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

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.

Effectiveness of photodynamic therapy on treatment response and survival of patients with recurrent oral squamous cell carcinoma: a systematic review protocol

OBJECTIVE

This review aims to systematically examine the effectiveness of photodynamic therapy for the treatment of patients with recurrent oral squamous cell carcinoma.

INTRODUCTION

Oral squamous cell carcinoma is a significant public health problem, and is the seventh most common cancer. Its incidence is mainly due to tobacco use, alcohol consumption, and HPV infection. The survival rates are poor due to diagnosis at advanced stages, with high recurrence rates. Although current evidence does not point to photodynamic therapy as a first-line option, this treatment might be suitable for treating recurrent stages of the cancer where conventional treatments were ineffective. Despite the potential of photodynamic therapy, there is a need to verify the scientific evidence to support its indication for the treatment of recurrent oral squamous cell carcinoma.

INCLUSION CRITERIA

This review will consider studies on any stage of recurrent oral squamous cell carcinoma treated with photodynamic therapy after receiving first-line conventional treatments. Patients of any age, gender, and geographic location will be included. The primary outcomes will be to evaluate response to treatment, focusing on remission, recurrence, change in size of the lesion, alleviation of symptoms, and survival. Secondary outcomes will be postoperative complications, presence of necrosis, patient quality of life after treatment, and patient satisfaction.

METHODS

Studies will be searched using a combination of index terms and keywords in MEDLINE, Cochrane Central, Web of Science, Embase, and ClinicalTrials.gov. No date limits will be applied. Articles written in English, French, Spanish, or Portuguese will be considered. Findings will be provided as a narrative synthesis, structured around the photodynamic therapy protocol used. A meta-analysis is planned and subgroup analysis will be conducted if possible. The certainty of findings will be assessed.

SYSTEMATIC REVIEW REGISTRATION NUMBER

PROSPERO CRD42020141075.

Photodynamic Therapy: A Compendium of Latest Reviews

Photodynamic therapy (PDT) is a promising therapy against cancer. Even though it has been investigated for more than 100 years, scientific publications have grown exponentially in the last two decades. For this reason, we present a brief compendium of reviews of the last two decades classified under different topics, namely, overviews, reviews about specific cancers, and meta-analyses of photosensitisers, PDT mechanisms, dosimetry, and light sources. The key issues and main conclusions are summarized, including ways and means to improve therapy and outcomes. Due to the broad scope of this work and it being the first time that a compendium of the latest reviews has been performed for PDT, it may be of interest to a wide audience.

Effects of jasplakinolide on cytotoxicity, cytoskeleton and apoptosis in two different colon cancer cell lines treated with m-THPC-PDT

Colorectal cancer (CRC) is a common malignant tumor, and metastasis is one of the most important challenges in the treatment of CRC. Photodynamic therapy (PDT) is a novel and non-invasive treatment that influence cytoskeleton and to reduce cancer metastases. In addition, cytoskeleton is related to cancer metastases. Two isogenic colorectal cancer cell lines SW480 and SW620 were used in the present study, we found that m-THPC mediated PDT changed the cytotoxicity, apoptosis and cytoskeleton in both cell lines. Interestingly, the expression of intermediate filaments protein cytokeratin18 were different in the two cell lines. In order to further confirm the relationship between cytoskeleton and cell migration, we combined with microfilament stabilizer jasplakinolide (JASP) to observe the effects of microfilaments on cell migration, cytotoxicity and apoptosis. Taken together, these findings suggest that m-THPC-PDT could induce cytoplasmic cytoskeleton destruction in both types of cells, especially on microfilaments and microtubules. Moreover, in SW480 cells, microtubules may participate in the apoptosis process induced by m-THPC-PDT, while microfilaments may participate in the process of m-THPC-PDT inhibiting cell migration. But in SW620 cells, only microfilaments may be involved in m-THPC-PDT induced apoptosis and inhibition of cell migration.

