Photodynamic therapy with 5-aminolevulinic acid is not effective in bile duct cancer

Probe-guided endoscopic system for 5-aminolevulinic acid-based photodynamic diagnosis in cholangiocarcinoma

BACKGROUND AND AIM

The diagnostic accuracy for cholangiocarcinoma (CCA) is inadequate, necessitating the exploration of novel diagnostic approaches. Protoporphyrin IX (Pp IX), a metabolic product of 5-aminolevulinic acid (5-ALA), emits red fluorescence upon blue light exposure. Because it accumulates selectively in cancer cells, photodynamic diagnosis using 5-ALA (5-ALA-PDD) has been integrated into clinical practice for diverse cancer types. Nevertheless, there is currently no device capable of capturing Pp IX-derived fluorescence for real-time 5-ALA-PDD within the biliary tract, largely due to challenges in device miniaturization.

METHODS

To investigate the feasibility of real-time 5ALA-PDD in CCA, we developed two essential components of the cholangioscopy system: a small-diameter flexible camera and a light guide for emitting blue light. We evaluated the detectability of Pp IX fluorescence using these devices in experimental gels and animal models.

RESULTS

Our camera and light guide were smoothly inserted into the lumen of existing cholangioscopes. Incorporating a long-pass filter at the camera tip enabled efficient detection of red fluorescence without significantly impacting white-light observation. The integration of these devices facilitated clear visualization of red fluorescence from gels containing Pp IX at concentrations of 5 μM or higher. Additionally, when observing subcutaneous human CCA tumor models in nude mice treated with 5-ALA, we successfully demonstrated distinct red fluorescence from Pp IX accumulation in tumors compared to peritumoral subcutaneous areas.

CONCLUSION

The integration of our device combination holds promise for real-time 5-ALA-PDD in human CCA, potentially enhancing the diagnostic accuracy for this complex condition.

Hyaluronic Acid-Conjugated with Hyperbranched Chlorin e6 Using Disulfide Linkage and Its Nanophotosensitizer for Enhanced Photodynamic Therapy of Cancer Cells

The main purpose of this study is to synthesize novel types of nanophotosensitizers that are based on hyperbranched chlorin e6 (Ce6) via disulfide linkages. Moreover, hyperbranched Ce6 was conjugated with hyaluronic acid (HA) for CD44-receptor mediated delivery and redox-sensitive photodynamic therapy (PDT) against cancer cells. Hyperbranched Ce6 was considered to make novel types of macromolecular photosensitizer since most of the previous studies regarding nanophotosensizers are concerned with simple conjugation between monomeric units of photosensitizer and polymer materials. Hyperbranched Ce6 was synthesized by conjugation of Ce6 each other while using disulfide linkage. To synthesize Ce6 tetramer, carboxyl groups of Ce6 were conjugated with cystamine and three equivalents of Ce6 were then conjugated again with the end of amine groups of Ce6-cystamine. To synthesize Ce6 decamer as a hyperbranched Ce6, six equivalents of Ce6 was conjugated with the end of Ce6 tetramer via cystamine linkage. Furthermore, HA-cystamine was attached with Ce6 tetramer or Ce6 decamer to synthesize HA-Ce6 tetramer (Ce6tetraHA) or HA-Ce6 decamer (Ce6decaHA) conjugates. Ce6tetraHA and Ce6decaHA nanophotosensitizers showed small diameters of less than 200 nm. The addition of dithiothreitol (DTT) and hyaluronidase (HAse) induced a faster Ce6 release rate in vitro drug release study, which indicated that Ce6tetraHA nanophotosensitizers possess redox-sensitive and HAse-sensitive release properties. Ce6tetraHA nanophotosensitizers showed higher intracellular Ce6 accumulation, higher ROS generation, and higher PDT efficacy than that of Ce6 alone. Ce6tetraHA nanophotosensitizers responded to the CD44 receptor of cancer cell surface, i.e., the pre-treatment of HA blocked CD44 receptor of U87MG or HCT116 cells and then inhibited delivery of nanophotosensitizers in vitro cell culture study. Furthermore, in vivo tumorxenograft study showed that fluorescence intensity in the tumor tissues was stronger than those of other organs, while CD44 receptor blocking by HA pretreatment induced a decrease of fluorescence intensity in tumor tissues when compared to liver. These results indicated that Ce6tetraHA nanophotosensitizers delivered to tumors by redox-sensitive and CD44-sensitive manner.

