This PDF file contains the front matter associated with SPIE Proceedings Volume 10860, including the Title Page, Copyright information, Table of Contents, Author and Conference Committee lists.

Two death pathways have been associated with photodynamic therapy (PDT): apoptosis and paraptosis. The former is characterized by caspase activation and nuclear fragmentation while the latter is associated with an unfolded protein response leading to an extensive pattern of cytoplasmic vacuole formation. In this study, we explore some of the determinants of a response involving paraptosis after photodynamic therapy in cell culture using a human-derived ovarian cancer cell line: OVCAR-5 cells. Experimental results are consistent with the hypothesis that paraptosis is evoked by ER photodamage. This leads to an extensive pattern of cytoplasmic vacuolization. While activation of JNK and related MAP kinases has been associated with paraptosis, the JNK antagonist SP600125 did not prevent a paraptotic response to ER photodamage in OVCAR-5. Translocation of the nuclear HMGB1 to the cell periphery had been proposed as a potential marker for paraptosis. We found this effect was not a reliable marker for paraptosis. Targeting the ER for photodamage may, however, be a useful approach to eradicating malignant cells with an impaired route to apoptosis.

Photodynamic therapy (PDT) is a light-activated modality using exogenous chromophore. The costly components of this therapy are the photosensitizers and lasers which are used typically as the illumination source. Although compared to oncology drugs, photosensitizers are, in general less expensive, the cost is not trivial. Additionally, a major expense associated with the modality could be the light source. We are beginning to see a move toward lowering sensitizer costs by using generic molecules and instrumentation by including light emitting diodes and battery, even solar battery powered devices. The use of smart phones to incorporate simple imaging for treatment guidance or target localization are additional low-cost options. These are potentially exciting developments and might increase the penetration of the technology further.

Standard chemoradiation often enriches drug-resistant tumor cell populations that can lead to recurrent and treatment-refractory disease. Preclinical models of glioblastoma brain tumors, for instance, suggest that the cancer stem cell subpopulation becomes enriched and re-populates the tumor milieu following conventional therapies. Here, we show evidence that photodynamic therapy (PDT) is effective against several patient-derived glioblastoma stem cell cultures. Moreover, sub-lethal PDT results in re-sensitization of cancer stem cell phenotypes with induced drug-resistance to chemotherapy.

Chemoresistance is a significant challenge in the treatment of patients with ovarian cancer. An important mechanism in resistance to cisplatin is increased drug efflux from tumor cells, potentially mediated by ATPdependent factors such as the ATPases, ATP7A/ATP7B, and the ATP binding cassette (ABC) family member, MRP2. Therefore, a promising strategy to overcome chemoresistance is targeted inhibition of ATP production in tumor cells. In this work, we developed a mitochondria-targeted photodynamic therapy (PDT) approach in ovarian tumors to overcome chemoresistance.

Background and Objectives: Finite Element Methods (FEM) and Monte Carlo (MC, FullMonte) simulations are employed to compute light propagation during interstitial photodynamic therapy. FullMonte models the light source as a fixed number of photons emitted from the center of the catheter. In the FEM, the light source is modeled as a flux of photons emitted from the outside diameter of the catheter. The objective of this study was to compare the FEM and MC computed light fluence rate distributions. Methods: A solid phantom with tissue optical properties was used to compare MC simulations conducted using FullMonte and FEM using COMSOL Multiphysics. A tetrahedral mesh of approximately 400,000 elements was created to mimic experiments in the phantom with one central 2 cm cylindrical diffuser fiber, and five IP85 detector fibers were inserted 5, 10, 15, 20, and 25 mm from the light source. FEM and FullMonte simulations were conducted for 50 and 100 mW/cm source power, and the resulting fluence rates were compared, at the detector locations. Results: Initially, the computed fluence rates differed significantly between the MC and FEM simulations. However, the light gradient was comparable between both methods. Changing the FEM boundary conditions such that the light source was modeled as a flux of photons emitted from inside the catheter approximately 0.6 mm from the outside diameter resulted in a better agreement (16% difference). Conclusions: The light source boundary condition is a major contributor to the difference between FEM and FullMonte computed light distributions. Acknowledgements: This work was supported in part by National Cancer Institute of the National Institutes of Health under Award Number R01CA193610 to G. Shafirstein