Lateral skull base surgery for posterior oral cavity cancer

The aim of this study was to better understand posterior oral cavity cancer (POCC) and its surgical treatment. This was a retrospective study of 76 patients who were diagnosed with POCC and underwent surgical treatment. Twenty-eight patients were treated with anatomical unit resection surgery (AURS) and 48 patients with conventional surgery. After initial treatment with curative intent, the patients were followed-up regularly with clinical examinations and imaging; the median duration of follow-up was 30.9 months (range 2-67 months). The 3-year overall survival was 64.3% in the experimental AURS group and 39.6% in the conventional surgery control group (hazard ratio 0.49, 95% confidence interval 0.26-0.93; P=0.031). The 3-year disease-free survival was 64.3% in the experimental group and 37.5% in the control group (hazard ratio 0.53, 95% confidence interval 0.27-1.02; P=0.114). In conclusion, AURS is an effective surgical treatment for POCC that can considerably improve patient survival rates.

Photodynamic Therapy as an Alternative Therapeutic Tool in Functionally Inoperable Oral and Oropharyngeal Carcinoma: A Single Tertiary Center Retrospective Cohort Analysis

Background: Head and neck cancer is typically treated with surgery, radiotherapy, chemoradiation, or a combination of these treatments. This study aims to retrospectively analyse oncological outcomes, adverse events and toxicity of treatment with temoporfin-mediated photodynamic therapy at a single tertiary referral center. More specifically, in a selected group of patients with otherwise (functionally) inoperable oral or oropharyngeal head and neck squamous cell carcinoma.

Methods: Twenty-six consecutive patients who received photodynamic therapy for oral or oropharyngeal squamous cell carcinoma from January 2002 until July 2019 at the University Hospitals Leuven were included. These were (1) patients with an accessible recurrent or new primary tumor in an extensively treated area of the head and neck, not suitable for standard treatment, or (2) patients that were judged medically unfit to undergo standard treatment modalities.

Results: Complete tumor response immediately after PDT was obtained in 76.9% of cases. During follow-up, a proportion of CR patients did recur, to reach recurrence-free rates at six months, one year and two years of 60.6%, 48.5% and 32.3%. Local control at the PDT treated area was 42.3% with a median recurrence free interval time of 9 months. Recurrence-free interval was statistically more favorable for oropharyngeal squamous cell carcinoma (with or without oral cavity extension) in comparison to oral cavity squamous cell carcinoma alone (p < 0.001). During a median follow-up period of 27 months, we report new tumor activity in 80.8% of patients. Median overall and disease-specific survival time was 31 and 34 months, respectively. Most reported adverse events were pain after treatment and facial edema. At the end of follow-up, swallowing and upper airway functionality were preserved in 76.9 and 95.7% of patients, respectively.

Conclusion: Photodynamic therapy is a valuable treatment option in highly selected patients with oral and/or oropharyngeal (functionally) inoperable head and neck squamous cell carcinoma. Treatment with this alternative modality can induce durable local control in an important fraction of treated patients, with an acceptable toxicity profile.

Photobiomodulation effects on photodynamic therapy in HNSCC cell lines

A combination of metabolic modifications by light stimulus and photodynamic action is very attractive. Photobiomodulation therapy (PBMT) comprehends a vast range of applications and has been shown to be suitable to ease morbidities caused by chemotherapy and radiation, such as mucositis and dermatitis. The current study investigates the effects of near-infrared PBMT combined with porphyrin-based photodynamic therapy (PDT) in squamous cell carcinoma cell lines SCC-25 and SCC-4. The aim is to evaluate the potential of this combination to improve PDT outcome by increasing cell toxicity. Many techniques were used to verify the combined effect. Photobiomodulation (PBM) enhanced PDT action in SCC-25 cells by increasing photosensitizer (PS) uptake and production of reactive oxygen species (ROS). The equivalent was not seen in SCC-4 cells compared to the PDT only group. We believe these effects are strongly related to the interval of application between PBMT, PS incubation and PDT. Additionally, the effect of ascorbic acid on preventing PBM effects in PDT shows that ROS play an important role in the early mechanisms of PBM-PDT. Therefore, we believe PBM-PDT combination is worth exploring, for its benefit-cost ratio and simple protocols, along with the possibility of improvement in treatment resuts.

