Photodynamic therapy in the treatment of multiple primary tumours in the head and neck, located to the oral cavity and oropharynx

Photodynamic therapy for squamous cell carcinoma of the head and neck: narrative review focusing on photosensitizers

This narrative review aimed to evaluate the effectiveness of PDT in early or advanced squamous cell carcinoma of the head and neck (SCCHN). Scopus, MEDLINE/PubMed, and Embase were searched electronically following the PRISMA protocol. Quality assessment was performed according to JBI, NIH, and AMSTAR protocols. The main outcomes evaluated were treatment response, recurrence, survival, and adverse effects. A total of 49 articles met the search criteria: 43 case series, two cohort studies, two prospective before-after clinical trials, one systematic review, and one meta-analysis. Data from 2121 SCCHN patients were included. The response to PDT was variable according to the type of photosensitizer, tumor location, and tumor stage. In general, higher complete responses rated were observed in T1/T2 SCCHN, mainly with mTHPC-mediated PDT. With regard to T3/T4 or advanced SCCHN tumors, there is no compelling evidence suggesting the effectiveness of PDT. Any adverse effects reported were well tolerated by patients. The present review suggests that PDT is a promising treatment modality for early-stage SCCHN. Although there are limitations due to the low level of evidence of the included studies, we believe that the present review could help to design robust clinical trials to determine the efficacy of PDT in SCCHN.

Photodynamic Therapy for Oral Squamous Cell Carcinoma: A Systematic Review and Meta-Analysis

To assess the efficacy of photodynamic therapy (PDT) for oral squamous cell carcinoma (OSCC), literature on this topic from Embase, PubMed, and Web of Science were obtained and analyzed. The response and recurrence rates with 95% confidence intervals (CI) were calculated using the DerSimonia–Laird method. The pooled complete response (CR) rate from the included studies was 0.799 (95% CI: 0.708–0.867), while the overall response (OR) rate was 0.967 (95% CI: 0.902–0.989). The recurrence rate (RR) was 0.158 (95% CI: 0.090–0.264). A subgroup analysis of lesion site, photosensitizer, laser type, radiant exposure, and power density revealed no statistically significant differences. In general, PDT is effective for the treatment of early OSCC. Investigations on the influence of PDT on the survival of OSCC patients, optimization of the treatment regimen, and evaluation of response after treatment are still needed.

Sensitivity of Papilloma Virus-Associated Cell Lines to Photodynamic Therapy with Curcumin-Loaded Liposomes

Simple Summary

Globally, the burden of papilloma virus-associated cancers is high. About 5% of all cancers worldwide are caused by the human papillomavirus (HPV). Photodynamic therapy (PDT) is considered as a useful therapeutic option to treat cancers, particularly those near the tissue surface, since it is typically well tolerated and less invasive with a lower risk of severe complications as compared to conventional treatment strategies. PDT requires the combination of a photosensitizer, light of a specific wavelength, and tissue oxygen. In the present study, we examined the effectiveness of PDT together with a curcumin (liposome)-based photosensitizer in three papilloma virus-associated cell lines. PDT with curcumin liposomes could inhibit proliferation, cell migration, and colony formation of the tested tumor cells. The results suggest that curcumin-encapsulated liposomes in conjunction with PDT could be a useful tool for the treatment of papilloma virus-associated tumors.

Abstract

Photodynamic therapy (PDT) is a minimally invasive therapeutic approach used in the treatment of various medical conditions and cancerous diseases, involving light, a photosensitizing substance, and oxygen. Curcumin, a naturally occurring compound, carries antitumor activities and potentially could be exploited as a photosensitizer in PDT. Only little is known about liposomal-encapsulated curcumin that could help in increasing the efficacy, stability, and bioavailability of this compound. This study investigates the in vitro effects of curcumin-loaded liposomes in combination with PDT. Three papilloma virus-associated cell lines were treated with curcumin-loaded liposomes corresponding to a curcumin concentration of 0–100 µmol/L for 4 h followed by illumination at 457 nm (blue) for 45, 136, and 227 s at a fluence of 220.2 W/m² (100 mA) corresponding to 1, 3 and 5 J·cm⁻². After 24 h, the biological outcome of the treatment was assessed with the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), SYTO9/PI (propidium iodide), Annexin V-FITC (fluorescein isothiocyanate)/PI, clonogenic survival, and scratch (wound closure) assays. Photoactivation of curcumin-loaded liposomes led to a significant reduction in colony formation and migratory abilities, as well as to an increase in tumor cell death. The results point to the combination of curcumin-loaded liposomes with PDT as a potentially useful tool for the treatment of papillomavirus-associated malignancies.