Pancreatic cancer is a highly lethal malignancy and a leading cause of cancer death in the world. Patients are either treated by surgery or by means of radiation therapy or by means of chemotherapy or by combining radiation and chemotherapy together depends upon the status of the pancreatic cancer. All these current treatments have limited efficacy as well as significant toxicity. Photodynamic therapy (PDT) is relatively free from side effects, but it is currently not applicable to pancreatic cancer due to its location in deep tissue. Herein, we developed a PDT system which uses poly (D, L-lactide-co-glycolide) (PLGA) polymeric nanoparticles incorporating a photosensitizer, verteporfin, to generate cytotoxic reactive oxygen species (ROS) by X-ray radiation of 6 MeV. The use of X-ray as the source of energy to trigger verteporfin avoids the limitation of poor penetration depth in conventional PDT. In addition, TAT peptide, a targeting moiety conjugated to the surface of the PLGA nanoconstructs facilitates the targeting of nanoparticles towards the nucleus of the cancer cells. The physiochemical characterisation as well as ROS generation capabilities of the nanoconstructs were studied under 6 MeV X-rays. We believe that the X-ray-induced ROS generation from Verteporfin molecules may be due to Cerenkov radiation (CR) and/or generation of energetic electron by the 6 MeV X-rays which then produce a cascade of ROSs. The cellular experiments carried out in Panc-1 cancer cell line suggest that an improved therapeutic effects can be achieved with the nanoconstructs triggered with X-ray radiation, compared with radiation alone.

Theranostic approaches to cancer management offer the possibility of tailoring treatments to individual patients or tumours. However, the development of theranostic nanoparticles optimally suitable for both diagnostic and therapeutic modalities to achieve this is challenging. Here we demonstrate an alternative nanoparticle-free theranostic approach that circumvents many of the difficulties currently hindering clinical translation. Through the use of a multimodal optical probe, we translate the theranostic burden from complex nanoparticles within the body to an external spectroscopic device, thus alleviating many of the constraints imposed on existing theranostic systems. Using this platform, we demonstrate the combination of Raman spectroscopic diagnosis with photodynamic therapy for optical cancer theranostics. Through selection of photosensitisers with suitable optical properties for combination with Raman spectroscopy, we achieve optical theranostics without the need for complex material systems. Sequential delivery of light for real-time Raman spectroscopic diagnosis followed by photosensitiser-specific illumination, enables cancer diagnosis and treatment during a single procedure. We demonstrate the feasibility of this theranostic approach using a panel of clinically-approved photosensitisers using in vitro cell assays across three cancerous cell lines, with in vivo demonstration using subcutaneous xenograft tumour models ongoing. Our results indicate that through careful instrument design, Raman spectroscopic diagnosis can be effectively performed on photosensitiser-containing cells and tissues without impaired diagnostic accuracy or undesired premature photosensitiser activation. Together, these results show that combination of Raman spectroscopy and photodynamic therapy for optical theranostics enables nanoparticle-free cancer detection, diagnosis, and treatment in real-time using a single optical system.

