This PDF file contains the front matter associated with SPIE Proceedings Volume 10047, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

We previously reported that a low level of lysosomal photoda mage can markedly promote the subsequent efficacy of PDT directed at mitochondria. This involves release of Ca²⁺ from photo damaged lysosomes, cleavage of the autophagy-associated protein ATG5 after activation of calpain and an interaction between the ATG5 fragment and mitochondria resulting in enhanced apoptosis. Inhibition of calpain activity abolished th is effect. We examined permissible irradiation sequences. Lysosomal photodamage must occur first with the ‘enhancement’ effect showing a short half-life (~ 15 min), presumably reflecting the survival of the ATG5 fragment. Simultaneous photo damage to both loci was found to be as effective as the sequential protocol. Since Photofrin can target both lysosomes and mitochondria for photo damage, this broad spectrum of photo damage may explain the efficacy of this photo sensitizing agent in spite of a sub-optimal absorbance profile at a sub- optimal wavelength for tissue transparency.

Considering the consistently poor prognoses for some of the deadliest cancers, as well as the skyrocketing costs (~$1-2 billion) and long time frame (~12-16 years) for developing a brand-new drug, rapidly translatable agents that offer improvements in outcomes are much needed. Drug repurposing is one such strategy to decrease costs, reduce time frame to clinical translation, and possibly increase success rates. This presentation will elucidate the benefit of this approach with drugs like the tetracyclines (a class of antibiotics), vitamins and chemotherapeutics combined with PDT to overcome chemoresistance in pancreatic and ovarian cancers.

Photodynamic therapy (PDT) involves the combination of a photosensitizer and light of a specific wavelength. Upon light activation in the presence of oxygen, photosensitizer molecules generate reactive oxygen species that cause cytotoxicity by inducing oxidative stress. Aminolevulinic acid (ALA) is a pro-drug used for the diagnosis and PDT treatment of various solid tumors based on endogenous production of heme precursor protoporphyrin IX (PpIX). Although nearly all types of human cells express heme biosynthesis enzymes and produce PpIX, tumor cells are found to have more PpIX production and accumulation than normal cells, allowing for the detection and treatment of solid tumors. The objective of my research is to explore therapeutic approaches to enhance ALA-based tumor detection and therapy. We have found that high ABCG2 transporter activity in triple negative breast cancer cells (TNBC) contributed to reduced PpIX levels in cells, causing them to be more resistant towards ALA-PDT. The administration of an ABCG2 inhibitor, Ko143, was able to reverse cell resistance to ALA-PDT by enhancing PpIX mitochondrial accumulation and sensitizing cancer cells to ALA-PDT. Ko143 treatment had little effect on PpIX production and ALA-PDT in normal and ER- or HER2-positive cells. Furthermore, since some tyrosine kinase inhibitors (TKI) are known to block ABCG2 transporter activity, we screened a panel of tyrosine kinase inhibitors to examine its effect on enhancing PpIX fluorescence and ALA-PDT efficacy. Several TKIs including lapatinib and gefitinib showed effectiveness in increasing ALA-PpIX fluorescence in TNBC leading to increased cell death after PDT administration. These results indicate that inhibiting ABCG2 transporter using TKIs is a promising approach for targeting TNBC with ALA-based modality.

Targeting the molecular and cellular cues that influence treatment resistance in tumors is critical to effectively treating unresponsive populations of stubborn disease. The informed design of mechanism-based combinations is emerging as increasingly important to targeting resistance and improving the efficacy of conventional treatments, while minimizing toxicity. Photodynamic therapy (PDT) has been shown to synergize with conventional agents and to overcome the evasion pathways that cause resistance. Increasing evidence shows that PDT-based combinations cooperate mechanistically with, and improve the therapeutic index of, traditional chemotherapies. These and other findings emphasize the importance of including PDT as part of comprehensive treatment plans for cancer, particularly in complex disease sites. Identifying effective combinations requires a multi-faceted approach that includes the development of bioengineered cancer models and corresponding image analysis tools. The molecular and phenotypic basis of verteporfin-mediated PDT-based enhancement of chemotherapeutic efficacy and predictability in complex 3D models for ovarian cancer will be presented.

Photodynamic therapy (PDT) for Actinic Kertoses (AK) using aminoluvelinic acid (ALA) is an FDA-approved treatment, which is generally effective, yet response rates vary. The origin of the variability is not well characterized, but may be related to inter-patient variability in the production of protoporphyrin IX (PpIX). While fiber-based point probe systems provide a method for measuring PpIX production, these measurements have demonstrated large spatial and inter-operator variability. Thus, in an effort to improve patient-specific dosimetry and treatment it is important to develop a robust system that accounts for spatial variability and reduces the chance of operator errors. To address this need, a wide-field multispectral imaging system was developed that is capable of quantifying maps of PpIX in both liquid phantoms and in vivo experiments, focusing on high sensitivity light signals. The system uses both red and blue excitation to elicit a fluorescent response at varying skin depths. A ten-position filter wheel with bandpass filters ranging from 635nm to 710nm are used to capture images along the emission band. A linear least-square spectral fitting algorithm provides the ability to decouple background autofluorescence from PpIX fluorescence, which has improved the system sensitivity by an order of magnitude, detecting nanomolar PpIX concentrations in liquid phantoms in the presence of 2% whole blood and 2% intralipid.