Photodynamic therapy induces autophagy-mediated cell death in human colorectal cancer cells via activation of the ROS/JNK signaling pathway

Evidence has shown that m-THPC and verteporfin (VP) are promising sensitizers in photodynamic therapy (PDT). In addition, autophagy can act as a tumor suppressor or a tumor promoter depending on the photosensitizer (PS) and the cancer cell type. However, the role of autophagy in m-THPC- and VP-mediated PDT in in vitro and in vivo models of human colorectal cancer (CRC) has not been reported. In this study, m-THPC-PDT or VP-PDT exhibited significant phototoxicity, inhibited proliferation, and induced the generation of large amounts of reactive oxygen species (ROS) in CRC cells. From immunoblotting, fluorescence image analysis, and transmission electron microscopy, we found extensive autophagic activation induced by ROS in cells. In addition, m-THPC-PDT or VP-PDT treatment significantly induced apoptosis in CRC cells. Interestingly, the inhibition of m-THPC-PDT-induced autophagy by knockdown of ATG5 or ATG7 substantially inhibited the apoptosis of CRC cells. Moreover, m-THPC-PDT treatment inhibited tumorigenesis of subcutaneous HCT116 xenografts. Meanwhile, antioxidant treatment markedly inhibited autophagy and apoptosis induced by PDT in CRC cells by inactivating JNK signaling. In conclusion, inhibition of autophagy can remarkably alleviate PDT-mediated anticancer efficiency in CRC cells via inactivation of the ROS/JNK signaling pathway. Our study provides evidence for the therapeutic application of m-THPC and VP in CRC.

Targeted Photodynamic Therapy of Human Head and Neck Squamous Cell Carcinoma with Anti-epidermal Growth Factor Receptor Antibody Cetuximab and Photosensitizer IR700DX in the Mouse Skin-fold Window Chamber Model

Targeted photodynamic therapy (PDT) in head/neck cancer patients with a conjugate of the anti-epidermal growth factor receptor (EGFR) antibody, Cetuximab and a phthalocyanine photosensitizer IR700DX is under way, but the exact mechanisms of action are still not fully understood. In this study, the EGFR-overexpressing human head/neck OSC-19-luc2-cGFP tumor with transfected GFP gene was used in a skin-fold window chamber model in BALB/c nude mice. The uptake and localization of the conjugate in the tumor and its surrounding normal tissues were studied by an intravital confocal laser scanning microscopy with image analyses. The tumor was also irradiated with 690 nm laser light 24 h after conjugate administration. The vascular and tumor responses were examined by morphological evaluation and immunohistochemistry (IHC). The amount of conjugate in the tumor peaked at 24-48 h after injection. Image analyses of colocalization correlation parameters demonstrated a high fraction of the conjugate IR700DX colocalized in the GFP-expressing tumor cells. PDT-treated tumors showed extensive necrotic/apoptotic destruction with little vascular damage, while IHC showed no HIF-1α expression and decreased EGFR and Ki67 expression with activated caspase-3 overexpression, indicating a direct killing of tumor cells through both necrotic and apoptotic cell death.