Effect of Photodynamic Therapy on Cyclin D1 and P53 mRNA Levels in Head and Neck Squamous Cell Carcinoma Cell Line

Background: Photodynamic Therapy (PDT) is considered as one of the alternative treatments for Head and Neck Squamous Cell Carcinoma (HNSCC). P53 mRNA is a tumor suppressor gene whose mutation increases the likelihood of uncontrolled cancer-like divisions. The mutation of CCND1 oncogenic increases the production of cyclin D1 as a tumorigenic protein. Objectives: This study aimed to determine the effect of PDT using toluidine blue as a photosensitizer on the CCND1 and P53 mRNA levels in the HNSCC cell line. Methods: A human HNSCC cell line from NCBI.C196 designation HN5 was used. Cells were divided into four groups: Group I (HNSCC cell line under the influence of toluidine blue and laser irradiation), group II (HNSCC cell line under the influence of toluidine blue), group III (HNSCC cell line under laser irradiation), group IV (control group, HNSCC cell line). A 660 nm THOR laser using toluidine blue as a photosensitizer was applied. The RNA extraction was performed in three steps, including cell degradation, purification, and precipitation by alcohol. The cDNA was prepared using Takara Kit. The Amplicon kit and Real-Time PCR analysis were used for the assessment of mRNA relative levels. Results: The P53 mRNA relative levels were 1.50 ± 0.33 in group I (P = 0.65), 1.49 ± 0.23 (P =0.5) in group II, and 1.40 ± 1.05 (P = 0.63) in group III. Compared to the control group, the mean increases in CCND1 mRNA were 18.01 ± 3.37 (p=0.04) in group I, 17.69 ± 3.3 (P = 0.03) in group II, and 9.01 ± 6.17 (P = 0.20) in group III. Conclusions: The comparison of the fold change index for P53 and CCND1 mRNA by the one-way ANOVA test showed that despite the increased expression of P53 and CCND1 mRNA in treatment groups compared to the control group, there was no statistically significant difference between the increases in P53 mRNA (P = 0.99) and CCND1 mRNA (P = 0.22) index between the groups. The results of this study could be a starting point for a better understanding of the mechanism of genes in PDT of the HNSCC cell line.

Novel therapies in the management of oral cancer: An update

An estimated 4% of all cancers are of the oral cavity or oropharyngeal. Presently, management of the oral cancers mainly includes surgery, radiotherapy, and chemotherapy either alone or in combination depending on the individual case. Each of these techniques has their advantages and disadvantages. Surgery demands removal of cancerous tissue causing disfigurement and functional impairment. Radiotherapy has significant side effects like mucositis, myelosuppression, xerostomia and dental caries. With the advent of newer treatment methods like the targeted therapy, immune therapy and gene therapy, treatment outcomes are better with fewer side effects. This has generally improved survival rates and quality of life of cancer patients.

Platform for ergonomic intraoral photodynamic therapy using low-cost, modular 3D-printed components: Design, comfort and clinical evaluation

