Photodynamic therapy for lung cancer and malignant pleural mesothelioma

Uncovering Porphyrin Accumulation in the Tumor Microenvironment

Heme, an iron-containing tetrapyrrole, is essential in almost all organisms. Heme biosynthesis needs to be precisely regulated particularly given the potential cytotoxicity of protoporphyrin IX, the intermediate preceding heme formation. Here, we report on the porphyrin intermediate accumulation within the tumor microenvironment (TME), which we propose to result from dysregulation of heme biosynthesis concomitant with an enhanced cancer survival dependence on mid-step genes, a process we recently termed "Porphyrin Overdrive". Specifically, porphyrins build up in both lung cancer cells and stromal cells in the TME. Within the TME's stromal cells, evidence supports cancer-associated fibroblasts (CAFs) actively producing porphyrins through an imbalanced pathway. Conversely, normal tissues exhibit no porphyrin accumulation, and CAFs deprived of tumor cease porphyrin overproduction, indicating that both cancer and tumor-stromal porphyrin overproduction is confined to the cancer-specific tissue niche. The clinical relevance of our findings is implied by establishing a correlation between imbalanced porphyrin production and overall poorer survival in more aggressive cancers. These findings illuminate the anomalous porphyrin dynamics specifically within the tumor microenvironment, suggesting a potential target for therapeutic intervention.

Bronchoscopic treatment of early-stage peripheral lung cancer

PURPOSE OF REVIEW

This review article focuses on bronchoscopic treatment of early-stage peripheral lung cancer.

RECENT FINDINGS

Bronchoscopic treatment modalities have garnered considerable attention for early-stage lung cancer. Studies using photodynamic therapy, thermal vapor ablation, laser ablation, cryoablation, and intra-tumoral injection have recently been published. However, the evidence supporting these approaches largely derives from single-arm studies with small sample sizes. Based on the IDEAL-D framework, no technology has progressed passed the idea phase (1). The main weakness of these technologies to date is lack of evidence suggesting they can achieve local control. Presently, no bronchoscopic intervention for lung cancer has sufficient data to warrant its use as part of the standard of care.

SUMMARY

Despite notable progress, current technologies remain suboptimal, and there is insufficient evidence to support their use outside of a research setting.

Apoptotic efficiency of Dicoma anomala biosynthesized silver nanoparticles against A549 lung cancer cells

Lung cancer is one of the common forms of cancer that affects both men and women and is regarded as the leading cause of cancer related deaths. It is characterized by unregulated cell division of altered cells within the lung tissues. Green nanotechnology is a promising therapeutic option that is adopted in cancer research. Dicoma anomala (D. anomala) is one of the commonly used African medicinal plant in the treatment of different medical conditions including cancer. In the present study, silver nanoparticles (AgNPs) were synthesized using D. anomala MeOH root extract. We evaluated the anticancer efficacy of the synthesized AgNPs as an individual treatment as well as in combination with pheophorbide a (PPBa) mediated photodynamic therapy (PDT) in vitro. UV-VIS spectroscopy, high-resolution transmission electron microscopy (HR-TEM), Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) was used to confirm the formation of D.A AgNPs. Post 24 h treatment, A549 cells were evaluated for ATP proliferation, morphological changes supported by LIVE/DEAD assay, and caspase activities. All experiments were repeated four times (n=4), with findings being analysed using SPSS statistical software version 27 set at 0.95 confidence interval. The results from the present study revealed a dose-dependent decrease in cell proliferation in both individual and combination therapy of PPBa mediated PDT and D.A AgNPs on A549 lung cancer cells with significant morphological changes. Additionally, LIVE/DEAD assay displayed a significant increase in the number of dead cell population in individual treatments (i.e., IC50's treated A549 cells) as well as in combination therapy. In conclusion, the findings from this study demonstrated the anticancer efficacy of green synthesized AgNPs as a mono-therapeutic drug as well as in combination with a chlorophyll derivative PPBa in PDT. Taken together, the findings highlight the therapeutic potential of green nanotechnology in medicine.

The use of photodynamic therapy in medical practice

Cancer therapy, especially for tumors near sensitive areas, demands precise treatment. This review explores photodynamic therapy (PDT), a method leveraging photosensitizers (PS), specific wavelength light, and oxygen to target cancer effectively. Recent advancements affirm PDT's efficacy, utilizing ROS generation to induce cancer cell death. With a history spanning over decades, PDT's dynamic evolution has expanded its application across dermatology, oncology, and dentistry. This review aims to dissect PDT's principles, from its inception to contemporary medical applications, highlighting its role in modern cancer treatment strategies.

Current State of Melanoma Therapy and Next Steps: Battling Therapeutic Resistance

Melanoma is the most aggressive and deadly form of skin cancer due to its high propensity to metastasize to distant organs. Significant progress has been made in the last few decades in melanoma therapeutics, most notably in targeted therapy and immunotherapy. These approaches have greatly improved treatment response outcomes; however, they remain limited in their abilities to hinder disease progression due, in part, to the onset of acquired resistance. In parallel, intrinsic resistance to therapy remains an issue to be resolved. In this review, we summarize currently available therapeutic options for melanoma treatment and focus on possible mechanisms that drive therapeutic resistance. A better understanding of therapy resistance will provide improved rational strategies to overcome these obstacles.

Clinical PDT dose dosimetry for pleural Photofrin-mediated photodynamic therapy

Significance

Photodynamic therapy (PDT) is an established cancer treatment utilizing light-activated photosensitizers (PS). Effective treatment hinges on the PDT dose-dependent on PS concentration and light fluence-delivered over time. We introduce an innovative eight-channel PDT dose dosimetry system capable of concurrently measuring light fluence and PS concentration during treatment.

Aim

We aim to develop and evaluate an eight-channel PDT dose dosimetry system for simultaneous measurement of light fluence and PS concentration. By addressing uncertainties due to tissue variations, the system enhances accurate PDT dosimetry for improved treatment outcomes.

Approach

The study positions eight isotropic detectors strategically within the pleural cavity before PDT. These detectors are linked to bifurcated fibers, distributing signals to both a photodiode and a spectrometer. Calibration techniques are applied to counter tissue-related variations and improve measurement accuracy. The fluorescence signal is normalized using the measured light fluence, compensating for variations in tissue properties. Measurements were taken in 78 sites in the pleural cavities of 20 patients.