Treatment planning is of utmost importance in interstitial photodynamic therapy, as it predicts the required light delivery to the target volume in an upcoming treatment. However, planning remains a major challenge due to several uncertainties such as the tissue optical properties and the concentrations of the photosensitizer and oxygen. Any difference in these parameters from the assumed values during planning could significantly affect the outcome of the actual treatment. This work introduces PDT-SPACE, a PDT light source power allocation using a convex optimization engine to minimize damage to organs-at-risk (OAR) with robustness against variation in tissue optical properties. Three power allocation methods are proposed and compared with respect to the resulting standard deviation in the damage to organs-at-risk and their runtime. The proposed approaches are demonstrated for ALA induced PpIX as photosensitizer in a virtual brain tumor that models a glioblastoma multiforme case. Results show that choosing a power allocation to minimize the OAR damage standard deviation under optical property variation tends to also minimize the tumor coverage as there is only one degree of freedom to optimize upon. This motivates simultaneous source position and power allocation optimization.

Interstitial photodynamic therapy (iPDT), which uses optical fibers to excite photosensitizers in PDT, is a promising approach in the treatment of internal tumors. To enhance the treatment efficacy, the placement of the inserted optical fibers should be optimized from the photosensitizer distribution in the affected area. Here, we propose a method to obtain a fluorescence distribution of photosensitizers during iPDT. The inserted optical fibers for iPDT can be also used for detection of the fluorescence from the photosensitizer in the tissue. In the proposed method, fluorescence signals from the photosensitizers are collected by changing the combination of the inserted optical fibers for excitation and detection. The detected fluorescence signals are modeled by using excitation light distribution, fluorescence detection efficiency, and photosensitizer distribution. The excitation light distribution and the fluorescence detection efficiency distribution are obtained by calculating light propagation in the tissue. The photosensitizer distribution is reconstructed from the detected signals with a compressive sensing algorithm with a sparsity constraint. As a demonstration, we performed numerical simulations to obtain a photosensitizer distribution in a biological tissue by inserting several optical fibers for excitation and detection. In the numerical simulation, we verified the spatial distribution of the photosensitizers in a biological tissue can be reconstructed from the fluorescence signals detected by inserting the optical fibers.

The effectiveness of photodynamic treatment depends on several factors including an accurate knowledge of optical properties of the tissue to be treated. Transmittance and diffuse reflectance spectroscopic techniques are commonly used to determine tissue optical properties. Although transmittance spectroscopy technique is accurate in determining tissue optical properties, it is only valid in an infinite medium and can only be used for interstitial measurements. Diffuse reflectance spectroscopy, on the other hand, is easily adapted to most tissue geometries including skin measurements that involve semi-infinte medium. However, the accuracy of the measured optical properties can be affected by uncertainty in the measurements themselves and/or due to the uncertainty in the fitting algorithm. In this study, we evaluate the accuracy of optical properties determination using diffuse reflectance spectroscopy implemented using a contact probe setup. We characterized the error of the optical properties fitted using two fitting algorithms, a wavelength wise fitting algorithm and a full reflectance spectral fitting algorithm. By conducting systematic investigation of the measurements and fitting algorithm of DRS, we gained an understanding of the uncertainties in the measured optical properties and outlined improvement measures to minimize these errors.

Total Skin Electron Therapy (TSET) utilizes high-energy electrons to treat cancers on the entire body surface. The otherwise invisible radiation beam can be observed via the optical Cherenkov photons emitted from interaction between the high-energy electron beam and tissue. Cherenkov emission is used to evaluate the dose uniformity on the surface of the patient in real-time. We have utilized a structured light sensor to determine the surface contour of each patient. Each patient was also monitored during TSET via in-vivo detectors (IVD) and/or scintillating discs in nine locations. The Cherenkov image is converted to dose distribution after a two-dimensional perspective geometry correction and the IVD measured dose at umbilicus. Cumulative dose on patient surface is obtained by projecting the two-dimensional dose distribution onto a cylindrical geometry representing the patient anatomic geometry. Patients undergoing TSET in various conditions (whole body and half body) were imaged and analysed, and the cumulative dose based on Cherenkov imaging was evaluated on various patients.