Oral cancer prevalence is increasing at an alarming rate worldwide, especially in developing countries which lack the medical infrastructure to manage it. For example, the oral cancer burden in India has been identified as a public health crisis. The high expense and logistical barriers to obtaining treatment with surgery, radiotherapy and chemotherapy often result in progression to unmanageable late stage disease with high morbidity. Even when curative, these approaches can be cosmetically and functionally disfiguring with extensive side effects. An alternate effective therapy for oral cancer is a light based spatially-targeted cytotoxic therapy called photodynamic therapy (PDT). Despite excellent healing of the oral mucosa in PDT, a lack of robust enabling technology for intraoral light delivery has limited its broader implementation. Leveraging advances in 3D printing, we have developed an intraoral light delivery system consisting of modular 3D printed light applicators with pre-calibrated dosimetry and mouth props that can be utilized to perform PDT in conscious subjects without the need of extensive infrastructure or manual positioning of an optical fiber. To evaluate the stability of the light applicators, we utilized an endoscope in lieu of the optical fiber to monitor motion in the fiducial markers. Here we showcase the stability (less than 2 mm deviation in both horizontal and vertical axis) and ergonomics of our applicators in delivering light precisely to the target location in ten healthy volunteers. We also demonstrate in five subjects with T1N0M0 oral lesions that our applicators coupled with a low-cost fiber coupled LED-based light source served as a complete platform for intraoral light delivery achieving complete tumor response with no residual disease at initial histopathology follow up in these patients. Overall, our approach potentiates PDT as a viable therapeutic option for early stage oral lesions that can be delivered in low resource settings.

Effect of Curcumin-Nanoemulsion Associated with Photodynamic Therapy in Cervical Carcinoma Cell Lines

Cervical cancer is the fourth cause of cancer death in women. Curcumin has antineoplastic properties. Furthermore, curcumin may be used as a photosensitizing agent in Photodynamic Therapy. This study aimed to investigate the effects of Photodynamic Therapy in cellular viability using curcumin-nanoemulsion as a photosensitizing drug in cervical carcinoma cell lines. The empty nanoemulsion presented very low cytotoxicity in all cell lines analyzed. Additionally, the incubation with curcumin-nanoemulsion at 20 μM of curcumin showed more than 80% of cell viability for cell lines. Nanoemulsions were shown to be internalized inside cells by fluorescence microscopy and were observed in the intracellular environment for up to 36 hours after incubation with cell lines. In addition, after the Photodynamic Therapy we observed a high phototoxic effect of the curcumin-nanoemulsion with less than 5% of viable cells after irradiation. This was accompanied by an increase in caspase-3/caspase-7 activities after cell treatment with curcumin-nanoemulsion and Photodynamic Therapy, suggesting cell death by apoptosis. We conclude that the curcumin-nanoemulsion formulation behaves as a photosensitizing drug in Photodynamic Therapy and shows potential as an alternative treatment to cervical lesions using an endoscopic diode fiber laser setup for in situ activation or cavity activation using a diffuse fiber delivery system.

Utility of photodynamic therapy for the management of oral potentially malignant disorders and oral cancer

Photodynamic therapy (PDT), defined as “the light-induced inactivation of cells, microorganisms, or molecules,” combines the use of a photosensitive agent or photosensitizer (PS) activated by irradiation with a light source to produce reactive oxygen species and highly reactive singlet oxygen. PDT has been used for the treatment of different oral diseases with promising results. This review describes the basic principles of PDT, including the nature of PS and the light sources, and focuses on evaluating the efficacy of this method, according to the existing data, for the treatment of different oral diseases. PubMed was used as the source of the relevant literature, about the clinical application of PDT in actinic cheilitis (AC), leukoplakia, oral lichen planus, oral lichenoid lesions, and oral cancer. Complete response to PDT as high as 100% has been reported not only in cases of AC but also in dysplasias/carcinomas in situ, T1N0, and T2N0. According to the available data, PDT appears to be a safe, well-tolerated therapy with limited adverse effects and excellent cosmetic outcome. Although PDT is a very promising therapy, further research is needed in order to investigate the cases that fail to respond, to examine the long-term prognosis for cases of reported complete response and thus avoid the future recurrence of diseases.