Light Sources and Dosimetry Techniques for Photodynamic Therapy

Effective treatment delivery in photodynamic therapy (PDT) requires coordination of the light source, the photosensitizer, and the delivery device appropriate to the target tissue. Lasers, light-emitting diodes (LEDs), and lamps are the main types of light sources utilized for PDT applications. The choice of light source depends on the target location, photosensitizer used, and light dose to be delivered. Geometry of minimally accessible areas also plays a role in deciding light applicator type. Typically, optical fiber-based devices are used to deliver the treatment light close to the target. The optical properties of tissue also affect the distribution of the treatment light. Treatment light undergoes scattering and absorption in tissue. Most tissue will scatter light, but highly pigmented areas will absorb light, especially at short wavelengths. This review will summarize the basic physics of light sources, and describe methods for determining the dose delivered to the patient.

Azulichlorins and Benzocarbachlorins Derived Therefrom

Acid-catalyzed condensation of azulidipyrrane aldehydes with a dihydrodipyrrin carbaldehyde afforded the first examples of azulichlorins. These macrocyclic products were isolated in a monoprotonated form, and the free bases proved to be somewhat unstable. The monocations were strongly diatropic, and proton NMR spectroscopy showed the internal C-H at ca. -2 ppm. Addition of TFA gave the related dications, but these exhibited significantly reduced aromatic ring currents. Reaction of an azulichlorin with tert-butyl hydroperoxide and KOH in dichloromethane/methanol gave a benzocarbachlorin and two related aldehydes. The UV-vis spectrum for the benzocarbachlorin showed a split Soret band at 414 and 430 nm, together with a strong chlorin-like absorption at 684 nm. The proton NMR spectrum indicated that the carbachlorin is strongly aromatic and the internal C-H was observed at -4.64 ppm. Addition of TFA afforded a C-protonated dication with a significantly increased diatropic ring current. The proton NMR spectrum, NICS calculations, and AICD plots indicated that the system favors a 22π electron delocalization pathway that runs through the fused benzo unit. Addition of TFA to the benzocarbachlorin aldehydes primarily led to the formation of monocations, and the generation of C-protonated dications was no longer favored due to the presence of electron-withdrawing formyl moieties.

Comparison of Cellular Death Pathways after mTHPC-mediated Photodynamic Therapy (PDT) in Five Human Cancer Cell Lines

One of the most promising photosensitizers (PS) used in photodynamic therapy (PDT) is the porphyrin derivative 5,10,15,20-tetra(m-hydroxyphenyl)chlorin (mTHPC, temoporfin), marketed in Europe under the trade name Foscan^®. A set of five human cancer cell lines from head and neck and other PDT-relevant tissues was used to investigate oxidative stress and underlying cell death mechanisms of mTHPC-mediated PDT in vitro. Cells were treated with mTHPC in equitoxic concentrations and illuminated with light doses of 1.8-7.0 J/cm² and harvested immediately, 6, 24, or 48 h post illumination for analyses. Our results confirm the induction of oxidative stress after mTHPC-based PDT by detecting a total loss of mitochondrial membrane potential (Δψ_m) and increased formation of ROS. However, lipid peroxidation (LPO) and loss of cell membrane integrity play only a minor role in cell death in most cell lines. Based on our results, apoptosis is the predominant death mechanism following mTHPC-mediated PDT. Autophagy can occur in parallel to apoptosis or the former can be dominant first, yet ultimately leading to autophagy-associated apoptosis. The death of the cells is in some cases accompanied by DNA fragmentation and a G₂/M phase arrest. In general, the overall phototoxic effects and the concentrations as well as the time to establish these effects varies between cell lines, suggesting that the cancer cells are not all dying by one defined mechanism, but rather succumb to an individual interplay of different cell death mechanisms. Besides the evaluation of the underlying cell death mechanisms, we focused on the comparison of results in a set of five identically treated cell lines in this study. Although cells were treated under equitoxic conditions and PDT acts via a rather unspecific ROS formation, very heterogeneous results were obtained with different cell lines. This study shows that general conclusions after PDT in vitro require testing on several cell lines to be reliable, which has too often been ignored in the past.