Results

Observations reveal minimal Photofrin concentration variation during PDT at each site, juxtaposed with significant intra- and inter-patient heterogeneities. Across 78 treated sites in 20 patients, the average Photofrin concentration for all 78 sites is 4.98    μ M , with a median concentration of 4.47    μ M . The average PDT dose for all 78 sites is 493.17    μ MJ / cm 2 , with a median dose of 442.79    μ MJ / cm 2 . A significant variation in PDT doses is observed, with a maximum difference of 3.1 times among all sites within one patient and a maximum difference of 9.8 times across all patients.

Conclusions

The introduced eight-channel PDT dose dosimetry system serves as a valuable real-time monitoring tool for light fluence and PS concentration during PDT. Its ability to mitigate uncertainties arising from tissue properties enhances dosimetry accuracy, thus optimizing treatment outcomes and bolstering the effectiveness of PDT in cancer therapy.

Fractionated Photofrin-Mediated Photodynamic Therapy Significantly Improves Long-Term Survival

This study investigates the effect of fractionated (two-part) PDT on the long-term local control rate (LCR) using the concentration of reactive oxygen species ([ROS]rx) as a dosimetry quantity. Groups with different fractionation schemes are examined, including a 2 h interval between light delivery sessions to cumulative fluences of 135, 180, and 225 J/cm2. While the total treatment time remains constant within each group, the division of treatment time between the first and second fractionations are explored to assess the impact on long-term survival at 90 days. In all preclinical studies, Photofrin is intravenously administered to mice at a concentration of 5 mg/kg, with an incubation period between 18 and 24 h before the first light delivery session. Fluence rate is fixed at 75 mW/cm2. Treatment ensues via a collimated laser beam, 1 cm in diameter, emitting light at 630 nm. Dosimetric quantities are assessed for all groups along with long-term (90 days) treatment outcomes. This study demonstrated a significant improvement in long-term survival after fractionated treatment schemes compared to single-fraction treatment, with the optimal 90-day survival increasing to 63%, 86%, and 100% vs. 20%, 25%, and 50%, respectively, for the three cumulative fluences. The threshold [ROS]rx for the optimal scheme of fractionated Photofrin-mediated PDT, set at 0.78 mM, is significantly lower than that for the single-fraction PDT, at 1.08 mM.

The use of nanomaterials in advancing photodynamic therapy (PDT) for deep-seated tumors and synergy with radiotherapy

Photodynamic therapy (PDT) has been under development for at least 40 years. Multiple studies have demonstrated significant anti-tumor efficacy with limited toxicity concerns. PDT was expected to become a major new therapeutic option in treating localized cancer. However, despite a shifting focus in oncology to aggressive local therapies, PDT has not to date gained widespread acceptance as a standard-of-care option. A major factor is the technical challenge of treating deep-seated and large tumors, due to the limited penetration and variability of the activating light in tissue. Poor tumor selectivity of PDT sensitizers has been problematic for many applications. Attempts to mitigate these limitations with the use of multiple interstitial fiberoptic catheters to deliver the light, new generations of photosensitizer with longer-wavelength activation, oxygen independence and better tumor specificity, as well as improved dosimetry and treatment planning are starting to show encouraging results. Nanomaterials used either as photosensitizers per se or to improve delivery of molecular photosensitizers is an emerging area of research. PDT can also benefit radiotherapy patients due to its complementary and potentially synergistic mechanisms-of-action, ability to treat radioresistant tumors and upregulation of anti-tumoral immune effects. Furthermore, recent advances may allow ionizing radiation energy, including high-energy X-rays, to replace external light sources, opening a novel therapeutic strategy (radioPDT), which is facilitated by novel nanomaterials. This may provide the best of both worlds by combining the precise targeting and treatment depth/volume capabilities of radiation therapy with the high therapeutic index and biological advantages of PDT, without increasing toxicities. Achieving this, however, will require novel agents, primarily developed with nanomaterials. This is under active investigation by many research groups using different approaches.

Fluorescence-guided photoimmunotherapy using targeted nanotechnology and ML7710 to manage peritoneal carcinomatosis

Fluorescence-guided intervention can bolster standard therapies by detecting and treating microscopic tumors before lethal recurrence. Tremendous progress in photoimmunotherapy and nanotechnology has been made to treat metastasis. However, many are lost in translation due to heterogeneous treatment effects. Here, we integrate three technological advances in targeted photo-activable multi-agent liposome (TPMAL), fluorescence-guided intervention, and laser endoscopy (ML7710) to improve photoimmunotherapy. TPMAL consists of a nanoliposome chemotherapy labeled with fluorophores for tracking and photosensitizer immunoconjugates for photoimmunotherapy. ML7710 is connected to Modulight Cloud to capture and analyze multispectral emission from TPMAL for fluorescence-guided drug delivery (FGDD) and fluorescence-guided light dosimetry (FGLD) in peritoneal carcinomatosis mouse models. FGDD revealed that TPMAL enhances drug delivery to metastases by 14-fold. ML7710 captured interpatient variability in TPMAL uptake and prompted FGLD in >50% of animals. By combining TPMAL, ML7710, and fluorescence-guided intervention, variation in treatment response was substantially reduced and tumor control improved without side effects.

Intrapleural Anticancer Therapy for Malignant Pleural Diseases: Facts or Fiction?

Malignant pleural diseases involves both primary pleural malignancies (e.g., mesothelioma) as well as metastatic disease involving the pleura. The management of primary pleural malignancies remains a challenge, given their limited response to conventional treatments such as surgery, systemic chemotherapy, and immunotherapy. In this article, we aimed to review the management of primary pleural malignancy as well as malignant pleural effusion and assess the current state of intrapleural anticancer therapies. We review the role intrapleural chemotherapy, immunotherapy, and immunogene therapy, as well as oncolytic viral, therapy and intrapleural drug device combination. We further discuss that while the pleural space offers a unique opportunity for local therapy as an adjuvant option to systemic therapy and may help decrease some of the systemic side effects, further patient outcome-oriented research is needed to determine the exact role of these treatments within the armamentarium of currently available options.

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.