Pancreatic tumors are characterized by large interstitial hypertension from enhanced deposition of extracellular matrix components, resulting in widespread vascular collapse and reduced molecular uptake of systemically delivered therapies. Although the origins of hypoperfusion is debated amongst researchers, spatial distribution of collagen density and hyaluronic acid content have shown to be a key metric in understanding the lack of efficacy for both acute and chronic therapies in these tumors. In this study, the AsPC-1 tumor model was used both subcutaneously and orthotopically to study the measurable factors which are related to this. A conventional piezoelectric pressure catheter was used to measure total tissue pressure (TTP), defined as a combination of solid stress (SS) and interstitial fluid pressure (IFP), TTP = SS + IFP, in multiple locations within the tumor interstitium. Matrix components such as collagen and hyaluronic acid were scored using masson’s trichrome stain and hyaluronic acid binding protein (HABP), respectively, and co-registered with values of TTP. The results show that these key measurements are related to the spatial distribution of verteporfin in the same tumors. Photodynamic treatment with verteporfin is known to ablate large regions of tumor tissue and also allow better permeability for chemotherapies. The study of spatial distribution of verteporfin in relation to stromal content and TTP will help us better control these types of combination therapies.

Uniform delivery of light fluence is an important goal for photodynamic therapy. We present summary results for an infrared (IR) navigation system to deliver light dose uniformly during intracavitory PDT by tracking the movement of the light source and providing real-time feedback on the light fluence rate on the entire cavity surface area. In the current intrapleural PDT protocol, 8 detectors placed in selected locations in the pleural cavity monitor the light doses. To improve the delivery of light dose uniformity, an IR camera system is used to track the motion of the light source as well as the surface contour of the pleural cavity. A MATLAB-based GUI program is developed to display the light dose in real-time during PDT to guide the PDT treatment delivery to improve the uniformity of the light dose. A dualcorrection algorithm is used to improve the agreement between calculations and in-situ measurements. A comprehensive analysis of the distribution of light fluence during PDT is presented in both phantom conditions and in clinical cases.

Photodynamic therapy (PDT) involves interactions between the three main components of light fluence, photosensitizer concentration, and oxygenation. Currently, singlet oxygen explicit dosimetry (SOED) has focused on the first two of these components. The macroscopic model to calculate reacted singlet oxygen has previously involved a fixed initial ground state oxygen concentration. A phosphorescence-based oxygen probe was used to measure ground state oxygen concentration throughout treatments for mice bearing radioactively induced fibroscarcoma tumors. Photofrin-, BPD-, and HPPH-mediated PDT was performed on mice. Model-calculated oxygen and measured oxygen was compared to evaluate the macroscopic model as well as the photochemical parameters involved. Oxygen measurements at various depths were compared to calculated values. Furthermore, we explored the use of noninvasive diffuse correlation spectroscopy (DCS) to measure tumor blood flow changes in response to PDT to improve the model calculation of reacted singlet oxygen. Mice were monitored after treatment to see the effect of oxygenation on long-term recurrence-free survival as well as the efficacy of using reacted singlet oxygen as a predictive measure of outcome. Measurement of oxygenation during treatment helps to improve SOED as well as confirm the photochemical parameters involved in the macroscopic model. Use of DCS in predicting oxygenation changes was also investigated.

The onset of inflammation is a well-known physiology in tumors treated with photodynamic therapy (PDT). After PDT, the release of danger signals causes an influx of neutrophils, activation of dendritic cells, and an eventual initiation of the adaptive immune response. However, inflammation also lies at a crucial fulcrum for treatment outcome, as it can stimulate the expression of resistance factors. Therefore, effective treatment with PDT requires an understanding of the holistic contribution of inflammation. Within, we outline two means of studying tumor inflammation in the setting of PDT. Experiments are conducted in murine models of mesothelioma, including those that incorporate surgery prior to PDT or pleural propagation of the disease. First, we use a chemiluminescent agent, luminol, to detect the influx of neutrophils by in vivo molecular imaging. This longitudinal approach allows for the repeated non-invasive monitoring of PDT-induced neutrophil influx. Data clearly identify protocol-specific differences in tumor-associated neutrophil activity. Second, we describe the application of cone-beam CT to detect the fibrosis associated with murine orthotropic mesothelioma models. This approach incorporates novel methods in image segmentation to accurately identify diffuse disease in the thoracic cavity. These studies lay the foundation for future research to correlate long-term response with local PDT-induced inflammation. Such methods in monitoring of inflammation or tumor burden will enable characterization of the consequences of combinatorial therapy (e.g., intraoperative PDT). Resulting data will guide the selection of pharmacological agents or molecular imaging techniques that respectively exploit inflammation for therapeutic or monitoring purposes.