Treatment of Head and Neck Cancer with Photodynamic Therapy with Redaporfin: A Clinical Case Report

Advanced head and neck squamous cell carcinoma, after locoregional treatment and multiple lines of systemic therapies, represents a great challenge to overcome acquired resistance. The present clinical case illustrates a successful treatment option and is the first to describe the use of photodynamic therapy (PDT) with Redaporfin, followed by immune checkpoint inhibition with an anti-PD1 antibody. This patient presented an extensive tumor in the mouth pavement progressing after surgery, radiotherapy, and multiple lines of systemic treatment. PDT with Redaporfin achieved the destruction of all visible tumor, and the sequential use of an immune checkpoint inhibitor allowed a sustained complete response. This case is an example of the effect of this therapeutic combination and may provide the basis for a new treatment modality.

Effects of meta-tetrahydroxyphenylchlorin photodynamic therapy on isogenic colorectal cancer SW480 and SW620 cells with different metastatic potentials

The aim of this study is to investigate the antitumor effects and possible mechanisms of meta-tetrahydroxyphenylchlorin-mediated photodynamic therapy (m-THPC-PDT) on human primary (SW480) and metastatic (SW620) colon cancer cell lines. SW480 and SW620 cells were incubated with various concentrations of m-THPC, followed by photodynamic irradiation. Subcellular localization of m-THPC in cells was observed with confocal laser scanning microscopy (CLSM). Photocytotoxicity of m-THPC in the two cells was investigated by using MTT assay. The flow cytometry was employed to detect the cell apoptosis. The migration and long-term recovery ability were determined by scratch test and colony formation assay respectively. CLSM showed that m-THPC was mainly distributed within the endoplasmic reticulum (ER) and lysosome of SW480 cells and within the lysosome and mitochondria of SW620 cells. m-THPC-PDT induced a dose-dependent and light energy-dependent cytotoxicity in SW480 and SW620 cells. Apoptosis rate was approximately 65 and 25% in SW480 and SW620 respectively when the concentration of m-THPC increased to 11.76 μM. However, the rate of necrotic cells had no significant changes in two cell lines. The colony formation and migration ability of the two cell lines were decreased with m-THPC-PDT treatment in a dose-dependent manner. PDT with m-THPC not only could effectively inhibit cell proliferation and decrease migration ability and colony formation ability, but also could effectively kill SW480 and SW620 cells in a dose-dependent manner in vitro. These results suggest that m-THPC is a promising sensitizer that warrants further development and extensive studies towards clinical use of colorectal cancer.

Synthesis and Properties of Carbaporphyrin and Carbachlorin Dimethyl Esters Derived from Cyclopentanedialdehydes

Norbornenes with two ester substituents were prepared by Diels-Alder cycloadditions of cyclopentadiene with dimethyl fumarate and dimethyl 1,1-ethylenedicarboxylate. Oxidation with potassium permanganate gave good yields of related diols that were oxidatively ring-opened to afford cyclopentane dialdehydes. MacDonald-type "3 + 1" condensations with a tripyrrane, followed by oxidation with DDQ in refluxing toluene, gave carbaporphyrin or carbachlorin products in good yields. The macrocyclic products were highly diatropic and produced porphyrin-like UV-vis spectra. The carbaporphyrin was converted into silver(III) and gold(III) organometallic derivatives. Reaction with methyl iodide in the presence of potassium carbonate gave mono- and dialkylation products, and treatment of the former with Ni(OAc)₂ or Pd(OAc)₂ afforded nickel(II) and palladium(II) complexes. The free base carbaporphyrin and carbachlorin, and the nickel and palladium complexes, were characterized by X-ray crystallography. The carbachlorin also reacted with silver(I) acetate to give a silver(III) derivative. Carbaporphyrins and carbachlorins underwent deuterium exchange at the meso-positions with deuteriated TFA, and this observation indicates that protonation is occurring at the bridging carbons. The new route to carbaporphyrins and carbachlorins has enabled detailed studies on the properties of these systems and provides the foundations for future investigations.