5-Aminolevulinic-acid-mediated Photodynamic Diagnosis Enhances the Detection of Peritoneal Metastases in Biliary Tract Cancer in Mice

BACKGROUND/AIM

Previous studies on the accuracy of 5-aminolevulinic-acid-mediated photodynamic diagnosis (5-ALA PDD) have been reported for various cancers and brain surgery. However, biliary tract cancer is rare. Therefore, 5-ALA PDD has not been fully evaluated in biliary tract cancers. Small biliary tract cancer lesions such as peritoneal dissemination, liver metastases, and lymph node metastases are negative prognosticators in patients with biliary cancer. The purpose of this exploratory study was to determine if 5-ALA PDD could detect small biliary tract cancer lesions in murine models of biliary cancers.

MATERIALS AND METHODS

Biliary cancer cell lines (TFK-1, HuCCT-1, G415, HuH28, SSP25, RBE, KKU055 and KKU100) and Normal human dermal fibroblast cells were used to evaluate protoporphyrin IX (PpIX) accumulation in vitro. Subcutaneous tumor mice were established using two cell lines (TFK-1 and HuCCT-1). 5-ALA (250 mg/kg) was administered intraperitoneally, and fluorescent 5ALA-PDD was performed 3 h later to evaluate tumoral PpIX accumulation. A murine peritoneal disseminated nodule model was established by intraperitoneal injection of TFK-1 cells. Four weeks later, 5-ALA was administered intraperitoneally, and 5-ALA-PDD was performed 3 h post administration to evaluate PpIX accumulation in the disseminated nodules. The presence of tumor cells in tumors and nodules was confirmed by haematoxylin and eosin staining.

RESULTS

Compared TO non-cancerous cell lines, PpIX accumulation was increased in biliary tract cancer cell lines. PpIX accumulation led to a strong fluorescent signal in all subcutaneous tumors. In the murine model of peritoneal dissemination, microdisseminated nodules (<1 mm) that could not be detected under white light were clearly visible using 5-ALA-PDD.

CONCLUSION

5-ALA PDD was useful for diagnosis of biliary tract cancer and detection of small peritoneal metastatic lesions in murine models of biliary cancers. Clinical studies and applications of 5-ALA PDD for biliary tract cancer are expected in the future.

Branched poly (lactic acid) microparticles for enhancing the 5-aminolevulinic acid phototoxicity

An innovative microcarrier based on a carboxy-enriched and branched polylactic acid derivative was developed to enhance the in vitro phototoxicity of the photosensitizer and prodrug 5-aminolevulinic. Microparticles, prepared by double emulsion technique and loaded with the prodrug were carefully characterized and the effect of the polymer structure on the chemical, physical and biological properties of the final product was evaluated. Results showed that microparticles have a spherical shape and ability to allocate up to 30 μg of the photosensitizer per mg of carrier despite their difference in solubility. Release studies performed in various simulated physiological conditions demonstrate the influence of the branched structure and the presence of the additional carboxylic groups on the release rate and the possibility to modulate it. In vitro assays conducted on human epithelial adenocarcinoma cells proved the not cytotoxicity of the carriers in a wide range of concentrations. The hemocompatibility and surface proteins adsorption were evaluated at different microparticles concentrations to evaluate the safety and estimate the possible microparticles residential time in the bloodstream. The advantages, of loading 5-aminolevulinic acid in the prepared carrier has been deeply described in terms of enhanced phototoxicity, compared to the free 5-aminolevulinic acid formulation after irradiation with light at 635 nm. The obtained results demonstrate the advantages of the prepared derivative compared to the linear polylactide for future application in photodynamic therapy based on the photosensitizer 5-aminolevulinic acid.

