A Review of Photodynamic Therapy for Neoplasms of the Head and Neck

The Implication of Photodynamic Therapy Applied to the Level of Tumor Resection on Postoperative Cerebral Edema and Intracranial Pressure Changes in Gliomas

AIM

The aim of our study was to explore the factors influencing cerebral edema and intracranial pressure in glioblastoma multiforme (GBM) patients who undergo photodynamic therapy (PDT) after resection.

APPROACH

This was a retrospective controlled study of GBM patients treated with PDT-assisted resections of varying scope from May 2021 to August 2023. The baseline clinical data, cerebral edema volumes, intracranial pressure values, and imaging data of the GBM patients were collected for statistical analysis.

RESULTS

A total of 56 GBM patients were included. Thirty of the patients underwent gross total resection (GTR), and the other 26 patients underwent subtotal resection (STR). We found that the cerebral edema volume and the mean intracranial pressure in patients who underwent GTR were lower than those in patients who underwent STR. Moreover, univariate analysis showed that the scope of tumor resection was an independent factor affecting cerebral edema and intracranial pressure after PDT.

CONCLUSIONS

Compared with STR, PDT combined with GTR significantly reduced postoperative brain edema volume and intracranial pressure in GBM patients.

Prediction of the short-term efficacy and recurrence of photodynamic therapy in the treatment of oral leukoplakia based on deep learning

BACKGROUND

The treatment of oral leukoplakia (OLK) with aminolaevulinic acid photodynamic therapy (ALA-PDT) is widespread. Nonetheless, there is variation in efficacy. Therefore, this study constructed a model for predicting the short-term efficacy and recurrence of OLK after ALA-PDT.

METHODS

The short-term efficacy and recurrence of ALA-PDT were calculated by statistical analysis, and the relevant influencing factors were analyzed by Logistic regression and COX regression model. Finally, prediction models for total response (TR) rate, complete response (CR) rate and recurrence in OLK patients after ALA-PDT treatment were established. Features from pathology sections were extracted using deep learning autoencoder and combined with clinical variables to improve prediction performance of the model.

RESULTS

The logistic regression analysis showed that the non-homogeneous (OR: 4.911, P: 0.023) OLK and lesions with moderate to severe epithelial dysplasia (OR: 4.288, P: 0.042) had better short-term efficacy. The area under receiver operating characteristic curve (AUC) of CR, TR and recurrence predict models after the ALA-PDT treatment of OLK patients is 0.872, 0.718, and 0.564, respectively. Feature extraction revealed an association between inflammatory cell infiltration in the lamina propria and recurrence after PDT. Combining clinical variables and deep learning improved the performance of recurrence model by more than 30 %.

CONCLUSIONS

ALA-PDT has excellent short-term efficacy in the management of OLK but the recurrence rate was high. Prediction model based on clinicopathological characteristics has excellent predictive effect for short-term efficacy but limited effect for recurrence. The use of deep learning and pathology images greatly improves predictive value of the models.

Smart nanozymes coupled with dynamic magnet field and laser exposures for cancer therapy

Developing nanozymes for cancer therapy has attracted great attention from researchers. However, enzymes-loaded magnetic particles triggered by both a low-frequency vibrating magnetic field (VMF) and laser for inhibiting tumor growth have never been reported. Herein, we developed a magnetic nanozyme with 3D flower-like nanostructures for cancer therapy. Specifically, the flower-like nanozymes exposed to a VMF could efficiently damage the mitochondrial membrane and cell structure, and inhibit tumor growth through magneto-mechanical force. In parallel, magnetic nanozymes in a weak acid environment containing glucose could generate abundant hydrogen peroxide through glucose oxidase-catalyzed oxidation of glucose, and further significantly promote the Fenton reaction. Interestingly, both glucose oxidase- and Fenton-based catalytic reactions were significantly promoted by the VMF exposure. Flower-like magnetic nanospheres upon a near-infrared laser irradiation could also damage cancer cells and tumor tissues through photothermal effect. The cell-killing efficiency of magnetic nanozymes triggered by the VMF or laser significantly increased in comparison with that of nanozymes without exposures. Mouse tumors grown after injection with magnetic nanozymes was inhibited in a significant way or the tumors disappeared after exposure to a VMF and laser due to the synergistic effect of four major stimuli, viz., magneto-mechanical force, photothermal conversion, improved Fenton reaction, and intratumoral glucose consumption-based starvation effect. This is a great platform that may be suitable for treating many solid tumors.

Comparative response to PDT with methyl-aminolevulinate and temoporfin in cutaneous and oral squamous cell carcinoma cells

Cutaneous and Head and Neck squamous cell carcinoma (CSCC, HNSCC) are among the most prevalent cancers. Both types of cancer can be treated with photodynamic therapy (PDT) by using the photosensitizer Temoporfin in HNSCC and the prodrug methyl-aminolevulinate (MAL) in CSCC. However, PDT is not always effective. Therefore, it is mandatory to correctly approach the therapy according to the characteristics of the tumour cells. For this reason, we have used cell lines of CSCC (A431 and SCC13) and HNSCC (HN5 and SCC9). The results obtained indicated that the better response to MAL-PDT was related to its localization in the plasma membrane (A431 and HN5 cells). However, with Temoporfin all cell lines showed lysosome localization, even the most sensitive ones (HN5). The expression of mesenchymal markers and migratory capacity was greater in HNSCC lines compared to CSCC, but no correlation with PDT response was observed. The translocation to the nucleus of β-catenin and GSK3β and the activation of NF-κβ is related to the poor response to PDT in the HNSCC lines. Therefore, we propose that intracellular localization of GSK3β could be a good marker of response to PDT in HNSCC. Although the molecular mechanism of response to PDT needs further elucidation, this work shows that the most MAL-resistant line of CSCC is more sensitive to Temoporfin.

Verteporfin fluorescence in antineoplastic-treated pancreatic cancer cells found concentrated in mitochondria

BACKGROUND

Traditional treatments for pancreatic cancer (PC) are inadequate. Photodynamic therapy (PDT) is non-invasive, and proven safe to kill cancer cells, including PC. However, the mitochondrial concentration of the photosensitizer, such as verteporfin, is key.

AIM

To investigate the distribution of fluorescence of verteporfin in PC cells treated with antitumor drugs, post-PDT.

METHODS

Workable survival rates of PC cells (AsPC-1, BxPC-3) were determined with chemotherapy [doxorubicin (DOX) and gemcitabine (GEM)] and non-chemotherapy [sirolimus (SRL) and cetuximab (CTX)] drugs in vitro, with or without verteporfin, as measured via MTT, flow cytometry, and laser confocal microscopy. Reduced cell proliferation was associated with GEM that was more enduring compared with DOX. Confocal laser microscopy allowed observation of GEM- and verteporfin-treated PC cells co-stained with 4',6-diamidino-2-phenylindole and MitoTracker Green to differentiate living and dead cells and subcellular localization of verteporfin, respectively.

RESULTS

Cell survival significantly dropped upon exposure to either chemotherapy drug, but not to SRL or CTX. Both cell lines responded similarly to GEM. The intensity of fluorescence was associated with the concentration of verteporfin. Additional experiments using GEM showed that survival rates of the PC cells treated with 10 μmol/L verteporfin (but not less) were significantly lower relative to nil verteporfin. Living and dead stained cells treated with GEM were distinguishable. After GEM treatment, verteporfin was observed primarily in the mitochondria.