The ALK1‑Smad1/5‑ID1 pathway participates in tumour angiogenesis induced by low‑dose photodynamic therapy

Photodynamic therapy (PDT) is an effective and low‑invasive tumour therapy. However, it can induce tumour angiogenesis, which is a main factor leading to tumour recurrence and metastasis. Activin receptor‑like kinase‑1 (ALK1) is a key factor regulating angiogenesis. However, it remains unclear whether ALK1 plays an unusual role in low‑dose PDT‑induced tumour angiogenesis. In the present study, human umbilical vein endothelial cells (HUVECs) co‑cultured with breast cancer MDA‑MB‑231 cells (termed HU‑231 cells) were used to construct an experimental model of tumour angiogenesis induced by low‑dose PDT. The viability, and the proliferative, invasive, migratory, as well as the tube‑forming ability of the HU‑231 cells were evaluated following low‑dose PDT. In particular, ALK1 inhibitor and and an adenovirus against ALK1 were used to further verify the role of ALK1 in low‑dose PDT‑induced tumour angiogenesis. Moreover, the expression of ALK1, inhibitor of DNA binding 1 (ID1), Smad 1, p‑Smad1/5, AKT and PI3K were detected in order to verify the underlying mechanisms. The findings indicated that low‑dose PDT enhanced the proliferative ability of the HU‑231 cells and reinforced their migratory, invasive and tube formation capacity. However, these effects were reversed with the addition of an ALK1 inhibitor or by the knockdown of ALK1 using adenovirus. These results indicated that ALK1 was involved and played a critical role in tumour angiogenesis induced by low‑dose PDT. Furthermore, ALK1 was found to participate in PDT‑induced tumour angiogenesis by activating the Smad1/5‑ID1 pathway, as opposed to the PI3K/AKT pathway. On the whole, the present study, for the first time, to the best of our knowledge, demonstrates that ALK1 is involved in PDT‑induced tumour angiogenesis. The inhibition of ALK1 can suppress PDT‑induced tumour angiogenesis, which can enhance the effects of PDT and may thus provide a novel treatment strategy for PDT.

An "IgG-hitchhiking" approach for rapid tumor accumulation and clearance of photosensitizers

Photodynamic therapy (PDT) has been widely used for the local treatment of a variety of cancer. To improve the therapeutic effect, delicate nanoparticles loading photosensitizers (PSs) have been designed to improve the accumulation of PSs in tumor. Different from the anti-cancer drugs for chemotherapy or immunotherapy, the delivery of PSs requires rapid tumor accumulation followed by quick elimination to reduce the potential risk of phototoxicity. However, owing to the nature of prolonged blood circulation of the nanoparticles, the conventional nanoparticulate delivery systems may decelerate the clearance of PSs. Here, we present a tumor-targeted delivery approach termed "IgG-hitchhiking" strategy through a self-assembled PSs nanostructure, according to the intrinsic binding between the photosensitizer pheophorbide A (PhA) and immunoglobulin (IgG). We utilize the intravital fluorescence microscopic imaging to uncover that the nanostructures (IgG:PhA NPs) increase the extravasation of PhA into tumor within the first hour post intravenous injection compared with free PhA, correlating with an improved efficacy of PDT. After ∼1 h post-injection, a quick decrease in the PhA amount in the tumor is observed, while the tumor IgG level is continuously increasing. The disparity of the tumor distribution between PhA and IgG allows the quick elimination of the PSs for minimized skin phototoxicity. Our results provide a direct evidence of the enhanced accumulation and elimination of the PSs in the tumor microenvironment through the "IgG-hitchhiking" approach. This strategy presents a promising tumor-targeted delivery approach for the PSs in lieu of the existing strategy for enhanced PDT with minimal toxicity in clinic.

Evaluation of Detector Position and Light Fluence Distribution Using an Infrared Navigation System during Pleural Photodynamic Therapy†

Photodynamic therapy (PDT) has been used to treat malignant pleural mesothelioma. Current practice involves delivering light to a prescribed light fluence with a point source, monitored by eight isotropic detectors inside the pleural cavity. An infrared (IR) navigation system was used to track the location of the point source throughout the treatment. The recorded data were used to reconstruct the pleural cavity and calculate the light fluence to the whole cavity. An automatic algorithm was developed recently to calculate the detector positions based on recorded data within an hour. This algorithm was applied to patient case studies and the calculated results were compared to the measured positions, with an average difference of 2.5 cm. Calculated light fluence at calculated positions were compared to measured values. The differences between the calculated and measured light fluence were within 14% for all cases, with a fixed scattering constant and a dual correction method. Fluence-surface histogram (FSH) was calculated for photofrin-mediated PDT to be able to cover 80% of pleural surface area to 50 J cm-2 (83.3% of 60 J cm-2 ). The study demonstrates that it will be possible to eliminate the manual measurement of the detector positions, reducing the patient's time under anesthesia.

Photodynamic therapy of lung cancer, where are we?

Lung cancer remains the leading threat of death globally, killing more people than colon, breast, and prostate cancers combined. Novel lung cancer treatments are being researched because of the ineffectiveness of conventional cancer treatments and the failure of remission. Photodynamic therapy (PDT), a cancer treatment method that is still underutilized, is a sophisticated cancer treatment that shows selective destruction of malignant cells via reactive oxygen species production. PDT has been extensively studied in vitro and clinically. Various PDT strategies have been shown to be effective in the treatment of lung cancer. PDT has been shown in clinical trials to considerably enhance the quality of life and survival in individuals with incurable malignancies. Furthermore, PDT, in conjunction with the use of nanoparticles, is currently being researched for use as an effective cancer treatment, with promising results. PDT and the new avenue of nanoPDT, which are novel treatment options for lung cancer with such promising results, should be tested in clinical trials to determine their efficacy and side effects. In this review, we examine the status and future potentials of nanoPDT in lung cancer treatment.

Phototherapeutic Induction of Immunogenic Cell Death and CD8+ T Cell-Granzyme B Mediated Cytolysis in Human Lung Cancer Cells and Organoids

Augmenting T cell mediated tumor killing via immunogenic cancer cell death (ICD) is the cornerstone of emerging immunotherapeutic approaches. We investigated the potential of methylene blue photodynamic therapy (MB-PDT) to induce ICD in human lung cancer. Non-Small Cell Lung Cancer (NSCLC) cell lines and primary human lung cancer organoids were evaluated in co-culture killing assays with MB-PDT and light emitting diodes (LEDs). ICD was characterised using immunoblotting, immunofluorescence, flow cytometry and confocal microscopy. Phototherapy with MB treatment and low energy LEDs decreased the proliferation of NSCLC cell lines inducing early necrosis associated with reduced expression of the anti-apoptotic protein, Bcl2 and increased expression of ICD markers, calreticulin (CRT), intercellular cell-adhesion molecule-1 (ICAM-1) and major histocompatibility complex I (MHC-I) in NSCLC cells. MB-PDT also potentiated CD8+ T cell-mediated cytolysis of lung cancer via granzyme B in lung cancer cells and primary human lung cancer organoids.

