignancy of the epithelial cells in the intrahepatic or extrahepatic biliary tree, is often diagnosed at later stages. Median survival duration ranges from 3 to 9 months with a less than ten percent 5-year survival rate. Thus, often treatment strategies are aimed more towards palliation instead of cure. With the majority of patients presenting with unresectable disease at the time of diagnosis, surgical intervention is not feasible, making less invasive endoscopic therapies more suitable. Initially, biliary stents were utilized for biliary decompression to mitigate cholestatic symptoms and prevent cholangitis; however, this strategy did not prove to provide significant survival benefit. Therefore, efforts to treat the tumor burden itself in addition to maintaining biliary patency became a focus of innovation and research in the endoscopic field. This study has led to the advent of therapies such as photodynamic therapy, radiofrequency ablation, and intraluminal brachytherapy. These options combined with biliary stenting have shown to not only offer the benefit of biliary decompression, but also to potentially improve stent patency and survival. Further, there is an anti-tumor effect of each of these modalities, portending an additional benefit in this subset of patients. Despite numerous retrospective and prospective studies assessing these ablative therapies, there is still a paucity of appropriately powered randomized controlled trials, and further research has yet to be done in the field. This review details the current literature entailing endobiliary ablative strategies.

Extrahepatic cholangiocarcinoma: Current status of endoscopic approach and additional therapies

The prognosis of patients with advanced or unresectable extrahepatic cholangiocarcinoma is poor. More than 50% of patients with jaundice are inoperable at the time of first diagnosis. Endoscopic treatment in patients with obstructive jaundice ensures bile duct drainage in preoperative or palliative settings. Relief of symptoms (pain, pruritus, jaundice) and improvement in quality of life are the aims of palliative therapy. Stent implantation by endoscopic retrograde cholangiopancreatography is generally preferred for long-term palliation. There is a vast variety of plastic and metal stents, covered or uncovered. The stent choice depends on the expected length of survival, quality of life, costs and physician expertise. This review will provide the framework for the endoscopic minimally invasive therapy in extrahepatic cholangiocarcinoma. Moreover, additional therapies, such as brachytherapy, photodynamic therapy, radiofrequency ablation, chemotherapy, molecular-targeted therapy and/or immunotherapy by the endoscopic approach, are the nonsurgical methods associated with survival improvement rate and/or local symptom palliation.

Photodynamic therapy of cancer of large duodenal papilla and extrahepatic bile ducts

The problem of treating patients with malignant neoplasms of the extrahepatic bile ducts and the large duodenal papilla remains relevant due to the growing incidence, high mortality, and a pronounced decrease in the quality of life of patients, despite the radical surgery. The purpose of this study was to evaluate the effectiveness of photodynamic therapy (PDT) in inoperable patients with malignant tumors of these localizations.

The study is based on the treatment of 79 patients with adenocarcinoma of large duodenal papilla and extrahepatic bile ducts. 29 patients received palliative bile drainage operations with PDT. 50 patients in the control group only had palliative bile drainage operations. Patients in the study group received from 1 to 3 PDT courses in a year. In total, 29 patients received 52 PDT courses. The tolerance to the method and the life expectancy of patients were evaluated. The median survival of patients who underwent PDT was 18 months (11–60 months); in the control group – 11.5 months. PDT, in combination with bile drainage operation, is an effective method for the treatment of inoperable patients with malignant neoplasms of the extrahepatic bile ducts and the large duodenal papilla in the absence of severe complications and with easy tolerance to therapy by patients. For the treatment and prolongation of life of patients whose radical surgical treatment is associated with a high risk of death, PDT seems to be the best treatment option. Results of PDT treatment for cancer of this localization are comparable with the results of radical surgeries and exceed those for palliative surgeries.

Endoscopic Retrograde Cholangiopancreatography-Guided Ablation for Cholangiocarcinoma

Most patients with perihilar cholangiocarcinoma present with surgically unresectable disease owing to the insidious nature of this malignancy. Relief of malignant perihilar biliary obstruction is a key aspect of cholangiocarcinoma. Although palliative stenting using uncovered metal stents has been advocated in patients with unresectable malignant perihilar biliary strictures, several endoscopic retrograde cholangiopancreatography-guided ablative modalities have emerged. Palliative photodynamic therapy, radiofrequency ablation, and intraluminal brachytherapy have been associated with improved stent patency and survival, although the ideal treatment approach remains unclear. This article reviews the published evidence for using each of these endobiliary ablative modalities in this difficult-to-treat patient population.

Cholangiocarcinoma: New Insights

Cholangiocarcinoma is a malignant neoplasm originating from biliary epithelial cells. The incidence and mortality of this cancer are rising in the world. Currently, cholangiocarcinoma is accepted as a stem cell disease with many risk factors. Diagnosis is relatively simple but therapy is extremely difficult. Surgery is the mainstay of treatment for early stage patients. Endobiliary approaches, chemotherapy and radiotherapy are other therapeutic approaches.

Efficacy and safety of photodynamic therapy for unresectable cholangiocarcinoma: A meta-analysis

BACKGROUND

Photodynamic therapy with the placement of a biliary stent may improve the prognosis in patients with unresectable cholangiocarcinoma. The aim of this research is to determine the hazard ratio of photodynamic therapy with stent compared to biliary stenting alone or other therapies for the treatment of cholangiocarcinoma.