Role of photodynamic therapy and intraductal radiofrequency ablation in cholangiocarcinoma

Cholangiocarcinoma comprises 3% of all gastrointestinal malignancies. Prognosis is poor as the disease is locally advanced at the time of its presentation. Biliary endoprosthesis are widely used for biliary decompression, however, they only provides temporary relief. Photodynamic therapy and Radiofrequency ablation are two innovative approaches performed endoscopically to locally destruct the malignant tissue. This chapter focuses on their application and appropriate use along with their benefits and complications.

Photodynamic therapy in cholangiocarcinoma: an overview

Cholangiocarcinoma is a challenge to manage; mortality rate is nearly as high as the incidence. Unless curative resection is performed, these tumours are rapidly fatal because they respond poorly to current therapies. Symptoms occur late in cholangiocarcinoma and curative resection can be performed in less than half of the patients. In non-resectable disease, endoprostheses insertion can relieve jaundice and improve quality of life, provided that tumour extension does not lead to diffuse intrahepatic stenoses of ductal system. However, tumour growth cannot be influenced and therefore, prognosis remains dismal. Despite the fact, that radiotherapy and chemotherapy could reduce tumour volume and growth, no survival advantage has yet been shown. Photodynamic therapy has been evaluated as an new additional, palliative option. A randomised trial comparing photodynamic therapy plus endoprostheses insertion versus endoprostheses insertion alone, indicates a considerably benefit on survival time, cholestasis and quality of life in large, advanced cholangiocarcinoma. Furthermore, few specific side effects occurred. Since photodynamic therapy is the first approach leading to an improvement of prognosis, it should be offered to patients with non-resectable cholangiocarcinoma.

5-aminolevulinic acid-incorporated nanoparticles of methoxy poly(ethylene glycol)-chitosan copolymer for photodynamic therapy

Purpose

The aim of this study was to make 5-aminolevulinic acid (5-ALA)-incorporated nanoparticles using methoxy polyethylene glycol/chitosan (PEG-Chito) copolymer for application in photodynamic therapy for colon cancer cells.

Methods

5-ALA-incorporated (PEG-Chito-5-ALA) nanoparticles were prepared by ion complex formation between 5-ALA and chitosan. Protoporphyrin IX accumulation in the tumor cells and phototoxicity induced by PEG-Chito-5-ALA nanoparticles were assessed using CT26 cells in vitro.

Results

PEG-Chito-5-ALA nanoparticles have spherical shapes with sizes diameters 200 nm. More specifically, microscopic observation revealed a core-shell structure of PEG-Chito-5-ALA nanoparticles. 1H NMR spectra showed that 5-ALA was incorporated in the core of the nanoparticles. In the absence of light irradiation, all components such as 5-ALA, empty nanoparticles, and PEG-Chito-5-ALA nanoparticles did not affect the viability of cells. However, 5-ALA or PEG-Chito-5-ALA nanoparticles induced tumor cell death under light irradiation, and the viability of tumor cells was dose-dependently decreased according to the increase in irradiation time. In particular, PEG-Chito-5-ALA nanoparticles induced increased phototoxicity and higher protoporphyrin IX accumulation into the tumor cells than did 5-ALA alone. Furthermore, PEG-Chito-5-ALA nanoparticles accelerated apoptosis/necrosis of tumor cells, compared to 5-ALA alone.

Conclusion

PEG-Chito-5-ALA nanoparticles showed superior delivery capacity of 5-ALA and phototoxicity against tumor cells. These results show that PEG-Chito-5-ALA nanoparticles are promising candidates for photodynamic therapy of colon cancer cells.