Prospects in the Application of Photodynamic Therapy in Oral Cancer and Premalignant Lesions

Oral cancer is a global health burden with significantly poor survival, especially when the diagnosis is at its late stage. Despite advances in current treatment modalities, there has been minimal improvement in survival rates over the last five decades. The development of local recurrence, regional failure, and the formation of second primary tumors accounts for this poor outcome. For survivors, cosmetic and functional compromises resulting from treatment are often devastating. These statistics underscore the need for novel approaches in the management of this deadly disease. Photodynamic therapy (PDT) is a treatment modality that involves administration of a light-sensitive drug, known as a photosensitizer, followed by light irradiation of an appropriate wavelength that corresponds to an absorbance band of the sensitizer. In the presence of tissue oxygen, cytotoxic free radicals that are produced cause direct tumor cell death, damage to the microvasculature, and induction of inflammatory reactions at the target sites. PDT offers a prospective new approach in controlling this disease at its various stages either as a stand-alone therapy for early lesions or as an adjuvant therapy for advanced cases. In this review, we aim to explore the applications of PDT in oral cancer therapy and to present an overview of the recent advances in PDT that can potentially reposition its utility for oral cancer treatment.

Photodynamic therapy: a review and its prospective role in the management of oral potentially malignant disorders

With the unreliability of epithelial dysplasia as a predictor to determine the risk of future malignant development, subjectivity associated in evaluating dysplasia by pathologists and paucity of biomarkers that could accurately predict the progression risks in oral potentially malignant disorders (PMDs), eradication of the lesions appears to be the most desirable approach to minimize the risk of invasive cancer formation. Interventions, such as surgery and chemoprevention, have not shown promising long-term results in the treatment of these lesions, and lack of guidelines and general consensus on their management has incited much anxiety and doubts in both patients and community clinicians. Topical photodynamic therapy (PDT) is a minimally invasive and minimally toxic technique that in recent years has shown great promise in the management of PMDs. In this review, we describe the historical developments in the field of PDT, its basic mechanisms, as well as related clinical studies, and its challenges in the management of oral PMDs. Based on its high efficacy and low side effects, its high patient acceptance/compliance, the simplicity of the procedure and its minimal pretreatment preparation, topical PDT is believed to have potential to play an important role in the management of PMDs, especially of the low-grade dysplasia.

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.

Vocal fold vibration after photofrin-mediated photodynamic therapy for treatment of early-stage laryngeal malignancies

OBJECTIVE/HYPOTHESIS

To analyze vocal fold vibration after photofrin-mediated photodynamic therapy (PDT) for the treatment of Tis and T1N0M0 squamous cell carcinoma (SqCCa) tumors of the larynx. It was hypothesized that key attributes of vocal fold vibration would return to baseline within 1-6 months of treatment.

STUDY DESIGN

Retrospective.

METHODS

Laryngovideostroboscopic data were retrospectively analyzed for eight patients with Tis-T1N0M0 SqCCa tumors of the larynx treated with photofrin-mediated PDT. Baseline and posttreatment videostroboscopy images of select vibratory characteristics of the vocal folds were randomized and analyzed by a speech-language pathologist and fellowship-trained laryngologist specializing in voice disorders.

RESULTS

Significant improvement in mucosal wave (P=0.003) and amplitude of vibration (P=0.004) occurred at greater than or equal to 20 weeks post-PDT compared with baseline. Comparing results within 5 weeks postprocedure to 10-19-weeks postprocedure revealed significant improvement in amplitude of vibration (P=0.013) and nonvibrating portion of the vocal fold (P=0.020). Comparing results within 5-weeks postprocedure to 20 or more weeks postprocedure revealed significant improvement in amplitude of vibration (P=0.001), mucosal wave (P=0.001), and nonvibrating portion of the effected fold (P=0.001).

CONCLUSION

Photofrin-mediated PDT allows for preservation of function and structure of the larynx without systemic toxicity; however, it may take 4-5 months or more for key vibratory characteristics of the vocal folds to recover posttreatment.

Lethal photosensitization of Porphyromonas gingivalis by their endogenous porphyrins under anaerobic conditions: an in vitro study

BACKGROUND

Lethal photosensitization has been previously demonstrated in Porphyromonas gingivalis, but oxygen is considered to be essential to this process. However, since P. gingivalis is a periodontal pathogen which grows in the low oxygen conditions found in the subgingival crevice, it was considered prudent to study its photosensitivity in anaerobic conditions.