CONCLUSION

Verteporfin was observed in living cells. In GEM -treated human PC cells, verteporfin was particularly prevalent in the mitochondria. This study supports further study of PDT for the treatment of PC after neoadjuvant chemotherapy.

Overcoming challenges in cancer treatment: Nano-enabled photodynamic therapy as a viable solution

Cancer presents a formidable challenge, necessitating innovative therapies that maximize effectiveness while minimizing harm to healthy tissues. Nanotechnology has emerged as a transformative force in cancer treatment, particularly through nano-enabled photodynamic therapy (NE-PDT), which leverages precise and targeted interventions. NE-PDT capitalizes on photosensitizers activated by light to generate reactive oxygen species (ROS) that initiate apoptotic pathways in cancer cells. Nanoparticle enhancements optimize this process, improving drug delivery, selectivity, and ROS production within tumors. This review dissects NE-PDT's mechanistic framework, showcasing its potential to harness apoptosis as a potent tool in cancer therapy. Furthermore, the review explores the synergy between NE-PDT and complementary treatments like chemotherapy, immunotherapy, and targeted therapies, highlighting the potential to amplify apoptotic responses, enhance immune recognition of cancer cells, and inhibit resistance mechanisms. Preclinical and clinical advancements in NE-PDT demonstrate its efficacy across various cancer types. Challenges in translating NE-PDT into clinical practice are also addressed, emphasizing the need for optimizing nanoparticle design, refining dosimetry, and ensuring long-term safety. Ultimately, NE-PDT represents a promising approach in cancer therapy, utilizing the intricate mechanisms of apoptosis to address therapeutic hurdles. The review underscores the importance of understanding the interplay between nanoparticles, ROS generation, and apoptotic pathways, contributing to a deeper comprehension of cancer biology and novel therapeutic strategies. As interdisciplinary collaborations continue to thrive, NE-PDT offers hope for effective and targeted cancer interventions, where apoptosis manipulation becomes central to conquering cancer. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Hypoxia: syndicating triple negative breast cancer against various therapeutic regimens

Triple-negative breast cancer (TNBC) is one of the deadliest subtypes of breast cancer (BC) for its high aggressiveness, heterogeneity, and hypoxic nature. Based on biological and clinical observations the TNBC related mortality is very high worldwide. Emerging studies have clearly demonstrated that hypoxia regulates the critical metabolic, developmental, and survival pathways in TNBC, which include glycolysis and angiogenesis. Alterations to these pathways accelerate the cancer stem cells (CSCs) enrichment and immune escape, which further lead to tumor invasion, migration, and metastasis. Beside this, hypoxia also manipulates the epigenetic plasticity and DNA damage response (DDR) to syndicate TNBC survival and its progression. Hypoxia fundamentally creates the low oxygen condition responsible for the alteration in Hypoxia-Inducible Factor-1alpha (HIF-1α) signaling within the tumor microenvironment, allowing tumors to survive and making them resistant to various therapies. Therefore, there is an urgent need for society to establish target-based therapies that overcome the resistance and limitations of the current treatment plan for TNBC. In this review article, we have thoroughly discussed the plausible significance of HIF-1α as a target in various therapeutic regimens such as chemotherapy, radiotherapy, immunotherapy, anti-angiogenic therapy, adjuvant therapy photodynamic therapy, adoptive cell therapy, combination therapies, antibody drug conjugates and cancer vaccines. Further, we also reviewed here the intrinsic mechanism and existing issues in targeting HIF-1α while improvising the current therapeutic strategies. This review highlights and discusses the future perspectives and the major alternatives to overcome TNBC resistance by targeting hypoxia-induced signaling.

Photodynamic and Photothermal Therapies: Synergy Opportunities for Nanomedicine

Tumoricidal photodynamic (PDT) and photothermal (PTT) therapies harness light to eliminate cancer cells with spatiotemporal precision by either generating reactive oxygen species or increasing temperature. Great strides have been made in understanding biological effects of PDT and PTT at the cellular, vascular and tumor microenvironmental levels, as well as translating both modalities in the clinic. Emerging evidence suggests that PDT and PTT may synergize due to their different mechanisms of action, and their nonoverlapping toxicity profiles make such combination potentially efficacious. Moreover, PDT/PTT combinations have gained momentum in recent years due to the development of multimodal nanoplatforms that simultaneously incorporate photodynamically- and photothermally active agents. In this review, we discuss how combining PDT and PTT can address the limitations of each modality alone and enhance treatment safety and efficacy. We provide an overview of recent literature featuring dual PDT/PTT nanoparticles and analyze the strengths and limitations of various nanoparticle design strategies. We also detail how treatment sequence and dose may affect cellular states, tumor pathophysiology and drug delivery, ultimately shaping the treatment response. Lastly, we analyze common experimental design pitfalls that complicate preclinical assessment of PDT/PTT combinations and propose rational guidelines to elucidate the mechanisms underlying PDT/PTT interactions.

Head and neck cancer treatment in the era of molecular medicine

Head and neck cancers are a heterogeneous group of highly aggressive tumors and collectively represent the sixth most common cancer worldwide. Most head and neck cancers are squamous cell carcinomas (HNSCCs). Current multimodal treatment concepts combine surgery, chemotherapy, irradiation, immunotherapy, and targeted therapeutics. Recent scientific advancements have enabled a more precise molecular characterization of HNSCC and revealed novel therapeutic targets and prognostic/predictive biomarkers. Notably, HNSCC is characterized by complex relations between stromal, epithelial, and immune cells within the tumor microenvironment (TME). The TME consists of different subsets of immune cells that infiltrate the tumors and interact with the tumor cells or with each other. Understanding multiple pivotal factors in HNSCC tumorigenesis and tumor progression may help define novel targets and develop more effective therapies for patients. This review provides a comprehensive overview of the latest advances in the molecular biology of HNSCC and their effects on clinical oncology; it is meant for a broad readership in the head and neck cancers field.

Photodynamic therapy in oral cancer: a review of clinical studies

A significant mortality rate is associated with oral cancer, particularly in cases of late-stage diagnosis. Since the last decades, oral cancer survival rates have only gradually improved despite advances in treatment. This poor success rate is mainly due to the development of secondary tumors, local recurrence, and regional failure. Invasive treatments frequently have a negative impact on the aesthetic and functional outcomes of survivors. Novel approaches are thus needed to manage this deadly disease in light of these statistics. In photodynamic therapy (PDT), a light-sensitive medication called a photosensitizer is given first, followed by exposure to light of the proper wavelength that matches the absorbance band of the photosensitizer. The tissue oxygen-induced cytotoxic free radicals kill tumor cells directly, harm the microvascular structure, and cause inflammatory reactions at the targeted sites. In the case of early lesions, PDT can be used as a stand-alone therapy, and in the case of advanced lesions, it can be used as adjuvant therapy. The current review article discussed the uses of PDT in oral cancer therapy based on recent advances in this field.

