Photodynamic therapy (PDT) using HPPH for the treatment of precancerous lesions associated with Barrett's esophagus

Novel chlorin e6-based conjugates of tyrosine kinase inhibitors: Synthesis and photobiological evaluation as potent photosensitizers for photodynamic therapy

Since tyrosine kinase inhibitor (TKI) could reverse ABCG2-mediated drug-resistance, novel chlorin e6-based conjugates of Dasatinib and Imatinib as photosensitizer (PS) were designed and synthesized. The results demonstrated that conjugate 10b showed strongest phototoxicity against HepG2 and B16-F10 cells, which was more phototoxic than chlorin e6 and Talaporfin. It could reduce efflux of intracellular PS by inhibiting ABCG2 in HepG2 cells, and localize in mitochondria, lysosomes, golgi and ER, resulting in higher cell apoptosis rate and ROS production than Talaporfin. Moreover, it could induce cell autophagy and block cell cycle in S phase, and significantly inhibit tumor growth and prolong survival time on BALB/c nude mice bearing HepG2 xenograft tumor to a greater extent than chlorin e6. Consequently, compound 10b could be applied as a promising candidate PS due to its good water-solubility and stability, low drug-resistance, high quantum yield of 1O2 and excellent antitumor efficacy in vitro and in vivo.

Recent Advances in Metal Complexes for Antimicrobial Photodynamic Therapy

Antimicrobial resistance (AMR) is a growing global problem with more than 1 million deaths due to AMR infection in 2019 alone. New and innovative therapeutics are required to overcome this challenge. Antimicrobial photodynamic therapy (aPDT) is a rapidly growing area of research poised to provide much needed help in the fight against AMR. aPDT works by administering a photosensitizer (PS) that is activated only when irradiated with light, allowing high spatiotemporal control and selectivity. The PS typically generates reactive oxygen species (ROS), which can damage a variety of key biological targets, potentially circumventing existing resistance mechanisms. Metal complexes are well known to display excellent optoelectronic properties, and recent focus has begun to shift towards their application in tackling microbial infections. Herein, we review the last five years of progress in the emerging field of small-molecule metal complex PSs for aPDT.

Excitation of a Single Compound by Light and Ultrasound Enhanced the Long-Term Cure of Mice Bearing Prostate Tumors

Current treatment for prostate cancer is dependent on the stages of the cancer, recurrence, and genetic factors. Treatment varies from active surveillance or watchful waiting to prostatectomy, chemotherapy, and radiation therapy in combination or alone. Although radical prostate cancer therapy reduces the advancement of the disease and its mortality, the increased disease treatment associated morbidity, erectile dysfunction, and incontinence affect the quality of life of cancer survivors. To overcome these problems, photodynamic therapy (PDT) has previously been investigated using Photofrin^TM as a photosensitizer (PS). However, Photofrin-PDT has shown limitations in treating prostate cancer due to its limited tumor-specificity and the depth of light penetration at 630 nm (the longest wavelength absorption of Photofrin^TM). The results presented herein show that this limitation can be solved by using a near infrared (NIR) compound as a photosensitizer (PS) for PDT and the same agent also acts as a sonosensitizer for SDT (using ultrasound to activate the compound). Compared to light, ultrasound has a stronger penetration ability in biological tissues. Exposing the PS (or sonosensitizer) to ultrasound (US) initiates an electron-transfer process with a biological substrate to form radicals and radical ions (type I reaction). In contrast, exposure of the PS to light (PDT) generates singlet oxygen (type II reaction). Therefore, the reactive oxygen species (ROS) produced by SDT and PDT follow two distinct pathways, i.e., type I (oxygen independent) and type II (oxygen dependent), respectively, and results in significantly enhanced destruction of tumor cells. The preliminary in vitro and in vivo results in a PC3 cell line and tumor model indicate that the tumor specificality of the therapeutic agent(s) can be increased by targeting galectin-1 and galectin-3, known for their overexpression in prostate cancer.

Advancements in photodynamic therapy of esophageal cancer

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

Impact of mono- and di-β-galactose moieties in in vitro / in vivo anticancer efficacy of pyropheophorbide-carbohydrate conjugates by photodynamic therapy

To investigate the impact of mono- and di-β-galactose moieties in tumor uptake and photodynamic therapy (PDT) efficacy, HPPH [3-(1'-hexyloxy)ethyl-3-devinylpyropheophorobide-a], the meso pyropheophorbide-a [3-ethyl-3-devinyl-pyropheophorbide-a], and the corresponding 20-benzoic acid analogs were used as starting materials. Reaction of the intermediates containing one or two carboxylic acid functionalities with 1-aminogalactose afforded the desired 17²- or 20(4')- mono- and 17², 20(4')-di galactose conjugated photosensitizers (PSs) with and without a carboxylic acid group. The overall lipophilicity caused by the presence of galactose in combination with either an ethyl or (1'-hexyloxy)ethyl side chain at position-3 of the macrocycle made a significant difference in in vitro uptake by tumor cells and photoreaction upon light exposure. Interestingly, among the PSs investigated, compared to HPPH 1 the carbohydrate conjugates 2 and 11 in which β-galactose moieties are conjugated at positions 17² and 20(4') of meso-pyro pheophorbide-a showed similar in vitro efficacy in FaDu cell lines, but in SCID mice bearing FaDu tumors (head & neck) Ps 11 gave significantly improved long-term tumor cure.

