Preliminary results of photodynamic therapy for recurrent nasopharyngeal carcinoma

Novel Therapies Boosting T Cell Immunity in Epstein Barr Virus-Associated Nasopharyngeal Carcinoma

Nasopharyngeal carcinoma (NPC) is a malignant tumour of the head and neck affecting localised regions of the world, with the highest rates described in Southeast Asia, Northern Africa, and Greenland. Its high morbidity rate is linked to both late-stage diagnosis and unresponsiveness to conventional anti-cancer treatments. Multiple aetiological factors have been described including environmental factors, genetics, and viral factors (Epstein Barr Virus, EBV), making NPC treatment that much more complex. The most common forms of NPCs are those that originate from the epithelial tissue lining the nasopharynx and are often linked to EBV infection. Indeed, they represent 75–95% of NPCs in the low-risk populations and almost 100% of NPCs in high-risk populations. Although conventional surgery has been improved with nasopharyngectomy’s being carried out using more sophisticated surgical equipment for better tumour resection, recent findings in the tumour microenvironment have led to novel treatment options including immunotherapies and photodynamic therapy, able to target the tumour and improve the immune system. This review provides an update on the disease’s aetiology and the future of NPC treatments with a focus on therapies activating T cell immunity.

Photodynamic therapy as salvage therapy for patients with nasopharyngeal carcinoma experiencing local failures following definitive radiotherapy

BACKGROUND

Treating local failures of nasopharyngeal carcinoma (NPC) is a challenge. This study evaluates photodynamic therapy (PDT) in the treatment of residual and recurrent NPC.

METHOD

In this phase II study, patients with local recurrent or residual NPC after curative intent (chemo-) radiation could be included. Exclusion criterion was a tumour depth more than 10mm. Foscan® 0.15mg/kg was administered intravenously. After 96h, the illumination was performed under local anaesthesia with a nasopharyngeal light applicator. Tumour response was measured 10 weeks after illumination by endoscopy, biopsy and CT-scan. Kaplan-Meier method was used for survival analysis.

RESULTS

Twenty-one patients were included. Fourteen patients were treated for residual disease (67%), and two for recurrent (10%). For five patients this distinction could not be made, due to uncertainty about complete response after initial treatment. The median follow-up time was 32 months. Twenty patients (95%) had a complete response 10 weeks post-treatment. Two patients had recurrent local disease at 5 and 7 months post-PDT. They received another course of PDT, one with success. The 2-year local control rate was 75%, progression free survival was 49% and overall survival was 65%. Nine patients (43%) had no evidence of disease and were in a good clinical condition (ECOG Performance Scale 0) at the end of the study period. No serious adverse events were observed.

CONCLUSION

This study showed that PDT is effective in treating local failures of NPC with a depth of less than 10mm. The treatment was easy to perform under local anaesthesia. Especially in regions were other modalities like radiation and surgery are limited PDT can be a good alternative treatment.

Ultrasound induces cellular destruction of nasopharyngeal carcinoma cells in the presence of curcumin

OBJECTIVES

Curcumin, a natural pigment from the traditional Chinese herb, has shown promise as an efficient enhancer of ultrasound. The present study aims to investigate ultrasound-induced cellular destruction of nasopharyngeal carcinoma cells in the presence of curcumin in vitro.

METHODS

Nasopharyngeal carcinoma cell line CNE2 cells were incubated by 10μm curcumin and then were treated by ultrasound for 8s at the intensity of 0.46W/cm(2). Cytotoxicity was evaluated using MTT assay and light microscopy. Mitochondrial damage was analyzed using a confocal laser scanning microcopy with Rhodamine 123 and ultrastructural changes were observed using a transmission electron microscopy (TEM).

RESULTS

MTT assay showed that cytotoxicity induced by ultrasound treatment alone and curcumin treatment alone was 18.16±2.37% and 24.93±8.30%, respectively. The cytotoxicity induced by the combined treatment of ultrasound and curcumin significantly increased up to 86.67±7.78%. TEM showed that microvillin disappearance, membrane blebbing, chromatin condensation, swollen mitochondria, and mitochondrial myelin-like body were observed in the cells treated by ultrasound and curcumin together. The significant collapse of mitochondrial membrane potential (MMP) was markedly observed in the CNE2 cells after the combined treatment of curcumin and ultrasound.