A method for intra-percardial PDT for malignant mesothelioma

We describe a case of a 35-year-old patient with recurrent non-resectable pleural mesothelioma cT4N0M0 with a confirmed malignant pericardial effusion, threatening for cardiac tamponade. We performed and described our experience of intrapericardial photodynamic therapy which was well tolerated and with a good survival result. After 12 months of follow-up our patient showed no signs of pericardial effusion and in stable condition, keeping high level of quality of life. This clinical case is an example of the excellent palliative effect of photodynamic therapy together with concomitant immunotherapy.

Current State of Pleural-Directed Adjuncts Against Malignant Pleural Mesothelioma

Multimodality therapy including surgical resection is the current paradigm in treating malignant pleural mesothelioma (MPM), a thoracic surface cancer without cure. The main limitation of all surgical approaches is the lack of long-term durability because macroscopic complete resection (R1 resection) commonly predisposes to locoregional relapse. Over the years, there have been many studies that describe various intrapleural strategies that aim to extend the effect of surgical resection. The majority of these approaches are intraoperative adjuvants. Broadly, there are three therapeutic classes that employ diverse agents. The most common, widely used group of adjuvants are comprised of direct therapeutics such as intracavitary chemotherapy (± hyperthermia). By comparison, the least commonly employed intrathoracic adjuvant is the class comprised of drug-device combinations like photodynamic therapy (PDT). But the most rapidly evolving (new) class with much potential for improved efficacy are therapeutics delivered by specialized drug vehicles such as a fibrin gel containing cisplatin. This review provides an updated perspective on pleural-directed adjuncts in the management of MPM as well as highlighting the most promising near-term technology breakthroughs.

LS-HB-Mediated Photodynamic Therapy Inhibits Proliferation and Induces Cell Apoptosis in Melanoma

Chlorin e6-C-15-ethyl ester (LS-HB), a newly identified photosensitizer, was isolated from chlorin e6. The mechanism of tumor cell death induced by photodynamic therapy with LS-HB (LS-HB-PDT) is still unknown. Here, we investigated the photophysical properties of LS-HB, evaluated the antitumor effect on melanoma in vitro and in vivo, and explored its possible mechanisms. LS-HB not only has an optimal spectral band of red wavelength (660 nm) for photosensitization but also has favorable photostability. More importantly, LS-HB-PDT elicited a potent dose-dependent phototoxic effect in vitro. We discovered that LS-HB located in the mitochondria of B16F10 cells was able to generate excess reactive oxygen species, which subsequently resulted in mitochondrial membrane potential loss and induced apoptosis via caspase-9 and caspase-3 pathways. Moreover, PDT with LS-HB markedly inhibited the growth of melanoma in vivo. Therefore, LS-HB is expected to be an effective potential photosensitizer in antitumor therapy.

The emerging role of photoacoustic imaging in clinical oncology

Clinical oncology can benefit substantially from imaging technologies that reveal physiological characteristics with multiscale observations. Complementing conventional imaging modalities, photoacoustic imaging (PAI) offers rapid imaging (for example, cross-sectional imaging in real time or whole-breast scanning in 10-15 s), scalably high levels of spatial resolution, safe operation and adaptable configurations. Most importantly, this novel imaging modality provides informative optical contrast that reveals details on anatomical, functional, molecular and histological features. In this Review, we describe the current state of development of PAI and the emerging roles of this technology in cancer screening, diagnosis and therapy. We comment on the performance of cutting-edge photoacoustic platforms, and discuss their clinical applications and utility in various clinical studies. Notably, the clinical translation of PAI is accelerating in the areas of macroscopic and mesoscopic imaging for patients with breast or skin cancers, as well as in microscopic imaging for histopathology. We also highlight the potential of future developments in technological capabilities and their clinical implications, which we anticipate will lead to PAI becoming a desirable and widely used imaging modality in oncological research and practice.

Combination of phototherapy with immune checkpoint blockade: Theory and practice in cancer

Immune checkpoint blockade (ICB) therapy has evolved as a revolutionized therapeutic modality to eradicate tumor cells by releasing the brake of the antitumor immune response. However, only a subset of patients could benefit from ICB treatment currently. Phototherapy usually includes photothermal therapy (PTT) and photodynamic therapy (PDT). PTT exerts a local therapeutic effect by using photothermal agents to generate heat upon laser irradiation. PDT utilizes irradiated photosensitizers with a laser to produce reactive oxygen species to kill the target cells. Both PTT and PDT can induce immunogenic cell death in tumors to activate antigen-presenting cells and promote T cell infiltration. Therefore, combining ICB treatment with PTT/PDT can enhance the antitumor immune response and prevent tumor metastases and recurrence. In this review, we summarized the mechanism of phototherapy in cancer immunotherapy and discussed the recent advances in the development of phototherapy combined with ICB therapy to treat malignant tumors. Moreover, we also outlined the significant progress of phototherapy combined with targeted therapy or chemotherapy to improve ICB in preclinical and clinical studies. Finally, we analyzed the current challenges of this novel combination treatment regimen. We believe that the next-generation technology breakthrough in cancer treatment may come from this combinational win-win strategy of photoimmunotherapy.

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.

Intratumoral Photosensitizer Delivery and Photodynamic Therapy

Photodynamic therapy (PDT) is a two-step procedure that involves the administration of special drugs, commonly called photosensitizers, followed by the application of certain wavelengths of light. The light activates these photosensitizers to produce reactive molecular species that induce cell death in tissues. There are numerous factors to consider when selecting the appropriate photosensitizer administration route, such as which part of the body is being targeted, the pharmacokinetics of photosensitizers, and the formulation of photosensitizers. While intravenous, topical, and oral administration of photosensitizers are widely used in preclinical and clinical applications of PDT, other administration routes, such as intraperitoneal, intra-arterial, and intratumoral injections, are gaining traction for their potential in treating advanced diseases and reducing off-target toxicities. With recent advances in targeted nanotechnology, biomaterials, and light delivery systems, the exciting possibilities of targeted photosensitizer delivery can be fully realized for preclinical and clinical applications. Further, in light of the growing burden of cancer mortality in low and middle-income countries and development of low-cost light sources and photosensitizers, PDT could be used to treat cancer patients in low-income settings. This short article introduces aspects of interfaces of intratumoral photosensitizer injections and nano-biomaterials for PDT applications in both high-income and low-income settings but does not present a comprehensive review due to space limitations.

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.

