The role of photodynamic therapy in the esophagus

Photophysical, rotational and translational properties of Radachlorin photosensitizer upon binding to serum albumins

INTRODUCTION

Although photophysical properties of Radachlorin photosensitizer (PS) were extensively studied in solutions and cells, no data is available on variations of its characteristics upon binding to serum albumins, which are major transporters in blood and nutrients in cell culture media.

OBJECTIVES

The primary objective of this study was to analyze changes in photophysical properties of Radachlorin molecules upon their binding to human and bovine serum albumins at different microenvironment properties.

METHODS

Experiments were performed using time-resolved fluorescence spectroscopy and fluorescence recovery after photobleaching. Variations in fluorescence spectra and lifetime, fluorescence anisotropy, rotational and translational diffusion of PS molecules upon binding to albumins were studied in normal, basic and acidic conditions and at different concentrations of albumin and PS molecules.

RESULTS

Radachlorin molecules effectively bind to both types of serum albumins, which causes changes in photophysical properties of the PS. A minor red shift of the fluorescence spectrum, an increase in fluorescence lifetime and anisotropy and substantial decrease of translational and rotational mobility of PS molecules were observed upon their binding to albumins. The analysis of rotational diffusion time provided robust evaluation of the bound fraction of PS molecules. Both the highly acidic microenvironment and increase in alcohol concentration above 40% resulted in detachment of PS molecules from albumins. Photophysical properties of Radachlorin in complexes with BSA and HSA were found to be slightly different.

CONCLUSIONS

Binding of Radachlorin photosensitizer to either BSA or HSA affects significantly its photophysical properties, which may also vary with microenvironment acidity and alcohol concentration.

Photophysical properties of Radachlorin photosensitizer in solutions of different pH, viscosity and polarity

We present a thorough experimental investigation of fluorescence properties of Radachlorin photosensitizer in solutions of different acidity, viscosity and polarity. Experiments were performed using time-resolved fluorescence lifetime imaging and time-resolved analysis of polarized fluorescence. Variations of solution acidity resulted in considerable changes of Radachlorin fluorescence quantum yield and lifetime in the pH range from 4 to 7, but did not affect the rotational diffusion time, and almost did not change the quantum yield and characteristic times of singlet oxygen phosphorescence. Variations of solution polarity and viscosity were achieved by changing ethanol or methanol fraction in aqueous solution. The decrease of solution polarity resulted in nonlinear rise of Radachlorin fluorescence quantum yield and lifetime up to alcohol concentration of 50%-65%, as well as in considerable rise of singlet oxygen quantum yield and significant changes in characteristic times of its phosphorescence. Variations of solution viscosity resulted in changes of rotational diffusion time of Radachlorin molecules, which appeared to be in perfect correlation with methanol solution viscosity. Good correspondence with ethanol solution viscosity was observed only up to 50% alcohol fraction. Deviations of rotational diffusion time of Radachlorin molecules from direct proportionality with solution viscosity at higher ethanol concentrations were suggested to be due to different solvation conditions. The data obtained can give important reference points for analysis of microenvironment of Radachlorin molecules, their intracellular localization and performance in singlet oxygen generation.

Fractionated Photofrin-Mediated Photodynamic Therapy Significantly Improves Long-Term Survival

This study investigates the effect of fractionated (two-part) PDT on the long-term local control rate (LCR) using the concentration of reactive oxygen species ([ROS]rx) as a dosimetry quantity. Groups with different fractionation schemes are examined, including a 2 h interval between light delivery sessions to cumulative fluences of 135, 180, and 225 J/cm2. While the total treatment time remains constant within each group, the division of treatment time between the first and second fractionations are explored to assess the impact on long-term survival at 90 days. In all preclinical studies, Photofrin is intravenously administered to mice at a concentration of 5 mg/kg, with an incubation period between 18 and 24 h before the first light delivery session. Fluence rate is fixed at 75 mW/cm2. Treatment ensues via a collimated laser beam, 1 cm in diameter, emitting light at 630 nm. Dosimetric quantities are assessed for all groups along with long-term (90 days) treatment outcomes. This study demonstrated a significant improvement in long-term survival after fractionated treatment schemes compared to single-fraction treatment, with the optimal 90-day survival increasing to 63%, 86%, and 100% vs. 20%, 25%, and 50%, respectively, for the three cumulative fluences. The threshold [ROS]rx for the optimal scheme of fractionated Photofrin-mediated PDT, set at 0.78 mM, is significantly lower than that for the single-fraction PDT, at 1.08 mM.