While Photofrin mediated PDT for bladder cancer was the first approved indication for this technique, it failed to attract the confidence of urologists as a treatment option, primarily due to the high incidence of incontinence linked to PDT damage to the bladder muscle. To mitigate this hazard a phase I clinical trial using instillation of the Ru(II) coordination complex TLD1433 and 530 nm activation light was initiated. To achieve the intended drug doses of 0.35 and 0.7 mg/cm2 and a radiant exposure of 90 J/cm2 the concentration of the instillation was adjusted to each patients' bladder volume and the irradiance was measured at up to 12 positions in the bladder. Irradiance monitoring proved helpful in adjusting the irradiation time to the bladder wall albedo and also for increased light scattering and absorption due to turbidity built up in the bladder void. The initial multiplication factors of the bladders (n=6) ranged from 1.1 to 2.8. Monte Carlo simulations based on CT-scans from all 6 participants approximate the range of irradiances observed during these studies. Nevertheless, a fraction of the surface can see a multiple of the average irradiance whereas other regions (typically less than 5% of the surface area) see significantly less than the average irradiance. These variations are due to the actual bladder shape and are somewhat independent of the position of the spherical emitter. Fitting of the measured surface irradiance to the simulated dose surface histograms enables extraction of the bladder wall and bladder void’s optical properties.

Deep tissue abscesses remain a significant cause of morbidity, mortality, and hospital stay despite improved surgical techniques and use of perioperative antibiotics. Long-term antibiotics increase risk of acquired resistance and polymicrobial infection, limiting future treatment options. We have therefore undertaken a Phase 1 clinical trial to evaluate safety and feasibility of methylene blue mediated photodynamic therapy (MB-PDT) at the time of drainage to treat deep tissue abscesses. This trial uses a fixed photosensitizer dose (1 mg/mL) delivered directly to the abscess cavity, and escalates light dose using a 3+3 design. Three patients were treated at the lowest light dose (20 mW/cm2, 6 J/cm2), with no study-related adverse events. Based on the technical success of this group, recruitment will continue for higher light dose groups with relaxed inclusion criteria. This trial restricts potential subjects to those with single abscesses less than 8 cm in diameter. To investigate MB-PDT feasibility in a wider population, we extracted CT images for patients receiving abscess drainage locally. Images were segmented and imported into a custom Monte Carlo simulation framework. Simulations were performed to determine whether 20 mW/cm2 could be delivered to 95% of the abscess wall, given the available 2 W of optical power at the treatment fiber output. Preliminary results show that this is achievable in 80% of abscesses examined, with volumes ranging from 30-250 mL. Optical power required ranged from 50-950 mW. Based on these initial results, it appears that a large number of abscesses drained may be candidates for MB-PDT.

Aminolevulinic acid based photodynamic therapy (ALA-PDT) is a popular and efficacious treatment for actinic keratosis (AK). However, standard PDT can elicit stinging pain during illumination, and hence is not always favored by patients. In a new regimen called metronomic PDT (mPDT), similar to daylight PDT but using blue light, the illumination is delivered concurrently with ALA application rather than after a 1-hour pre-incubation (conventional regimen, PDT). In the clinic, mPDT is not only painless but also nearly as effective as PDT for AK lesion clearance. In this investigation, a murine AK model (generated by repeated UVB exposure) was treated with either mPDT or PDT. Lesion clearance was followed by area measurement, and samples were harvested for mechanistic analyses. Compared to pretreatment (100%), the average lesion area was reduced to 47% and 32% in PDT, and to 57% and 40% in mPDT at 1- and 2-weeks post PDT, respectively. Relative to untreated controls, enhanced cell death (histomorphology by H&E staining and apoptosis by TUNEL assay), and generation of Reactive Oxygen Species (ROS; CM-H2DCFDA staining) were observed in both PDT and mPDT samples. Activation of cleaved Caspase-3 was specifically observed only in PDT samples. Immunomodulation by inflammatory cells was observed by enhanced infiltration/retention of neutrophils and macrophages in metronomic PDT samples. Our results suggest that metronomic PDT can be just as effective as conventional PDT for treatment of AK, but the mechanisms may be quite different.