Aminolevulinic acid (ALA): photodynamic detection and potential therapeutic applications

Aminolevulinic acid (ALA) is a heme precursor that may have potential applications for photodynamic detection and photodynamic therapy-based treatment of solid tumors in a variety of malignancies. ALA may have a role in other applications in surgical oncology based on its ability to discriminate neoplastic tissue from adjacent normal tissue. In this review, we provide a comprehensive summary of the published studies of ALA in noncutaneous solid malignancies.

Photodynamic therapy for cholangiocarcinoma using low dose mTHPC (Foscan(®))

BACKGROUND

Photodynamic therapy (PDT) combined with stenting is an effective treatment modality for palliation of nonresectable cholangiocarcinoma (CC). A drawback of standard PDT using Photofrin(®) as photosensitizer is the long lasting skin photosensitivity of up to 3 months. The aim of this study was to show the outcome of PDT of CC, potential side effects and to determine the best drug light interval (DLI) using mTHPC (Foscan(®)) at a low dose.

METHODS

13 patients with nonresectable CC were treated with stenting and PDT (3mg Foscan(®) per treatment, 0.032-0.063 mg/kg body weight, 652 nm, 50 J/cm). Fluorescence measurements were performed with a single bare fiber for 5/13 patients prior to PDT at the tumor site to determine the fluorescence contrast. For another 7/13 patients, long-term fluorescence-kinetics were measured on the oral mucosa to determine the time of maximal relative fluorescence intensity.

RESULTS

The results so far indicate a median survival time of 13 months. Side effects such as perforations or skin phototoxicity could not be observed. Foscan(®) fluorescence within the tumor site was clearly detectable but a significant fluorescence contrast of tumor to adjacent healthy tissue could not be found. The fluorescence kinetics measured in the oral mucosa showed a maximum at 3.85 days (median) after drug administration.

CONCLUSION

Combined stenting and PDT performed with a low Foscan(®) dose results in equal and potentially longer survival times compared to standard Photofrin(®) PDT, while lowering the risk of side effects strongly. Thus it may improve the quality of life.

Photodynamic therapy for unresectable cholangiocarcinoma

Cholangiocarcinoma (CC) is a rare primary malignancy of the biliary tract with a dismal prognosis. Curative resection can only be applied to a small proportion of early diagnosed patients. Palliative biliary drainage by either percutaneous or endoscopic insertion of endoprostheses improves quality-of-life by reducing pruritis, cholangitis, and pain, but has been reported to improve survival time only slightly. Photodynamic therapy (PDT) is a relatively new local, minimally invasive palliative strategy for unresectable CC. PDT uses a photosensitive molecule that accumulates in proliferating tissue such as tumors. Activation of the photosensitizer by use of light of a specific wavelength generates reactive oxygen species leading to selective tumor-cell death. After initial feasibility studies and promising prospective phase II studies, results from two prospective randomized controlled trials comparing PDT after endoprostheses insertion with endoprostheses alone for patients with unresectable CC have been published. One study resulted in dramatically prolonged median survival in the PDT group (493 days) compared with the non-PDT group (98 days) (P < 0.0001), and significantly improved performance status (PS) in the PDT group. A second study with high baseline patients' PS confirmed the benefit of PDT for survival (630 days in the PDT group compared with 210 days for endoprostheses alone, P < 0.01). The procedures were generally well tolerated. PDT has also been reported to have a favorable outcome as adjuvant and neoadjuvant therapy for CC. Although accumulated data and local expertise are limited, PDT can be regarded as a standard palliative therapy for unresectable CC.

Effect of surfactant on 5-aminolevulinic acid uptake and PpIX generation in human cholangiocarcinoma cell

Photodynamic therapy (PDT) is a palliative therapy and has been used to cure cholangiocarcinoma (CC), which has a poor prognosis and limited available curative therapy. PDT was shown to improve the median survival time of advanced-stage patients. Recently, 5-aminolevulinic acid (ALA) has been used as a pro-photosensitizer, which can be transferred to intercellular protoporphyrin IX (PpIX), which is a strong photosensitizer, via the heme pathway. The main limitation of using ALA in PDT is the hydrophilic properties of ALA, which results in low cellular uptake. In this study, non-ionic surfactants, pluronic F68 (PF68) and Tween 80 (TW80), were used to address this limitation. The human CC cell line, HuCC-T1, was cotreated with ALA and different concentrations of surfactants for 4h. The effect of surfactants was evaluated by monitoring the uptake of ALA, the fluorescence intensity of PpIX, and the cell survival rate after suitable light irradiation. Cotreatment with the surfactant resulted in an increased intracellular ALA level, PpIX formation, and phototoxicity.