Advancements in photodynamic therapy of esophageal cancer

The poor prognosis of patients with esophageal cancer leads to the constant search for new ways of treatment of this disease. One of the methods used in high-grade dysplasia, superficial invasive carcinoma, and sometimes palliative care is photodynamic therapy (PDT). This method has come a long way from the first experimental studies to registration in the treatment of esophageal cancer and is constantly being improved and refined. This review describes esophageal cancer, current treatment methods, the introduction to PDT, the photosensitizers (PSs) used in esophageal carcinoma PDT, PDT in squamous cell carcinoma (SCC) of the esophagus, and PDT in invasive adenocarcinoma of the esophagus. For this review, research and review articles from PubMed and Web of Science databases were used. The keywords used were "photodynamic therapy in esophageal cancer" in the years 2000-2020. The total number of papers returned was 1,000. After the review was divided into topic blocks and the searched publications were analyzed, 117 articles were selected.

Singlet oxygen generation in aerosol jet and on biological surfaces

The paper presents steady-state and time-resolved experiments on photophysical processes associated with photodynamic inactivation of infections provided by nebulization of Radachlorin photosensitizer solution. As models of surfaces subjected to photodynamic inactivation we used glass, plant leaf, mushroom cap peel and superficial fascia of chicken and salmon skin flaps. The oxygen content in the photosensitizer solution was varied by blowing with atmospheric air and with pure oxygen. It was shown that singlet oxygen was generated efficiently in the aerosol jet and that its amount increased noticeably at higher oxygen concentrations. The kinetics of photosensitizer photobleaching on different surfaces were found to be significantly different with characteristic decay times varying from seconds for leaf and glass to minutes for fascial flaps. This observation was attributed to much faster oxygen depletion on rough crumbly surfaces of biological samples due to effective oxidation reactions occurred. The singlet oxygen generation and degradation times, and the relative quantum yield were determined on different surfaces by recording time-resolved phosphorescence at about 1270 nm under normoxic and hyperoxic conditions and analyzed on the basis of the set of master equations. The results obtained provide reference marks for choosing optimal irradiation durations for photodynamic inactivation of pathogenic infectious agents (bacteria, mycobacteria, fungi, viruses) on mucous membranes, including the tracheobronchial tree.

Implications of photodynamic cancer therapy: an overview of PDT mechanisms basically and practically

BACKGROUND

Tumor eradication is one of the most important challengeable categories in oncological studies. In this account, besides the molecular genetics methods including cell therapy, gene therapy, immunotherapy, and general cancer therapy procedures like surgery, radiotherapy, and chemotherapy, photodynamic adjuvant therapy is of great importance. Photodynamic therapy (PDT) as a relatively noninvasive therapeutic method utilizes the irradiation of an appropriate wavelength which is absorbed by a photosensitizing agent in the presence of oxygen. In this procedure, a series of events lead to the direct death of malignant cells such as damage to the microvasculature and also the induction of a local inflammatory function. PDT has participated with other treatment modalities especially in the early stage of malignant tumors and has resulted in decreasing morbidity besides improving survival rate and quality of life. High spatial resolution of PDT has attracted considerable attention in the field of image-guided photodynamic therapy combined with chemotherapy of multidrug resistance cancers. Although PDT outcomes vary across the different tumor types, minimal natural tissue toxicity, minor systemic effects, significant reduction in long-term disease, lack of innate or acquired resistance mechanisms, and excellent cosmetic effects, as well as limb function, make it a valuable treatment option for combination therapies.

SHORT CONCLUSION

In this review article, we tried to discuss the potential of PDT in the treatment of some dermatologic and solid tumors, particularly all its important mechanisms.

High optical-throughput spectroscopic singlet oxygen and photosensitizer luminescence dosimeter for monitoring of photodynamic therapy

We report a high light-throughput spectroscopic dosimeter system that is able to noninvasively measure luminescence signals of singlet oxygen (¹ O₂ ) produced during photodynamic therapy (PDT) using a CW (continuous wave) light source. The system is based on a compact, fiber-coupled, high collection efficiency spectrometer (>50% transmittance) designed to maximize optical throughput but with sufficient spectral resolution (~7 nm). This is adequate to detect ¹ O₂ phosphorescence in the presence of strong luminescence background in vivo. This system provides simultaneous acquisition of multiple spectral data points, allowing for more accurate determination of luminescence baseline via spectral fitting and thus the extraction of ¹ O₂ phosphorescence signal based solely on spectroscopic decomposition, without the need for time-gating. Simultaneous collection of photons at different wavelengths improves the quantum efficiency of the system when compared to sequential spectral measurements such as filter-wheel or tunable-filter based systems. A prototype system was tested during in vivo PDT tumor regression experiments using benzoporphyrin derivative (BPD) photosensitizer. It was found that the treatment efficacy (tumor growth inhibition rate) correlated more strongly with ¹ O₂ phosphorescence than with PS fluorescence. These results indicate that this high photon-collection efficiency spectrometer instrument may offer a viable option for real-time ¹ O₂ dosimetry during PDT treatment using CW light.