Targeted Photodynamic Diagnosis and Therapy for Esophageal Cancer: Potential Role of Functionalized Nanomedicine

Esophageal cancer is often diagnosed at the late stage when cancer has already spread and is characterized by a poor prognosis. Therefore, early diagnosis is vital for a better and efficient treatment outcome. Upper endoscopy with biopsy is the standard diagnostic tool for esophageal cancer but is challenging to diagnose at its premalignant stage, while conventional treatments such as surgery, chemotherapy, and irradiation therapy, are challenging to eliminate the tumor. Photodynamic diagnosis (PDD) and therapy (PDT) modalities that employ photosensitizers (PSs) are emerging diagnostic and therapeutic strategies for esophageal cancer. However, some flaws associated with the classic PSs have limited their clinical applications. Functionalized nanomedicine has emerged as a potential drug delivery system to enhance PS drug biodistribution and cellular internalization. The conjugation of PSs with functionalized nanomedicine enables increased localization within esophageal cancer cells due to improved solubility and stability in blood circulation. This review highlights PS drugs used for PDD and PDT for esophageal cancer. In addition, it focuses on the various functionalized nanomedicine explored for esophageal cancer and their role in targeted PDD and PDT for diagnosis and treatment.

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

BACKGROUND

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

SHORT CONCLUSION

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

Current Advances in Photoactive Agents for Cancer Imaging and Therapy

Photoactive agents are promising complements for both early diagnosis and targeted treatment of cancer. The dual combination of diagnostics and therapeutics is known as theranostics. Photoactive theranostic agents are activated by a specific wavelength of light and emit another wavelength, which can be detected for imaging tumors, used to generate reactive oxygen species for ablating tumors, or both. Photodynamic therapy (PDT) combines photosensitizer (PS) accumulation and site-directed light irradiation for simultaneous imaging diagnostics and spatially targeted therapy. Although utilized since the early 1900s, advances in the fields of cancer biology, materials science, and nanomedicine have expanded photoactive agents to modern medical treatments. In this review we summarize the origins of PDT and the subsequent generations of PSs and analyze seminal research contributions that have provided insight into rational PS design, such as photophysics, modes of cell death, tumor-targeting mechanisms, and light dosing regimens. We highlight optimizable parameters that, with further exploration, can expand clinical applications of photoactive agents to revolutionize cancer diagnostics and treatment.

Chitosan oligosaccharide decorated liposomes combined with TH302 for photodynamic therapy in triple negative breast cancer

BACKGROUND

Triple negative breast cancer (TNBC) is an aggressive tumor with extremely high mortality that results from its lack of effective therapeutic targets. As an adhesion molecule related to tumorigenesis and tumor metastasis, cluster of differentiation-44 (also known as CD44) is overexpressed in TNBC. Moreover, CD44 can be effectively targeted by a specific hyaluronic acid analog, namely, chitosan oligosaccharide (CO). In this study, a CO-coated liposome was designed, with Photochlor (HPPH) as the 660 nm light mediated photosensitizer and evofosfamide (also known as TH302) as the hypoxia-activated prodrug. The obtained liposomes can help diagnose TNBC by fluorescence imaging and produce antitumor therapy by synergetic photodynamic therapy (PDT) and chemotherapy.

RESULTS

Compared with the nontargeted liposomes, the targeted liposomes exhibited good biocompatibility and targeting capability in vitro; in vivo, the targeted liposomes exhibited much better fluorescence imaging capability. Additionally, liposomes loaded with HPPH and TH302 showed significantly better antitumor effects than the other monotherapy groups both in vitro and in vivo.

CONCLUSION

The impressive synergistic antitumor effects, together with the superior fluorescence imaging capability, good biocompatibility and minor side effects confers the liposomes with potential for future translational research in the diagnosis and CD44-overexpressing cancer therapy, especially TNBC.