Photodynamic therapy for cholangiocarcinoma: overview and new developments

PURPOSE OF REVIEW

Photodynamic therapy (PDT) with hematoporphyrins has emerged as promising treatment for nonresectable cholangiocarcinoma in several prospective observational studies and two randomized studies. This review describes the mechanism of action of PDT, gives an overview of clinical experience in cholangiocarcinoma and summarizes the results published in 2007 and 2008.

RECENT FINDINGS

The mechanism of action of PDT has been further elucidated. PDT induces an apoptotic, antiangiogenic as well as an immunomodulatory response. Interleukin-6, a bile duct epithelium growth factor correlating with tumor burden, decreases after PDT. The efficacy of PDT was confirmed in a comparative study in the United States. Patients with no visible mass on imaging studies, high serum albumin levels and treatment immediately after diagnosis seem to benefit most from PDT. Although it is recommended to perform PDT in bile ducts without stents in place, illumination through metal stents is possible if the light dose is adjusted. Meso-tetrahydroxyphenyl chlorine is a new potent photosensitizer for PDT of cholangiocarcinoma.

SUMMARY

In advanced nonresectable cholangiocarcinoma, PDT is the only evidence-based treatment that improves survival when compared with stenting. Therefore, PDT should be offered to those who are unsuitable for surgery.

Systematic review: photodynamic therapy for unresectable cholangiocarcinoma

BACKGROUND

Palliative therapies for unresectable cholangiocarcinoma such as stent, radiotherapy and chemotherapy have generally been disappointing. Therefore, it is necessary to find a new approach to fighting the disease. Several published clinical trials have reported the therapeutic effect of photodynamic therapy (PDT) for unresectable cholangiocarcinoma.

OBJECTIVE

To assess the safety and efficacy of photodynamic therapy for patients with unresectable cholangiocarcinoma.

METHODS

Relevant studies were retrieved from the Medline, Current Contents, Embase, and Cochrane Library databases. Inclusion of papers was determined by using a predetermined protocol; independent assessments and the final consensus decision were performed by two independent reviewers. Acceptable study designs included randomized controlled trials (RCTs), controlled clinical trials (CCTs), case studies, and case reports. Twenty studies met the inclusion criteria, and were tabulated and critically appraised in terms of characteristics, methods, outcomes, and complications.

RESULTS

Twenty studies were included. The quality of the available evidence was low to moderate with the majority of studies being uncontrolled before and after design and thus limited by the retrospective nature of much of the available data. After PDT, it is reported that bilirubin serum levels declined, quality of life improved and survival time increased in most of the patients. At the same time, there were few complications.

CONCLUSIONS

Based on currently available evidence, PDT was safe and effective for patients with inoperable cholangiocarcinoma.