METHODS

Several databases were searched from inception to December 31 2013 for trials comparing photodynamic therapy+stent vs. stent-only or other treatments for cholangiocarcinoma. The outcomes of interest included patient survival, the changes of serum bilirubin levels, the quality of life (Karnofsky performance status), and adverse events. The hazard ratios (HR) were extracted from the survival curves using Tierney's Method. LnHR and its variance were pooled using an inverse variance-weighted average. Inconsistency was quantified using I(2) statistics.

RESULTS

In all, 8 trials comparing PDT+stent with other therapeutic methods were selected. We made a meta-analysis based on the 7 trials, which compared the result of PDT+stent and the stent-only group. HR summarizes the survival for the two groups. Overall survival was significantly better in patients who received photodynamic therapy than those who did not [HR=0.49, 95% confidence interval (CI), 0.33∼0.73, P=0.0005]. Among the 8 trials (642 subjects), 5 assessed the changes of serum bilirubin levels, and/or Karnofsky performance status, as other indications for improvement. In all, the incidence for phototoxic reaction is 11.11%. The incidence for other events in photodynamic therapy and the stent-only group was 13.64% and 12.79%, respectively.

CONCLUSION

The palliative treatment of cholangiocarcinoma, with photodynamic therapy, is associated with an increased survival benefit, an improved biliary drainage, and a better quality of life. However, the quality of this evidence is low.

Biliary Tumor Ablation with Photodynamic Therapy and Radiofrequency Ablation

Within the past two decades, major progress has been made in biliary endoscopy both with stenting and with ablative therapy. A primary goal in patients with malignant biliary lesions who are not candidates for surgery is to provide localized and efficient necrosis of the lesions. This article summarizes the current literature on biliary tumor ablation with photodynamic therapy and radiofrequency ablation. Prognosis, treatment technique, potential complications, treatment efficacy, and controversies are discussed.

Endoscopic treatment options for cholangiocarcinomas

Cholangiocellular carcinoma (CCC) is a very aggressive tumor, which remains highly resistant to current chemoradiation therapies. Death is usually caused by the tumor burden. However, biliary obstruction, which leads to cholangitis and liver failure, is also a cause of death. Therefore, relief of biliary obstruction is one of the key palliative treatment options for patients with hilar or distal CCC. Radiologic or endoscopic insertions of stents (plastic or self-expanding metal) are definite biliary drainage options. Whereas stents alone can help achieve relief of bile duct obstruction, endoscopic ablative interventions with photodynamic therapy or radiofrequency ablation are also useful in destroying intraluminal tumor. Destroying the tumor leads to an increase in the luminal diameter of the obstructed bile duct, allowing for placement of more or larger diameter stents, and thus improving bile flow. Besides decreasing morbidity associated with obstruction, ablative therapies such as photodynamic therapy have also been associated with improved survival in a sub-group of patients with CCC and should therefore be incorporated into the treatment algorithm of any center treating patients with CCC.

Ursodeoxycholic acid-conjugated chitosan for photodynamic treatment of HuCC-T1 human cholangiocarcinoma cells

Chitosan was hydrophobically modified with ursodeoxycholic acid (UDCA) to fabricate nano-photosensitizer for photodynamic therapy (PDT) of HuCC-T1 cholangiocarcinoma cells. Synthesis of UDCA-conjugated chitosan (ChitoUDCA) was confirmed using (1)H NMR spectra. Chlorin E6 (Ce6) was used as a photosensitizer and incorporated into ChitoUDCA nanoparticles through formation of ion complexes. Morphology of Ce6-incorporated ChitoUDCA nanoparticles was observed using TEM and their shapes were spherical with sizes around 200-400 nm. The PDT potential of Ce6-incorporated ChitoUDCA nanoparticles were studied with HuCC-T1 human cholangiocarcinoma cells. The results showed that ChitoUDCA nanoparticles enhances of Ce6 uptake into tumor cells, phototoxicity, and ROS generation compared to Ce6 itself. Furthermore, Ce6-incorporated ChitoUDCA nanoparticles showed quenching in aqueous solution and sensing at tumor cells. We suggest that Ce6-incorporated ChitoUDCA nanoparticles are promising candidates for PDT of cholangiocarcinoma cells.

Choledochoscopy/cholangioscopy

Miniature endoscopes that can be introduced into the bile duct through the duodenoscope during endoscopic retrograde cholangiopancreatography were developed to allow nonsurgical management of difficult biliary stones. The direct visualization enabled by these cholangioscopes of the biliary epithelium provides additional data in the assessment of biliary strictures. Cholangioscopy allows assessment of the biliary lumen, biliary epithelium, targeted tissue acquisition, targeted therapy, and wire guidance.

Spyglass direct visualization system

Although endoscopic retrograde cholangiopancreatography is considered the gold standard to manage biliary disorders, it has its own limitations. The single-operator cholangioscopy (SOC) system (Spyglass) may offer an interesting compromise for most advanced biliary endoscopists, in terms of size (10 Fr diameter) and complexity of use. SOC is a great step toward intraductal visualization and therapy but the best is yet to come.