Intrapleural photodynamic therapy (PDT) has been used in combination with lung sparing surgery to treat patients with malignant pleural mesothelioma. The light, photosensitizers and tissue oxygen are the three most important factors required by type II PDT to produce singlet oxygen, ¹O₂, which is the main photocytotoxic agent that damages the tumor vasculature and stimulates the body’s anti-tumor immune response. Although light fluence rate and photosensitizer concentrations are routinely monitored during clinical PDT, there is so far a lack of a Food and Drug Administration (FDA)-approved non-invasive technique that can be employed clinically to monitor tissue oxygen in vivo. In this paper, we demonstrated that blood flow correlates well with tissue oxygen concentration during PDT and can be used in place of [³O₂] to calculate reacted singlet oxygen concentration [¹O₂]_rx using the macroscopic singlet oxygen model. Diffuse correlation spectroscopy (DCS) was used to monitor the change in tissue blood flow non-invasively during pleural PDT. A contact probe with three source and detectors separations, 0.4, 0.7 and 1.0-cm, was sutured to the pleural cavity wall of the patients after surgical resection of the pleural mesothelioma tumor to monitor the tissue blood flow during intraoperative PDT treatment. The changes of blood flow during PDT of 2 patients are found to be in good correlation with the treatment light fluence rate recorded by the isotropic detector placed adjacent to the DCS probe. [1O2]rx calculated based on light fluence, mean photosensitizer concentration, and relative blood flow was found to be 32% higher in patient #4 (0.50mM) than that for patient #3 (0.38mM).

Photodynamic therapy (PDT) has emerged as an effective treatment modality for various malignant neoplasia and diseases. In PDT, the photochemical interaction of photosensitizer (PS), light and molecular oxygen produces singlet oxygen which can lead to tumour cell apoptosis, necrosis or autophagy. The success of PDT is limited by the hydrophobic characteristic of the PS which hinders treatment administration and efficiency. To circumvent this limitation, PS can be incorporated in nanostructured drug delivery systems such as gold nanoparticles (AuNPs). In this study, we investigated the effectiveness of free zinc monocarboxyphenoxy phthalocyanine (ZnMCPPc) and ZnMCPPc conjugated to AuNPs. Commercially purchased melanoma cancer cells cultured as cell monolayers were used in this study. Changes in cellular response were evaluated using cellular morphology, viability, proliferation and cytotoxicity. Untreated cells showed no changes in cellular morphology, proliferation and cytotoxicity. However, photoactivated free ZnMCPPc and ZnMCPPc conjugated to AuNPs showed changes in cellular morphology and a dose dependent decrease in cellular viability and proliferation as well as an increase in cell membrane. ZnMCPPc conjugated to AuNPs showed an improved efficiency in PDT as compared to free ZnMCPPc, which might be as a result of the vehicle effect of AuNPs. Both PSs used in this study were effective in inducing cell death with ZnMCPPc conjugated to AuNPs showing great potential as an effective PS for PDT.

Photodynamic therapy (PDT) is an effective anticancer procedure that relies on tumor localization of a photosensitizer followed by light activation to generate cytotoxic reactive oxygen species. We recently reported the rational design of a Hf-porphyrin nanoscale metal-organic framework, DBP-UiO, as an exceptionally effective photosensitizer for PDT of resistant head and neck cancer. DBP-UiO efficiently generates singlet oxygen owing to site isolation of porphyrin ligands, enhanced intersystem crossing by heavy Hf centers, and facile singlet oxygen diffusion through porous DBP-UiO nanoplates. Consequently, DBP-UiO displayed greatly enhanced PDT efficacy both in vitro and in vivo, leading to complete tumor eradication in half of the mice receiving a single DBP-UiO dose and a single light exposure. The photophysical properties of DBP-UiO are however not optimum with the lowest energy absorption at 634 nm and a relatively small extinction coefficient of 2200 M-1·cm-1. We recently designed a chlorin-based NMOF, DBC-UiO, with much improved photophysical properties and PDT efficacy in two colon cancer mouse models. Reduction of the DBP ligands in DBP-UiO to the DBC ligands in DBC-UiO led to a 13 nm red-shift and an 11-fold extinction coefficient increase of the lowest energy Q-band. While inheriting the crystallinity, stability, porosity, and nanoplate morphology of DBP-UiO, DBC-UiO sensitizes more efficient singlet oxygen generation and exhibits much enhanced photodynamic therapy (PDT) efficacy on two colon cancer mouse models as a result of its improved photophysical properties. Both apoptosis and immunogenic cell death contributed to cancer cell-killing in DBC-UiO induced PDT. Our work has thus demonstrated that NMOFs represent a new class of highly potent PDT agents and hold great promise in treating resistant cancers in the clinic.

The paper first reviews the main laser based cancer therapies and then presents a new 9xx nm high power laser diode system specifically devised to irradiate carbon graphitic nanoparticles that have shown photodynamic and photo-thermal behavior when exposed to near-IR laser light. The peculiarity of the laser system is that its delivery is through a fiber probe that integrates Bragg gratings to allow monitoring the induced temperature increase without introducing artifacts due to the interaction with the laser beam. Experimental validations through EPR spectrum and temperature measurements on hydroxylated fullerene and carbon nanoparticle samples are provided to assess the effectiveness of the developed system.