Systematic Review and Meta-Analysis of In Vitro Anti-Human Cancer Experiments Investigating the Use of 5-Aminolevulinic Acid (5-ALA) for Photodynamic Therapy

5-Aminolevulinic acid (5-ALA) is an amino acid derivative and a precursor of protoporphyrin IX (PpIX). The photophysical feature of PpIX is clinically used in photodynamic diagnosis (PDD) and photodynamic therapy (PDT). These clinical applications are potentially based on in vitro cell culture experiments. Thus, conducting a systematic review and meta-analysis of in vitro 5-ALA PDT experiments is meaningful and may provide opportunities to consider future perspectives in this field. We conducted a systematic literature search in PubMed to summarize the in vitro 5-ALA PDT experiments and calculated the effectiveness of 5-ALA PDT for several cancer cell types. In total, 412 articles were identified, and 77 were extracted based on our inclusion criteria. The calculated effectiveness of 5-ALA PDT was statistically analyzed, which revealed a tendency of cancer-classification-dependent sensitivity to 5-ALA PDT, and stomach cancer was significantly more sensitive to 5-ALA PDT compared with cancers of different origins. Based on our analysis, we suggest a standardized in vitro experimental protocol for 5-ALA PDT.

PDT dose dosimetry for Photofrin-mediated pleural photodynamic therapy (pPDT)

Photosensitizer fluorescence excited by photodynamic therapy (PDT) treatment light can be used to monitor the in vivo concentration of the photosensitizer and its photobleaching. The temporal integral of the product of in vivo photosensitizer concentration and light fluence is called PDT dose, which is an important dosimetry quantity for PDT. However, the detected photosensitizer fluorescence may be distorted by variations in the absorption and scattering of both excitation and fluorescence light in tissue. Therefore, correction of the measured fluorescence for distortion due to variable optical properties is required for absolute quantification of photosensitizer concentration. In this study, we have developed a four-channel PDT dose dosimetry system to simultaneously acquire light dosimetry and photosensitizer fluorescence data. We measured PDT dose at four sites in the pleural cavity during pleural PDT. We have determined an empirical optical property correction function using Monte Carlo simulations of fluorescence for a range of physiologically relevant tissue optical properties. Parameters of the optical property correction function for Photofrin fluorescence were determined experimentally using tissue-simulating phantoms. In vivo measurements of photosensitizer fluorescence showed negligible photobleaching of Photofrin during the PDT treatment, but large intra- and inter-patient heterogeneities of in vivo Photofrin concentration are observed. PDT doses delivered to 22 sites in the pleural cavity of 8 patients were different by 2.9 times intra-patient and 8.3 times inter-patient.

Photodynamic therapy versus endoscopic submucosal dissection for management of patients with early esophageal neoplasia: a retrospective study

Background

Photodynamic therapy (PDT) and endoscopic submucosal dissection (ESD) have been proposed as a treatment for early esophageal neoplasia. The objective of this study is to compare between the clinical outcome after ESD and PDT to reach the best management for early esophageal neoplasia.

Methods

All patients undergoing ESD or PDT for early esophageal neoplasia between 2014 and 2015 were eligible for the study. A retrospective analysis for comparison between the results of ESD and PDT was done.

Results

36 patients underwent ESD and Thirty PDT. No significant difference was found between the two groups regarding the demographic or pathologic data. Also, there was no significant difference regarding the length of hospital stay, presence of hydrothorax, fever, and pain. Operative time was significantly longer in ESD than in PDT (72 vs. 8 minutes, P<0.001). In addition, bleeding was significantly lower in ESD than PDT (12 vs. 2, P<0.05). There was a significant difference regarding stricture and cost which were less in ESD (6 vs. 15, P<0.05). However, perforation was much more in ESD (6 vs. 0, P<0.05). There was no significant difference between the two groups regarding the disease free survival (DFS), but it was observed that patients who underwent PDT had more favorable 2-year DFS rates than patients received ESD.

Conclusions

The PDT may be comparable to the ESD. With the exception of esophageal stenosis, PDT could reduce many complications and have longer DFS in comparison with ESD. PDT is feasible for patients with early esophageal neoplasia confined to the mucosal layer without regional lymph nodal or distant metastasis.

A Comparison of Dose Metrics to Predict Local Tumor Control for Photofrin-mediated Photodynamic Therapy