Photobiomodulation effects on photodynamic therapy in HNSCC cell lines

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

Synthesis, Tumor Specificity, and Photosensitizing Efficacy of Erlotinib-Conjugated Chlorins and Bacteriochlorins: Identification of a Highly Effective Candidate for Photodynamic Therapy of Cancer

Erlotinib was covalently linked to 3-(1'-hexyloxy)ethyl-3-devinylpyropheophorbide-a (HPPH) and structurally related chlorins and bacteriochlorins at different positions of the tetrapyrrole ring. The functional consequence of each modification was determined by quantifying the uptake and subcellular deposition of the erlotinib conjugates, cellular response to therapeutic light treatment in tissue cultures, and in eliminating of corresponding tumors grown as a xenograft in SCID mice. The experimental human cancer models the established cell lines UMUC3 (bladder), FaDu (hypopharynx), and primary cultures of head and neck tumor cells. The effectiveness of the compounds was compared to that of HPPH. Furthermore, specific functional contribution of the carboxylic acid side group at position 172 and the chiral methyl group at 3(1') to the overall activity of the chimeric compounds was assessed. Among the conjugates investigated, the PS 10 was identified as the most effective candidate for achieving tumor cell-specific accumulation and yielding improved long-term tumor control.

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.

Recent advances in photodynamic therapy for cancer and infectious diseases

Photodynamic therapy (PDT) is a treatment by combining light and a photosensitizer to generate reactive oxygen species (ROS) for cellular damage, and is used to treat cancer and infectious diseases. In this review, we focus on recent advances in design of new photosensitizers for increased production of ROS and in genetic engineering of biological photosensitizers to study cellular signaling pathways. A new concept has been proposed that PDT-induced acute inflammation can mediate neutrophil infiltration to deliver therapeutics in deep tumor tissues. Combination of PDT and immunotherapies (neutrophil-mediated therapeutic delivery) has shown the promising translation of PDT for cancer therapies. Furthermore, a new area in PDT is to treat bacterial infections to overcome the antimicrobial resistance. Finally, we have discussed the new directions of PDT for therapies of cancer and infectious diseases. In summary, we believe that rational design and innovations in nanomaterials may have a great impact on translation of PDT in cancer and infectious diseases. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Recent advances in photodynamic therapy for cancer and infectious diseases

Photodynamic therapy (PDT) is a treatment by combining light and a photosensitizer to generate reactive oxygen species (ROS) for cellular damage, and is used to treat cancer and infectious diseases. In this review, we focus on recent advances in design of new photosensitizers for increased production of ROS and in genetic engineering of biological photosensitizers to study cellular signaling pathways. A new concept has been proposed that PDT-induced acute inflammation can mediate neutrophil infiltration to deliver therapeutics in deep tumor tissues. Combination of PDT and immunotherapies (neutrophil-mediated therapeutic delivery) has shown the promising translation of PDT for cancer therapies. Furthermore, a new area in PDT is to treat bacterial infections to overcome the antimicrobial resistance. Finally, we have discussed the new directions of PDT for therapies of cancer and infectious diseases. In summary, we believe that rational design and innovations in nanomaterials may have a great impact on translation of PDT in cancer and infectious diseases. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Population pharmacokinetic modeling and simulation of HPPH in Chinese patients with esophageal carcinoma

1. 2-[1-Hexyloxyethyl]-2-devinyl pyropheophorbide-a (HPPH), a second-generation photosensitizer, has been widely employed in photodynamic therapy (PDT) for the treatment of malignant lesions. The objective of this study was to characterize the pharmacokinetics of HPPH in Chinese patients using a population pharmacokinetic (PopPK) approach.2. For the first time, a PopPK model of HPPH for Chinese (n = 20) was developed (registration number: CTR20160425). The pharmacokinetics of HPPH was described by a three-compartment model with linear elimination. Through the stepwise addition (p < 0.05) and backward elimination (p < 0.001) approach, fat-free mass (FFM) was identified to be the most significant covariate and V₁ increased with FFM. Visual predictive check (VPC) was employed for the evaluation of the final model. Subsequent full covariate analysis indicated that FFM has considerable impact (∼30%) on HPPH exposure and fat mass also has a modest (∼25%) impact.3. The simulations suggested that a dose adjustment of HPPH may be necessary for Chinese and the dose of 3 mg/m² should be appropriate. HPPH exposure increases with fat mass while being inversely related to FFM. HPPH-PDT for overweight patients should be monitored with more caution and PDT conditions should be optimized if necessary.