Nanotherapeutic Intervention in Photodynamic Therapy for Cancer

The clinical need for photodynamic therapy (PDT) has been growing for several decades. Notably, PDT is often used in oncology to treat a variety of tumors since it is a low-risk therapy with excellent selectivity, does not conflict with other therapies, and may be repeated as necessary. The mechanism of action of PDT is the photoactivation of a particular photosensitizer (PS) in a tumor microenvironment in the presence of oxygen. During PDT, cancer cells produce singlet oxygen (¹O₂) and reactive oxygen species (ROS) upon activation of PSs by irradiation, which efficiently kills the tumor. However, PDT's effectiveness in curing a deep-seated malignancy is constrained by three key reasons: a tumor's inadequate PS accumulation in tumor tissues, a hypoxic core with low oxygen content in solid tumors, and limited depth of light penetration. PDTs are therefore restricted to the management of thin and superficial cancers. With the development of nanotechnology, PDT's ability to penetrate deep tumor tissues and exert desired therapeutic effects has become a reality. However, further advancement in this field of research is necessary to address the challenges with PDT and ameliorate the therapeutic outcome. This review presents an overview of PSs, the mechanism of loading of PSs, nanomedicine-based solutions for enhancing PDT, and their biological applications including chemodynamic therapy, chemo-photodynamic therapy, PDT-electroporation, photodynamic-photothermal (PDT-PTT) therapy, and PDT-immunotherapy. Furthermore, the review discusses the mechanism of ROS generation in PDT advantages and challenges of PSs in PDT.

Current Insights and Progress in the Clinical Management of Head and Neck Cancer

Head and neck cancer (HNC), also known as the cancer that can affect the structures between the dura mater and the pleura, is the 6th most common type of cancer. This heterogeneous group of malignancies is usually treated with a combination of surgery and radio- and chemotherapy, depending on if the disease is localized or at an advanced stage. However, most HNC patients are diagnosed at an advanced stage, resulting in the death of half of these patients. Thus, the prognosis of advanced or recurrent/metastatic HNC, especially HNC squamous cell carcinoma (HNSCC), is notably poorer than the prognosis of patients diagnosed with localized HNC. This review explores the epidemiology and etiologic factors of HNC, the histopathology of this heterogeneous cancer, and the diagnosis methods and treatment approaches currently available. Moreover, special interest is given to the novel therapies used to treat HNC subtypes with worse prognosis, exploring immunotherapies and targeted/multi-targeted drugs undergoing clinical trials, as well as light-based therapies (i.e., photodynamic and photothermal therapies).

Photodynamic therapy in breast cancer treatment

Breast cancer is a serious public problem in modern society. Photodynamic therapy (PDT) is increasingly used in modern medicine. Currently, PDT is an innovative method of treating breast cancer. Irreversible damage to neoplastic tissues is associated with the use of physicochemical processes. Generating cytotoxic reactive oxygen species [singlet oxygen (1O2)] is leading to tumor cell death. At the same time, valuable information can be extracted from breast cancer cells. Photogenerated 1O2 is the major factor responsible for cell necrosis during PDT. 1O2 can react rapidly intracellularly with all organic substances. The use of photodynamic therapy on tissues in vitro creates conditions for testing various types of solutions and implementing them in in vivo treatment. This article is a review of recent advances in PDT for treatment of breast cancer. PDT is a novel cancer diagnostic and cancer treatment therapy. Therefore, an understanding of the possibility to generate a toxic form of 1O2 is necessary. The knowledge gained from the basics of PDT in vitro can be useful in biomedical applications in vivo. The current literature mentions PDT in the treatment of cancers located very deep within the human body. Therefore, the development of agents used to deliver 1O2 to the deep cancerous tissue is a new challenge which can have an efficient impact on this discipline. This review covers the literature between 2000-2022.

Tumor cell-specific retention of photosensitizers determines the outcome of photodynamic therapy for head and neck cancer

Pheophorbide-based photosensitizers have demonstrated tumor cell-specific retention. The lead compound 3-[1'-hexyloxyethyl]-2-devinylpyropheophorbide-a (HPPH) in a clinical trial for photodynamic therapy of head and neck cancer lesions indicated a complete response in 80% of patients. The question arises whether the partial response in 20% of patients is due to inefficient retention of photosensitizers by tumor cells and, if so, can the photosensitizer preference of individual cancer cases be identified prior to photodynamic therapy. This study determined the specificity of head and neck cancer cells and tumor tissues for the uptake and retention of diffusible pheophorbides differing in peripheral groups on the macrocycle that contribute to cellular binding. The relationship between photosensitizer level and light-mediated photoreaction was characterized to identify markers for predicting the effectiveness of photodynamic therapy in situ. The experimental models were stromal and epithelial cells isolated from head and neck tumor samples and integrated into monotypic tissue cultures, reconstituted three-dimensional co-cultures, and xenografts. Tumor cell-specific photosensitizer retention patterns were identified, and a procedure was developed to allow the diagnostic evaluation of HPPH binding by tumor cells in individual cancer cases. The findings of this study may assist in designing conditions for photosensitizer application and photodynamic therapy of head and neck cancer lesions optimized for each patient's case.

Multi-Modal Optical Imaging and Combined Phototherapy of Nasopharyngeal Carcinoma Based on a Nanoplatform

Nasopharyngeal carcinoma (NPC) is a common malignant tumor of the head and neck with a high incidence rate worldwide, especially in southern China. Phototheranostics in combination with nanoparticles is an integrated strategy for enabling simultaneous diagnosis, real-time monitoring, and administration of precision therapy for nasopharyngeal carcinoma (NPC). It has shown great potential in the field of cancer diagnosis and treatment owing to its unique noninvasive advantages. Many Chinese and international research teams have applied nano-targeted drugs to optical diagnosis and treatment technology to conduct multimodal imaging and collaborative treatment of NPC, which has become a hot research topic. In this review, we aimed to introduce the recent developments in phototheranostics of NPC based on a nanoplatform. This study aimed to elaborate on the applications of nanoplatform-based optical imaging strategies and treatment modalities, including fluorescence imaging, photoacoustic imaging, Raman spectroscopy imaging, photodynamic therapy, and photothermal therapy. This study is expected to provide a scientific basis for further research and development of NPC diagnosis and treatment.

Which cell death modality wins the contest for photodynamic therapy of cancer?

Photodynamic therapy (PDT) was discovered more than 100 years ago. Since then, many protocols and agents for PDT have been proposed for the treatment of several types of cancer. Traditionally, cell death induced by PDT was categorized into three types: apoptosis, cell death associated with autophagy, and necrosis. However, with the discovery of several other regulated cell death modalities in recent years, it has become clear that this is a rather simple understanding of the mechanisms of action of PDT. New observations revealed that cancer cells exposed to PDT can pass through various non-conventional cell death pathways, such as paraptosis, parthanatos, mitotic catastrophe, pyroptosis, necroptosis, and ferroptosis. Nowadays, immunogenic cell death (ICD) has become one of the most promising ways to eradicate tumor cells by activation of the T-cell adaptive immune response and induction of long-term immunological memory. ICD can be triggered by many anti-cancer treatment methods, including PDT. In this review, we critically discuss recent findings on the non-conventional cell death mechanisms triggered by PDT. Next, we emphasize the role and contribution of ICD in these PDT-induced non-conventional cell death modalities. Finally, we discuss the obstacles and propose several areas of research that will help to overcome these challenges and lead to the development of highly effective anti-cancer therapy based on PDT.