This preclinical study examines light fluence, photodynamic therapy (PDT) dose and "apparent reacted singlet oxygen," [¹ O₂ ]_rx , to predict local control rate (LCR) for Photofrin-mediated PDT of radiation-induced fibrosarcoma (RIF) tumors. Mice bearing RIF tumors were treated with in-air fluences (50-250 J cm^-2 ) and in-air fluence rates (50-150 mW cm^-2 ) at Photofrin dosages of 5 and 15 mg kg^-1 and a drug-light interval of 24 h using a 630-nm, 1-cm-diameter collimated laser. A macroscopic model was used to calculate [¹ O₂ ]_rx and PDT dose based on in vivo explicit dosimetry of the drug concentration, light fluence and tissue optical properties. PDT dose and [¹ O₂ ]_rx were defined as a temporal integral of drug concentration and fluence rate, and singlet oxygen concentration consumed divided by the singlet oxygen lifetime, respectively. LCR was stratified for different dose metrics for 74 mice (66 + 8 control). Complete tumor control at 14 days was observed for [¹ O₂ ]_rx ≥ 1.1 mm or PDT dose ≥1200 μm J cm^-2 but cannot be predicted with fluence alone. LCR increases with increasing [¹ O₂ ]_rx and PDT dose but is not well correlated with fluence. Comparing dosimetric quantities, [¹ O₂ ]_rx outperformed both PDT dose and fluence in predicting tumor response and correlating with LCR.

Macroscopic singlet oxygen modeling for dosimetry of Photofrin-mediated photodynamic therapy: an in-vivo study

Although photodynamic therapy (PDT) is an established modality for cancer treatment, current dosimetric quantities, such as light fluence and PDT dose, do not account for the differences in PDT oxygen consumption for different fluence rates ( ? ). A macroscopic model was adopted to evaluate using calculated reacted singlet oxygen concentration ( [ O 2 1 ] rx ) to predict Photofrin-PDT outcome in mice bearing radiation-induced fibrosarcoma tumors, as singlet oxygen is the primary cytotoxic species responsible for cell death in type II PDT. Using a combination of fluences (50, 135, 200, and 250 ?? J / cm 2 ) and ? (50, 75, and 150 ?? mW / cm 2 ), tumor regrowth rate, k , was determined for each condition. A tumor cure index, CI = 1 ? k / k control , was calculated based on the k between PDT-treated groups and that of the control, Available on the SPIE Digital Library.

Photodynamic therapy: oncologic horizons

Photodynamic therapy (PDT) is a light-based intervention with a long and successful clinical track record for both oncology and non-malignancies. In cancer patients, a photosensitizing agent is intravenously, orally or topically applied and allowed time to preferentially accumulate in the tumor region. Light of the appropriate wavelength and intensity to activate the particular photosensitizer employed is then introduced to the tumor bed. The light energy will activate the photosensitizer, which in the presence of oxygen should allow for creation of the toxic photodynamic reaction generating reactive oxygen species. The photodynamic reaction creates a cascading series of events including initiation of apoptotic and necrotic pathways both in tumor and neovasculature, leading to permanent lesion destruction often with upregulation of the immune system. Cutaneous phototoxicity from unintentional sunlight exposure remains the most common morbidity from PDT. This paper will highlight current research and outcomes from the basic science and clinical applications of oncologic PDT and interpret how these findings may lead to enhanced and refined future PDT.

In vitro multiwavelength PDT with 3IL states: teaching old molecules new tricks

The purpose of the present investigation was to ascertain whether (3)IL excited states with microsecond lifetimes are universally potent for photodynamic applications, and if these long-lived states are superior to their (3)MLCT counterparts as in vitro PDT agents. A family of blue-green absorbing, Ru(II)-based transition metal complexes derived from the π-expansive dppn ligand was prepared and characterized according to its photodynamic activity against HL-60 cells, and toward DNA in cell-free media. Complexes in this series that are characterized by low-energy and long-lived (3)IL excited states photocleaved DNA with blue, green, red, and near-IR light. This panchromatic photodynamic effect translated to in vitro multiwavelength photodynamic therapy (PDT) with red-light cytotoxicities as low as 1.5 μM (EC50) for the parent complex and 400 nM for its more lipophilic counterpart. This potency is similar to that achieved with Ru(II)-based dyads containing long-lived (3)IL excitons located on appended pyrenyl units, and appears to be a general property of sufficiently long-lived excited states. Moreover, the red PDT observed for certain members of this family was almost 5 times more potent than Photofrin with therapeutic indices 30 times greater. Related Ru(II) complexes having lowest-lying (3)MLCT states of much shorter duration (≤1 μs) did not yield DNA photodamage or in vitro PDT with red or near-IR light, nor did the corresponding Os(II) complex with a submicrosecond (3)IL excited state lifetime. Therefore, metal complexes that utilize highly photosensitizing (3)IL excited states, with suitably long lifetimes (≫ 1 μs), are well-poised to elicit PDT at wavelengths even where their molar extinction coefficients are very low (<100 M(-1) cm(-1)). Herein we demonstrate that such unexpected reactivity gives rise to very effective PDT in the typical therapeutic window (600-850 nm).

Predictors of esophageal stricture formation post endoscopic mucosal resection

BACKGROUND/AIMS

Stricture formation is a common complication after endoscopic mucosal resection. Predictors of stricture formation have not been well studied.