Cell-specific Retention and Action of Pheophorbide-based Photosensitizers in Human Lung Cancer Cells

This study determined in primary cultures of human lung cancer cells the cell specificity of chlorin-based photosensitizers. Epithelial cells (ECs) preferentially retained 3-[1-hexyloxyethyl]-2-devinylpyropheophorbide-a (HPPH) and related structural variants. Tumor-associated fibroblasts (Fb) differ from EC by a higher efflux rate of HPPH. Immunoblot analyses indicated dimerization of STAT3 as a reliable biomarker of the photoreaction. Compared to mitochondria/ER-localized photoreaction by HPPH, the photoreaction by lysosomally targeted HPPH-lactose showed a trend toward lower STAT3 cross-linking. Lethal consequence of the photoreaction differed between EC and Fb with the latter cells being more resistant. A survey of lung tumor cases indicated a large quantitative range by which EC retains HPPH. The specificity of HPPH retention defined in vitro could be confirmed in vivo in selected cases grown as xenografts. HPPH retention as a function of the tetrapyrrole structure was evaluated by altering side groups on the porphyrin macrocycle. The presence or absence of a carboxylic acid at position 17² proved to be critical. A benzyl group at position 20 enhanced retention in a subset of cancer cells with low HPPH binding. This study indicated experimental tools that are potentially effective in defining the photosensitizer preference and application for individual patient's cancer lesions.

The Noninvasive Treatment for Sentinel Lymph Node Metastasis by Photodynamic Therapy Using Phospholipid Polymer as a Nanotransporter of Verteporfin

Aim. The usefulness of photodynamic therapy (PDT) for treating sentinel lymph node (SLN) metastasis was evaluated. Materials and Methods. Verteporfin, a hydrophobic photosensitizer, forms a soluble aggregate with poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) (PMB). The concentrations of verteporfin were determined by measuring the fluorescence emitted at 700 nm. Seven days after the inoculation of A431 cells at the forearm of BALB/c nude mice, PMB-verteporfin was injected at dorsum manus and 75 J of light energy was delivered for 1 minute. Fifty-three mice were randomly assigned to the combination of PMB-verteporfin injection and light exposure, light exposure alone, PMB-verteporfin injection alone, and no treatment groups. Ten days after PDT, brachial lymph nodes, which were considered as SLNs, were harvested and evaluated. Results. The concentration of verteporfin in SLN was significantly higher than other organs. The combination of PMB-verteporfin injection and light exposure group significantly reduced the SLN metastasis (13%) comparing with no treatment group (52%), light exposure alone group (57%), and PMB-verteporfin injection alone group (46%). Conclusions. These data suggested that PDT using PMB as a nanotransporter of verteporfin could be a minimally invasive treatment of SLN metastasis in breast cancer and represent a potential alternative procedure to SLNB.

Oncologic Photodynamic Therapy: Basic Principles, Current Clinical Status and Future Directions

Photodynamic therapy (PDT) is a clinically approved cancer therapy, based on a photochemical reaction between a light activatable molecule or photosensitizer, light, and molecular oxygen. When these three harmless components are present together, reactive oxygen species are formed. These can directly damage cells and/or vasculature, and induce inflammatory and immune responses. PDT is a two-stage procedure, which starts with photosensitizer administration followed by a locally directed light exposure, with the aim of confined tumor destruction. Since its regulatory approval, over 30 years ago, PDT has been the subject of numerous studies and has proven to be an effective form of cancer therapy. This review provides an overview of the clinical trials conducted over the last 10 years, illustrating how PDT is applied in the clinic today. Furthermore, examples from ongoing clinical trials and the most recent preclinical studies are presented, to show the directions, in which PDT is headed, in the near and distant future. Despite the clinical success reported, PDT is still currently underutilized in the clinic. We also discuss the factors that hamper the exploration of this effective therapy and what should be changed to render it a more effective and more widely available option for patients.

Manipulating tumor hypoxia toward enhanced photodynamic therapy (PDT)

This mini-review summarizes various methods for overcoming or utilizing hypoxia for enhanced PDT.

Novel theranostic nanoporphyrins for photodynamic diagnosis and trimodal therapy for bladder cancer

The overall prognosis of bladder cancer has not been improved over the last 30 years and therefore, there is a great medical need to develop novel diagnosis and therapy approaches for bladder cancer. We developed a multifunctional nanoporphyrin platform that was coated with a bladder cancer-specific ligand named PLZ4. PLZ4-nanoporphyrin (PNP) integrates photodynamic diagnosis, image-guided photodynamic therapy, photothermal therapy and targeted chemotherapy in a single procedure. PNPs are spherical, relatively small (around 23 nm), and have the ability to preferably emit fluorescence/heat/reactive oxygen species upon illumination with near infrared light. Doxorubicin (DOX) loaded PNPs possess slower drug release and dramatically longer systemic circulation time compared to free DOX. The fluorescence signal of PNPs efficiently and selectively increased in bladder cancer cells but not normal urothelial cells in vitro and in an orthotopic patient derived bladder cancer xenograft (PDX) models, indicating their great potential for photodynamic diagnosis. Photodynamic therapy with PNPs was significantly more potent than 5-aminolevulinic acid, and eliminated orthotopic PDX bladder cancers after intravesical treatment. Image-guided photodynamic and photothermal therapies synergized with targeted chemotherapy of DOX and significantly prolonged overall survival of mice carrying PDXs. In conclusion, this uniquely engineered targeting PNP selectively targeted tumor cells for photodynamic diagnosis, and served as effective triple-modality (photodynamic/photothermal/chemo) therapeutic agents against bladder cancers. This platform can be easily adapted to individualized medicine in a clinical setting and has tremendous potential to improve the management of bladder cancer in the clinic.