Successful photodynamic therapy for biliary papillomatosis: A case report

Papillomatosis of the bile duct is a rare disease with a high risk of malignant transformation. Therapeutical options include partial hepatectomy and liver transplantation. A previously healthy 65-years old male developed jaundice and right upper abdominal quadrant pain in 1996. A villous adenoma of the distal bile duct was diagnosed. A Whipple procedure was performed. In 2002 the patient turned symptomatic again. Another adenoma was found in the right hepatic duct resulting in a right hepatectomy. Two years later the patient again developed cholestasis. After drainage of the left hepatic duct with a percutaneous transhepatic cholangial drainage (PTCD) catheter, a recurrent biliary adenomatosis was diagnosed by cholangioscopy. As there was no surgical option left, the patient received photodynamic therapy (PDT) for the recurrent biliary papillomatosis. Three mo after he received further photodynamic therapies, the bile duct epithelium appeared normal and the patient had no signs of adenomatosis, both macroscopically and histologically. The follow-up cholangioscopy in late 2005 revealed only a small papilloma without the need for intervention. In early 2006, the patient died of multi organ failure without signs of extrahepatic cholestasis or cholangitis at the age of 75, 10 years after the diagnosis of biliary papillomatosis was established. The patient exceeded the average life expectancy of patients with biliary papillomatosis by far. Thus, PDT might be a sufficient therapeutic option for recurrent papillomatosis patients with no significant side effects.

Photodynamic therapy of cholangiocarcinoma

Photodynamic therapy (PDT) is a local photochemical tumor treatment that consists of a photosensitizing agent in combination with laser irradiation of a distinct wavelength. In some case reports and small non-randomized pilot studies, PDT has proved feasible in patients with hilar bile duct cancer. Those studies showed an astonishing long survival time of the treated patients. In the yet published two randomized controlled studies, PDT showed a significant extension of survival compared to sole bile duct stenting. A possible explanation for this improved survival is a suspected anti-tumor immunological effect induced by PDT. PDT reaches the same level of survival time as incomplete resection. The main complication is a high risk of severe bacterial cholangitis and liver abscesses requiring peri-interventional antibiotics. Skin phototoxicity, which at the beginning of PDT was the most dreaded potential complication, seems to play an ancillary role using mild light protection. As the available photosensitizers, mainly hematoporphyrin derivative (HPD), are not very effective in terms of depth of tumor necrosis, newer photosensitizers with light absorption in the near infrared spectrum and therefore deeper penetration depth are currently under investigation.

Technology insight: Photodynamic therapy for cholangiocarcinoma

Cholangiocarcinoma is, in most cases, rapidly fatal. Curative resection can only be offered to approximately 10% of patients. Even after seemingly curative resection, recurrence frequently occurs. Adjuvant chemotherapy and/or radiotherapy do not reduce the recurrence rate after resection. In the palliative setting, endoscopic or percutaneous biliary drainage is performed to relieve jaundice; however, poor results have been obtained in patients with tumors involving the intrahepatic bile ducts. Biliary drainage alleviates jaundice, but there is no evidence that it prolongs life. Palliative chemotherapy and/or radiotherapy have not been proven to prolong life and relieve jaundice. Photodynamic therapy (PDT) is a relatively new local, minimally invasive procedure that can be used to treat cholangiocarcinoma. PDT uses the physical properties of light-absorbing molecules, so-called photosensitizers, which accumulate within proliferating cells. Activation of the photosensitizer by a non-thermal laser leads to selective photochemical destruction of tumors. In a randomized trial of patients with nonresectable cholangiocarcinoma, PDT prolonged survival time, improved cholestasis and quality of life considerably, and had a favorable side-effect profile. A second randomized trial confirmed the beneficial effect of PDT. For the time being, PDT is recommended for patients with nonresectable disease. The role of PDT before and after surgical resection needs to be assessed.

Palliation of nonresectable bile duct cancer: improved survival after photodynamic therapy

OBJECTIVES

Preliminary uncontrolled studies of photodynamic therapy (PDT) of bile duct cancer (BDC) have shown astonishingly good results in the reduction of cholestasis, improvement of life quality, and potential improvement of survival time. Therefore, we investigated the influence of PDT on survival time in advanced BDC in a randomized controlled study.

METHODS

Thirty-two patients with nonresectable BDC were randomized. In the PDT group 48 h after intravenous application of 2 mg/kg body weight of Photosan-3((R)), light activation was performed. In the control group, patients were treated with endoprostheses but no PDT.