METHODS

We conducted a retrospective, observational, descriptive study by using a prospective endoscopic mucosal resection database in a tertiary referral center. For each patient, we extracted the age, sex, lesion size, use of ablative therapy, and detection of esophageal strictures. The primary outcome was the presence of esophageal stricture at follow-up. Multivariate logistic regression was used to analyze the association between the primary outcome and predictors.

RESULTS

Of 136 patients, 27% (n=37) had esophageal strictures. Thirty-two percent (n=44) needed endoscopic dilation to relieve dysphagia (median, 2; range, 1 to 8). Multivariate logistic regression analysis showed that the size of the lesion excised is associated with increased odds of having a stricture (odds ratio, 1.6; 95% confidence interval, 1.1 to 2.3; p=0.01), when controlling for age, sex, and ablative modalities. Similarly, the number of lesions removed in the index procedure was associated with increased odds of developing a stricture (odds ratio, 2.3; 95% confidence interval, 1.3 to 4.2; p=0.007).

CONCLUSIONS

Stricture formation after esophageal endoscopic mucosal resection is common. Risk factors for stricture formation include large mucosal resections and the resection of multiple lesions on the initial procedure.

Survival in esophageal high-grade dysplasia/adenocarcinoma post endoscopic resection

BACKGROUND

Endoscopic resection followed by ablative therapy is frequently used to treat esophageal high-grade dysplasia or early esophageal adenocarcinoma.

AIMS

To study outcomes in patients with high-grade dysplasia compared to those with esophageal adenocarcinoma after endoscopic resection.

METHODS

Retrospective, observational, descriptive, single-centre study from a prospective database. We extracted data from 116 endoscopic resections. Survival was plotted using Kaplan-Meier curves multivariable Cox-proportional hazard assess for possible predictors of survival post-endoscopic resection was performed.

RESULTS

116 patients (64 esophageal adenocarcinoma, 52 high-grade dysplasia) underwent endoscopic resection from May 2003 to June 2010. Mean age was 71 ± 11 years for high-grade dysplasia and 72 ± 10 years for esophageal adenocarcinoma. Median follow-up was 17 months. Eighty-five patients had negative margins on endoscopic resection. Five-year survivals for high-grade dysplasia and esophageal adenocarcinoma were 86% (range 68-100%) and 78% (59-96%), respectively. Survival was not significantly different between groups (p=0.20). Overall mortality rate was 10.6% (9/85). At multivariable Cox regression increased Barrett's oesophagus length was associated with worse survival (HR 1.18 [1.06-1.33], p=0.0039). Survival was not affected by the pathology before resection: HR 2.4 [95%CI, 0.70-8.4], p=0.16.

CONCLUSIONS

Survival in patients with high-grade dysplasia of the oesophagus is similar to those with esophageal adenocarcinoma. Longer Barrett's oesophagus segments are associated with decreased survival.

Endoscopic management of esophageal cancer after definitive chemoradiotherapy

BACKGROUND

Concurrent chemoradiotherapy (CRT) is a potentially curative non-surgical option for locally advanced esophageal cancer, with pathological complete response (CR) ranging from 13 to 49 %. The rate of persistent and recurrent disease within the esophagus remains high at 40-60 %, and treatment of these tumors may improve disease-free survival. The aim of this review is to assess the efficacy of salvage endoscopic therapies for recurrent esophageal cancer.

METHODS

Medline and Embase were searched for relevant studies published in the English-language literature that reported use of endoscopic modalities, including photodynamic therapy (PDT), endoscopic mucosal resection (EMR), and spray cryotherapy, as salvage therapies for esophageal cancer.

RESULTS

A total of 12 studies were identified. In small case series of PDT, CR varied from 20 to 100 %, with 1-, 3-, and 5-year overall survival rates of 65-80, 34-47, and 36 %, respectively. Data from three studies of EMR in squamous cell cancer show CR in 50 % of cases, with 3- and 5-year overall survival of 56-81 and 49 %, respectively. Endoscopic spray cryotherapy has recently been used in this setting with an observed CR of 37.5 %.

CONCLUSIONS

Endoscopic salvage therapies are options for those patients with disease limited to the superficial esophageal wall and those who are unfit to undergo salvage esophagectomy. Widespread application of endoscopic salvage therapies is limited by the lack of awareness and guidelines for endoscopic surveillance post-CRT and limited data on the effectiveness of endoscopic therapies.