CONCLUSIONS

Our findings demonstrated that ultrasound sonication in the presence of curcumin significantly killed the CNE2 cells and induced ultrastructural damage and the dysfunction of mitochondria, suggesting that ultrasound treatment remarkably induced cellular destruction of nasopharyngeal carcinoma cells in the presence of curcumin.

Ultrasound-Induced Cell Death of Nasopharyngeal Carcinoma Cells in the Presence of Curcumin

Objectives. Curcumin, a natural pigment from a traditional Chinese herb, has been attracting extensive attention. The present study aims to investigate cell death of nasopharyngeal carcinoma (NPC) cells induced by ultrasound sonication in the presence of curcumin in vitro. Methods. The NPC cell line CNE2 was chosen as a tumor model, and curcumin concentration was kept constant at 10 µM while the cells were subjected to ultrasound exposure for 8 s at an intensity of 0.46 W/cm2. Cell death was evaluated using flow cytometry with annexinV-FITC and propidium iodine staining, and nuclear staining with Hoechst 33258. Mitochondrial membrane potential and intracellular reactive oxygen species (ROS) were analyzed using flow cytometry with rhodamine 123 and dichlorodihydrofluorecein diacetate staining. Results. Flow cytometry showed that the combination of ultrasound and curcumin significantly increased the necrotic or late apoptotic rate by up to 31.37% compared with the controls. Nuclear condensation was observed in the nuclear staining, and collapse of ΔΨm and ROS increase were found in the CNE2 cells after the treatment with curcumin and ultrasound. Conclusions. The findings demonstrate that the presence of curcumin significantly enhances the ultrasound-induced cell death and ROS level, and induces the collapse of ΔΨm, suggesting that ultrasound sonication can increase the cell death of NPC cells in the presence of curcumin and that the treatment using curcumin and ultrasound together is a potential therapeutic modality in the management of malignant tumors.

Photodynamic therapy in the therapy for recurrent/persistent nasopharyngeal cancer

To determine the efficacy of Photodynamic therapy of patients with recurrent Nasopharyngeal Carcinoma we reviewed all available literature.

Since the treatment options for recurrent or persistent Nasopharyngeal Carcinoma are limited, the survival rates poor and the complications severe; there is definitely a place for alternative treatment modalities with more efficacy and less morbidity. Photodynamic therapy (PDT) has the potential to be a very effective local treatment modality for recurrent or persistent nasopharyngeal cancer, without the severe side effects seen with re-irradiation. This review shows all reported results of Photodynamic therapy in the treatment for Nasopharyngeal Carcinoma.

Induction of early apoptosis in human nasopharyngeal carcinoma cells by mTHPC-mediated photocytotoxicity

OBJECTIVES

In this study, the early apoptotic events elicited by mTHPC-mediated photo-cytotoxicity were explored in a human nasopharyngeal carcinoma cell line (NPC/HK1).

METHODS AND MATERIALS

NPC/HK1 cells (5 x 10(3)) were incubated with photosensitizer mTHPC (0.8 microg/ml) in chamber slides for 20h and subjected to light irradiation at 2J/cm(2) (LD(80)). Morphologic changes of treated cells were examined under light microscopy and confocal microscopy at 0-4h after the light irradiation. The early stage of apoptosis was detected by fluorescein-conjugated Annexin V (Annexin V-FITC) assay. Mitochondrial membrane damage and cytochrome c release were determined by flowcytometric analysis. Bcl-2 expression was measured by Western blot analysis.

RESULTS

One hour after mTHPC-mediated photodynamic therapy (PDT), microscopic examination showed membrane blebbing and cell shrinkage. Annexin V-FITC assay showed that a considerable number of NPC/HK1 cells became apoptotic. Flowcytometric analysis showed that the cytochrome c was released at 1h after PDT. Bcl-2 expression also declined significantly compared to control groups.

CONCLUSIONS

mTHPC-mediated photo-cytotoxicity can effectively induce early apoptotic responses in NPC/HK1 cells which might be modulated by mitochondrial damages and Bcl-2 inhibition.