Photodynamic Therapy for Pancreatic Ductal Adenocarcinoma

Simple Summary

Pancreatic ductal adenocarcinoma (PDAC) is among the most lethal of human cancers. Numerous clinical trials evaluating various combinations of chemotherapy and targeted agents and radiotherapy have failed to provide meaningful improvements in survival. A growing number of studies however have indicated that photodynamic therapy (PDT) may be a viable approach for treatment of some pancreatic tumors. PDT, which uses light to activate a photosensitizing agent in target tissue, has seen widespread adoption primarily for dermatological and other applications where superficial light delivery is relatively straightforward. Advances in fiber optic light delivery and dosimetry however have been leveraged to enable PDT even for challenging internal sites, including the pancreas. The aim of this article is to help inform future directions by reviewing relevant literature on the basic science, current clinical status, and potential challenges in the development of PDT as a treatment for PDAC.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is among the most lethal of human cancers. Clinical trials of various chemotherapy, radiotherapy, targeted agents and combination strategies have generally failed to provide meaningful improvement in survival for patients with unresectable disease. Photodynamic therapy (PDT) is a photochemistry-based approach that enables selective cell killing using tumor-localizing agents activated by visible or near-infrared light. In recent years, clinical studies have demonstrated the technical feasibility of PDT for patients with locally advanced PDAC while a growing body of preclinical literature has shown that PDT can overcome drug resistance and target problematic and aggressive disease. Emerging evidence also suggests the ability of PDT to target PDAC stroma, which is known to act as both a barrier to drug delivery and a tumor-promoting signaling partner. Here, we review the literature which indicates an emergent role of PDT in clinical management of PDAC, including the potential for combination with other targeted agents and RNA medicine.

Potential Alternatives to Conventional Cancer Therapeutic Approaches: The Way Forward

onventional cancer therapeutic approaches broadly include chemotherapy, radiation therapy and surgery. These established approaches have evolved over several decades of clinical experience. For a complex disease like cancer, satisfactory treatment remains an enigma for the simple fact that the causal factors for cancer are extremely diverse. In order to overcome existing therapeutic limitations, consistent scientific endeavors have evolved several potential therapeutic approaches, majority of which focuses essentially on targeted drug delivery, minimal concomitant ramification, and selective high cytotoxicity. The current review focuses on highlighting some of these potential alternatives that are currently in various stages of in vitro, in vivo, and clinical trials. These include physical, chemical and biological entities that are avidly being explored for therapeutic alternatives. Some of these entities include suicide gene, micro RNA, modulatory peptides, ultrasonic waves, free radicals, nanoparticles, phytochemicals, and gene knockout, and stem cells. Each of these techniques may be exploited exclusively and in combination with conventional therapeutic approaches thereby enhancing the therapeutic efficacy of the treatment. The review intends to briefly discuss the mechanism of action, pros, and cons of potential alternatives to conventional therapeutic approaches.

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.

A Review of Chemotherapy and Photodynamic Therapy for Lung Cancer Treatment

Cancer is among the leading causes of mortality and morbidity worldwide. Among the different types of cancers, lung cancer is considered to be the leading cause of death related to cancer and the most commonly diagnosed form of such disease. Chemotherapy remains a dominant treatment modality for many types of cancers at different stages. However, in many cases, cancer cells develop drug resistance and become nonresponsive to chemotherapy, thus, necessitating the exploration of alternative and /or complementary treatment modalities. Photodynamic Therapy (PDT) has emerged as an effective treatment modality for various malignant neoplasia and tumors. In PDT, the photochemical interaction of light, Photosensitizer (PS) and molecular oxygen produces Reactive Oxygen Species (ROS), which induces cell death. Combination therapy, by using PDT and chemotherapy, can promote synergistic effect against this fatal disease with the elimination of drug resistance, and enhancement of the efficacy of cancer eradication. In this review, we give an overview of chemotherapeutic modalities, PDT, and the different types of drugs associated with each therapy. Furthermore, we also explored the combined use of chemotherapy and PDT in the course of lung cancer treatment and how this approach could be the last resort for thousands of patients that have been diagnosed by this fatal disease.

An update in clinical utilization of photodynamic therapy for lung cancer

Lung cancer is one of the leading causes of cancer-related death worldwide, with nearly 1.8 million-diagnosis and 1.59 million deaths. Surgery, radiotherapy, and chemotherapy in individual or combination are commonly used to treat lung cancers. Photodynamic therapy (PDT) is a highly selective method for the destruction of cancer cells by exerting cytotoxic activity on malignant cells. PDT has been the subject of numerous clinical studies and has proven to be an effective strategy for cancer therapy. Clinical studies revealed that PDT could prolong survival in patients with inoperable cancers and significantly improve quality of life. For inoperable lung cancer cases, PDT could be an effective therapy. Despite the clinical success reported, PDT is still currently underutilized to treat lung cancer and other tumors. PTD is still a new treatment approach for lung cancer mainly due to the lack of enough clinical research evaluating its' effectiveness and side effects. In this review, we discuss the current prospects and future potentials of PDT in lung cancer treatment.

Bronchoscopic treatment of inoperable nonsmall cell lung cancer

Patients with unresectable lung cancer range from those with early-stage or pre-invasive disease with comorbidities that preclude surgery to those with advanced stage disease in whom surgery is contraindicated. In such cases, a multidisciplinary approach to treatment is warranted, and may involve medical specialties including medical oncology, radiation oncology and interventional pulmonology. In this article we review bronchoscopic approaches to surgically unresectable lung cancer, including photodynamic therapy, brachytherapy, endoscopic ablation techniques and airway stenting. Current and past literature is reviewed to provide an overview of the topic, including a highlight of potential emerging approaches.

Verteporfin Is a Promising Anti-Tumor Agent for Cervical Carcinoma by Targeting Endoplasmic Reticulum Stress Pathway

Accumulated evidence has shown that the photosensitizer Verteporfin (VP) may be an ideal agent for various cancer types. However, the effect and mechanism of VP on human cervical carcinoma remain rudimentary. The aim of this study was to investigate the effect of VP on human cervical carcinoma cells (HeLa and SiHa cells) and to elucidate the possible mechanism. CCK-8, wound healing assay, flow cytometry analysis, western blotting, TUNEL staining were performed to evaluate the effects of VP on HeLa and SiHa cells in vitro as well as in vivo on a xenograft model. In addition, the role of endoplasmic reticulum (ER) stress in VP-induced apoptosis was investigated using RT-qPCR and western blotting. The results showed that the viability of HeLa and SiHa cells was suppressed by VP in dose- and time-dependent manners. Compared with the control group, apoptosis rates were higher with stronger TUNEL fluorescence signals in the experimental group, which substantiated that VP induced apoptosis at both 2D and 3D cell levels. Besides, VP can squelch the growth of tumors in both sizes and weights on the xenograft models without impairing ovarian reserve. Mechanism studies demonstrated that VP activated ER stress by upregulating the expression of GRP78, CHOP, and Caspase-12, and VP-induced apoptosis can be alleviated when ER stress pathway was inhibited. Our results provided a foundation for repurposing VP as a promising agent for cervical cancer patients without obvious reproductive toxicity by targeting ER stress pathway, and more researches are required to support its application in clinical practice.