PhotoImmunoNanoTherapy reveals an anticancer role for sphingosine kinase 2 and dihydrosphingosine-1-phosphate

Tumor-associated inflammation mediates the development of a systemic immunosuppressive milieu that is a major obstacle to effective treatment of cancer. Inflammation has been shown to promote the systemic expansion of immature myeloid cells which have been shown to exert immunosuppressive activity in laboratory models of cancer as well as cancer patients. Consequentially, significant effort is underway toward the development of therapies that decrease tumor-associated inflammation and immunosuppressive cells. The current study demonstrated that a previously described deep tissue imaging modality, which utilized indocyanine green-loaded calcium phosphosilicate nanoparticles (ICG-CPSNPs), could be utilized as an immunoregulatory agent. The theranostic application of ICG-CPSNPs as photosensitizers for photodynamic therapy was shown to block tumor growth in murine models of breast cancer, pancreatic cancer, and metastatic osteosarcoma by decreasing inflammation-expanded immature myeloid cells. Therefore, this therapeutic modality was termed PhotoImmunoNanoTherapy. As phosphorylated sphingolipid metabolites have been shown to have immunomodulatory roles, it was hypothesized that the reduction of immature myeloid cells by PhotoImmunoNanoTherapy was dependent upon bioactive sphingolipids. Mechanistically, PhotoImmunoNanoTherapy induced a sphingosine kinase 2-dependent increase in sphingosine-1-phosphate and dihydrosphingosine-1-phosphate. Furthermore, dihydrosphingosine-1-phosphate was shown to selectively abrogate myeloid lineage cells while concomitantly allowing the expansion of lymphocytes that exerted an antitumor effect. Collectively, these findings revealed that PhotoImmunoNanoTherapy, utilizing the novel nontoxic theranostic agent ICG-CPSNP, can decrease tumor-associated inflammation and immature myeloid cells in a sphingosine kinase 2-dependent manner. These findings further defined a novel myeloid regulatory role for dihydrosphingosine-1-phosphate. PhotoImmunoNanoTherapy holds the potential to be a revolutionary treatment for cancers with inflammatory and immunosuppressive phenotypes.

Peritoneal sarcomatosis in pediatric malignancies

Peritoneal sarcomatosis (PSC) is defined as peritoneal involvement of multiple sarcomatous tumors. Desmoplastic small round cell tumors (DSRCT) and rhabdomyosarcomas are the most common pediatric PSC cases. PSC has been treated with chemotherapy and mainly palliative surgery, but long-term outcome has been poor. New imaging technologies have improved the evaluation of disease extent and patterns of peritoneal dissemination, and cytoreductive surgery followed by hyperthermic intraperitoneal chemotherapy (HIPEC) is being evaluated as a treatment option to prolong remission in pediatric patients. We will review the clinical characteristics, potential biologic mechanisms, radiographic characteristics, and potential therapies for pediatric PSC patients.

Endotherapy for Barrett's esophagus

Endotherapy is now the mainstay of therapy for Barrett's associated neoplasia. The approach should begin with confirmation of neoplasia by a gastrointestinal pathologist, patient counseling, and appropriate endoscopic work up. Detailed examination with high-resolution white light endoscopy is the most important tool for detection of neoplasia. Further validation studies are needed for many enhanced imaging modalities before being recommended as part of the standard work up and assessment of patients with Barrett's esophagus (BE). Endoscopic mucosal resection is required for any visible lesion in the setting of dysplasia for accurate histological diagnosis. The remainder of the epithelium may be treated with resection or ablative therapy, followed by adequate surveillance. Patients with nondysplastic Barrett's require further risk stratification before incorporation of ablative therapy for this population. The future will fortify the endoscopic role in Barrett's with validation trials for endoscopic assessment, further long-term results for each of the treatment modalities, potential risk stratification for patients with BE, and improved guidelines for surveillance after therapy.

Insights into photodynamic therapy dosimetry: simultaneous singlet oxygen luminescence and photosensitizer photobleaching measurements

Photodynamic therapy (PDT) is generally based on the generation of highly reactive singlet oxygen ((1)O(2)) through interactions of photosensitizer, light, and oxygen ((3)O(2)). These three components are highly interdependent and dynamic, resulting in variable temporal and spatial (1)O(2) dose deposition. Robust dosimetry that accounts for this complexity could improve treatment outcomes. Although the 1270 nm luminescence emission from (1)O(2) provides a direct and predictive PDT dose metric, it may not be clinically practical. We used (1)O(2) luminescence (or singlet oxygen luminescence (SOL)) as a gold-standard metric to evaluate potentially more clinically feasible dosimetry based on photosensitizer bleaching. We performed in vitro dose-response studies with simultaneous SOL and photosensitizer fluorescence measurements under various conditions, including variable (3)O(2), using the photosensitizer meta-tetra(hydroxyphenyl)chlorin (mTHPC). The results show that SOL was always predictive of cytotoxicity and immune to PDT's complex dynamics, whereas photobleaching-based dosimetry failed under hypoxic conditions. However, we identified a previously unreported 613 nm emission from mTHPC that indicates critically low (3)O(2) levels and can be used to salvage photobleaching-based dosimetry. These studies improve our understanding of PDT processes, demonstrate that SOL is a valuable gold-standard dose metric, and show that when used judiciously, photobleaching can serve as a surrogate for (1)O(2) dose.