Performance of a dedicated light delivery and dosimetry device for photodynamic therapy of nasopharyngeal carcinoma: phantom and volunteer experiments

The objective of this study was to develop a light delivery and measurement device for photodynamic therapy (PDT) in the nasopharyngeal cavity, which achieves a homogeneous and reproducible fluence rate distribution to a target area and provides proper shielding of predefined risk areas.

MATERIALS AND METHODS

A flexible silicone applicator was developed, incorporating light delivery and dosimetry fibers. The applicator can be inserted through the mouth and fixed in the nasopharyngeal cavity. Tissue optical phantoms were prepared on the basis of optical properties measured in vivo using diffuse reflectance spectroscopy (DRS). The fluence rate over the length of the applicator surface was measured in air, in tissue optical phantoms and in five healthy volunteers.

RESULTS

The fluence rate distribution over the applicator surface in air and tissue optical phantom was found to be more homogeneous (SD/mean 3.8% and 18.3%, respectively) than the fluence rate distribution in five volunteers (SD/mean ranging from 19% up to 52%). The maximum observed fluence rate build-up in the nasopharynx varied between subjects and ranged from a factor of 4.1-6.9. Shielding of the risk area such as the soft palate and tongue was effective.

CONCLUSIONS

In air and in tissue optical phantoms the fluence rate distribution of the device was highly homogeneous. The observed inter-subject and intra-subject variations in fluence rate in healthy volunteers originated from differences in optical properties and nasopharyngeal geometry. Light delivery based on a single tissue surface measurement will not be adequate. In situ dosimetric measurements are required to determine the light fluence delivered to a geometrically complex site such as the nasopharynx. These observations should be taken in consideration when developing light applicators for PDT of the nasopharynx and other non-uniform surfaces.

Clinical study of Photofrin photodynamic therapy for the treatment of relapse nasopharyngeal carcinoma

OBJECTIVES

To evaluate the clinical response and adverse effects of Photofrin photodynamic therapy (PDT) in patients with relapse nasal pharyngeal cancer.

METHODS

Thirty patients with relapse nasal pharyngeal cancer were randomly divided into PDT group and chemotherapy group. In PDT group, patients received intravenous administration of Photofrin (2mg/kg b.w.) and 48h later light (200-300J/cm) was delivered by a 630nm diode laser through a cylinder diffuser under endoscopic assistance. Two days after PDT the necrotic tissues were removed and newly identified sites were subject to another round of light irradiation. In chemotherapy group, the routine cisplatin and 5-fluorouracil (DDP/5-FU) remedy was used. Endoscopic and radiological examinations were performed during 6 months follow-up. The Karnofsy Score was used to evaluate the quality of life.

RESULTS

The local response and nasal cavity obstruction remission rate in PDT group were better than that in chemotherapy group. The Karnofsy Score was also improved in PDT group.

CONCLUSION

This pilot study suggests that Photofrin PDT is effective and safe in treatment of advanced nasal pharyngeal cancer and management of nasal obstruction.

Photodynamic effects on nasopharyngeal carcinoma (NPC) cells with 5-aminolevulinic acid or its hexyl ester

Nasopharyngeal carcinoma (NPC) is a prevalent cancer in Hong Kong and southern China. To explore a new modality of NPC treatment, 5-aminolevulinic acid (ALA) or its hexyl ester (ALA-H) mediated photodynamic therapy (PDT) was studied in vitro. The results show that NPC cells are sensitive to both ALA and ALA-H mediated PDT. However, ALA-H PDT is much more effective at cell inactivation than ALA-PDT, due to a higher efficiency of ALA-H on producing endogenous protoporphyrin (PpIX) in cells. Both apoptosis and necrosis are involved in cell death, but apoptosis plays a major role under the short time incubation of drugs. ALA and ALA-H mediated PDT not only destroy the cells directly, but also inhibit the expression of matrix metalloproteinase-2 (MMP2) in cells, a maker for tumor metastasis. The ALA-H shows promising PDT results on NPC in vitro; therefore it is worth investigating further in vivo for NPC treatment.