Optically triggered nanoparticles can provide safe and tumor specific thermal or chemical ablation methods for treating solid tumors. Nanoparticles trap in tumors with aberrant and leaky vasculature via enhanced permeation and retention effect. Theranostic nanoparticles (TNPs) which combine cross-sectional imaging with a therapeutics such as photothermal gold nanoconstructs, or photosensitizers allows for non-invasive tracking of nanoparticle transport to tumors and therapy planning for optimal spatio-temporal control of light triggered ablation. However, systemic delivery of TNPs leads to variable and often low tumor uptake, reducing phototherapy efficacy. We propose two strategies for personalizing optically triggered nanoparticle therapies to tumors for improving therapy outcomes. The first approach piggybacks the interventional radiology workflows for chemoembolization of liver cancer and metastasis for image guided local vascular delivery of TNPs and therapeutic light, while the second approach identifies the genetically inherited factors which control the tumor vascular micro-environment and affect nanoparticle delivery and response to photothermal and other therapies. Both approaches are studied with recently developed theranostic nanoparticles (TNPs) based on gold nanorods coated with Gadolinium oxide doped with rare earth elements to produce native X-ray, MRI, and 2nd NIR window (~1500 nm) optical luminescent contrasts and photothermal action upon 808 nm light illumination. While these results are reported in a photothermal therapy (PTT) context, they are valid for nanoparticle mediated photodynamic therapies as well. NIR (808nm) resonant Au-rods (10 nm dia, 50 nm length) were encapsulated with Gd2O3 shell doped with Yb and Er and terminated with 5000 mw PEG chains to result in 75nm TNPs with -4.8mV zeta potential, dose dependent X-ray and T1-weighted MR contrast. To validate the tumor delivery benefits via interventional radiology methods, Six ~400g immunocompetent Wistar rats were implanted with colorectal liver metastasis (CC-531) tumors. The animals were injected with TNPs (0.5 mL, 1013 NP/mL) either locally into the liver via portal vein and navigating to tumor site or systemically via tail vein. Rats were imaged with T1 MR scans immediately after injection for portal vein group, and at 4, 24, and 72 h for the tail vein group. DynaCT imaging was acquired by injecting 0.5 mL of TNP (3x1014 NP/mL). Uptake of the TPN into the liver vis site-selective vs IV- methods was compared via analysis of cross-sectional MR images. Local delivery resulted in ~3.2 times increase tumor dose. DynaCT images clearly shows the CT enhancement (HU) for both Post-NP and Post-PTT treated rats, as compared to Pre-NP rats. Furthermore, the ex vivo TEM images of CRLM tumor tissue indicated TPN uptake in tumor cells following site-selective delivery, as well as consistency in TNP shape and lack of aggregation, which in turn resulted in superior response to photothermal therapy and tripling of survival duration in a separate group of animals. Thus, patient specific interventional image guided local vascular injections are superior to systemic injections for nanoparticle and therapeutic light delivery to interior organ malignancies such as liver metastasis. [1] The second personalization strategy investigated the role of inherited factors governing tumor vascular microenvironment in a breast cancer setting. Breast and many other cancers are highly heritable, yet most causative variants are unknown. Of the known risk variants, most are considered tumor cell-autonomous, with far less emphasis placed on testing germline variants that impact the tumor microenvironment, that is expected to play a major role both in tumor cell proliferation but also in chemo or radiotherapy delivery and response. We observed that germline host microenvironment variation in vascular perfusion, and tumor architecture play a critical role in both TNP uptake and response to nanoparticle mediated photothermal ablation of breast cancer. We used our recently developed Consomic Xenograft Model (CXM), which maps TME-specific genetic modifiers to single chromosomes [2, 3]. In CXM, human breast cancer cells are orthotopically implanted into consomic xenograft host strains that differ from the parental xenograft host strain by one substituted chromosome. Because the host backgrounds genetically differ by one chromosome, whereas the tumor cells are unvaried, any observed phenotypic changes are due to TME modifier(s) and can be linked to a single chromosome. Thus, CXM offers for the first time, an experimental platform for mapping the host TME modifiers that potentially impact NP delivery and efficacy in BC. Using the CXM strategy, we recently localized vascular-specific DLL4 function as a heritable host TME modifier of enhanced permeability and retention (EPR). Notably, DLL4 is a master regulator of angiogenic vascular patterning and inhibition of DLL4 attenuates tumor growth and progression by eliciting nonproductive angiogenesis yet the explicit role of DLL4 in EPR and its influence on nanoparticle delivery and efficacy remains untested. Even less understood is the potential impact that inheritance of functionally distinct DLL4 alleles might have on the patient-to-patient variability in response to nanomedicine therapy, which ultimately leads to the failure of NP in clinical trials. Here, we used the triple negative breast cancer MDA-MB-231luc+ orthotopic implanted Consomic models (SSIL2Rg- and SS.BN3IL2Rg-) models to determine the impact of vascular organization on TNP uptake and accumulation in tumor, photothermal response to NIR radiation and treatment efficacy. The bio distribution study with inductive coupled plasma-mass spectroscopy (ICP-MS) and MR imaging with TNPs revealed almost equal distribution of NPs in breast tumors of SSIL2Rg- and SS.BN3IL2Rg- . Interestingly, microscopic examination of distribution of NPs in the tissue sections of tumor revealed that TNPs are more closely arranged on and near the blood vessels in SS.BN3IL2Rg tumors which disrupted tumor vasculature with PTT and subsequent loss of tumor with no recurrence, whereas in SSIL2Rg hosts, photothermal therapy response was transient and tumor relapse was observed in most treated animals. This suggests that pattern of distribution of nanoparticles, governed by inherited vascular factors can lead to dramatic difference in the therapy response for the same tumor, and provides vascular targets for nanoparticle therapies in patients prone to aggressive and therapy resistant tumors. DLL4 targeted TNPs were developed and validated for preferential endothelial targeting in tumor promoting SSIL2Rg- hosts. 1. Parchur, A.K., et al., Vascular Interventional Radiology Guided Photothermal Therapy of Colorectal Cancer Liver Metastasis with Theranostic Gold Nanorods. ACS Nano, 2018. 2. Flister, M.J., et al., Host genetic modifiers of nonproductive angiogenesis inhibit breast cancer. Breast Cancer Res Treat, 2017. 165(1): p. 53-64. 3. Jagtap, J., et al., Methods for detecting host genetic modifiers of tumor vascular function using dynamic near-infrared fluorescence imaging. Biomed Opt Express, 2018. 9(2): p. 543-556.