Preliminary low-dose photodynamic exposure to the skin cancer with chlorin e6 photosensitizer

BACKGROUND

The study was aimed to investigate the chlorin e6 photosensitizer distribution in the tumor and tumor border (5 mm) during low-dose photodynamic treatment and to increase the effectiveness of the therapy for skin neoplasms.

METHODS

Sensitized boundaries of neoplasms were evaluated by video fluorescence imaging. The study of changes in the chlorin e6 distribution before/after photodynamic therapy and in the process of low-dose photodynamic exposure was carried out by the method of spectral fluorescence diagnostics.

RESULTS

All 19 patients with basal-cell skin cancer had a contrast of chlorin e6 accumulation compared to normal tissues. 3 hours after intravenous administration of the photosensitizer at a dose of 1 mg/kg, the chlorin e6 concentration was: in normal tissues - 0.18 mg/kg, in the tumor - 1.26 mg/kg, in the tumor border - 0.63 mg/kg. In most cases, the fluorescence indices of chlorin e6 in tumor tissues after low-dose photodynamic therapy increased and exceeded the values before light exposure.

CONCLUSION

Low-dose photodynamic therapy seems to be the optimal method for treating neoplasms, which does not cause severe pain in patients during the light exposure and allows locally increasing of the photosensitizer concentration in tumor tissues. This method of photodynamic therapy can improve the effectiveness of thе treatment.

BODIPY nanoparticles functionalized with lactose for cancer-targeted and fluorescence imaging-guided photodynamic therapy

A series of four lactose-modified BODIPY photosensitizers (PSs) with different substituents (-I, -H, -OCH₃, and -NO₂) in the para-phenyl moiety attached to the meso-position of the BODIPY core were synthesized; the photophysical properties and photodynamic anticancer activities of these sensitizers were investigated, focusing on the electronic properties of the different substituent groups. Compared to parent BODIPY H, iodine substitution (BODIPY I) enhanced the intersystem crossing (ISC) to produce singlet oxygen (¹O₂) due to the heavy atom effect, and maintained a high fluorescence quantum yield (Φ_F) of 0.45. Substitution with the electron-donating methoxy group (BODIPY OMe) results in a significant perturbation of occupied frontier molecular orbitals and consequently achieves higher ¹O₂ generation capability with a high Φ_F of 0.49, while substitution with the electron-withdrawing nitro group (BODIPY NO2) led a perturbation of unoccupied frontier molecular orbitals and induces a forbidden dark S₁ state, which is negative for both fluorescence and ¹O₂ generation efficiencies. The BODIPY PSs formed water-soluble nanoparticles (NPs) functionalized with lactose as liver cancer-targeting ligands. BODIPY I and OMe NPs showed good fluorescence imaging and PDT activity against various tumor cells (HeLa and Huh-7 cells). Collectively, the BODIPY NPs demonstrated high ¹O₂ generation capability and Φ_F may create a new opportunity to develop useful imaging-guided PDT agents for tumor cells.

Synthesis of N-aryl-2,6-diphenyl-2H-pyrazolo[4,3-c]pyridin-7-amines and their photodynamic properties in the human skin melanoma cell line G361

A small series of N-aryl-2,6-diphenyl-2H-pyrazolo[4,3-c]pyridin-7-amines was synthesized from easily accessible 1-phenyl-1H-pyrazol-3-ol via 7-iodo-2,6-diphenyl-2H-pyrazolo[4,3-c]pyridine and 7-iodo-4-methyl-2,6-diphenyl-2H-pyrazolo[4,3-c]pyridine intermediates and their subsequent use in palladium catalyzed Buchwald-Hartwig cross-coupling reaction with various anilines. Majority of the compounds were not significantly cytotoxic to melanoma G361 cells in the dark up to 10 µM concentration, but their activity could be increased by irradiation with visible blue light (414 nm). The most active compound 10 possessed EC₅₀ values of 3.5, 1.6 and 0.9 µM in cells irradiated with 1, 5 and 10 J/cm², respectively. The treatment caused generation of reactive oxygen species in cells and extensive DNA damage, documented by the comet assay and by detection of phosphorylated histone H2A.X, followed by apoptotic cell death. Our results suggest that N-aryl-2,6-diphenyl-2H-pyrazolo[4,3-c]pyridin-7-amines could serve as a potential source of photosensitizing compounds with anticancer activities.

Stimuli-responsive drug delivery systems for head and neck cancer therapy

Head and neck cancer (HNC) is among the most common malignancy that has a profound impact on human health and life quality. The treatment for HNC, especially for the advanced cancer is stage-dependent and in need of combined therapies. Various forms of adjuvant treatments such as chemotherapy, phototherapy, hyperthermia, gene therapy have been included in the HNC therapy. However, there are still restrictions with traditional administration such as limited in situ therapeutic effect, systemic toxicity, drug resistance, etc. In recent years, stimuli-responsive drug delivery systems (DDSs) have attracted the great attention in HNC therapy. These intelligent DDSs could respond to unique tumor microenvironment, external triggers or dual/multi stimulus with more specific drug delivery and release, leading to enhanced treatment efficiency and less reduced side effects. In this article, recent studies on stimuli-responsive DDSs for HNC therapy were summarized, which could respond to endogenous and exogenous triggers including pH, matrix metalloproteinases (MMPs), reactive oxygen species (ROS), redox condition, light, magnetic field and multi stimuli. Their therapeutic remarks, current limits and future prospect for these intelligent DDSs were discussed. Furthermore, multifunctional stimuli-responsive DDSs have also been reviewed. With the modification of drug carriers or co-loading with therapeutic agents. Those intelligent DDSs showed more biofunctions such as combined therapeutic effects or integration of diagnosis and treatment for HNC. It is believed that stimuli-responsive drug delivery systems showed great potential for future clinic translation and application for the treatment of HNC.

Phonosurgery: A review of current methodologies

Cold-steel has served as the gold standard modality of phonosurgery for most of its history. Surgical laser technology has revolutionized this field with its wide use of applications. Additional modalities have also been introduced such as coagulative lasers, photodynamic therapy, and cryotherapy. This review will compare the surgical modalities of cold steel, surgical lasers, phototherapy and cryotherapy. The mechanism of action, tissue effects and typical uses will be addressed for each modality.

Photodynamic Therapy Induced Cell Death Mechanisms in Breast Cancer

Breast cancer is the second most common cancer globally and the pioneering cause of mortality among women. It usually begins from the ducts or lobules, referred to as ductal carcinoma in situ, or lobular carcinoma in situ. Age, mutations in Breast Cancer Gene 1 or 2 (BRCA1 or BRCA2) genes, and dense breast tissue are the highest risk factors. Current treatments are associated with various side effects, relapse, and a low quality of life. Although conventional treatments, such as surgery and chemotherapy, have been used for decades, their adverse side effects on normal cells and tissues pose a major weakness, which calls for a non-invasive treatment option. Photodynamic therapy (PDT) has proven to be a promising form of cancer therapy. It is less invasive, target-specific, and with reduced cytotoxicity to normal cells and tissues. It involves the use of a photosensitizer (PS) and light at a specific wavelength to produce reactive oxygen species. One of the reasons for the target specificity is associated with the dense vascularization of cancer tissues, which tends to increase the surface area for the PS uptake. Photosensitizers are light-sensitive molecules, which result in cancer cell destruction followed by light irradiation. Depending on the localization of the PS within the cancer cell, its destruction may be via apoptosis, necrosis, or autophagy. This review focuses on the breast cancer etiopathology and PDT-induced cell death mechanisms in breast cancer cells.