In vivo fluence rate measurements during Foscan-mediated photodynamic therapy of persistent and recurrent nasopharyngeal carcinomas using a dedicated light applicator

The objective of this study was to evaluate the performance of a dedicated light applicator for light delivery and fluence rate monitoring during Foscan-mediated photodynamic therapy of nasopharyngeal carcinoma in a clinical phase I/II study. We have developed a flexible silicone applicator that can be inserted through the mouth and fixed in the nasopharyngeal cavity. Three isotropic fibers, for measuring of the fluence (rate) during therapy, were located within the nasopharyngeal tumor target area and one was manually positioned to monitor structures at risk in the shielded area. A flexible black silicon patch tailored to the patient's anatomy is attached to the applicator to shield the soft palate and oral cavity from the 652-nm laser light. Fourteen patients were included in the study, resulting in 26 fluence rate measurements in the risk volume (two failures). We observed a systematic reduction in fluence rate during therapy in 20 out of 26 illuminations, which may be related to photodynamic therapy-induced increased blood content, decreased oxygenation, or reduced scattering. Our findings demonstrate that the applicator was easily inserted into the nasopharynx. The average light distribution in the target area was reasonably uniform over the length of the applicator, thus giving an acceptably homogeneous illumination throughout the cavity. Shielding of the risk area was adequate. Large interpatient variations in fluence rate stress the need for in vivo dosimetry. This enables corrections to be made for differences in optical properties and geometry resulting in comparable amounts of light available for Foscan absorption.

The cytotoxic and genotoxic potential of 5-aminolevulinic acid on lymphocytes: a comet assay study

BACKGROUND

5-aminolevulinic acid (ALA) and its hexylester (ALA-H) are the drugs currently used in photodynamic therapy (PDT). The side effect, especially the long-term side effect of these drugs is a problem of concern in this field, which has not been clearly understood yet.

PURPOSE

The normal lymphocytes and nasopharyngeal carcinoma (NPC) cells were used as the cell models to evaluate the side effects of ALA or ALA-H in the absence of light or under sub-lethal doses of light.

METHODS

The cytotoxic and DNA-damaging effects of ALA or ALA-H on lymphocytes and NPC cells were studied by means of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and the alkaline comet assay. ALA at 0.75 mM concentration and ALA-H at 10-microM concentrations were selected in the studies. This is because under these concentrations, ALA- or ALA-H-mediated PDT can destroy most NPC cells in vitro. The intracellular distributions of the protoporphyrin IX (PpIX), induced by the ALA or ALA-H, were measured by the confocal laser scanning microscope to provide more information for understanding the DNA damage.

RESULTS

The incubation of 0.75 mM ALA or 10 microM ALA-H alone (without light) did not cause DNA damage as well as the considerable cytotoxic effect on NPC cells. However, after ALA (0.75 mM) incubation and without light irradiation, the serious cytotoxicity and remarkable DNA damage were found in lymphocytes. When the lymphocytes were incubated with ALA-H (10 microM) alone (in the absence of light), no DNA damage could be detected and a slight cytotoxic effect was found. Both ALA and ALA-H induced PpIX in the lymphocytes. The fluorescence images of PpIX intracellular localization demonstrated that the PpIX diffused into the nuclear region in ALA-(0.75 mM)-incubated lymphocytes but not existed in the nucleus of ALA-H(10 microM)- incubated lymphocytes, providing an explanation for the facts that ALA (0.75 mM) induced the DNA damage while ALA-H (10 microM) did not.

CONCLUSION

These results suggested that the genotoxic potential of lymphocytes seems high for ALA (0.75 mM) and could be excluded for ALA-H (10 microM).

Photodynamic therapy with topical 5-aminolevulinic acid as a post-operative adjuvant therapy for an incompletely resected primary nasopharyngeal papillary adenocarcinoma: A case report

BACKGROUND AND OBJECTIVES

Surgical excision of primary nasopharyngeal papillary adenocarcinoma is sometimes incomplete with remaining microscopic disease. Post-operative radiotherapy only has limited efficacy but may cause many complications.

STUDY DESIGN/MATERIALS AND METHODS

Photodynamic therapy (PDT) was used as a post-operative adjuvant therapy for an incompletely resected primary nasopharyngeal papillary adenocarcinoma. A special form of 20% topical 5-aminolevulinic acid (5-ALA), which was originally a liquid form and became a gel form after applied on the nasopharynx, was used as the photosensitizer. A 2-mm optic fiber delivered the light (633 nm wavelength) to the lesion with a fluence rate of 100 mW/cm2 generated by a diode laser under 5 mm 0 degrees endoscope assistance. The total energy delivered was 150 joules/cm2.