We designed X-ray triggered liposomes by co-embedding photosensitizers and gold nanoparticles (3-5 nm) inside a lipid bilayer. Gold was chosen in this work as, due to its high atomic number it strongly interacts with X-ray radiation as shown, for example, by gold nanoparticle-induced radiation enhancement inside biological tissue. As a photosensitizer we chose verteporfin (VP), clinically approved for photodynamic therapy (PDT) of age-related macular degeneration. 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1, 2-di-(9Z-octadecenoyl)-3-trimethylammonium-propane (DOTAP) were chosen as lipid components in the liposome formulation because DOPC can load highly hydrophobic molecules and DOTAP can facilitate cellular uptake due to its positive charge. The singlet oxygen generation from different liposome samples and destabilization of the lipid bilayer under X-ray radiation with different dosage (1, 2 and 4 Gy) were assessed by using the Singlet Oxygen Green Sensor (SOSG) and calcein release assays, respectively. The 6 MeV X-ray radiation induces verteporfin to produce singlet oxygen, which destabilises the liposomal membrane and causes the release of cargos from the liposomal cavity. This triggering strategy is demonstrated by the increased effectiveness of chemotherapy in vivo. Our work indicates the feasibility of a combinatorial treatment and possible synergistic effects in the course of standard radiotherapy combined with chemotherapy delivered via X-ray triggered liposomes. Importantly, our X-ray mediated liposome release strategy offers prospects for deep tissue photodynamic therapy, by removing its depth limitation. Additionally, the strategy described here has been designed to be compatible with future clinical translation. The materials and approaches used in this study, such as verteporfin, lipids, Dox and X-rays, are clinically used in treatment of tumours. Although gold nanoparticles used in this study have not yet been approved by the regulatory agencies, their size is compatible with the requirements of renal clearance. In this way, long-term nanoparticle toxicity is likely to be minimized if not eliminated. Moreover, the ease of conjugation of targeting ligands to liposome surface with appropriate linkers, for example, lipid-polyethylene glycol (PEG), would be an added advantage when applied to the targeted therapy, in particular for tumour treatment. From a clinical point of view, it would be beneficial to have access to this multimodality treatment, given our evidence of better therapeutic effect (or, potentially, equal therapeutic effect) at diminished toxicity in the case when single modality treatment options alone can only produce desired therapeutic effects at a significant cost of short and long term toxicity.