RESULTS

PDT group and the control group were comparable due to age, gender, performance status, bilirubin level, and BDC stage (Bismuth classification). The median survival time after randomization was 7 months for the control group and 21 months for the PDT group (p= 0.0109). In half of the initially percutaneously treated patients, we could change from percutaneous to transpapillary drainage after PDT. Four patients showed infectious complications after PDT versus one patient in the control group.

DISCUSSION

PDT is minimally invasive but shows a considerable postinterventional cholangitis rate. PDT has the potential to result in a changeover of current palliative treatment of BDC.

Uses of photodynamic therapy in premalignant and malignant lesions of the gastrointestinal tract beyond the esophagus

Much has recently been written regarding the use of photodynamic therapy for the treatment of esophageal carcinoma and dysplastic Barrett's esophagus. This review, however, describes the clinical experience using photodynamic therapy with various photosensitizer agents for the treatment of diseases in other areas of the gut, especially the pancreaticobiliary tract where European studies have established the role of porfimer sodium photodynamic therapy in the management of patients with cholangiocarcinoma.

Photodynamic therapy for pancreatic and biliary tract carcinoma

The prognosis of patients with pancreatic and biliary tract cancer treated with conventional therapies such as stent insertion or chemotherapy is often poor, and new approaches are urgently needed. Surgery is the only curative treatment but is appropriate in less than 20% of cases, and even then it is associated with a 5-yr survival of less than 30% in selected series. Photodynamic therapy represents a novel treatment for pancreaticobiliary malignancy. It is a way of producing localized tissue necrosis with light, most conveniently from a low-power, red laser, after prior administration of a photosensitizing agent, thereby initiating a non-thermal cytotoxic effect and tissue necrosis. This review outlines the mechanisms of action of photodynamic therapy including direct cell death, vascular injury, and immune system activation, and summarizes the results of preclinical and clinical studies of photodynamic therapy for pancreaticobiliary malignancy.

A review and update on cholangiocarcinoma

Cholangiocarcinoma is a malignant neoplasm arising from the biliary epithelium that was first described by Durand-Fardel in 1840. Today, it continues to defy diagnosis and treatment. It is difficult to diagnose in part because of its relative rarity, and because it is clinically silent until it becomes advanced disease with obstructive symptoms. The worldwide incidence of cholangiocarcinoma has risen over the past three decades. There is marked geographic variability in the prevalence of this disease, due in large part to regional environmental risk factors. Surgical resection remains the only curative treatment, and high priorities are improving diagnostic methods, and clinical staging for resection once the disease is suspected. A recent trend towards aggressive surgical management has improved outcomes. Chemotherapy, palliative stenting, and radiation are reserved for patients who are not resectable, those with recurrence after surgery, and those who decline surgical intervention. Recent trials using combination systemic chemotherapy and neoadjuvant chemoradiation are promising, but require further study. Over the past five years, several important studies have yielded new insights into the molecular mechanisms of cholangiocarcinoma tumorigenesis. In this review we discuss epidemiology, etiologic factors, molecular pathogenesis, diagnosis, staging, and treatment of cholangiocarcinoma. Particular focus is on recent studies into the cellular and molecular pathogenesis of the disease, recent chemotherapy trials, and newer methods of staging and screening for this devastating malignancy.

Diagnosis and treatment of cholangiocarcinoma

Cholangiocarcinoma presents a formidable diagnostic and treatment challenge. The majority of patients present with unresectable disease and have a survival of less than 12 months following diagnosis. Progress has been made by the appropriate selection of patients for treatment options including resection, with the routine use of more aggressive resections in order to achieve margin-negative resections. This has resulted in longer survival times for these patients. Neoadjuvant and adjuvant therapies have, for the most part, not improved survival in patients with this tumor, and new strategies are needed to improve this line of therapy. The prognosis for unresectable patients is poor, and palliative measures should be aimed at increasing quality of life first and increasing survival second.