RESULTS

No significant acute side effect was noted and the nasopharyngeal wound healed rapidly. The patient is alive without locoregional recurrence or distant metastasis for 5 years. Articulation, salivation, and swallowing functions are all well preserved.

CONCLUSION

Post-operative adjuvant PDT can successfully cure an otherwise difficult to treat disease with preservation of good life quality of the patient. Potential complications of PDT (e.g., photosensitivity) can be prevented by a special formulation of topical 5-ALA preparation.

Enhancing the therapeutic responsiveness of photodynamic therapy with the antiangiogenic agents SU5416 and SU6668 in murine nasopharyngeal carcinoma models

BACKGROUND

Photodynamic therapy (PDT) is a promising therapeutic modality using a tumor localizing photosensitizer and light to destroy tumor cells. A major limitation of PDT is tumor recurrence, which is partly due to neovascularization.

PURPOSE

The objective of the present study was to determine whether combination therapy with PDT and antiangiogenic agents (i.e. SU5416 and SU6668) would be more effective in controlling tumor recurrence in a mouse model of human CNE2 poorly differentiated nasopharyngeal carcinoma compared with PDT or antiangiogenic agents administered alone.

METHODS

Athymic mice bearing CNE2 tumor xenografts received daily i.p. injections of 20 mg/kg SU5416 or 100 mg/kg SU6668 for 28 consecutive days either alone or following a single hypericin-PDT treatment.

RESULTS

Significant inhibition of CNE2 tumor growth was observed in all treatment groups. Differences in 4x tumor growth time, the number of mice with 4x tumor growth, tumor growth inhibition as well as the percent of mice surviving were not statistically significant among individual treatment groups. However, the number of mice with 4x tumor growth observed in SU6668 monotherapy and combined PDT and SU6668 treatment groups was significantly less than that in the control group (P<0.05 and 0.01, respectively). Moreover, compared with the control group, only the combined PDT and SU6668 treatment significantly extended survival of tumor-bearing host mice (P<0.05). The semiquantitative RT-PCR results showed that the expression of HIF-1alpha, VEGF, COX-2 and bFGF were increased in PDT-treated tumor samples collected 24 h post-PDT, suggesting that PDT-induced damage to tumor microvasculature and the resultant hypoxia upregulate the expression of certain proangiogenic factors.

CONCLUSIONS

The effectiveness of PDT can be enhanced by antiangiogenic treatment with the synthetic RTK inhibitors. Of the two synthetic RTK inhibitors tested, SU6668 was more effective than SU5416 in enhancing tumor responsiveness to PDT.

Selected Laser-based Therapies in Otolaryngology

This article has discussed selected applications of laser therapies in otolaryngology. Lasers are the treatment of choice for PWS lesions, but new advances are needed to achieve complete blanching in the majority of cases. Noninvasive in vivo imaging and laser therapy coupled with PDT are two areas showing promise to improve outcome. PDT has the potential to offer new, cost-effective treatment options, and possibly cure, to cancer patients who are not candidates for traditional surgery, chemotherapy, and radiotherapy.

Clinical outcomes of photodynamic therapy for head-and-neck cancer

Head-and-neck cancers not only carry poor prognoses, but also reduced quality of life for the patients. Disease control is often achieved at the expense of substantial functional loss and disfigurement. Photodynamic therapy (PDT) is particularly well suited to the treatment of head-and-neck-tumors because it has little effect on underlying functional structures and has an excellent cosmetic outcome. Studies in the past decades have shown that PDT is of similar efficacy as traditional measures in the treatment of early-stage head-and-neck cancers with an overall response rate of 85%-100% with up to 75% of the complete responses sustained at 2 years after PDT. For advanced head-and-neck cancers, studies were also conducted to evaluate the palliative effects of PDT. Overall, 58%-70% palliative benefit can be observed in these patients. Using interstitial PDT, median survival of the patients with recurrent unresectable head-and-neck cancers can be improved to 14 months (cf. 226 days by using surface illumination PDT). PDT is thus a therapeutic option that may prove a useful addition to the armamentarium of the integrated head and neck oncology team.