METHODS

A series of experiments were undertaken to attempt to induce lethal photosensitization in P. gingivalis (ATCC 33277) under strict anaerobic conditions using two different 405 nm light sources. Samples of P. gingivalis were grown on a blood-containing, solid growth medium before being suspended in saline and then exposed to 405 nm light delivered by either a hand-held light source (Toothcare™) (11.4 mW/cm(2)) or a laser pointer (328.5 mW/cm(2)). With the exception of the adjustment of the P. gingivalis suspensions to a fixed optical density, the experiments were carried out in their entirety within an anaerobic chamber.

RESULTS

The lowest Toothcare light dose tested (0.34 J/cm(2); 30s) yielded a statically significant kill of 63.4% which increased to 94.1% kill at higher light doses (3.42 J/cm(2); 300 s). The laser pointer similarly achieved kills of 90.2% at the lower light dose tested (9.86 J/cm(2); 30s) and 94.5% kill at the highest light dose (98.55 J/cm(2); 300 s).

CONCLUSIONS

Lethal photosensitization can be instigated in planktonic suspensions of P. gingivalis at 405 nm delivered by hand-held devices under anaerobic conditions. This suggests the possibility that lethal photosensitization occurred by the oxygen-independent type I pathway as oppose to the oxygen-dependent type II pathway.

mTHPC-mediated photodynamic therapy of early stage oral squamous cell carcinoma: a comparison to surgical treatment

BACKGROUND

mTHPC-mediated photodynamic therapy (PDT) is used for treatment of early head and neck squamous cell carcinoma. This study is a retrospective comparison of PDT with transoral surgery in the treatment of early primary squamous cell carcinoma of the oral cavity/oropharynx.

METHODS

PDT data were retrieved from four study databases; surgical results were retrieved from our institutional database. To select similar primary tumors, infiltration depth was restricted to 5 mm for the surgery group. A total of 126 T1 and 30 T2 tumors were included in the PDT group, and 58 T1 and 33 T2 tumors were included in the surgically treated group.

RESULTS

Complete response rates with PDT and surgery were 86 and 76% for T1, respectively, and for T2 63 and 78%. Lower local disease-free survival for PDT compared to surgery was found. However, when comparing the need for local retreatment, no significant difference for T1 tumors was found, while for T2 tumors surgery resulted in significantly less need for local retreatment. No significant differences in overall survival between surgery and PDT were observed.

CONCLUSIONS

PDT for T1 tumors results in a similar need for retreatment compared to surgery, while for T2 tumors PDT performs worse. Local disease-free survival for surgery is better than for PDT. This may be influenced by the benefit surgery has of having histology available. This allows an early decision on reintervention, while for PDT one has to follow a wait-and-see policy. Future prospective studies should compare efficacy as well as morbidity.

A cell-targeted photodynamic nanomedicine strategy for head and neck cancers

Photodynamic therapy (PDT) holds great promise for the treatment of head and neck (H&N) carcinomas where repeated loco-regional therapy often becomes necessary due to the highly aggressive and recurrent nature of the cancers. While interstitial light delivery technologies are being refined for PDT of H&N and other cancers, a parallel clinically relevant research area is the formulation of photosensitizers in nanovehicles that allow systemic administration yet preferential enhanced uptake in the tumor. This approach can render dual-selectivity of PDT, by harnessing both the drug and the light delivery within the tumor. To this end, we report on a cell-targeted nanomedicine approach for the photosensitizer silicon phthalocyanine-4 (Pc 4), by packaging it within polymeric micelles that are surface-decorated with GE11-peptides to promote enhanced cell-selective binding and receptor-mediated internalization in EGFR-overexpressing H&N cancer cells. Using fluorescence spectroscopy and confocal microscopy, we demonstrate in vitro that the EGFR-targeted Pc 4-nanoformulation undergoes faster and higher uptake in EGFR-overexpressing H&N SCC-15 cells. We further demonstrate that this enhanced Pc 4 uptake results in significant cell-killing and drastically reduced post-PDT clonogenicity. Building on this in vitro data, we demonstrate that the EGFR-targeted Pc 4-nanoformulation results in significant intratumoral drug uptake and subsequent enhanced PDT response, in vivo, in SCC-15 xenografts in mice. Altogether our results show significant promise toward a cell-targeted photodynamic nanomedicine for effective treatment of H&N carcinomas.