Cutaneous metastasis (CM) occurs in 20% of patients with breast carcinoma (BCA), and is extremely difficult to treat. These CM are relatively resistant to chemotherapy, generally responding only to ionizing radiation (IR). Multiple rounds of IR, however, lead to debilitating fibrosis and radiation dermatitis. An alternative to IR is needed for better management of BCA/CM. In our laboratory, we have developed differentiation-enhanced combination PDT (cPDT), a concept in which a pro-differentiating agent (methotrexate; vitamin D; or 5-fluorouracil, 5FU) is used as a neoadjuvant prior to PDT. After using these neoadjuvants, levels of protoporphyrin IX (PpIX) were elevated in animal tumor models of skin, prostate, and BCA, leading to better PDT efficacy. However, all the agents have toxicity issues. Here, we use a nontoxic 5FU precursor called Capecitabine (CPBN) for cPDT. CBPN is a standard chemotherapeutic for metastatic BCA, and is metabolized to 5FU specifically within tumor tissue. Murine (4T1) and human (MCF-7) BCA cell lines were injected into breast fat pads of nude mice. After tumor nodules appeared, CPBN (400-600 mg/kg/day) was administered by oral gavage for five days followed by intraperitoneal ALA administration on day 6. Mice were sacrificed and tumors harvested. CPBN pretreatment led to a 4-fold elevation of PpIX levels in tumors, relative to vehicle control. Not only did PpIX levels increase, but also PpIX distribution became more homogeneous after CPBN pretreatment. In summary, the use of non-toxic CPBN as a neoadjuvant prior to PDT is a combination approach with significant potential for translation into the clinic.

Laser speckle imaging is a technique that has been developed to non-invasively monitor in vivo blood flow dynamics and vascular structure, at high spatial and temporal resolution. It can record the full-field spatio-temporal characteristics of microcirculation and has therefore, often been used to study the blood flow in tumors after photodynamic therapy (PDT). Yet, there is a paucity of reports on real-time laser speckle imaging (RTLSI) during PDT. Vascular-targeted photodynamic therapy (VTP) with WST11, a water-soluble bacteriochlorophyll derivative, achieves tumor ablation through rapid occlusion of the tumor vasculature followed by a cascade of events that actively kill the tumor cells. WST11-VTP has been already approved for treatment of early/intermediate prostate cancer at a certain drug dose, time and intensity of illumination. Application to other cancers may require different light dosage. However, incomplete vascular occlusion at lower light dose may result in cancer cell survival and tumor relapse while excessive light dose may lead to toxicity of nearby healthy tissues. Here we provide evidence for the feasibility of concomitant RTLSI of the blood flow dynamics in the tumor and surrounding normal tissues during and after WST11-VTP. Fast decrease in the blood flow is followed by partial mild reperfusion and a complete flow arrest within the tumor by the end of illumination. While the primary occlusion of the tumor feeding arteries and draining veins agrees with previous data published by our group, the late effects underscore the significance of light dose control to minimize normal tissue impairment. In conclusion- RTSLI application should allow to optimize VTP efficacy vs toxicity in both the preclinical and clinical arenas.

Glioblastoma (GBM) is the most common primary brain tumor. Its incidence is estimated at 5 to 7 new cases each year for 100 000 inhabitants. Despite reference treatment, including surgery, radiation oncology and chemotherapy, GBM still has a very poor prognosis (median survival of 15 months). Because of a systematic relapse of the tumor, the main challenge is to improve local control. In this context, PhotoDynamic Therapy (PDT) may offer a new treatment modality. GBM recurrence mainly occurs inside the surgical cavity borders. Thus, a new light applicator was designed for delivering light during a PDT procedure on surgical cavity borders after Fluorescence Guided Resection. This device combines an inflatable balloon and a light source. Several experimentations (temperature and impermeability tests, homogeneity of the light distribution and ex-vivo studies) were conducted to characterize the device. An abacus was created to determine illumination time from the balloon volume in order to reach a therapeutic fluence value inside the borders of the surgical cavity. According to our experience, cavity volumes usually observed in the neurosurgery department lead to an acceptable average lighting duration, from 20 to 40 minutes. Thus, extra-time needed for PDT remains suitable with anesthesia constraints. A pilot clinical trial is planned to start in 2017 in our institution. In view of the encouraging results observed in preclinical or clinical, this intraoperative PDT treatment can be easily included in the current standard of care.