Photodynamic activities of sulfonamide derivatives of porphycene on nasopharyngeal carcinoma cells

Two sulfonamide derivatives of porphycene, namely PS6 and PS6A, were synthesized, and their photodynamic efficacies on the nasopharyngeal carcinoma (NPC) cell line NPC/CNE-2 were evaluated. By comparing the 50% lethal concentrations (LC(50)) of these photosensitizers, we found that PS6A with a cationic ammonium group on the side chain exhibited potent photocytotoxicity on the NPC cell line. At a light dose of 1 J/cm(2), the LC(50) values of PS6 and PS6A for NPC cells were 11.6 and 1.92 microM, respectively. CNE-2 was found to rapidly take up PS6A in the first hour of incubation, and the uptake kinetics steadily increased to a plateau level after 18 h of incubation. The uptake of PS6A was temperature dependent. Over 99% of CNE-2 cells were sensitized by PS6A 24 h after drug treatment. Collapse of the mitochondrial membrane potential was also observed in PS6A photodynamic therapy (PDT)-treated CNE-2 cells 1.5 h after PDT. Confocal microscopy revealed that PS6A was predominantly localized in the mitochondria, lysosomes and Golgi bodies of NPC cells. Significant genotoxicity was not observed in CNE-2 cells. In functional studies, the in vitro formation of a capillary-like network of human umbilical vein endothelial cells in Matrigel was greatly inhibited by PS6A PDT in a dose-dependent manner. In conclusion, PS6A mediates both in vitro antitumor and antiangiogenic activities. PS6A might be a candidate for photodynamic treatment of NPCs.

Photocytotoxic and DNA damaging effect of temoporfin (mTHPC) and merocyanine 540 (MC540) on nasopharyngeal carcinoma cell

Photodynamic therapy (PDT) is a new approach to cancer treatment for a variety of malignant tumors. In this study, two clinical photosensitizers, Temoporfin (meta-tetra-hydroxyl-phenyl-chlorin; mTHPC) and merocyanine 540 (MC540), were selected to explore for their photocytotoxic and genotoxic effects on nasopharyngeal carcinoma cells (NPC/HK1 and CNE2). Results of tetrazolium reduction assay showed that 80% cell killing were achieved for both cell lines at 0.4 microg/ml mTHPC for 24 h incubation and then with 40 kJ/m2 light irradiation, whereas 40 microg/ml MC540 with 50 kJ/m2 light dosage was required to attain the same level of phototoxicity for NPC/HK1. On the contrary, NPC/CNE2 was quite resistant to MC540. Hence, mTHPC-mediated PDT exerted a more potent effect than MC540-mediated PDT, even though the molar extinction coefficient of the main absorption peak for MC540 is much higher than that of mTHPC. Dark cytotoxicity remained negligible for both sensitizers. Comet assay was used to evaluate the DNA strand break and potential genotoxic effect induced by mTHPC and MC540 on the NPC cells. No DNA strand break was detected in the absence of light, and under sublethal treatment (LD25) for either sensitizer-loaded cells. Confocal laser scanning microscopy showed that mTHPC and MC540 localized in the cytoplasm but not in the nucleus of the tumor cells, which provided evidence for undetectable DNA damage under dark and low photodynamic dose.

Prospects for future studies in head and neck cancer

Present therapy of head and neck cancer patients includes surgical procedures, radiotherapy and sometimes chemotherapy. Over recent decades no dramatic improvements have been obtained with these treatment modalities with respect to efficacy and associated morbidity. Of patients with early stage disease (stage I and II), about 25% cannot be cured, while for patients with advanced disease (stage III and IV) this percentage may be as high as 70%. However, owing to advances in our knowledge of molecular biology, immunology, (bio)chemistry and biology of head and neck squamous cell carcinoma (HNSCC), new perspectives on therapy are arising. After several years of optimization several new therapeutic approaches are leaving their infancy and are being evaluated in clinical trials with HNSCC patients. Among other approaches, photodynamic therapy, gene therapy and antibody-based therapy are attracting most attention. The basic concepts and the potential applications of these treatment modalities in the management of head and neck cancer are discussed in this paper.