Optimal management of Barrett's esophagus: pharmacologic, endoscopic, and surgical interventions

Esophageal adenocarcinoma and its precursor, Barrett’s esophagus, are rapidly rising in incidence. This review serves to highlight the role of pharmacologic, endoscopic, and surgical intervention in the management of Barrett’s esophagus, which requires acid suppression and endoscopic assessment. Treatment with a proton pump inhibitor may decrease acid exposure and delay the progression to dysplasia. Patients who require aspirin for cardioprotection or other indications may also benefit in terms of a protective effect against the development of esophageal cancer. However, without other indications, aspirin is not indicated solely to prevent cancer. A careful endoscopic examination should include assessment of any visible lesions in a Barrett’s segment. An expert gastrointestinal pathologist should confirm neoplasia in the setting of Barrett’s esophagus. For those patients with high-grade dysplasia or intramucosal carcinoma, careful consideration of endoscopic therapy or surgical therapy must be given. All visible lesions in the setting of dysplasia should be targeted with focal endoscopic mucosal resection for both accurate histopathologic diagnosis and treatment. The remainder of the Barrett’s epithelium should be eradicated to address all synchronous and metachronous lesions. This may be done by tissue acquiring or nontissue acquiring means. Radiofrequency ablation has a positive benefit-risk profile for flat Barrett’s esophagus. At this time, endoscopic therapy is not indicated for nondysplastic Barrett’s esophagus. Esophagectomy is still reserved for selected cases with evidence of lymph node metastasis, unsuccessful endoscopic therapy, or with high-risk features of high-grade dysplasia or intramucosal carcinoma.

Temoporfin (Foscan®, 5,10,15,20-tetra(m-hydroxyphenyl)chlorin)--a second-generation photosensitizer

This review traces the development and study of the second-generation photosensitizer 5,10,15,20-tetra(m-hydroxyphenyl)chlorin through to its acceptance and clinical use in modern photodynamic (cancer) therapy. The literature has been covered up to early 2011.

Tissue responses to hexyl 5-aminolevulinate-induced photodynamic treatment in syngeneic orthotopic rat bladder cancer model: possible pathways of action

Orthotopic bladder cancer model in rats mimics human bladder cancer with respect to urothelial tumorigenesis and progression. Utilizing this model at pT1 (superficial stage), we analyze the tissue responses to hexyl 5-aminolevulinate-induced photodynamic therapy (HAL-PDT). In comparison to untreated rats, HAL-PDT causes little change in tumor-free rat bladder but induces inflammatory changes with increased lymphocytes and mononuclear cell infiltration in rat bladders with tumor. Immunohistochemistry reveals that HAL-PDT is without effect on proliferating cell nuclear antigen expression within the tumor and increases caspase-3 expression in both normal urothelium and the tumor. Transmission electron microscopy reveals severe mitochondrial damage, formations of apoptotic bodies, vacuoles, and lipofuscin bodies, but no microvillus-formed niches in HAL-PDT-treated bladder cancer rats. Bioinformatics analysis of the gene expression profile indicates an activation of T-cell receptor signaling pathway in bladder cancer rats without PDT. HAL-PDT increases the expression of CD3 and CD45RA in the tumor (determined by immunohistochemistry). We suggest that pathways of action of HAL-PDT may include, at least, activations of mitochondrial apoptosis and autophagy, breakdown of cancer stem cell niches, and importantly, enhancement of T-cell activation.

Endotherapy for Barrett's esophagus: Which, how, when, and who?

Recent developments in endoscopic therapeutic options for Barrett's esophagus (BE) early neoplasia have resulted in a dramatic paradigm shift in its clinical management. With multiple endoscopic choices available, it is important to discern subtle differences between these approaches based on the available current data and known limitations of each modality. The goals of endoscopic therapy of Barrett's neoplasia are to preserve the esophagus while ablating or removing the entire BE segment. This article reviews the currently available BE endoscopic treatments with emphasis on appropriate selection of patients, indications and timing of use, and clinical management considerations.

Photodynamic therapy

Photodynamic therapy (PDT) is a photochemical process that uses a photosensitizer drug activated by laser light to produce mucosal ablation. Porfimer sodium PDT has proved long-term efficacy and durability in the treatment of Barrett's esophagus and high-grade dysplasia and early esophageal adenocarcinoma. Its use has been limited by serious side effects including prolonged cutaneous photosensitivity and stricture formation. Other photosensitizers with a better safety profile have been used mostly in Europe with limited experience. The future of PDT lies on a better understanding of dosimetry, tissue properties, and host genetic factors.