Pancreatic ductal adenocarcinoma (PDAC) is characterized by extracellular matrix-rich stromal involvement, but it is not clear how ECM properties that affect invasiveness and chemotherapy response influence efficacy of photodynamic therapy (PDT). To disentangle the mechanical and biochemical effects of ECM composition, we measured the effects of various combinations of ECM proteins on growth behavior, invasive potential, and therapeutic response of multicellular 3D pancreatic tumor models. These spheroids were grown in attachment-free conditions before embedding in combinations of rheologically characterized collagen 1 and Matrigel combinations and treated with oxaliplatin chemotherapy and PDT. We find that cells invading from collagen-embedded tumor spheroids, the least rigid ECM substrate described here, displayed better response to PDT than to oxaliplatin chemotherapy. Overall, our results support that ECM-mediated invading PDAC populations remain responsive to PDT in conditions that induce chemoresistance.

The main goal of the study was a vasculature targeted PDT. A new approach named M-mode-like OCT (MML OCT) was applied to monitor early response to PDT. Due to the chosen filtering parameters (96 Hz filter threshold), this approach visualizes only vessels with flowing blood. Without flowing blood even filled vessels are not visualized because flow-less blood causes speckle variations with significantly lower frequencies (<50 Hz corresponding to speckle decorrelation time for stationary blood). This feature allows us to detect thrombosis of blood vessels, the results of MML OCT and histological examination being perfectly coinciding. The advantages of MML OCT such as a simple and fast process of obtaining microvasculature images and label-free nature of the visualization makes this method perspective in routine clinical monitoring of antitumor therapies.

Effective photodynamic therapy (PDT) treatment planning and treatment monitoring requires computer simulations of both light transport in tissue and photosensitizer (PS) photophysics to accurately estimate singlet oxygen. Simply using fixed prescribed values of light dose (fluence) or PDT dose (the time integral of ‘PS concentration’ times the ‘fluence rate’) – one value for all patients – does not account for differences in the amount of singlet oxygen formed when fluence rates change or patient tissue parameters change. We will focus on singlet oxygen dose which is calculated by solving the photokinetics rate equations and which determines the effectiveness of the subsequent reactions of singlet oxygen with the cancer target and the negative effect of PS photobleaching.

Accurate and rapid evaluation of lymph node metastasis is required in tumor staging and the decision of treatment strategy. General intraoperative pathological evaluation, however, takes at least a few tens of minutes or longer for metastasis diagnosis. 5-aminolevulinic acid (5-ALA)-based fluorescence diagnosis is a solution for accurate and ultrarapid diagnosis of malignant lesions. 5-ALA-based diagnosis evaluates fluorescence intensity of a fluorescent metabolite of 5-ALA, protoporphyrin IX (PPIX); however, the fluorescence of PPIX is often affected by autofluorescence of tissue chromophores, such as collagen and flavins. To enhance the accuracy of the diagnosis of malignant lesions based on the PPIX fluorescence, elimination of the autofluroescence is required. In this study, we proposed and experimentally demonstrated background-free PPIX fluorescence estimation method by simplified and optimized multispectral imaging. To realize background-free PPIX fluorescence estimation, we computationally optimized observation wavelength regions in terms of minimizing prediction error of PPIX fluorescence intensity in the presence of typical chromophores, collagen and flavins. We verified the fundamental detection capability of our method by using known-chemical mixtures. Furthermore, we applied our method to lymph node metastasis, and successfully realized background-free histopathological evaluation of metastatic lesions of lymph node metastasis. Our results confirmed the potential of the background-free estimation method of PPIX fluorescence for 5-ALA-based fluorescence diagnosis of malignant lesions, and we expect this method to be beneficial for intraoperative and rapid cancer diagnosis.

Experimental Photodynamic Therapy (PDT), either in vivo or in vitro, is normally carried out under distinct conditions making it difficult to compare results in order to propose the best combination for optimized outcomes. In this work, a threshold distribution model was used to investigate the PDT response in vitro. It is known that different types of cells present distinguished resistance to treatment, which can be due to several factors. The threshold distribution obtained from the differentiation of the dose-response curves, is under discussion by several authors. The main parameters of the distribution are related with the most frequent threshold in the population, given by the dose of the peak, and its variability is represented by the the distribution width. To evaluate how PDT response differs, we used normal and tumor cell lines from liver (HepaRG, HepG2, respectively) and breast tissues (MCF-7 and HMEC). We also performed an induction protocol of tumor resistance to assess the variations in the threshold distributions of the derived cells. Results show that the normal cell lines generally present a more homogenous response since the threshold distributions are more symmetric and narrower than the ones from the tumor cell lines. We also observed that MCF-7 is more resistant to PDT than HepaRG and HepG2. Experiments to investigate the causes for the different responses, such as photosensitizer uptake and reactive oxygen species (ROS) production, were performed. The findings are promising and encourage the further investigation ofvariability in PDT responses using the threshold distribution model.

Fluorescence molecular tomography (FMT) is developing rapidly in the field of molecular imaging. FMT has been used in surgical navigation for tumor resection and has many potential applications at the physiological, metabolic, and molecular levels in tissues. Due to the ill-posed nature of the problem, many regularized methods are generally adopted. In this paper, we propose a region reconstruction method for FMT in which the trace norm regularization. The trace norm penalty was defined as the sum of the singular values of the matrix. The proposed method adopts a priori information which is the structured sparsity of the fluorescent regions for FMT reconstruction. In order to improve the solution efficiency, the accelerated proximal gradient algorithms was used to accelerate the computation. The numerical phantom experiment was conducted to evaluate the performance of the proposed trace norm regularization method. The simulation study shows that the proposed method achieves accurate and is able to reconstruct image effectively.