We compare previously reported 2-(1-hexyloxyethyl)-2-divinyl pyropheophorbide (HPPH) mediated photodynamic therapy (PDT) experimental results for singlet oxygen dose on mice with simulations using a new, integrated, hardware and software device, Dosie^TM, that calculates light transport and photokinetics for PDT. The two sets of results are consistent and validate the use of the device simulations to predict HPPH-mediated PDT results on mice animal studies.

Photodynamic Therapy (PDT) is a promising modality for cancer treatment. Typically, a laser is used to photo-excite a photosensitizer (PS) that subsequently collides with oxygen molecules promoting them to the metastable singlet delta state O₂(¹Δ). Singlet oxygen molecules are believed to be the species that destroys cancerous cells during PDT. In this paper we describe a novel 2D imaging sensor for photosensitizer fluorescence and singlet oxygen luminescence. We describe our instrument and initial results from both in-vitro and in-vivo studies that indicate that this system may be a valuable dosimeter for both PDT researchers and eventually for clinical application.

While most cancer therapy options rely on a systemic delivery of pharmacologic drugs into the tumor site, physiologic barriers intrinsic to solid tumors seriously limit drug distribution. In pancreatic ductal adenocarcinoma (PDAC) tumors, it is well-characterized that tumor stroma with a dense desmoplasia hinders drug uptake due to the overproduction of extracellular matrix (ECM) macromolecules such as collagen and hyaluronan. These major components of the ECM exert a high pressure on blood vessels thus collapsing them. This study focused on reducing the overexpression of cancer associated fibroblasts (CAF) by administering an angiotensin II receptor blocker, losartan, to examine its effects on tumor microenvironment modulation for photodynamic therapy. Treatments were conducted on orthotopic xenograft models of AsPC-1 tumor line, which represented the dense stroma of PDAC with highly disordered collagen bundles. Drug delivery efficiency was examined by quantifying verteporfin uptake and vascular patency. Results showed that pancreatic tumor stroma can be modulated by angiotensin II receptor blockers. Losartan treated mice showed an increase in verteporfin uptake and patent vessel area. Collagen structure change was observed which required more texture analysis to quantify. Tumor size between the two groups did not show significant shrinkage, which indicated the importance of treatment start time especially for malignant tumors with narrow treatment windows such as AsPC-1. The enhancement of drug uptake and vascular perfusion suggested that photodynamic therapeutic outcome could be improved by targeting the tumor stroma to improve verteporfin uptake.