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

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

Management of Barrett's esophagus: From screening to newer treatments

Barrett's esophagus is a premalignant condition of the esophagus in which the squamous epithelium of the lower end of the esophagus is replaced with columnar epithelium. Since the incidence of esophageal adenocarcinoma is on the rise, the major gastroenterology societies have come up with their recommendations for screening and surveillance. Specific factors like obesity, white race, age over 50 years, early age of onset of GERD, smoking and hiatal hernia have been identified as increasing the risk of Barrett's esophagus and adenocarcinoma. The diagnosis requires both endoscopic identification of columnar-lined mucosa and histological confirmation with biopsy. Most medical societies recommend screening people with GERD and other risk factors with endoscopy, but other alternatives employing less invasive methods are currently being studied. Surveillance strategies vary depending on the endoscopic findings and the Seattle biopsy protocol with random 4-quadrant sampling is recommended. Biomarkers have shown promising results, but more studies are needed in the future. White light endoscopy is the standard practice, but other advanced imaging modalities have shown variable results and hence more studies are awaited for further validation. Endoscopic eradication techniques, including both resection and ablation, have shown good but variable results for treating dysplastic lesions confined to the mucosa. Resection procedures to remove visible lesions followed by ablation of the dysplastic mucosa have shown the best results with higher eradication rates and lower recurrence rates. Surgical management is reserved for lesions with sub-mucosal invasion and lymph node spread with increased risk of metastasis.

A Phase I Study of Light Dose for Photodynamic Therapy Using 2-[1-Hexyloxyethyl]-2 Devinyl Pyropheophorbide-a for the Treatment of Non-Small Cell Carcinoma In Situ or Non-Small Cell Microinvasive Bronchogenic Carcinoma: A Dose Ranging Study

INTRODUCTION

We report a phase I trial of photodynamic therapy (PDT) of carcinoma in situ (CIS) and microinvasive cancer (MIC) of the central airways with the photosensitizer (PS) 2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide-a (HPPH). HPPH has the advantage of minimal general phototoxicity over the commonly used photosensitizer porfimer sodium (Photofrin; Pinnacle Biologics, Chicago, IL).

METHODS

The objectives of this study were (1) to determine the maximally tolerated light dose at a fixed photosensitizer dose and (2) to gain initial insight into the effectiveness of this treatment approach. Seventeen patients with 21 CIS/MIC lesions were treated with HPPH with light dose escalation starting from 75 J/cm2 and increasing to 85, 95,125, and 150 J/cm2 respectively. Follow-up bronchoscopy for response assessment was performed at 1 and 6 months, respectively.

RESULTS

The rate of pathological complete response (CR) was 82.4% (14 of 17 evaluable lesions; 14 patients) at 1 month and 72.7% (8/11 evaluable lesions; 8 patients) at 6 months. Only four patients developed mild skin erythema. One of the three patients in the 150 J/cm2 light dose group experienced a serious adverse event. This patient had respiratory distress caused by mucus plugging, which precipitated cardiac ischemia. Two additional patients treated subsequently at this light dose had no adverse events. The sixth patient in this dose group was not recruited and the study was terminated because of delays in HPPH supply. However, given the observed serious adverse event, it is recommended that the light dose does not exceed 125 J/cm2.

CONCLUSIONS

PDT with HPPH can be safely used for the treatment of CIS/MIC of the airways, with potential effectiveness comparable to that reported for porfimer sodium in earlier studies.

Photodynamic therapy with 3-(1'-hexyloxyethyl) pyropheophorbide-a for early-stage cancer of the larynx: Phase Ib study

Background

The purpose of this study was for us to report results regarding the safety of 3‐(1′‐hexyloxyethyl) pyropheophorbide‐a (HPPH) mediated photodynamic therapy (PDT) in early laryngeal disease, and offer preliminary information on treatment responses.

Methods

A single‐institution, phase Ib, open label, noncomparative study of HPPH‐PDT in patients with high‐risk dysplasia, carcinoma in situ, and T1 squamous cell carcinoma (SCC) of the larynx. The primary outcomes were safety and maximum tolerated dose (MTD), and the secondary outcome was response.