Photo-immunotherapy (PIT) is an emerging low-side-effect cancer therapy based on monoclonal antibody (mAb) conjugated with a near-infrared (NIR) phthalocyanine dye IRDye700DX (IR700 is not only fluorescent which can be used as an imaging agent, but also phototoxic) that induces rapid cell death after exposure to NIR light. PIT induces highly-selective cancer cell death while leaving most of tumor blood vessels unharmed, leading to an effect termed super-enhanced permeability and retention (SUPR), which significantly improve the effectiveness of anti-cancer drug. Currently, the therapeutic effects of PIT were monitored using IR700 fluorescent signal based on macroscopic fluorescence reflectance imager, which lacks the resolution and depth information to reveal the intra-tumor heterogeneity of mAb-IR700 distribution. We developed a minimally-invasive two-channel fluorescence fiber imaging system by combining the traditional fluorescence imaging microscope with two imaging fiber bundles (~0.85 mm) to monitor mAb-IR700 distribution and therapeutic effects during PIT at different intra-tumor locations (e.g. tumor periphery vs. tumor rim) in situ and in real time simutaneously, thereby enabling evaluation of the therapeutic effects in vivo and optimization of treatment regimens accordingly. Experiments were carried out on ten mice. The average fluorescence intensity recovery after PIT in tumor rim is 91.50% while 100.63% in tumor periphery. Significantly higher fluorescence redistribution (P=0.0371) in tumor periphery than tumor rim after PIT treatment were observed. In order to verify the results, two-photon microscopy combining with micro-prism was also used to record the mAb-IR700 distribution at different depth locations of the tumor during PIT.

Photodynamic therapy (PDT) is a well-established treatment modality for cancer and other malignant diseases; however, quantities such as light fluence, photosensitizer photobleaching rate, and PDT dose do not fully account for all of the dynamic interactions between the key components involved. In particular, fluence rate (Φ) effects are not accounted for, which has a large effect on the oxygen consumption rate. In this preclinical study, reacted singlet oxygen [¹O₂]_rx was investigated as a dosimetric quantity for PDT outcome. The ability of [¹O₂]_rx to predict the long-term local tumor control rate (LCR) for BPD-mediated PDT was examined. Mice bearing radioactivelyinduced fibrosarcoma (RIF) tumors were treated with different in-air fluences (250, 300, and 350 J/cm²) and in-air ϕ (75, 100, and150 mW/cm2) with a BPD dose of 1 mg/kg and a drug-light interval of 3 hours. Treatment was delivered with a collimated laser beam of 1 cm diameter at 690 nm. Explicit dosimetry of initial tissue oxygen concentration, tissue optical properties, and BPD concentration was used to calculate [¹O₂]_rx. Φ was calculated for the treatment volume based on Monte-Carlo simulations and measured tissue optical properties. Kaplan-Meier analyses for LCR were done for an endpoint of tumor volume ≤ 100 mm³ using four dose metrics: light fluence, photosensitizer photobleaching rate, PDT dose, and [¹O₂]_rx. PDT dose was defined as the product of the timeintegral of photosensitizer concentration and Φ at a 3 mm tumor depth. Preliminary studies show that [¹O₂]_rx better correlates with LCR and is an effective dosimetric quantity that can predict treatment outcome.

We studied a 3-compartment dynamic model of talaporfin sodium pharmacokinetics in silico. Drug distribution might change after intravenous injection from plasma to interstitial space and then into myocardial cells. We have developed a new cardiac ablation using photosensitization reaction with laser irradiation shortly after talaporfin sodium injection. We think that the major cell-killing factor in our cardiac ablation would be an oxidation by singlet oxygen produced in the interstitial space in myocardium with laser irradiation shortly after the photosensitizer administration. So that the talaporfin sodium concentration change in time in the interstitial space should be investigated. We constructed the pharmacokinetics dynamic model composed by 3-compartments, that is, plasma, interstitial space, and cell. We measured talaporfin sodium fluorescence time change in human skin by our developed fluorescence measurement system in vivo. Using the measured concentration data in plasma and skin in human, we verified the calculation accuracy of our in silico model. We compared the simulated transition tendency of talaporfin sodium concentration from interstitial space to cells in our in silico model with the reported uptake tendency using cultured myocardial cell. We identified the transition coefficients between plasma, interstitial space, and cell compartment, and metabolization coefficient from plasma by the fitting with measured data.