Regioselective and Switchable meso-Aminations and Couplings of 5,15-Diarylchlorins

Controllable chemo- and regiodivergent amination reactions of anilines and chlorins are accomplished by employing different oxidants and substrates, constructing aminated chlorin monomers and dimers with high structural diversity. Importantly, besides preferential 20-meso-position, the oxidative amination was also realized at the inactive 10-meso-position by using phenyliodine bis(trifluoroacetate) (PIFA) and gold(III)-based reagents.

The potential of photodynamic therapy (PDT)-Experimental investigations and clinical use

Photodynamic therapy (PDT) is an intensively studied part of medicine based on free radicals. These reactive species, extremely harmful for whole human organism, are used for eradication numerous diseases. Specific structure of ill tissues causes accumulation free radicals inside them without attack remaining healthy tissues. A rapid development of medicine and scientific research has led to extension of PDT towards treatment many diseases such as cancer, herpes, acne and based on antimicrobials. The presented review article is focused on the aforementioned disorders with accurate analysis of the newest available scientific achievements. The discussed cases explicitly indicate on high efficacy of the therapy. In most cases, free radicals turned out to be solution of many afflictions. Photodynamic therapy can be considered as promising treatment with comparable effectiveness but without side effects characteristic for chemotherapy.

Inhibition of hypoxia inducible factor 1 and topoisomerase with acriflavine sensitizes perihilar cholangiocarcinomas to photodynamic therapy

BACKGROUND

Photodynamic therapy (PDT) induces tumor cell death by oxidative stress and hypoxia but also survival signaling through activation of hypoxia-inducible factor 1 (HIF-1). Since perihilar cholangiocarcinomas are relatively recalcitrant to PDT, the aims were to (1) determine the expression levels of HIF-1-associated proteins in human perihilar cholangiocarcinomas, (2) investigate the role of HIF-1 in PDT-treated human perihilar cholangiocarcinoma cells, and (3) determine whether HIF-1 inhibition reduces survival signaling and enhances PDT efficacy.

RESULTS

Increased expression of VEGF, CD105, CD31/Ki-67, and GLUT-1 was confirmed in human perihilar cholangiocarcinomas. PDT with liposome-delivered zinc phthalocyanine caused HIF-1α stabilization in SK-ChA-1 cells and increased transcription of HIF-1α downstream genes. Acriflavine was taken up by SK-ChA-1 cells and translocated to the nucleus under hypoxic conditions. Importantly, pretreatment of SK-ChA-1 cells with acriflavine enhanced PDT efficacy via inhibition of HIF-1 and topoisomerases I and II.

METHODS

The expression of VEGF, CD105, CD31/Ki-67, and GLUT-1 was determined by immunohistochemistry in human perihilar cholangiocarcinomas. In addition, the response of human perihilar cholangiocarcinoma (SK-ChA-1) cells to PDT with liposome-delivered zinc phthalocyanine was investigated under both normoxic and hypoxic conditions. Acriflavine, a HIF-1α/HIF-1β dimerization inhibitor and a potential dual topoisomerase I/II inhibitor, was evaluated for its adjuvant effect on PDT efficacy.

CONCLUSIONS

HIF-1, which is activated in human hilar cholangiocarcinomas, contributes to tumor cell survival following PDT in vitro. Combining PDT with acriflavine pretreatment improves PDT efficacy in cultured cells and therefore warrants further preclinical validation for therapy-recalcitrant perihilar cholangiocarcinomas.

DNA photo-cleaving agents in the far-red to near-infrared range – a review

Ideal photonucleases for clinical applications cleave DNA upon activation with deeply penetrating far-red to near-infrared light.