From Basic Mechanisms to Clinical Research: Photodynamic Therapy Applications in Head and Neck Malignancies and Vascular Anomalies

Head and neck cancers are largely squamous cell carcinomas derived from the epithelial lining of the structures in the region, and are often classified anatomically into oral, oropharyngeal, nasopharyngeal and laryngeal carcinomas. The region’s component structures serve complex and intricate functions, such as speaking, swallowing and breathing, which are often compromised by these neoplasms. Such lesions may also cause disfigurement, leading to distressing social and psychological issues. Conventional treatments of these neoplasms usually involve surgical intervention with or without chemoradiotherapy. These have shown to be efficacious; however, they can also cause damage to healthy as well as diseased tissue, exacerbating the aforementioned problems. Access to a given region to deliver the treatments is also often a problem, due to the complex anatomical structures involved. The use of photodynamic therapy in the head and neck region has been established for about two decades. In this review, we looked at the basic mechanisms of this intervention, examined its use in common head and neck malignancies and vascular anomalies, and reported on the most recent clinical studies. We further included a clinical guide which can help replicate the use of this technology by any unit. Based on this review, photodynamic therapy has been shown to be efficacious in the treatment of head and neck malignancies and vascular tumours. This therapy can be targeted to the diseased tissue and causes no damage to underlying structures. Recent studies have shown this therapy to be as effective as conventional therapies, without causing major adverse effects.

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.

Metavariables Resuming Host Immune Features and Nodal Involvement Are Associated with Oncological Outcomes in Oral Cavity Squamous Cell Carcinoma

Oral cavity squamous cell carcinoma (OSCC) is a common head and neck cancer characterized by a poor prognosis associated with locoregional or distant failure. Among the predictors of prognosis, a dense infiltration of adaptive immune cells is protective and associated with improved clinical outcomes. However, few tools are available to integrate immune contexture variables into clinical settings. By using digital microscopy analysis of a large retrospective OSCC cohort (n = 182), we explored the clinical significance of tumor-infiltrating CD8+ T-cells. To this end, CD8+ T-cells counts were combined with well-established clinical variables and peripheral blood immune cell parameters. Through variable clustering, five metavariables (MV) were obtained and included descriptors of nodal (NODALMV) and primary tumor (TUMORMV) involvement, the frequency of myeloid (MYELOIDMV) or lymphoid (LYMPHOIDMV) peripheral blood immune cell populations, and the density of tumor-infiltrating CD8+ T-cells (TI-CD8MV). The clinical relevance of the MV was evaluated in the multivariable survival models. The NODALMV was significantly associated with all tested outcomes (p < 0.001), the LYMPHOIDMV showed a significant association with the overall, disease-specific and distant recurrence-free survival (p < 0.05) and the MYELOIDMV with the locoregional control only (p < 0.001). Finally, TI-CD8MV was associated with distant recurrence-free survival (p = 0.029). Notably, the performance in terms of survival prediction of the combined effect of NODALMV and immune metavariables (LYMPHOIDMV, MYELOIDMV and TI-CD8MV) was superior to the TNM stage for most of the outcomes analyzed. These findings indicate that the analysis of the baseline host immune features are promising tools to complement clinical features, in stratifying the risk of recurrences.

Characteristics of an Impaired PDT Response

A concurrent human papilloma virus (HPV) infection potentiates the efficacy of ionizing radiation for treatment of head and neck cancer by promoting apoptosis. Studies in cell culture indicated an opposite effect for photodynamic therapy (PDT) when this leads to mitochondrial and ER photodamage. The explanation for this difference in PDT efficacy remains to be established. While apoptosis was impaired in HPV(-) cells, such cells can be killed via photodamage directed at the ER: this leads to a nonapoptotic death pathway termed paraptosis. No differences in photosensitizer uptake or reactive oxygen species (ROS) production were observed in HPV(+) vs. HPV(-) tumors. We now provide evidence that death pathways initiated by ER/mitochondrial photodamage leading to either paraptosis or apoptosis are impaired in an HPV(+) head and neck cell line. These results illustrate the complex determinants of PDT efficacy, a topic that has yet to be fully explored.

Perspectives on interstitial photodynamic therapy for malignant tumors

SIGNIFICANCE

Despite remarkable advances in the core modalities used in combating cancer, malignant diseases remain the second largest cause of death globally. Interstitial photodynamic therapy (IPDT) has emerged as an alternative approach for the treatment of solid tumors.

AIM

The aim of our study is to outline the advancements in IPDT in recent years and provide our vision for the inclusion of IPDT in standard-of-care (SoC) treatment guidelines of specific malignant diseases.

APPROACH

First, the SoC treatment for solid tumors is described, and the attractive properties of IPDT are presented. Second, the application of IPDT for selected types of tumors is discussed. Finally, future opportunities are considered.

RESULTS

Strong research efforts in academic, clinical, and industrial settings have led to significant improvements in the current implementation of IPDT, and these studies have demonstrated the unique advantages of this modality for the treatment of solid tumors. It is envisioned that further randomized prospective clinical trials and treatment optimization will enable a wide acceptance of IPDT in the clinical community and inclusion in SoC guidelines for well-defined clinical indications.

CONCLUSIONS

The minimally invasive nature of this treatment modality combined with the relatively mild side effects makes IPDT a compelling alternative option for treatment in a number of clinical applications. The adaptability of this technique provides many opportunities to both optimize and personalize the treatment.

Potential of Cyanine Derived Dyes in Photodynamic Therapy

Photodynamic therapy (PDT) is a method of cancer treatment that leads to the disintegration of cancer cells and has developed significantly in recent years. The clinically used photosensitizers are primarily porphyrin, which absorbs light in the red spectrum and their absorbance maxima are relatively short. This review presents group of compounds and their derivatives that are considered to be potential photosensitizers in PDT. Cyanine dyes are compounds that typically absorb light in the visible to near-infrared-I (NIR-I) spectrum range (750-900 nm). This meta-analysis comprises the current studies on cyanine dye derivatives, such as indocyanine green (so far used solely as a diagnostic agent), heptamethine and pentamethine dyes, squaraine dyes, merocyanines and phthalocyanines. The wide array of the cyanine derivatives arises from their structural modifications (e.g., halogenation, incorporation of metal atoms or organic structures, or synthesis of lactosomes, emulsions or conjugation). All the following modifications aim to increase solubility in aqueous media, enhance phototoxicity, and decrease photobleaching. In addition, the changes introduce new features like pH-sensitivity. The cyanine dyes involved in photodynamic reactions could be incorporated into sets of PDT agents.

Biosafety, Nontoxic Nanoparticles for VL-NIR Photothermal Therapy Against Oral Squamous Cell Carcinoma

Semiconductor nanocrystals with extraordinary physicochemical and biosafety properties with unique nanostructures have shown tremendous potential as photothermal therapy (PTT) nanosensitizers. Herein, we successfully synthesized chiral molybdenum (Cys-MoO_3–x) nanoparticles (NPs) for overcoming the general limitation on electron energy bands and biotoxicity. The obtained Cys-MoO_3–x NPs are selected as an ideal design for the treatment of oral squamous cell carcinoma (OSCC) cells through the decoration of cysteine molecules due to excellent initial photothermal spectral analysis of conductivity and light absorbance. Notably, NPs possess the ability to act as visible light (VL) and near-infrared (NIR) double-reactive agents to ablate cancer cells. By combining photoconductive PTT with hypotoxicity biochemotherapy, the treatment validity of OSCC cancer cells can be improved in vitro by up to 89% (808 nm) and get potential PTT effect under VL irradiation, which intuitively proved that the nontoxic NPs were lethally effective for cancer cells under laser irradiation. Hence, this work highlights a powerful and safe NP platform for NIR light-triggered PTT for use in head and neck cancer (HNC) cells, showing promising application prospects in oral tumor treatment.