This preclinical study examines four dosimetric quantities (light fluence, photosensitizer photobleaching ratio, PDT dose, and reacted singlet oxygen ([¹O₂]_rx)) to predict local control rate (LCR) for 2-(1-Hexyloxyethyl)-2-devinyl pyropheophorbide (HPPH)-mediated photodynamic therapy (PDT). Mice bearing radiation-induced fibrosarcoma (RIF) tumors were treated with different in-air fluences (135, 250 and 350 J/cm²) and in-air fluence rates (50, 75 and 150 mW/cm²) at 0.25 mg/kg HPPH and a drug-light interval of 24 hours using a 1 cm diameter collimated laser beam at 665 nm wavelength. A macroscopic model was used to calculate ([¹O₂]_rx)) based on in vivo explicit dosimetry of the initial tissue oxygenation, photosensitizer concentration, and tissue optical properties. PDT dose was defined as a temporal integral of drug concentration and fluence rate (φ) at a 3 mm tumor depth. Light fluence rate was calculated throughout the treatment volume based on Monte-Carlo simulation and measured tissue optical properties. The tumor volume of each mouse was tracked for 30 days after PDT and Kaplan-Meier analyses for LCR were performed based on a tumor volume ≤100 mm3, for four dose metrics: fluence, HPPH photobleaching rate, PDT dose, and ([¹O₂]_rx)). The results of this study showed that ([¹O₂]_rx)) is the best dosimetric quantity that can predict tumor response and correlate with LCR.

Although photodynamic therapy (PDT) is an established modality for the treatment of cancer, current dosimetric quantities do not account for the variations in PDT oxygen consumption for different fluence rates (φ). In this study we examine the efficacy of reacted singlet oxygen concentration ([¹O₂]_rx) to predict long-term local control rate (LCR) for Photofrin-mediated PDT. Radiation-induced fibrosarcoma (RIF) tumors in the right shoulders of female C3H mice are treated with different in-air fluences of 225-540 J/cm² and in-air fluence rate (φair) of 50 and 75 mW/cm² at 5 mg/kg Photofrin and a drug-light interval of 24 hours using a 1 cm diameter collimated laser beam at 630 nm wavelength. [1O2]rx is calculated by using a macroscopic model based on explicit dosimetry of Photofrin concentration, tissue optical properties, tissue oxygenation and blood flow changes during PDT. The tumor volume of each mouse is tracked for 90 days after PDT and Kaplan-Meier analyses for LCR are performed based on a tumor volume ≤100 mm3, for the four dose metrics light fluence, photosensitizer photobleaching rate, PDT dose and [¹O₂]_rx. PDT dose is defined as a temporal integral of photosensitizer concentration and Φ at a 3 mm tumor depth. φ is calculated throughout the treatment volume based on Monte-Carlo simulation and measured tissue optical properties. Our preliminary studies show that [¹O₂]_rx is the best dosimetric quantity that can predict tumor response and correlate with LCR. Moreover, [¹O₂]_rx calculated using the blood flow changes was in agreement with [¹O₂]_rx calculated based on the actual tissue oxygenation.

Photodynamic therapy (PDT) is a technique used for several tumor types treatment. Light penetration on biological tissue is one limiting factor for PDT applied to large tumors. An alternative is using interstitial PDT, in which optical fibers are inserted into tumors. Cylindrical diffusers have been used in interstitial PDT. Light emission of different diffusers depends on the manufacturing process, size and optical properties of fibers, which make difficult to establish an adequate light dosimetry, since usually light profile is not designed for direct tissue-fiber contact. This study discusses the relevance of light distribution by a cylindrical diffuser into a turbid lipid emulsion solution, and how parts of a single diffuser contribute to illumination. A 2 cm-long cylindrical diffuser optical fiber was connected to a diode laser (630 nm), and the light spatial distribution was measured by scanning the solution with a collection probe. From the light field profile generated by a 1 mm-long intermediary element of a 20 mm-long cylindrical diffuser, recovery of light distribution for the entire diffuser was obtained. PDT was performed in rat healthy liver for a real treatment outcome analysis. By using computational tools, a typical necrosis profile generated by the irradiation with such a diffuser fiber was reconstructed. The results showed that it was possible predicting theoretically the shape of a necrosis profile in a healthy, homogeneous tissue with reasonable accuracy. The ability to predict the necrosis profile obtained from an interstitial illumination by optical diffusers has the potential improve light dosimetry for interstitial PDT.

Photodynamic therapy (PDT) has emerged as an alternative approach to chemotherapy and radiotherapy for cancer treatment. The photosensitizer (PS) is perhaps the most critical component of PDT, and continues to be an area of intense scientific research. Traditionally, PS molecules like porphyrins have dominated the field. Nevertheless, these PS agents have several disadvantages, with low water solubility, poor light absorption, and reduced selectivity for targeted tissues being some of the main drawbacks. Polysilsesquioxane (PSilQ) nanoparticles provide an interesting platform for developing PS-loaded hybrid nanocarriers. Several advantages can be foreseen by using this platform such as carrying a large payload of PS molecules; their surface and composition can be tailored to develop multifunctional systems (e.g. target-specific); and due to their small size, nanoparticles can penetrate deep into tissues and be readily internalized by cells. In this work, porphyrin-loaded PSilQ nanoparticles with a high payload of photosensitizers were synthesized, characterized, and applied in vitro. The network of this nanomaterial is formed by porphyrin-based photosensitizers chemically connected via a redox-responsive linker. Under reducing environment such as the one found in cancer cells the nanoparticles can be degraded to efficiently release single photosensitizers in the cytoplasm. The platform was further functionalized with polyethylene glycol (PEG) and folic acid as targeting ligand to improve its biocompatibility and target specificity toward cancer cells overexpressing folate receptors. The effectiveness of this porphyrin-based hybrid nanomaterial was successfully demonstrated in vitro using MDA-MB-231 breast cancer cell line.