Photodynamic therapy in the management of lesions of the head and neck

Photodynamic therapy (PDT) is a promising and effective treatment for lesions of the head and neck. It uses illumination with light of a specific wavelength, which activates a photosensitising drug in the presence of oxygen. It can be used in combination with other treatments or on its own, and results in the cellular destruction of the lesion through a free-radical process. Photosensitisers can be applied topically or given systemically depending on the lesion being treated. Results indicate that PDT is an effective adjunct to standard conventional treatments. We review its use.

mTHPC mediated photodynamic therapy (PDT) of squamous cell carcinoma in the head and neck: a systematic review

OBJECTIVE

Photodynamic therapy (PDT) is used in curative and palliative treatment of head and neck squamous cell carcinoma (HNSCC). To evaluate available evidence on the use of mTHPC (Foscan®) mediated PDT, we conducted a review of the literature.

MATERIALS AND METHODS

A systematic review was performed by searching seven bibliographic databases on database specific mesh terms and free text words in the categories; "head and neck neoplasms", "Photodynamic Therapy" and "Foscan". Papers identified were assessed on several criteria by two independent reviewers.

RESULTS

The search identified 566 unique papers. Twelve studies were included for our review. Six studies reported PDT with curative intent and six studies reported PDT with palliative intent, of which three studies used interstitial PDT. The studies did not compare PDT to other treatments and none exceeded level 3 using the Oxford levels of evidence. Pooling of data (n=301) was possible for four of the six studies with curative intent. T1 tumors showed higher complete response rates compared to T2 (86% vs 63%). PDT with palliative intent was predominantly used in patients unsuitable for further conventional treatment. After PDT, substantial tumor response and increase in quality of life was observed. Complications of PDT were mostly related to non-compliance to light restriction guidelines.

CONCLUSION

The studies on mTHPC mediated PDT for HNSCC are not sufficient for adequate assessment of the efficacy for curative intent. To assess efficacy of PDT with curative intent, high quality comparative, randomized studies are needed. Palliative treatment with PDT seems to increase the quality of life in otherwise untreatable patients.

Monitoring microcirculatory alterations in oral squamous cell carcinoma following photodynamic therapy

BACKGROUND

One of the mechanisms through which photodynamic therapy (PDT) is thought to elicit tumour destruction is by producing microvascular damage and obstruction of nutritive blood flow. The aim of this study was to directly monitor and quantify microcirculatory changes following tissue illumination by PDT for oral squamous cell carcinoma.

METHODS

Ten consecutive patients receiving PDT for a carcinoma in situ, a T1 or T2 tumour in the oral cavity without evidence of lymph node metastasis were selected for this study. Tumour and marginal healthy mucosa total capillary density (TCD) and functional capillary density (FCD) inside the field of illumination were measured and compared using sidestream dark-field (SDF) imaging prior to tissue illumination, immediately after PDT, and again after 15min.

RESULTS

Baseline mean tumour TCD was 21.2±5capillaries per square millimetres (cpll/mm²) and 24.9±19cpll/mm² in the surrounding marginal healthy tissue; there were no significant differences between tumour and healthy tissue or time points. Comparisons between baseline and post-illumination time points revealed significant differences in both tumour and healthy tissue FCD (P<0.05). No significant differences in FCD were observed between the two tissues.

CONCLUSIONS

Our findings using SDF imaging demonstrate that PDT significantly attenuates tumour and marginal healthy tissue perfusion by directly disrupting the functionality of the microcirculation.