Antimicrobial and antimycotic photodynamic therapy (review of literature)

This review highlights the possibilities of photodynamic therapy (PDT) using drugs based on chlorin e6, aluminum phthalocyanine, methylene blue as photosensitizers for bacterial and fungal pathologies. This method was developed initially to treat tumor diseases, where it had shown its high efficiency and safety. Now photodynamic therapy is actively used in the treatment of cancers of the skin, bronchi, stomach, cervix, larynx, or other regions. However, numerous studies have been carried out for the entire existence of the method, demonstrating new possibilities of its application. This review highlights a number of studies in which the efficacy and safety of antimicrobial and antimycotic PDT were studied in vivo and in vitro. It has been proven to have a positive effect on the reparative processes in the wound. An experimental study was carried out to study the effectiveness of photodynamic therapy in the treatment of peritonitis in mice. Demonstrated anti-inflammatory potential in the treatment of autoimmune diseases.

Progress in Application of Nanotechnology in Sorafenib

Dysregulation of the tyrosine kinase signaling pathway is closely related to tumor development, and tyrosine kinase inhibitors are important targets for potential anticancer strategies. In particular, sorafenib, as a representative drug of multitarget tyrosine kinase inhibitors, has an important clinical status and is widely used for treating various solid tumors and diabetic complications. However, poor aqueous solubility of sorafenib, poor bioavailability of commonly used oral dose forms, poor accumulation at tumor sites, and severe off-target effects that tend to induce intolerable systemic side effects in patients have greatly reduced its therapeutic efficiency and limited its extensive clinical application. To improve the properties of sorafenib, increase the efficiency of clinical treatment, and overcome the increasingly prominent phenomenon of sorafenib resistance, multiple investigations have been conducted. Numerous studies have reported that the properties of nanomaterials, such as small particle size, large specific surface area, high surface activity and high adsorption capacity, make nanotechnology promising for the construction of ideal sorafenib nanodelivery systems to achieve timed and targeted delivery of sorafenib to tumors, prolong the blood circulation time of the drug, improve the utilization efficiency of the drug and reduce systemic toxic side effects. This review summarizes the progress of research applications in nanotechnology related to sorafenib, discusses the current problems, and expresses expectations for the prospect of clinical applications of sorafenib with improved performance.

Novel Cationic Meso-Arylporphyrins and Their Antiviral Activity against HSV-1

This work is devoted to the search for new antiherpes simplex virus type 1 (HSV-1) drugs among synthetic tetrapyrroles and to an investigation of their antiviral properties under nonphotodynamic conditions. In this study, novel amphiphilic 5,10,15,20-tetrakis(4-(3-pyridyl-n-propanoyl)oxyphenyl)porphyrin tetrabromide (3a), 5,10,15,20-tetrakis(4-(6-pyridyl-n-hexanoyl)oxyphenyl)porphyrin tetrabromide (3b) and known 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphyrin tetraiodide (TMePyP) were synthesized, and their dark antiviral activity in vitro against HSV-1 was studied. The influence of porphyrin’s nanosized delivery vehicles based on Pluronic F127 on anti-HSV-1 activity was estimated. All the received compounds 3a, 3b and TMePyP showed virucidal efficiency and had an effect on viral replication stages. The new compound 3b showed the highest antiviral activity, close to 100%, with the lowest concentration, while the maximum TMePyP activity was observed with a high concentration; porphyrin 3a was the least active. The inclusion of the synthesized compounds in Pluronic F-127 polymeric micelles had a noticeable effect on antiviral activity only at higher porphyrin concentrations. Action of the received compounds differs by influence on the early or later reproduction stages. While 3a and TMePyP acted on all stages of the viral replication cycle, porphyrin 3b inhibited viral replication during the early stages of infection. The resulting compounds are promising for the development of utilitarian antiviral agents and, possibly, medical antiviral drugs.

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.

Single Small Molecule-Assembled Mitochondria Targeting Nanofibers for Enhanced Photodynamic Cancer Therapy in Vivo

Photodynamic therapy (PDT) has emerged as an attractive alternative in cancer therapy, but its therapeutic effects are limited by the nonselective subcellular localization and poor intratumoral retention of small-molecule photosensitizes. Here a fiber-forming nanophotosensitizer (PQC NF) that is composed of mitochondria targeting small molecules of amphiphilicity is reported. Harnessing the specific mitochondria targeting, the light-activated PQC NFs produce approximately 110-fold higher amount of reactive oxygen species (ROS) in cells than free photosensitizers and can dramatically induce mitochondrial disruption to trigger intense apoptosis, showing 20-50 times better in vitro anticancer potency than traditional photosensitizers. As fiber-shaped nanomaterials, PQC NFs also demonstrated a long-term retention in tumor sites, solving the challenge of rapid clearance of small-molecule photosensitizers from tumors. With these advantages, PQC NFs achieve a 100% complete cure rate in both subcutaneous and orthotopic oral cancer models with the administration of only a single dose. This type of single small molecule-assembled mitochondria targeting nanofibers offer an advantageous strategy to improve the in vivo therapeutic effects of conventional PDT.

Biogenic Gold Nanoparticles Decrease Methylene Blue Photobleaching and Enhance Antimicrobial Photodynamic Therapy

Antibiotic resistance is a growing concern that is driving the exploration of alternative ways of killing bacteria. Here we show that gold nanoparticles synthesized by the mycelium of Mucor plumbeus are an effective medium for antimicrobial photodynamic therapy (PDT). These particles are spherical in shape, uniformly distributed without any significant agglomeration, and show a single plasmon band at 522–523 nm. The nanoparticle sizes range from 13 to 25 nm, and possess an average size of 17 ± 4 nm. In PDT, light (from a source consisting of nine LEDs with a peak wavelength of 640 nm and FWMH 20 nm arranged in a 3 × 3 array), a photosensitiser (methylene blue), and oxygen are used to kill undesired cells. We show that the biogenic nanoparticles enhance the effectiveness of the photosensitiser, methylene blue, and so can be used to kill both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. The enhanced effectiveness means that we could kill these bacteria with a simple, small LED-based light source. We show that the biogenic gold nanoparticles prevent fast photobleaching, thereby enhancing the photoactivity of the methylene blue (MB) molecules and their bactericidal effect.

Effect of photodynamic therapy on expression of HRAS, NRAS and caspase 3 genes at mRNA levels, apoptosis of head and neck squamous cell carcinoma cell line

OBJECTIVES

This study aimed to assess the effect of photodynamic therapy (PDT) on expression of CASP3, NRAS and HRAS genes at mRNA levels, and apoptosis of head and neck squamous cell carcinoma (HNSCC) cell line.