Reactive oxygen species explicit dosimetry to predict local tumor growth for Photofrin-mediated photodynamic therapy

Although photodynamic therapy (PDT) is an established modality for cancer treatment, current dosimetric quantities, such as light fluence and PDT dose, do not account for the differences in PDT oxygen consumption for different fluence rates (ϕ). A macroscopic model was adopted to calculate reactive oxygen species concentration ([ROS]_rx) to predict Photofrin-PDT outcome in mice bearing radiation-induced fibrosarcoma (RIF) tumors. Singlet oxygen is the primary cytotoxic species for ROS, which is responsible for cell death in type II PDT, although other type I ROS is included in the parameters used in our model. Using a combination of fluences (50-250 J∕cm²) and ϕ (75 or 150 mW∕cm²), tumor regrowth rate, k, was determined for each condition by fitting the tumor volume versus time to V₀ *exp(k*t). Treatment was delivered with a collimated laser beam of 1 cm diameter at 630 nm. Explicit dosimetry of light fluence rate on tissue surface, tissue oxygen concentration, tissue optical properties, and Photofrin concentration were performed. Light fluence rate at 3 mm depth (ϕ _3mm) was determined for the treatment volume based on Monte-Carlo simulations and measured tissue optical properties. Initial tissue oxygenation [³ O ₂]₀ was measured by an Oxylite oxygen probe before PDT and used to calculate [ROS]_rx,calc. This value was compared to [ROS]_rx,meas as calculated with the entire tissue oxygen spectrum [³ O ₂](t), measured over the duration of light delivery for PDT. Cure index, CI = 1-k/k_ctr , for tumor growth up to 14 days after PDT was predicted by four dose metrics: light fluence, PDT dose, and [ROS]_rx,calc, and [ROS]_rx,meas. PDT dose was defined as the product of the time-integral of photosensitizer concentration and ϕ at a 3 mm tumor depth. These studies show that [ROS]_rx,meas best correlates with CI and is an effective dosimetric quantity that can predict treatment outcome.

TLD1433-Mediated Photodynamic Therapy with an Optical Surface Applicator in the Treatment of Lung Cancer Cells In Vitro

Intra-operative photodynamic therapy (IO-PDT) in combination with surgery for the treatment of non-small cell lung cancer and malignant pleural mesothelioma has shown promise in improving overall survival in patients. Here, we developed a PDT platform consisting of a ruthenium-based photosensitizer (TLD1433) activated by an optical surface applicator (OSA) for the management of residual disease. Human lung adenocarcinoma (A549) cell viability was assessed after treatment with TLD1433-mediated PDT illuminated with either 532- or 630-nm light with a micro-lens laser fiber. This TLD1433-mediated PDT induced an EC50 of 1.98 μM (J/cm2) and 4807 μM (J/cm2) for green and red light, respectively. Cells were then treated with 10 µM TLD1433 in a 96-well plate with the OSA using two 2-cm radial diffusers, each transmitted 532 nm light at 50 mW/cm for 278 s. Monte Carlo simulations of the surface light propagation from the OSA computed light fluence (J/cm2) and irradiance (mW/cm2) distribution. In regions where 100% loss in cell viability was measured, the simulations suggest that >20 J/cm2 of 532 nm was delivered. Our studies indicate that TLD1433-mediated PDT with the OSA and light simulations have the potential to become a platform for treatment planning for IO-PDT.

Gender-based Disparities in Receipt of Care and Survival in Malignant Pleural Mesothelioma

BACKGROUND

Despite accounting for a minority of malignant pleural mesothelioma (MPM) diagnoses, females may experience differential survival relative to males. It is unclear if there are gender-based differences in receipt of treatment or disease-related outcomes for patients with MPM. We therefore utilized the National Cancer Database (NCDB) to assess patterns-of-care and overall survival (OS) among patients with MPM by gender.

MATERIALS AND METHODS

Patients with histologically confirmed MPM treated from 2004 to 2013 were identified from the NCDB. The association between female gender and OS was assessed using multivariable Cox proportional hazards models with propensity score matching. Patterns-of-care were assessed using multivariable logistic regression. The overall treatment effect was tested in subsets of patients by treatment strategy, histology, and clinical stage.

RESULTS

A total of 18,799 patients were identified, of whom 14,728 (78%) were male and 4071 (22%) were female. Females were statistically more likely to present at a younger age, with fewer comorbidities, and with epithelioid histology. Despite these favorable prognostic features, women were less likely to receive surgery (P ≤ .001) or chemotherapy (P ≤ .001) compared with males. On multivariable analysis, female gender was associated with improved OS (hazard ratio, 0.83; 95% confidence interval, 0.80-0.86; P ≤ .001). Gender-based survival differences were seen across all stages, but only among patients with epithelioid (P ≤ .001) and not biphasic (P = .17) or sarcomatoid (P = 1.00) histology.

CONCLUSIONS

Surgery and chemotherapy are disproportionately underutilized in female patients with MPM. Despite this concerning disparity, female gender is independently associated with improved survival relative to males. Further research to understand factors that lead to gender disparities in MPM is warranted.

Susceptibility and Resistance Mechanisms During Photodynamic Therapy of Melanoma

Melanoma is the most aggressive malignant skin tumor and arises from melanocytes. The resistance of melanoma cells to various treatments results in rapid tumor growth and high mortality. As a local therapeutic modality, photodynamic therapy has been successfully applied for clinical treatment of skin diseases. Photodynamic therapy is a relatively new treatment method for various types of malignant tumors in humans and, compared to conventional treatment methods, has fewer side effects, and is more accurate and non-invasive. Although several in vivo and in vitro studies have shown encouraging results regarding the potential benefits of photodynamic therapy as an adjuvant treatment for melanoma, its clinical application remains limited owing to its relative inefficiency. This review article discusses the use of photodynamic therapy in melanoma treatment as well as the latest progress made in deciphering the mechanism of tolerance. Lastly, potential targets are identified that may improve photodynamic therapy against melanoma cells.