Results

Twenty‐nine patients and 30 lesions were treated. The most common adverse event (AE) was transient hoarseness of voice. Severe edema, requiring tracheostomy, was the most serious AE, which occurred in 2 patients within several hours of therapy. The MTD was 100 J/cm². Patients with T1 SCC seemed to have good complete response rate (82%) to HPPH‐PDT at MTD.

Conclusion

HPPH‐PDT can be safely used to treat early‐stage laryngeal cancer, with potential efficacy. © 2015 The Authors Head & Neck Published by Wiley Periodicals, Inc. Head Neck38: E377–E383, 2016

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

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

Photo activation of HPPH encapsulated in "Pocket" liposomes triggers multiple drug release and tumor cell killing in mouse breast cancer xenografts

We recently reported laser-triggered release of photosensitive compounds from liposomes containing dipalmitoylphosphatidylcholine (DPPC) and 1,2 bis(tricosa-10,12-diynoyl)-sn-glycero-3-phosphocholine (DC(8,9)PC). We hypothesized that the permeation of photoactivated compounds occurs through domains of enhanced fluidity in the liposome membrane and have thus called them "Pocket" liposomes. In this study we have encapsulated the red light activatable anticancer photodynamic therapy drug 2-(1-Hexyloxyethyl)-2-devinyl pyropheophorbide-a (HPPH) (Ex/Em410/670 nm) together with calcein (Ex/Em490/517 nm) as a marker for drug release in Pocket liposomes. A mole ratio of 7.6:1 lipid:HPPH was found to be optimal, with >80% of HPPH being included in the liposomes. Exposure of liposomes with a cw-diode 660 nm laser (90 mW, 0-5 minutes) resulted in calcein release only when HPPH was included in the liposomes. Further analysis of the quenching ratios of liposome-entrapped calcein in the laser treated samples indicated that the laser-triggered release occurred via the graded mechanism. In vitro studies with MDA-MB-231-LM2 breast cancer cell line showed significant cell killing upon treatment of cell-liposome suspensions with the laser. To assess in vivo efficacy, we implanted MDA-MB-231-LM2 cells containing the luciferase gene along the mammary fat pads on the ribcage of mice. For biodistribution experiments, trace amounts of a near infrared lipid probe DiR (Ex/Em745/840 nm) were included in the liposomes. Liposomes were injected intravenously and laser treatments (90 mW, 0.9 cm diameter, for an exposure duration ranging from 5-8 minutes) were done 4 hours postinjection (only one tumor per mouse was treated, keeping the second flank tumor as control). Calcein release occurred as indicated by an increase in calcein fluorescence from laser treated tumors only. The animals were observed for up to 15 days postinjection and tumor volume and luciferase expression was measured. A significant decrease in luciferase expression and reduction in tumor volume was observed only in laser treated animal groups injected with liposomes containing HPPH. Histopathological examination of tumor tissues indicated tumor necrosis resulting from laser treatment of the HPPH-encapsulated liposomes that were taken up into the tumor area.

Photodynamic therapy with 3-(1'-hexyloxyethyl) pyropheophorbide a for cancer of the oral cavity

PURPOSE

The primary objective was to evaluate safety of 3-(1'-hexyloxyethyl)pyropheophorbide-a (HPPH) photodynamic therapy (HPPH-PDT) for dysplasia and early squamous cell carcinoma of the head and neck (HNSCC). Secondary objectives were the assessment of treatment response and reporters for an effective PDT reaction.

EXPERIMENTAL DESIGN

Patients with histologically proven oral dysplasia, carcinoma in situ, or early-stage HNSCC were enrolled in two sequentially conducted dose escalation studies with an expanded cohort at the highest dose level. These studies used an HPPH dose of 4 mg/m(2) and light doses from 50 to 140 J/cm(2). Pathologic tumor responses were assessed at 3 months. Clinical follow up range was 5 to 40 months. PDT induced cross-linking of STAT3 were assessed as potential indicators of PDT effective reaction.

RESULTS

Forty patients received HPPH-PDT. Common adverse events were pain and treatment site edema. Biopsy proven complete response rates were 46% for dysplasia and carcinoma in situ and 82% for squamous cell carcinomas (SCC) lesions at 140 J/cm(2). The responses in the carcinoma in situ/dysplasia cohort are not durable. The PDT-induced STAT3 cross-links is significantly higher (P = 0.0033) in SCC than in carcinoma in situ/dysplasia for all light doses.

CONCLUSION

HPPH-PDT is safe for the treatment of carcinoma in situ/dysplasia and early-stage cancer of the oral cavity. Early-stage oral HNSCC seems to respond better to HPPH-PDT in comparison with premalignant lesions. The degree of STAT3 cross-linking is a significant reporter to evaluate HPPH-PDT-mediated photoreaction.

Adjuvant intraoperative photodynamic therapy in head and neck cancer

IMPORTANCE

There is an immediate need to develop local intraoperative adjuvant treatment strategies to improve outcomes in patients with cancer who undergo head and neck surgery.