MATERIALS AND METHODS

In order to complete the present in vitro study, HNSCC cell line (NCBI C196 HN5) purchased from Pasteur Institute. Cells were divided into four groups; Group 1: photodynamic treatment (laser + methylene blue (MB) as photosensitizer), group 2: MB, group 3: laser (with 660 nm wavelength), and group 4: control (without any treatment). To determine the optimal concentration of MB, in a pilot study, toxicity of MB in different concentration was assessed using MTT assay. Cells in group 1, 2 and 3 was treated at optimal concentration of MB (1.6 μg/mL). Gene expression at mRNA levels was assessed after 24 h incubation, using real-time (qRT)-PCR. The expression of BAX and BCL2 genes at the mRNA levels was analyzed to evaluate apoptosis. 2^-ΔΔCt values of BCL2, BAX, CASP3, NRAS, and HRAS in groups was analyzed using ANOVA. Tukey's HSD and Games Howell test was used to compare between two groups.

RESULTS

Over-expression of BAX (p < 0.001), CASP3 (p < 0.001) and down-regulation of BCL2 (p = 0.004), HRAS (p = 0.023) and NRAS (p = 0.045) were noted in group 1 (PDT), compared with the control group. Treatment by laser alone induce down-regulation of CASP3 (p < 0.05), BAX (p < 0.05), BCL2 (p > 0.05), HRAS (p > 0.05) and NRAS (p > 0.05).

CONCLUSION

PDT caused down-regulation of NRAS, HRAS and BCL2 and over-expression of CASP3 and BAX genes at mRNA levels in HNSCC cell line. The present study raises the possibility that the role of MB on BCL2 down-regulation and BAX and CASP3 over-expression was higher than laser alone while it seems that laser alone was more effective than MB in HRAS and NRAS down-regulation.

In silico analysis of the association of hsa-miR-16 expression and cell survival in MDA-MB-231 breast cancer cells subjected to photodynamic therapy

BACKGROUND

Breast cancer is the most common malignancy effecting women, and the triple-negative breast cancer (TNBC) subtype is particularly aggressive. This study aimed to evaluate the differential expression pattern of microRNAs (miRNAs) between untreated MDA-MB-231 cells (TNBC cell model) and those that survived photodynamic therapy (PDT) to gain insights into cell survival mechanisms.

METHODS

Two PDT cycles were applied to MDA-MB-231 cells, using δ-aminolevulinic acid (ALA) followed by laser light at 635 nm. RNA was obtained from cells surviving PDT and untreated cells. The miRNAs expression profile was analyzed to detect the differences between the two groups. The potential target network of hsa-miR-16 was examined in silico with the integrative database Ingenuity® Pathway Analysis software.

RESULTS

After the first and second PDT cycles, 17.8% and 49.6% of the MDA-MB-231 cells were viable. Microarray profiling of miRNAs showed decreased hsa-miR-16 expression (p < 0.05) in MDA-MB-231 cells surviving PDT when compared to the control cells. The predicted downstream targets of hsa-miR-16 were: 1) tumor suppressor protein 53; 2) molecules related to the cell cycle, such as cyclin D1, D3, and E1, and checkpoint kinase 1; 3) cell proliferation molecules, including fibroblast growth factor 1, 2 and 7 and fibroblast growth factor receptor 1; and 4) apoptosis-related molecules, consisting of BCL-2, B-cell leukemia/lymphoma 2, caspase 3, and cytochrome c.

CONCLUSIONS

The differential expression of hsa-miR-16 between untreated MDA-MB-231 cells and those surviving PDT has not been previously reported. There was a lower expression of hsa-miR-16 in treated cells, which probably altered its downstream target network. In silico analysis predicted, a network related to the cell cycle, proliferation and apoptosis. These results are congruent with previous descriptions of hsa-miR-16 as a tumor suppressor and suggest that the treated population has increased their capacity to survive.

Vitamin D and Other Differentiation-promoting Agents as Neoadjuvants for Photodynamic Therapy of Cancer

The efficacy of photodynamic therapy (PDT) using aminolevulinic acid (ALA), which is preferentially taken up by cancerous cells and converted to protoporphyrin IX (PpIX), can be substantially improved by pretreating the tumor cells with vitamin D (Vit D). Vit D is one of several "differentiation-promoting agents" that can promote the preferential accumulation of PpIX within the mitochondria of neoplastic cells, making them better targets for PDT. This article provides a historical overview of how the concept of using combination agents ("neoadjuvants") for PDT evolved, from initial discoveries about neoadjuvant effects of methotrexate and fluorouracil to later studies to determine how vitamin D and other agents actually work to augment PDT efficacy. While this review focuses mainly on skin cancer, it includes a discussion about how these concepts may be applied more broadly toward improving PDT outcomes in other types of cancer.

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.

Effects of HPV Status on Responsiveness to Ionizing Radiation vs Photodynamic Therapy in Head and Neck Cancer Cell lines

Efficacy of ionizing radiation (I/R) was compared with phototoxic effects of photodynamic therapy (PDT) in vitro using two cell lines derived from patients with head and neck squamous cell carcinoma (HNSCC). A cell line derived from a donor with a human papilloma virus (HPV) infection was more responsive to I/R but significantly less responsive to PDT than a cell line derived from an HPV-free patient. Cell death after I/R in the HPV(+) cell line was associated with increased DEVDase activity, a hallmark of apoptosis. The HPV(-) line was considerably less responsive to I/R, with DEVDase activity greatly reduced, suggesting an impaired apoptotic program. In contrast, the HPV(-) cells were readily killed by PDT when the ER was among the targets for photodamage. While DEVDase activity was enhanced, the death pathway appears to involve paraptosis until the degree of photodamage reached the LD99 range. These data suggest that PDT-induced paraptosis can be a death pathway for cells with an impaired apoptotic program.

Application of photodynamic therapy for liver malignancies

Liver malignancies include primary and metastatic tumors. Limited progress has been achieved in improving the survival rate of patients with advanced stage liver cancer and who are unsuitable for surgery. Apart from surgery, chemoradiotherapy, trans-arterial chemoembolization and radiofrequency ablation, a novel therapeutic modality is needed for the clinical treatment of liver cancer. Photodynamic therapy (PDT) is a novel strategy for treating patients with advanced cancers; it uses a light-triggered cytotoxic photosensitizer and a laser light. PDT provides patients with a potential treatment approach with minimal invasion and low toxicity, that is, the whole course of treatment is painless, harmless, and repeatable. Therefore, PDT has been considered an effective palliative treatment for advanced liver cancers. To date, PDT has been used to treat hepatocellular carcinoma, cholangiocarcinoma, hepatoblastoma and liver metastases. Clinical outcomes reveal that PDT can be considered a promising treatment modality for all liver cancers to improve the quality and quantity of life of patients. Despite the advances achieved with this approach, several challenges still impede the application of PDT to liver malignancies. In this review, we focus on the recent advancements and discuss the future prospects of PDT in treating liver malignancies.

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.