Photodynamic therapy in cholangiocarcinomas

Symptoms occur late in cholangiocarcinoma and therefore only about half of the patients at the time of diagnosis are candidates for curative surgery. In patients with advanced non-resectable cholangiocarcinoma palliative treatment options are limited. Until now, insertion of endoprostheses for the treatment of cholestasis has been the method of choice. However, tumour growth cannot be influenced and so that prognosis is dismal. Although radiotherapy and chemotherapy are frequently used, prospective, randomized trials showing an improvement in survival time are missing. Encouraging results from prospective, single-arm phase II trials and a randomized trial using photodynamic therapy (PDT) in non-resectable cholangiocarcinoma indicate considerable benefit on survival with a good quality of life. Furthermore, PDT is well tolerated, with only few specific side-effects. This is of great importance in patients with short life expectancy. PDT should therefore be offered to all patients with non-resectable cholangiocarcinoma. However, before initiating PDT or any other palliative measure, a proper staging and a surgical consultation is necessary to avoid missing a curative surgical option.

Successful photodynamic therapy for nonresectable cholangiocarcinoma: a randomized prospective study

BACKGROUND & AIMS

In nonrandomized trials, photodynamic therapy (PDT) had a promising effect on nonresectable cholangiocarcinoma (NCC). This prospective, open-label, randomized, multicenter study with a group sequential design compared PDT in addition to stenting (group A) with stenting alone (group B) in patients with NCC.

METHODS

In patients with histologically confirmed cholangiocarcinoma, endoscopic or percutaneous double stenting was performed. Patients fulfilling inclusion criteria were randomized to group A (stenting and subsequent PDT) and group B (stenting alone). For PDT, Photofrin 2 mg/kg body wt was injected intravenously 2 days before intraluminal photoactivation (wavelength, 630 nm; light dose, 180 J/cm(2)). Further treatments were performed in cases of residual tumor in the bile duct. The primary outcome parameter was survival time. Secondary outcome parameters were cholestasis and quality of life.

RESULTS

PDT resulted in prolongation of survival (group A: n = 20, median 493 days; group B: n = 19, median 98 days; P < 0.0001). It also improved biliary drainage and quality of life.

CONCLUSIONS

PDT, given in addition to best supportive care, improves survival in patients with NCC. The study was terminated prematurely because PDT proved to be so superior to simple stenting treatment that further randomization was deemed unethical.

Delta-aminolevulinic acid transport in cancer cells of the human extrahepatic biliary duct

This study was performed to characterize the transport of the endogenous photosensitizer delta-aminolevulinic acid in tumor cells of the extrahepatic biliary duct. Uptake of [(3)H]delta-aminolevulinic acid into human cholangiocarcinoma SK-ChA-1 cells was linear for up to 10 min, independent of a Na(+) gradient, but stimulated 3- to 4-fold by an inwardly directed H(+) gradient. Uptake of delta-aminolevulinic acid was mediated by a single transport system with an apparent affinity (K(t)) of 2.1 mM and a maximal velocity (V(max)) of 60.1 nmol. 10 min(-1). mg of protein(-1). Glycylsarcosine, alanylalanine, and cefadroxil strongly inhibited the [(3)H]delta-aminolevulinic acid uptake with K(i) values of 1.3, 0.2, and 3.6 mM, respectively. In contrast, gamma-aminobutyric acid, glycine, L-glutamic acid, and L-aspartic acid (all 10 mM) had no effect on the total [(3)H]delta-aminolevulinic acid uptake, neither at pH 6.0 nor at pH 7.5. Applying a Dixon type of experiment and the ABC test revealed that glycylsarcosine and delta-aminolevulinic acid are transported via the same system, PEPT1. Treatment of the cells with phorbol 12-myristate 13-acetate, a phorbol ester that activates protein kinase C, resulted in a significant inhibition of the transport rate. This inhibition could be blocked by cotreatment with staurosporine. We conclude that delta-aminolevulinic acid is transported by the H(+)/peptide cotransporter PEPT1 into epithelial cells of the extrahepatic biliary duct. delta-Aminolevulinic acid can be accumulated specifically in bile duct tumor cells before photodynamic therapy.