Porphyrin-based photosensitizers and the corresponding multifunctional nanoplatforms for cancer-imaging and phototherapy

This review article briefly describes: (a) the advantages in developing multifunctional nanoparticles for cancer-imaging and therapy, (b) the advantages and limitations of most of the porphyrin-based compounds in fluorescence imaging and photodynamic therapy (PDT), (c) problems associated with current Food and Drug Administration (FDA) approved photosensitizers, (d) challenges in developing in vivo target-specific PDT agents, (e) development of porphyrin-based nuclear-imaging agents (PET, SPECT) with an option of PDT, (f) the importance of light dosimetry in PDT, (g) the role of whole body or local hyperthermia in enhancing tumor-uptake, tumor-imaging and phototherapy and finally, (h) the advantages of photosensitizer-gold nanocages (Ps- Au NC) in photoacoustic and PDT.

Multifunctional calcium phosphate nanoparticles for combining near-infrared fluorescence imaging and photodynamic therapy

Photodynamic therapy (PDT) of tumors causes skin photosensitivity as a result of unspecific accumulation behavior of the photosensitizers. PDT of tumors was improved by calcium phosphate nanoparticles conjugated with (i) Temoporfin as a photosensitizer, (ii) the RGDfK peptide for favored tumor targeting and (iii) the fluorescent dye molecule DY682-NHS for enabling near-infrared fluorescence (NIRF) optical imaging in vivo. The nanoparticles were characterized with regard to size, spectroscopic properties and uptake into CAL-27 cells. The nanoparticles had a hydrodynamic diameter of approximately 200 nm and a zeta potential of around +22mV. Their biodistribution at 24h after injection was investigated via NIRF optical imaging. After treating tumor-bearing CAL-27 mice with nanoparticle-PDT, the therapeutic efficacy was assessed by a fluorescent DY-734-annexin V probe at 2 days and 2 weeks after treatment to detect apoptosis. Additionally, the contrast agent IRDye® 800CW RGD was used to assess tumor vascularization (up to 4 weeks after PDT). After nanoparticle-PDT in mice, apoptosis in the tumor was detected after 2 days. Decreases in tumor vascularization and tumor volume were detected in the next few days. Calcium phosphate nanoparticles can be used as multifunctional tools for NIRF optical imaging, PDT and tumor targeting as they exhibited a high therapeutic efficacy, being capable of inducing apoptosis and destroying tumor vascularization.

Targeted photodynamic therapy in head and neck squamous cell carcinoma: heading into the future

The aim of this article is to give an insight into the future of photodynamic therapy (PDT) in head and neck squamous cell carcinoma (HNSCC). Through the combination of a photosensitizing agent with light and oxygen, PDT produces highly cytotoxic reactive oxygen species leading to selective tumor eradication. PDT is an attractive treatment for focal therapy of localized tumors, especially in the case of unresectable tumors. In HNSCC, over 1500 patients have been treated by PDT, and the majority of them responded quite favorably to this treatment. However, the non-negligible photosensitization of healthy tissue is a major limitation for the clinical application of PDT. Improvement in tumor selectivity is the main challenge that can be taken up by the use of a new generation of photosensitizing nanoparticles. Passive targeting, by using functionalised nanocarriers to target to overexpressed transmembrane receptors afford attractive solutions. To this day, epidermal growth factor receptor (EGFR) remains the only validated molecular target for HNSCC, and photosensitizer immunoconjugates to EGFR have been developed for the intracellular delivery of photosensitizing agents. Depending on coordinated research between biomarkers, specific ligands, and photosensitizers, similar approaches could be rapidly developed. In addition, some photosensitizers hold high fluorescence yield and therefore could emerge as theranostic agents.

[Renaissance of pedicled flaps in oral and maxillofacial surgery]

A retrospective analysis in the period 2007 to 2011 included 71 surgically treated patients for carcinoma of the head and neck region and subsequent reconstruction with 36 pedicled distant flaps and 47 free flaps. Patient specific parameters of data collection with SPSS 17.0 were age and sex distribution, TNM stage and treatment. The specific type of flap reconstruction, duration of surgery, complications, intensive care and inpatient treatment were recorded. The results showed that the healing process was uneventful in 26 (72.2 %) pedicled flaps, 14 (38.9 %) pedicled flaps were transplanted in a preoperatively irradiated area of the head and neck region and in 86.0 % with a positive healing process. Tumor stage, general physical condition of the patient and type of therapy are the key parameters for the choice of reconstruction.