On the Development of a Light Dosimetry Planning Tool for Photodynamic Therapy in Arbitrary Shaped Cavities: Initial Results

Previous dosimetric studies during photodynamic therapy (PDT) of superficial lesions within a cavity such as the nasopharynx, demonstrated significant intra- and interpatient variations in fluence rate build-up as a result of tissue surface re-emitted and reflected photons, which depends on the optical properties. This scattering effect affects the response to PDT. Recently, a meta-tetra(hydroxyphenyl)chlorin-mediated PDT study of malignancies in the paranasal sinuses after salvage surgery was initiated. These geometries are complex in shape, with spatially varying optical properties. Therefore, preplanning and in vivo dosimetry is required to ensure an effective fluence delivered to the tumor. For this purpose, two 3D light distribution models were developed: first, a simple empirical model that directly calculates the fluence rate at the cavity surface using a simple linear function that includes the scatter contribution as function of the light source to surface distance. And second, an analytical model based on Lambert's cosine law assuming a global diffuse reflectance constant. The models were evaluated by means of three 3D printed optical phantoms and one porcine tissue phantom. Predictive fluence rate distributions of both models are within ± 20% accurate and have the potential to determine the optimal source location and light source output power settings.

Photodynamic Therapy in Primary Breast Cancer

Photodynamic therapy (PDT) is a technique for producing localized necrosis with light after prior administration of a photosensitizing agent. This study investigates the nature, safety, and efficacy of PDT for image-guided treatment of primary breast cancer. We performed a phase I/IIa dose escalation study in 12 female patients with a new diagnosis of invasive ductal breast cancer and scheduled to undergo mastectomy as a first treatment. The photosensitizer verteporfin (0.4 mg/kg) was administered intravenously followed by exposure to escalating light doses (20, 30, 40, 50 J; 3 patients per dose) delivered via a laser fiber positioned interstitially under ultrasound guidance. MRI (magnetic resonance imaging) scans were performed prior to and 4 days after PDT. Histological examination of the excised tissue was performed. PDT was well tolerated, with no adverse events. PDT effects were detected by MRI in 7 patients and histology in 8 patients, increasing in extent with the delivered light dose, with good correlation between the 2 modalities. Histologically, there were distinctive features of PDT necrosis, in contrast to spontaneous necrosis. Apoptosis was detected in adjacent normal tissue. Median follow-up of 50 months revealed no adverse effects and outcomes no worse than a comparable control population. This study confirms a potential role for PDT in the management of early breast cancer.

Acute cellular and vascular responses to photodynamic therapy using EGFR-targeted nanobody-photosensitizer conjugates studied with intravital optical imaging and magnetic resonance imaging

Targeted photodynamic therapy (PDT) has the potential to selectively damage tumor tissue and to increase tumor vessel permeability. Here we characterize the tissue biodistribution of two EGFR-targeted nanobody-photosensitizer conjugates (NB-PS), the monovalent 7D12-PS and the biparatopic 7D12-9G8-PS. In addition, we report on the local and acute phototoxic effects triggered by illumination of these NB-PS which have previously shown to lead to extensive tumor damage. Methods: Intravital microscopy and the skin-fold chamber model, containing OSC-19-luc2-cGFP tumors, were used to investigate: a) the fluorescence kinetics and distribution, b) the vascular response and c) the induction of necrosis after illumination at 1 or 24 h post administration of 7D12-PS and 7D12-9G8-PS. In addition, dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) of a solid tumor model was used to investigate the microvascular status 2 h after 7D12-PS mediated PDT. Results: Image analysis showed significant tumor colocalization for both NB-PS which was higher for 7D12-9G8-PS. Intravital imaging showed clear tumor cell membrane localization 1 and 2 h after administration of 7D12-9G8-PS, and fluorescence in or close to endothelial cells in normal tissue for both NB-PS. PDT lead to vasoconstriction and leakage of tumor and normal tissue vessels in the skin-fold chamber model. DCE-MRI confirmed the reduction of tumor perfusion after 7D12-PS mediated PDT. PDT induced extensive tumor necrosis and moderate normal tissue damage, which was similar for both NB-PS conjugates. This was significantly reduced when illumination was performed at 24 h compared to 1 h after administration. Discussion: Although differences were observed in distribution of the two NB-PS conjugates, both led to similar necrosis. Clearly, the response to PDT using NB-PS conjugates is the result of a complex mixture of tumor cell responses and vascular effects, which is likely to be necessary for a maximally effective treatment.

In-Vivo Optical Monitoring of the Efficacy of Epidermal Growth Factor Receptor Targeted Photodynamic Therapy: The Effect of Fluence Rate

Targeted photodynamic therapy (PDT) has the potential to improve the therapeutic effect of PDT due to significantly better tumor responses and less normal tissue damage. Here we investigated if the efficacy of epidermal growth factor receptor (EGFR) targeted PDT using cetuximab-IRDye700DX is fluence rate dependent. Cell survival after treatment with different fluence rates was investigated in three cell lines. Singlet oxygen formation was investigated using the singlet oxygen quencher sodium azide and singlet oxygen sensor green (SOSG). The long-term response (to 90 days) of solid OSC-19-luc2-cGFP tumors in mice was determined after illumination with 20, 50, or 150 mW·cm-2. Reflectance and fluorescence spectroscopy were used to monitor therapy. Singlet oxygen was formed during illumination as shown by the increase in SOSG fluorescence and the decreased response in the presence of sodium azide. Significantly more cell death and more cures were observed after reducing the fluence rate from 150 mW·cm-2 to 20 mW·cm-2 both in-vitro and in-vivo. Photobleaching of IRDye700DX increased with lower fluence rates and correlated with efficacy. The response in EGFR targeted PDT is strongly dependent on fluence rate used. The effectiveness of targeted PDT is, like PDT, dependent on the generation of singlet oxygen and thus the availability of intracellular oxygen.

Carcinoembryonic antigen-targeted photodynamic therapy in colorectal cancer models

BACKGROUND

In colorectal cancer, survival of patients is drastically reduced when complete resection is hampered by involvement of critical structures. Targeted photodynamic therapy (tPDT) is a local and targeted therapy which could play a role in eradicating residual tumor cells after incomplete resection. Since carcinoembryonic antigen (CEA; CEACAM5) is abundantly overexpressed in colorectal cancer, it is a potential target for tPDT of colorectal cancer.

METHODS

To address the potential of CEA-targeted PDT, we compared colorectal cancer cell lines with different CEA-expression levels (SW-48, SW-480, SW-620, SW-1222, WiDr, HT-29, DLD-1, LS174T, and LoVo) under identical experimental conditions. We evaluated the susceptibility to tPDT by varying radiant exposure and concentration of our antibody conjugate (DTPA-hMN-14-IRDye700DX). Finally, we assessed the efficacy of tPDT in vivo in 18 mice (BALB/cAnNRj-Foxn1nu/nu) with subcutaneously xenografted LoVo tumors.

RESULTS

In vitro, the treatment effect of tPDT varied per cell line and was dependent on both radiant exposure and antibody concentration. Under standardized conditions (94.5 J/cm2 and 0.5 μg/μL antibody conjugate concentration), the effect of tPDT was higher in cells with higher CEA availability: SW-1222, LS174T, LoVo, and SW-48 (22.8%, 52.8%, 49.9%, and 51.9% reduction of viable cells, respectively) compared to cells with lower CEA availability. Compared to control groups (light or antibody conjugate only), tumor growth rate was reduced in mice with s.c. LoVo tumors receiving tPDT.

CONCLUSION

Our findings suggest cells (and tumors) have different levels of susceptibility for tPDT even though they all express CEA. Furthermore, tPDT can effectively reduce tumor growth in vivo.