In recent years, numerous publications have documented the growing consensus among dermatologists for daylight-photodynamic therapy (dPDT) treatment of Actinic Kerasotis (AK), with additional evidence supporting treatment of certain non-melanoma skin cancers (NMSC). While these publications aim to address the minimum effective surface-irradiance required for successful clearance, our current work investigates how the tissue optical properties influence the fluence rate within tissue. While it is known red and blue light will have drastically different attenuation profiles in tissue, it is harder to quantify this for broad-spectrum light sources. Our model aims to expand the current PpIX-weighted irradiance metric by incorporating a clinically relevant depth distribution factor. Using a 7-layer skin model, Monte Carlo simulations of optical photons ranging from 350nm – 900nm provide insight into the potential depth of activation of the photosensitizer. Additionally, these models can be applied to known light spectra for both narrow-band conventional treatments (415nm, 633nm), as well as for the Sun and other white light sources (CFL, Halogen). Using this model, we show even when the effective surface-irradiance of the Sun is 4x a halogen light source, the effective fluence within the top 3mm of tissue is generally equivalent, due to the higher proportion of UV-blue light in Sun spectrum which is highly attenuated within the first 50m. We plan to use this model to inform which light source or light combinations would be most appropriate for specific lesion morphologies.

In clinical delivery of PDT, in-situ measurement of PpIX concentration is rarely done, and yet point-probe measurements have shown extreme heterogeneity exists between patients and between lesions. Direct measurements of PpIX can provide guidance in PDT, informing critical decisions about treatment time and retreatment or further skin preparation. In this work, we present a smartphone-based fluorescence imaging system to map PpIX concentration onto a 2D image for the use in PDT treatment optimization. The hand-held system utilizes a custom application on an iPhone 6s in conjunction with a 3D-printed measurement base containing custom miniaturized light source and electronics and filter system. The prototype has been produced and tested in phantoms and in pre-clinical evaluation. Intralipid phantom measurements detected clinicallyrelevant concentrations of PpIX within the 0.05μM - 4μM range. Preclinical tests on mice showed the ability to detect PpIX concentration for topically applied ALA within 20-30 minute incubation. These results showcase the viability of the system to map pixel intensities to PpIX concentrations and perform in-vivo detection within a clinically relevant timeframe. Clinical trials are in preparation with results expected in the next few months.

This paper describes the assembly and characterization of a system to treat and monitor ALA-based photodynamic therapy, using near-infrared fluorescence images for photosensitizer monitoring. The system is portable, user friendly and low cost, using a diode laser emitting at 633 nm as treatment light, capable to delivery up to 150 mW/cm² at the lesion surface. The PpIX fluorescence is excited by the treatment light itself, and detected by camera in real-time. Since the excitation and emission wavelengths are in the red-NIR spectral regions, the penetration into the skin is improved and the volume measured by the fluorescence images is larger when compared to the widely used violet excitation.

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 (50 - 150 mW∕cm²), tumor regrowth rate, k, was determined for each condition by fitting the tumor volume vs. time to V₀*exp(k*t). Treatment was delivered with a collimated laser beam of 1 cm diameter at 630 nm. Explicit dosimetry of initial tissue oxygen concentration, tissue optical properties, and Photofrin concentration was used to calculate [ROS]rx,cal. Φ was determined for the treatment volume based on Monte-Carlo simulations and measured tissue optical properties. Tissue oxygenation is measured using an oxylite oxygen probe to throughout the treatment to calculate the measured [ROS]_rx,mea. Cure index, CI = 1-k/k_ctr, for tumor gowth up to 14 days were determined as an endpoint using five dose metrics: light fluence, PDT dose, and [ROS]_rx,cal, and [ROS]_rx,mea. PDT dose was defined as the product of the time-integral of photosensitizer concentration and Φ at a 3 mm tumor depth. Preliminary studies show that [ROS]_rx,mea best correlates with CI and is an effective dosimetric quantity that can predict treatment outcome.