OBJECTIVES

To determine the safety of photodynamic therapy with 2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide-a (HPPH) in combination with surgery in patients with head and neck squamous cell carcinoma.

DESIGN, SETTING, AND PARTICIPANTS

Nonrandomized, single-arm, single-site, phase 1 study at a comprehensive cancer center among 16 adult patients (median age, 65 years) with biopsy-proved primary or recurrent resectable head and neck squamous cell carcinoma.

INTERVENTIONS

Intravenous injection of HPPH (4.0 mg/m2), followed by activation with 665-nm laser light in the surgical bed immediately after tumor resection.

MAIN OUTCOMES AND MEASURES

Adverse events and highest laser light dose.

RESULTS

Fifteen patients received the full course of treatment, and 1 patient received HPPH without intraoperative laser light because of an unrelated myocardial infarction. Disease sites included larynx (7 patients), oral cavity (6 patients), skin (1 patient), ear canal (1 patient), and oropharynx (1 patient, who received HPPH only). The most frequent adverse events related to photodynamic therapy were mild to moderate edema (9 patients) and pain (3 patients). One patient developed a grade 3 fistula after salvage laryngectomy, and another patient developed a grade 3 wound infection and mandibular fracture. Phototoxicity reactions included 1 moderate photophobia and 2 mild to moderate skin burns (2 due to operating room spotlights and 1 due to the pulse oximeter). The highest laser light dose was 75 J/cm2.

CONCLUSIONS AND RELEVANCE

The adjuvant use of HPPH-photodynamic therapy and surgery for head and neck squamous cell carcinoma seems safe and deserves further study.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00470496.

Evaluation of polymethine dyes as potential probes for near infrared fluorescence imaging of tumors: part - 1

Near-infrared (NIR) organic dyes have become important for many biomedical applications, including in vivo optical imaging. Conjugation of NIR fluorescent dyes to photosensitizing molecules (photosensitizers) holds strong potential for NIR fluorescence image guided photodynamic therapy (PDT) of cancer. Therefore, we were interested in investigating the photophysical properties, in vivo tumor-affinity and fluorescence imaging potential of a series of heterocyclic polymethine dyes, which could then be conjugated to certain PDT agents. For our present study, we selected a series of symmetrical polymethine dyes containing a variety of bis-N-substituted indole or benzindole moieties linked by linear conjugation with and without a fused substituted cyclohexene ring. The N-alkyl side chain at the C-terminal position was functionalized with sulfonic, carboxylic acid, methyl ester or hydroxyl groups. Although, among the parent cyanine dyes investigated, the commercially available, cyanine dye IR783 (3) (bis-indole-N-butylsulfonate)-polymethine dye with a cyclic chloro-cyclohexene moiety showed best fluorescence-imaging ability, based on its spectral properties (λ_Abs=782 nm, λ_Fl=810 nm, ε = 261,000 M^-1cm^-1, Φ_Fl≈0.08) and tumor affinity. In addition to 3, parent dyes IR820 and Cypate (6) were also selected and subjected to further modifications by introducing desired functional groups, which could enable further conjugation of the cyanine dyes to an effective photosensitizer HPPH developed in our laboratory. The synthesis and biological studies (tumor-imaging and PDT) of the resulting bifunctional conjugates are discussed in succeeding paper (Part-2 of this study).

Confocal fluorescence imaging enables noninvasive quantitative assessment of host cell populations in vivo following photodynamic therapy

We report the use of optical imaging strategies to noninvasively examine photosensitizer distribution and physiological and host responses to 2-[1-hexyloxyethyl]-2 devinyl pyropheophorbide-a (HPPH)-mediated photodynamic therapy (PDT) of EMT6 tumors established in the ears of BALB/c mice. 24 h following intravenous (IV) administration of 1 μmol kg(-1) HPPH, wide-field fluorescence imaging reveals tumor selectivity with an approximately 2-3-fold differential between tumor and adjacent normal tissue. Confocal microscopy demonstrates a relatively homogeneous intratumor HPPH distribution. Labeling of host cells using fluorophore-conjugated antibodies allowed the visualization of Gr1(+)/CD11b(+) leukocytes and major histocompatibility complex class II (MHC-II)(+) cells in vivo. Imaging of the treated site at different time-points following irradiation shows significant and rapid increases in Gr1(+) cells in response to therapy. The maximum accumulation of Gr1(+) cells is found at 24 h post-irradiation, followed by a decrease at the 48 h time-point. Using IV-injected FITC-conjugated dextran as a fluorescent perfusion marker, we imaged tissue perfusion at different times post-irradiation and found that the reduced Gr1(+ )cell density at 48 h correlated strongly with functional damage to the vasculature as reported via decreased perfusion status. Dual color confocal imaging experiments demonstrates that about 90% of the anti-Gr1 cell population co-localized with anti-CD11b labeling, thus indicating that majority of the Gr1-labeled cells were neutrophils. At 24 h post-PDT, an approximately 2-fold increase in MHC-II+ cells relative to untreated control is also observed. Co-localization analysis reveals an increase in the fraction of Gr1(+) cells expressing MHC-II, suggesting that HPPH-PDT is stimulating neutrophils to express an antigen-presenting phenotype.