Localization of liposomal mTHPC formulations within normal epithelium, dysplastic tissue, and carcinoma of oral epithelium in the 4NQO-carcinogenesis rat model

BACKGROUND AND OBJECTIVE

Foslip and Fospeg are liposomal formulations of the photosensitizer mTHPC (Foscan), which is used for photodynamic therapy (PDT) of malignancies. Literature suggests that liposomal mTHPC formulations have better properties and increased tumor uptake compared to Foscan. To investigate this, we used the 4NQO-induced carcinogen model to compare the localization of the different mTHPC formulations within normal, precancerous, and cancerous tissue. In contrast to xenograft models, the 4NQO model closely mimics the carcinogenesis of human oral dysplasia.

MATERIALS AND METHODS

Fifty-four rats drank water with the carcinogen 4NQO. When oral examination revealed tumor, the rats received 0.15 mg/kg mTHPC (Foscan, Foslip, or Fospeg). At 2, 4, 8, 24, 48, or 96 hours after injection the rats were sacrificed. Oral tissue was sectioned for HE slides and for fluorescence confocal microscopy. The HE slides were scored on the severity of dysplasia by the epithelial atypia index (EAI). The calibrated fluorescence intensity per formulation or time point was correlated to EAI.

RESULTS

Fospeg showed higher mTHPC fluorescence in normal and tumor tissue compared to both Foscan and Foslip. Significant differences in fluorescence between tumor and normal tissue were found for all formulations. However, at 4, 8, and 24 hours only Fospeg showed a significant difference. The Pearson's correlation between EAI and mTHPC fluorescence proved weak for all formulations.

CONCLUSION

In our induced carcinogenesis model, Fospeg exhibited a tendency for higher fluorescence in normal and tumor tissue compared to Foslip and Foscan. In contrast to Foscan and Foslip, Fospeg showed significantly higher fluorescence in tumor versus normal tissue at earlier time points, suggesting a possible clinical benefit compared to Foscan. Low correlation between grade of dysplasia and mTHPC fluorescence was found.

The role of re-irradiation of secondary and recurrent head and neck carcinomas. Is it a potentially curative treatment? A practical approach

Despite aggressive efforts to cure head and neck cancer patients, including altered fractionation and the addition of chemotherapy to radiation, locoregional recurrence remains a serious issue to face in clinical practice. Indeed, recurrent and second primary tumors occurring in previously irradiated area are common clinical challenge. Whenever possible, patients are advised to undergo salvage surgery. Nevertheless, few patients are suitable candidates for curative resection. In such cases, chemotherapy alone has traditionally been considered, with a poor response rate. It has been questioned whether re-irradiation toxicity outweighs the potential benefits, considering that the median survival of re-irradiated patients marginally exceeds the benefits observed with chemotherapy alone. However, full-dose re-irradiation is a viable treatment option, offering long-term survival for selected patients. Moreover, several prognostic factors should be considered for patients undergoing re-irradiation, such as basic patient characteristics, performance status, the location and extension of recurrent disease, patient co-morbidities, current speech and swallowing function, the interval from the initial radiation therapy to recurrence, previously received doses by critical structures and prior treatment toxicity. Nevertheless, several questions remain unanswered. The purpose of this review is to evaluate the major issues in the field of re-irradiation regarding the current evidence. Therefore, the major selection criteria and new treatment strategies are discussed to define the ideal candidates to undergo re-irradiation and describe a practical approach to these patients. Given the limited evidence in this field, the optimal treatment of recurrent and second primary cancers remains to be defined. Future prospective study of this approach is warranted.

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.