Infrared navigation system for light dosimetry during pleural photodynamic therapy

Pleural photodynamic therapy (PDT) is performed intraoperatively for the treatment of microscopic disease in patients with malignant pleural mesothelioma. Accurate delivery of light dose is critical to PDT efficiency. As a standard of care, light fluence is delivered to the prescribed fluence using eight isotropic detectors in pre-determined discrete locations inside the pleural cavity that is filled with a dilute Intralipid solution. An optical infrared (IR) navigation system was used to monitor reflective passive markers on a modified and improved treatment delivery wand to track the position of the light source within the treatment cavity during light delivery. This information was used to calculate the light dose, incorporating a constant scattered light dose and using a dual correction method. Calculation methods were extensively compared for eight detector locations and seven patient case studies. The light fluence uniformity was also quantified by representing the unraveled three-dimensional geometry on a two-dimensional plane. Calculated light fluence at the end of treatment delivery was compared to measured values from isotropic detectors. Using a constant scattered dose for all detector locations along with a dual correction method, the difference between calculated and measured values for each detector was within 15%. Primary light dose alone does not fully account for the light delivered inside the cavity. This is useful in determining the light dose delivered to areas of the pleural cavity between detector locations, and can serve to improve treatment delivery with implementation in real-time in the surgical setting. We concluded that the standard deviation of light fluence uniformity for this method of pleural PDT is 10%.

Light Fluence Rate and Tissue Oxygenation (St O2 ) Distributions Within the Thoracic Cavity of Patients Receiving Intraoperative Photodynamic Therapy for Malignant Pleural Mesothelioma

The distributions of light and tissue oxygenation (S_t O₂ ) within the chest cavity were determined for 15 subjects undergoing macroscopic complete resection followed by intraoperative photodynamic therapy (PDT) as part of a clinical trial for the treatment of malignant pleural mesothelioma (MPM). Over the course of light delivery, detectors at each of eight different sites recorded exposure to variable fluence rate. Nevertheless, the treatment-averaged fluence rate was similar among sites, ranging from a median of 40-61 mW cm^-2 during periods of light exposure to a detector. S_t O₂ at each tissue site varied by subject, but posterior mediastinum and posterior sulcus were the most consistently well oxygenated (median S_t O₂ >90%; interquartile ranges ~85-95%). PDT effect on S_t O₂ was characterized as the S_t O₂ ratio (post-PDT S_t O₂ /pre-PDT S_t O₂ ). High S_t O₂ pre-PDT was significantly associated with oxygen depletion (S_t O₂ ratio < 1), although the extent of oxygen depletion was mild (median S_t O₂ ratio of 0.8). Overall, PDT of the thoracic cavity resulted in moderate treatment-averaged fluence rate that was consistent among treated tissue sites, despite instantaneous exposure to high fluence rate. Mild oxygen depletion after PDT was experienced at tissue sites with high pre-PDT S_t O₂ , which may suggest the presence of a treatment effect.

The YAP1 Signaling Inhibitors, Verteporfin and CA3, Suppress the Mesothelioma Cancer Stem Cell Phenotype

Mesothelioma is an aggressive cancer that has a poor prognosis. Tumors develop in the mesothelial lining of the pleural and peritoneal cavities in response to asbestos exposure. Surgical debulking followed by chemotherapy is initially effective, but this treatment ultimately selects for resistant cells that form aggressive and therapy-resistant recurrent tumors. Mesothelioma cancer stem cells (MCS) are a highly aggressive subpopulation present in these tumors that are responsible for tumor maintenance and drug resistance. In this article, we examine the impact of targeting YAP1/TAZ/TEAD signaling in MCS cells. YAP1, TAZ, and TEADs are transcriptional mediators of the Hippo signaling cascade that activate gene expression to drive tumor formation. We show that two YAP1 signaling inhibitors, verteporfin and CA3, attenuate the MCS cell phenotype. Verteporfin or CA3 treatment reduces YAP1/TEAD level/activity to suppress MCS cell spheroid formation, Matrigel invasion, migration, and tumor formation. These agents also increase MCS cell apoptosis. Moreover, constitutively active YAP1 expression antagonizes inhibitor action, suggesting that loss of YAP1/TAZ/TEAD signaling is required for response to verteporfin and CA3. These agents are active against mesothelioma cells derived from peritoneal (epithelioid) and patient-derived pleural (sarcomatoid) mesothelioma, suggesting that targeting YAP1/TEAD signaling may be a useful treatment strategy. IMPLICATIONS: These studies suggest that inhibition of YAP1 signaling may be a viable approach to treating mesothelioma.

Nanoscale ZnO-based photosensitizers for photodynamic therapy

Due to the ability to induce the generation of reactive oxygen species (ROS) under light irradiation, ZnO nanoparticles show great potential in photodynamic therapy (PDT). Photo-triggered ROS production by ZnO nanoparticles and the resulting phototoxicity are efficient in killing cancer cells. This review highlights the recent exciting progress on the nanoscale ZnO-based photosensitizers (PSs) for PDT. Both the semplice ZnO nanoparticles as the PSs and the various chemicals (organic PS, dopant, metal and chemotherapeutic drugs) modified ZnO nanoparticles as the PSs show good ROS generation efficiency. The productive rate of ROS, the wavelength of exciting lights, and the therapeutic effect can be altered by doping different chemicals into ZnO nanoparticles at will. Additionally, we give some outlook on the design and functionalization of next-generation ZnO nanoparticles for more effective anti-cancer applications.

Reactive Oxygen Species Explicit Dosimetry for Photofrin-mediated Pleural Photodynamic Therapy

Explicit dosimetry of treatment light fluence and implicit dosimetry of photosensitizer photobleaching are commonly used methods to guide dose delivery during clinical PDT. Tissue oxygen, however, is not routinely monitored intraoperatively even though it is one of the three major components of treatment. Quantitative information about in vivo tissue oxygenation during PDT is desirable, because it enables reactive oxygen species explicit dosimetry (ROSED) for prediction of treatment outcome based on PDT-induced changes in tumor oxygen level. Here, we demonstrate ROSED in a clinical setting, Photofrin-mediated pleural photodynamic therapy, by utilizing tumor blood flow information measured by diffuse correlation spectroscopy (DCS). A DCS contact probe was sutured to the pleural cavity wall after surgical resection of pleural mesothelioma tumor to monitor tissue blood flow (blood flow index) during intraoperative PDT treatment. Isotropic detectors were used to measure treatment light fluence and photosensitizer concentration. Blood-flow-derived tumor oxygen concentration, estimated by applying a preclinically determined conversion factor of 1.5 × 10⁹ μMs cm^-2 to the blood flow index, was used in the ROSED model to calculate the total reacted reactive oxygen species [ROS]rx. Seven patients and 12 different pleural sites were assessed and large inter- and intrapatient heterogeneities in [ROS]rx were observed although an identical light dose of 60 J cm^-2 was prescribed to all patients.