EGFR-mediated intracellular delivery of Pc 4 nanoformulation for targeted photodynamic therapy of cancer: in vitro studies

In photodynamic therapy (PDT), the light activation of a photosensitizer leads to the generation of reactive oxygen species that can trigger various mechanisms of cell death. Harnessing this process within cancer cells enables minimally invasive yet targeted cancer treatment. With this rationale, here we demonstrate tumor-targeted delivery of a highly hydrophobic photosensitizer Pc 4 loaded within biocompatible poly(ethylene glycol)-poly(ɛ-caprolactone) block co-polymer micelles. The micelles were surface-modified with epidermal growth factor receptor (EGFR)-targeting GE11 peptides for active targeting of EGFR-overexpressing cancer cells, in vitro. Pc 4-loaded EGFR-targeted micelles were incubated with EGFR-overexpressing A431 epidermoid carcinoma cells for various time periods, to determine Pc 4 uptake by epifluorescence microscopy. The cells were subsequently photoirradiated, and PDT-induced cell death for various incubation periods was determined by MTT assay and fluorescence Live/Dead assay. Our results indicate that active EGFR targeting of the Pc 4-loaded micelles accelerates intracellular uptake of the drug. Consequently, this enhances the PDT-induced cytotoxicity within shorter time periods.

FROM THE CLINICAL EDITOR

Photodynamic cancer therapy using Pc 4, a light activated and highly hydrophobic photosensitizer is demonstrated in this paper in vitro. Pc 4 was delivered in block-copolymer micelles surface-modified with GE11 peptides targeting EGFR-overexpressing cancer cells.

Photodynamic therapy: The minimally invasive surgical intervention for advanced and/or recurrent tongue base carcinoma

INTRODUCTION

The management of tongue base carcinoma continues to be a major challenge in head and neck oncology. Our aim in this prospective study was to evaluate the outcome following ultrasound-guided interstitial photodynamic therapy (US-iPDT) of stage IV tongue base carcinoma patients. Patients' reports on quality of life with clinical and radiological evaluation were the main end point parameters used to assess the outcome.

MATERIAL AND METHODS

Twenty-one consecutive patients referred to the UCLH Head and Neck Centre for treatment of advanced and/or recurrent tongue base cancer were included in this study. Two-thirds of the referred patients had not been offered further conventional therapeutic options apart from palliative treatment. It was decided, by the multidisciplinary team, that the only available option was to offer US-iPDT under general anesthesia, using mTHPC (Foscan®) as the photosensitizing agent. Following treatment, patients were followed-up for a mean of 36 months (min. 21, max. 45).

RESULTS

Nine of the 11 patients who presented with breathing problems reported improvement after treatment. Also, 19 of the 21 patients reported improvement of swallowing. Improvement of speech was reported by 11 of 13 patients. Clinical assessment showed that more than half of the patients had "good response" to the treatment and about a third reported "moderate response." Radiological assessment comparing imaging 6-week post-PDT to the baseline showed stable pathology with no change in size in four patients, minimal response in seven patients, moderate response in six patients, and significant response in two patients. Eight patients died; four of which due to loco-regional disease; and two from distant tumor spread. Kaplan-Meir survival curve was generated from the survival and follow-up data.

CONCLUSIONS

Photodynamic therapy is a successful palliative modality in the treatment of advanced and/or recurrent tongue base carcinoma.

Photodynamic therapy in the management of pre-malignant head and neck mucosal dysplasia and microinvasive carcinoma

The management of head and neck mucosal dysplasia and microinvasive carcinoma is an appealing strategy to prevent the development of invasive carcinomas. While surgery remains the standard of care, photodynamic therapy (PDT) offers several advantages including the ability to provide superficial yet wide field mucosal ablative treatment. This is particularly attractive where defining the extent of the dysplasia can be difficult. PDT can also retreat the mucosa without any cumulative fibrotic complications affecting function. To date, clinical experience suggests that this treatment approach can be effective in obtaining a complete response for the treated lesion but long term follow-up is limited. Further research efforts are needed to define not only the risk of malignant transformation with PDT but also to develop site specific treatment recommendations that include the fluence, fluence rate and light delivery technique.