Glioblastoma (GBM) is the most common primary brain tumor. PhotoDynamic Therapy (PDT) appears as an interesting research field to improve GBM treatment. Nevertheless, PDT cannot fit into the current therapeutic modalities according to several reasons: the lack of reliable and reproducible therapy schemes (devices, light delivery system), the lack of consensus on a photosensitizer and the absence of randomized and controlled multicenter clinical trial. The main objective of this study is to bring a common support for PDT planning. Here, we describe a proof of concept of Treatment Planning System (TPS) dedicated to interstitial PDT for GBM treatment. The TPS was developed with the integrated development environment C++ Builder XE8 and the environment ArtiMED, developed in our laboratory. This software enables stereotactic registration of DICOM images, light sources insertion and an accelerated CUDA GPU dosimetry modeling. Although, Monte-Carlo is more robust to describe light diffusion in biological tissue, analytical model accelerated by GPU remains relevant for dose preview or fast reverse planning processes. Finally, this preliminary work proposes a new tool to plan interstitial or intraoperative PDT treatment and might be included in the design of future clinical trials in order to deliver PDT straightforwardly and homogenously in investigator centers.

Photodynamic therapy (PDT) is a minimally invasive therapeutic modality for the treatment of neoplastic and non-neoplastic diseases. In PDT of cancer, irradiation with light of a specific wavelength leads to activation of a photosensitizer which results in generation of reactive oxygen species (ROS) which induces cell death. Many phthalocyanine photosensitizers are hydrophobic and insoluble in water, which limits their therapeutic efficiency. Consequently, advanced delivery systems and strategies are needed to improve the effectiveness of these photosensitizers. Nanoparticles have shown promising results in increasing aqueous solubility, bioavailability, stability and delivery of photosensitizers to their target. This study investigated the photodynamic activity of zinc monocarboxyphenoxy phthalocyanine (ZnMCPPc) conjugated to gold silver (AuAg) nanoparticles in melanoma cancer cells. The photodynamic activity of ZnMCPPc conjugated to AuAg nanoparticles were evaluated using cellular morphology, viability, proliferation and cytotoxicity. Untreated cells showed no changes in cellular morphology, proliferation and cytotoxicity. However, photoactivated ZnMCPPc conjugated to AuAg nanoparticles showed changes in cell morphology and a dose dependent decrease in cellular viability, proliferation and an increase in cell membrane damage. The ZnMCPPc conjugated to AuAg nanoparticles used in this study was highly effective in inducing cell death of melanoma cancer cells.

We have developed a four-channel PDT dose dosimetry system to simultaneously acquire light dosimetry and sensitizer fluorescence data from four sites in the thoracic cavity during pleural photodynamic therapy (PDT). Photosensitizer fluorescence emitted during PDT is of interest for the monitoring of local concentration of the photosensitizer and its photobleaching. However, the variation in tissue optical properties will cause the photosensitizer fluorescence to alter. Optical properties correction to the measured fluorescence is required for absolute quantification of photosensitizer concentration. In this study, we determine an empirical optical properties correction function using Monte Carlo (MC) simulations of fluorescence for a range of physiologically relevant tissue optical properties. Optical properties correction factors for Photofrin fluorescence were determined experimentally using the same empirical function to recover the Photofrin concentration from measured fluorescence during PDT. The results showed no photobleaching of Photofrin during the course of PDT. PDT doses delivered to multiple sites in the thoracic cavity of 4 patients were presented and showed that PDT dose can be different by 4.4 times intra-patients and 9.1 times inter-patients.

To evaluate the synergistic effect of radiotherapy and radiofrequency hyperthermia therapy in the treatment of lung and liver cancers, we studied the mechanism of heat absorption and transfer in the tumor using electro-thermal simulation and high-resolution temperature mapping techniques. A realistic tumor-induced mouse anatomy, which was reconstructed and segmented from computed tomography images, was used to determine the thermal distribution in tumors during radiofrequency (RF) heating at 13.56 MHz. An RF electrode was used as a heat source, and computations were performed with the aid of the multiphysics simulation platform Sim4Life. Experiments were carried out on a tumor-mimicking agar phantom and a mouse tumor model to obtain a spatiotemporal temperature map and thermal dose distribution. A high temperature increase was achieved in the tumor from both the computation and measurement, which elucidated that there was selective high-energy absorption in tumor tissue compared to the normal surrounding tissues. The study allows for effective treatment planning for combined radiation and hyperthermia therapy based on the high-resolution temperature mapping and high-precision thermal dose calculation.