Advances in endoscopic diagnosis and treatment of Barrett's esophagus

Barrett's esophagus (BE) is defined as abnormal specialized columnar metaplasia with intestinalization in place of the normal squamous esophageal epithelium. Gastroesophageal reflux disease is a known risk factor for BE; nonetheless BE is also detected in asymptomatic individuals. Other risk factors for BE include smoking, male gender, age over 50 and obesity. Patients diagnosed with BE (without dysplasia) are recommended to undergo endoscopic surveillance every 3-5 years. Advances in imaging techniques (such as narrow band imaging, autofluorescence imaging and confocal laser endomicroscopy) have the potential to improve the detection of dysplasia and early cancer, thus making surveillance a more cost-effective endeavor. Patients with high grade dysplasia (HGD) and early cancer have a high rate of progression to invasive adenocarcinoma and traditionally these patients were treated with esophagectomy. The rapid advancement of endoscopic therapeutic techniques along with a low risk of complications have made endoscopic therapy an acceptable alternative to an esophagectomy in patients with HGD and early cancer. Several endoscopic treatment techniques such as endoscopic mucosal resection, multipolar electrocoagulation, photodynamic therapy, argon plasma coagulation, cryotherapy, and radiofrequency ablation have been studied for endoscopic treatment.

New endoscopic and surgical treatment options for early esophageal adenocarcinoma

Although the outcome for advanced stage esophageal cancer is poor, the early detection and treatment of early stage disease is usually associated with a much better outcome. Until recently, esophagectomy has been the treatment of choice in fit patients. However, morbidity is significant, and this has encouraged the development of newer endoscopic treatments that preserve the esophagus. These techniques include ablation and mucosal resection. Promising results are described, and endoscopic methods might provide a reasonable alternative for the treatment of early esophageal cancer. However, follow-up remains short and endoscopic treatment does not deal with potential lymphatic spread. Hence, careful selection is required. Minimally invasive techniques for esophageal resection have also been shown to be feasible, although there is only limited evidence that they reduce postoperative morbidity. Better data are still required to demonstrate improved outcomes from endoscopic treatment and minimally invasive esophagectomy.

Continuous or fractionated photodynamic therapy? Comparison of three PDT schemes for ovarian peritoneal micrometastasis treatment in a rat model

OBJECTIVE

This experimental study aimed to compare three illumination schemes to optimize hexaminolaevulinate (HAL)-PDT in a rat tumor model with advanced ovarian cancer.

MATERIALS AND METHODS

Peritoneal carcinomatosis was induced by intraperitoneal 5×10(6)NuTu-19 cells injection in 60 female rats Fisher 344. Carcinomatosis was obtained 50 days post-tumor induction. Four hours post-intraperitoneal HAL (Photocure ASA, Oslo, Norway) injection, three different schemes of PDT were performed during 25 min on a 1cm(2) area. (A) Fractionated illumination (n=20) with an on-off cycle ("on": 2 min and "off": 1 min) at 30mW cm(-2) until a fluence of 30J cm(-2), (B) continuous illumination (n=20) at 30mW cm(-2) with a fluence of (45J cm(-2)C) continuous illumination (n=20) at 20mW cm(-2) with a fluence of 30J cm(-2). Laser light was generated using a 532nm KTP laser (Laser Quantum, Stockport, UK). Biopsies were taken 24h after treatment. Quantitative histology was performed. Necrosis value was determined: 0-no necrosis to 4-full necrosis. Depth of necrosis was then measured for each sample and correlated to Necrosis value.

RESULTS

HAL-PDT was efficient in producing necrosis irrespective of the scheme. Tumor destruction was superior with fractionated illumination compared to both continuous illumination schemes regarding to the depth of necrosis (213±113μm vs 154±133μm vs 171±155μm) (p<0.05) or to the full necrosis rate (50% vs 30% vs 10%) (p<0.0001).

CONCLUSION

Fractionated illumination during photodynamic therapy (PDT) was shown to improve tumor response. Fractionated illumination with short intervals should be considered for an effective PDT of advanced ovarian cancer.

Endoscopic treatment of Barrett’s esophagus: From metaplasia to intramucosal carcinoma

The annual incidence of adenocarcinoma arising from Barrett’s esophagus (BE) is approximately 0.5%. Through a process of gradual transformation from low-grade dysplasia to high-grade dysplasia (HGD), adenocarcinoma can develop in the setting of BE. The clinical importance of appropriate identification and treatment of BE in its various stages, from intestinal metaplasia to intramucosal carcinoma (IMC) hinges on the dramatically different prognostic status between early neoplasia and more advanced stages. Once a patient has symptoms of adenocarcinoma, there is usually locally advanced disease with an approximate 5-year survival rate of about 20%. Esophagectomy has been the gold standard treatment for BE with HGD, due to the suspected risk of harboring occult invasive carcinoma, which was traditionally estimated to be as high as 40%. In recent years, the paradigm of BE early neoplasia management has recently evolved, and endoscopic therapies (endoscopic mucosal resection, radiofrequency ablation, and cryotherapy) have entered the clinical forefront as acceptable non-surgical alternatives for HGD and IMC. The goal of endoscopic therapy for HGD or IMC is to ablate all BE epithelium (both dysplastic and non-dysplastic) due to risk of synchronous/metachronous lesion development in the remaining BE segment.