Photodynamic therapy of cancer: an update

Photodynamic therapy (PDT) is a clinically approved, minimally invasive therapeutic procedure that can exert a selective cytotoxic activity toward malignant cells. The procedure involves administration of a photosensitizing agent followed by irradiation at a wavelength corresponding to an absorbance band of the sensitizer. In the presence of oxygen, a series of events lead to direct tumor cell death, damage to the microvasculature, and induction of a local inflammatory reaction. Clinical studies revealed that PDT can be curative, particularly in early stage tumors. It can prolong survival in patients with inoperable cancers and significantly improve quality of life. Minimal normal tissue toxicity, negligible systemic effects, greatly reduced long-term morbidity, lack of intrinsic or acquired resistance mechanisms, and excellent cosmetic as well as organ function-sparing effects of this treatment make it a valuable therapeutic option for combination treatments. With a number of recent technological improvements, PDT has the potential to become integrated into the mainstream of cancer treatment.

The application and challenges of clinical PD-PDT in the head and neck region: a short review

We review current clinical applications of photodiagnosis (PD) and photodynamic therapy (PDT) in the head and neck field and highlight the actual status, problems, challenges as well as the future of this emerging treatment modality. In recent years literature presented input from many new developments and their applications. This is due to better awareness and developing knowledge about PD-PDT from the clinical staff, both nurses and doctors. But it is also a result of improved drug and hardware development such as lasers, LEDs and related optical devices. Current photo-medical applications in the head and neck region range from diagnostics, treatment of premalignant and malignant lesions, aesthetic and cosmetic applications to the ever expanding anti-microbial applications. Although treatment of premalignant and early malignant lesions of the oropharyngeal cavity have long been the favourite lesions to treat with PDT patients with unsalvageable tumors have also been responding remarkably well to PDT, adding significant quality of life. There is growing interest in anti-microbiological PDT and recent progress has shown that this application is able to significantly reduce the number or even eradicate specific microbial pathogens. During many surgical treatments better control of microbiological activity through PDT may lead to a better outcome. Despite progressive development in this field a few problems remain: prolonged phototoxicity, limited penetration of the photosensitizer and light, inadequate specificity, PDT-related pain as well as the lack of uniformly accepted protocols both for light application as well as photosensitizers. Recent studies have shown that PDT based pain can be separated from other forms of pain, offering hope that a specific management of pain will be possible. If PDT will become fully accepted by patients and doctors we must care about the negative factors such as pain and prolonged phototoxicity.

Monitoring interstitial m-THPC-PDT in vivo using fluorescence and reflectance spectroscopy

BACKGROUND AND OBJECTIVE

In order to understand the mechanisms of photodynamic therapy (PDT) it is important to monitor parameters during illumination that yield information on deposited PDT dose. The aim of this study is to investigate the possibility of monitoring implicit parameters, such as photobleaching, in addition to monitoring explicit parameters (fluence (rate), oxygenation, photosensitizer concentration) directly or indirectly. These parameters are monitored during PDT without interrupting the therapeutic illumination.

MATERIALS AND METHODS

Rats were injected with 0.3 mg kg(-1) m-THPC. Sixteen hours after administration the abdominal muscle in rats was irradiated for 1,500 seconds using clinically relevant fluence rates of 50, 100, and 250 mW cm(-1) of diffuser length at 652 nm. In addition to the linear diffuser for delivering treatment light, isotropic fiber-optic probes and fiber-optic probes for differential path-length spectroscopy (DPS) were placed on both sides of the muscle to monitor tissue physiological parameters, fluence rate, and fluorescence.

RESULTS

The m-THPC treatment groups show a decrease in fluence rate throughout PDT of 16%, 19%, and 27% for the 50, 100, and 250 mW cm(-1) groups, respectively. Both during and post-PDT differences in vascular response between treatment groups and animals within the same treatment group are observed. Furthermore we show fluence rate dependent bleaching of m-THPC up to a measured fluence rate of 100 mW cm(-1).

CONCLUSION

The data presented in this study show the possibility of simultaneously monitoring fluence (rate), fluorescence, hemoglobin oxygen saturation, and blood volume during PDT without interruptions to the therapeutic illumination. Differences in saturation profiles between animals and treatment groups indicate differences in vascular response during illumination. Furthermore, the relationship between fluence rate and m-THPC fluorescence photobleaching is complex in an interstitial environment.