Evaluation of Light Fluence Distribution Using an IR Navigation System for HPPH-mediated Pleural Photodynamic Therapy (pPDT)

Uniform light fluence distribution for patients undergoing photodynamic therapy (PDT) is critical to ensure predictable PDT outcomes. However, current practice when delivering intrapleural PDT uses a point source to deliver light that is monitored by seven isotropic detectors placed within the pleural cavity to assess its uniformity. We have developed a real-time infrared (IR) tracking camera to follow the movement of the light point source and the surface contour of the treatment area. The calculated light fluence rates were matched with isotropic detectors using a two-correction factor method and an empirical model that includes both direct and scattered light components. Our clinical trial demonstrated that we can successfully implement the IR navigation system in 75% (15/20) of the patients. Data were successfully analyzed in 80% (12/15) patients because detector locations were not available for three patients. We conclude that it is feasible to use an IR camera-based system to track the motion of the light source during PDT and demonstrate its use to quantify the uniformity of light distribution, which deviated by a standard deviation of 18% from the prescribed light dose. The navigation system will fail when insufficient percentage of light source positions is obtained (<30%) during PDT.

Porphyrin-lipid assemblies and nanovesicles overcome ABC transporter-mediated photodynamic therapy resistance in cancer cells

Photodynamic therapy (PDT) involves light activation of the photosensitizer to generate reactive molecular species that induce cell modulation or death. Based on earlier findings showing that the photosensitizer benzoporphyrin derivative (BPD) is a breast cancer resistance protein (ABCG2) substrate, we investigated the ability of the P-glycoprotein (P-gp) and multidrug resistance-associated protein 1 (MRP1) to transport BPD. In a panel of breast cancer cell lines overexpressing P-gp, MRP1, or ABCG2, BPD transport occurs only in cells overexpressing P-gp and ABCG2. Intracellular BPD fluorescence is not affected by MRP1, as determined by flow cytometry. To bypass P-gp- and ABCG2-mediated efflux of BPD, we introduce a lipidation strategy to create BPD derivatives that are no longer P-gp and ABCG2 substrates. The phospholipid-conjugated BPD and its nanoliposomal formulation evade both P-gp- and ABCG2-mediated transport. In cytotoxicity assays, lipidated BPD and its nanoliposomal formulation abrogate P-gp- and ABCG2-mediated PDT resistance. We verify that P-gp, like ABCG2, plays a role in BPD transport and BPD-PDT resistance. Furthermore, we introduce porphyrin-lipid nanovesicles as a new strategy to escape P-gp and ABCG2-mediated efflux of BPD for improved PDT outcomes in two breast cancer cell lines.

Chitosan-Based Drug Delivery Systems for Optimization of Photodynamic Therapy: a Review

Drug delivery systems (DDS) can be designed to enrich the pharmacological and therapeutic properties of several drugs. Many of the initial obstacles that impeded the clinical applications of conventional DDS have been overcome with nanotechnology-based DDS, especially those formed by chitosan (CS). CS is a linear polysaccharide obtained by the deacetylation of chitin, which has potential properties such as biocompatibility, hydrophilicity, biodegradability, non-toxicity, high bioavailability, simplicity of modification, aqueous solubility, and excellent chemical resistance. Furthermore, CS can prepare several DDS as films, gels, nanoparticles, and microparticles to improve delivery of drugs, such as photosensitizers (PS). Thus, CS-based DDS are broadly investigated for photodynamic therapy (PDT) of cancer and fungal and bacterial diseases. In PDT, a PS is activated by light of a specific wavelength, which provokes selective damage to the target tissue and its surrounding vasculature, but most PS have low water solubility and cutaneous photosensitivity impairing the clinical use of PDT. Based on this, the application of nanotechnology using chitosan-based DDS in PDT may offer great possibilities in the treatment of diseases. Therefore, this review presents numerous applications of chitosan-based DDS in order to improve the PDT for cancer and fungal and bacterial diseases.

Lymphangitic carcinomatosis: A common radiographic manifestation of local failure following extended pleurectomy/decortication in patients with malignant pleural mesothelioma

INTRODUCTION

The lymphangitic carcinomatosis (LC) pattern of metastatic malignancy is associated with a poor prognosis but is currently not well defined in malignant pleural mesothelioma (MPM). Here, we report the incidence and prognostic significance of the radiographic development of LC in MPM following extended pleurectomy/decortication (EPD).

METHODS

Consecutive patients with biopsy-proven MPM undergoing EPD with intraoperative photodynamic therapy (PDT) at our institution from 2008 to 2014 were included in this retrospective study. Patients without available post-surgical clinical or imaging data for direct review were excluded. CT images were reviewed by an experienced, board-certified thoracic radiologist and confirmed by consensus review. Overall survival (OS) and progression-free survival (PFS) were calculated by Kaplan Meier methodology. Hazard ratios were compared with a cox proportional hazard model.

RESULTS

44 patients underwent EPD with PDT during the study period and had available clinical and imaging data. During the follow-up period (median 34 months), 17 patients (39%) developed LC at a median of 10 months after surgery (IQR 5-21 months). 16 of the 17 patients who developed LC (94%) died during the follow-up period, compared to 17 of the 27 who did not develop LC (63%). OS for the LC versus non-LC group was 53% versus 93% at 1 year and 18% versus 67% at 3 years. LC was significantly associated with a lower OS (HR 4.07; 95% confidence interval 1.44-11.48; p = 0.008). PFS for the LC group versus non-LC group was 8 months (IQR 5-9 months) compared to 17 months (IQR 11-24 months) (p < 0.001).

CONCLUSION

LC is a common form of failure in MPM following EPD and is associated with a poor prognosis. Thus, further studies are warranted to determine if any evidence of preoperative LC should be an absolute contraindication to EPD and may warrant an EPP or no surgery at all.