Optical property measurements establish the feasibility of photodynamic therapy as a minimally invasive intervention for tumors of the kidney

We measured the optical properties of freshly excised kidneys with renal parenchymal tumors to assess the feasibility of photodynamic therapy (PDT) in these patients. Kidneys were collected from 16 patients during surgical nephrectomies. Spatially resolved, white light, steady-state diffuse reflectance measurements were performed on normal and neoplastic tissue identified by a pathologist. Reflectance data were fit using a radiative transport model to obtain absorption (μa) and transport scattering coefficients (μs'), which define a characteristic light propagation distance, δ. Monte Carlo (MC) simulations of light propagation from cylindrical diffusing fibers were run using the optical properties extracted from each of the kidneys. Interpretable spectra were obtained from 14 kidneys. Optical properties of human renal cancers exhibit significant inter-lesion heterogeneity. For all diagnoses, however, there is a trend toward increased light penetration at longer wavelengths. For renal cell carcinomas (RCC), mean values of δ increase from 1.28 to 2.78 mm as the PDT treatment wavelength is increased from 630 to 780 nm. MC simulations of light propagation from interstitial optical fibers show that fluence distribution in tumors is significantly improved at 780 versus 630 nm. Our results support the feasibility of PDT in selected renal cancer patients, especially with photosensitizers activated at longer wavelengths.

Imaging a photodynamic therapy photosensitizer in vivo with a time-gated fluorescence tomography system

We report the tomographic imaging of a photodynamic therapy (PDT) photosensitizer, 2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide-a (HPPH) in vivo with time-domain fluorescence diffuse optical tomography (TD-FDOT). Simultaneous reconstruction of fluorescence yield and lifetime of HPPH was performed before and after PDT. The methodology was validated in phantom experiments, and depth-resolved in vivo imaging was achieved through simultaneous three-dimensional (3-D) mappings of fluorescence yield and lifetime contrasts. The tomographic images of a human head-and-neck xenograft in a mouse confirmed the preferential uptake and retention of HPPH by the tumor 24-h post-injection. HPPH-mediated PDT induced significant changes in fluorescence yield and lifetime. This pilot study demonstrates that TD-FDOT may be a good imaging modality for assessing photosensitizer distributions in deep tissue during PDT monitoring.

The effect of photodynamic therapy on tumor cell expression of major histocompatibility complex (MHC) class I and MHC class I-related molecules

BACKGROUND AND OBJECTIVE

Photodynamic therapy (PDT) is FDA-approved anti-cancer modality for elimination of early disease and palliation in advanced disease. PDT efficacy depends in part on elicitation of a tumor-specific immune response that is dependent on cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells. The cytolytic potential of CTLs and NK cells is mediated by the ability of these cells to recognize major histocompatibility complex (MHC) class I and MHC class I-related molecules. The MHC class I-related molecules MICA and MICB are induced by oxidative stress and have been reported to activate NK cells and co-stimulate CD8(+) T cells. The purpose of this study was to examine the effect of PDT on tumor cell expression of MHC classes I and II-related molecules in vivo and in vitro.

STUDY DESIGN/MATERIALS AND METHODS

Human colon carcinoma Colo205 cells and murine CT26 tumors were treated with 2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide-a (HPPH)-PDT at various doses. MHC classes I and I-related molecule expression following treatment of Colo205 cells was temporally examined by flow cytometry using antibodies specific for components of MHC class I molecules and by quantitative PCR using specific primers. Expression of MHC class I-related molecules following HPPH-based PDT (HPPH-PDT) of murine tumors was monitored using a chimeric NKG2D receptor.

RESULTS

In vitro HPPH-PDT significantly induces MICA in Colo205 cells, but had no effect on MHC class I molecule expression. PDT also induced expression of NKG2D ligands (NKG2DL) following in vivo HPPH-PDT of a murine tumor. Induction of MICA corresponded to increased NK killing of PDT-treated tumor cells.

CONCLUSIONS

PDT induction of MICA on human tumor cells and increased expression of NKG2DL by murine tumors following PDT may play a role in PDT induction of anti-tumor immunity. This conclusion is supported by our results demonstrating that tumor cells have increased sensitivity to NK cell lysis following PDT.