Light Fluence Rate Research Articles

Development of a protocol for whole-lung in vivo lung perfusion-assisted photodynamic therapy using a porcine model.

Standard treatments for isolated lung metastases remain a clinical challenge. In vivo lung perfusion technique provides flexibility to overcome the limitations of photodynamic therapy (PDT) by replacing the blood with acellular perfusate, allowing greater light penetration. Using Monte Carlo-based simulations, we will evaluate the abilities of a light delivery system to irradiate the lung homogenously. Afterward, we aim to demonstrate the feasibility and safety profile of a whole-lung perfusion-assisted PDT protocol using 5-ALA and Chlorin e6. A porcine model of a simplified lung perfusion procedure was used. PDT was performed at 630 or 660nm with 5-ALA or Chlorin e6, respectively. Light fluence rate measurements and computed tomography (CT) scan segmentations were used to create in silico models of light propagation. Physiologic, gross, CT, and histological assessment of lung toxicity was performed 72h post-PDT. Dose-volume histograms showed homogeneity of light intensity throughout the lung. Predicted and measured fluence rates showed strong reliability. The photodynamic threshold of 5-ALA was , whereas Chlorin e6 showed negligible uptake in lung tissue. We lay the groundwork for personalized preoperative in silico dosimetry planning to achieve desired treatment volumes within the therapeutic range. Chlorin e6 demonstrated the greatest therapeutic potential, with a minimal uptake in healthy lung tissues.

Multispectral singlet oxygen luminescent dosimetry (MSOLD) for Photofrin-mediated PDT

SignificanceMultispectral singlet oxygen dosimetry (MSOLD) provides a mean for direct detection of singlet oxygen, responsible for tumor kill for type II PDT. ApproachAn InGaAs spectrometer or an InGaAs detector coupled with to narrow beam filters (1200, 1240, 1250, 1270, 1300 nm) via 1 mm optical fibers are used to measure singlet oxygen (SO) luminescent spectrum in in-vitro and in-vivo conditions. The spectrum, after fitted to a phosphorescence background a gaussian function for the singlet oxygen peak, is used to determine the singlet oxygen (SO) emission signal. The MSOLD signal is then compared with the singlet oxygen explicit dosimetry (SOED) results, based on direct measurements of light fluence (rate), Photofrin concentration, and tissue oxygenation concentration. ResultsMSOLD signal is affected by tissue absorption and scattering and is increasing with increasing Photofrin concentration and light fluence rate. ConclusionsMSOLD is feasible in vitro and in vivo for detecting SO directly.

Reactive Oxygen Species Explicit dosimetry for Pleural PDT

SignificancePreclinical studies show improved prediction of treatment outcome using [ROS]rx than light fluence rate or PDT dose. We demonstrate ROSED in a clinical setting. ApproachExplicit dosimetry of light fluence, photosensitizer concentration, and oxygen concentration is used to quantify the reactive oxygen species explicit dosimetry (ROSED) during Photofrin-mediated pleural PDT. Light fluence and photosensitizer concentration were measured by a customized multi-channel PDT dose dosimeter system. Diffuse correlation spectroscopy (DCS) contact probes were sutured to the pleural cavity wall after surgical resection of pleural mesothelioma tumor to monitor tissue blood flow (BFI) during intraoperative PDT treatment. Tissue oxygen concentration can be determined by utilizing tumor blood flow measured by DCS. ResultsLarge inter- and intra-patient heterogeneities in [ROS]rx were observed although an identical light dose of 60 J/cm2 was prescribed to all patients. ConclusionsThis study summarizes the current results of ROSED for a Phase II pleural PDT clinical trial.

A novel investigational preclinical model to assess fluence rate for dental oral craniofacial tissues

ObjectivePhotodynamic Therapy (PDT) and Photobiomodulation (PBM) are recognized for their potential in treating head and neck conditions. The heterogeneity of human tissue optical properties presents a challenge for effective dosimetry. The porcine mandible cadaver serves as an excellent model and has several similarities to human tissues of the dental oral craniofacial complex. This study aims to validate a novel modeling system that will help refine PDT and PBM dosimetry for the head and neck region. Methods and MaterialsLight transmission was analyzed through several tissue combinations at distances of 2 mm to 10 mm. Maximum light fluence rates (mW/cm2) were compared across tissue types to reveal the effects of tissue heterogeneity. ResultsThe study revealed that light fluence is affected by tissue composition, with dentin/enamel showing reduced transmission and soft tissue regions exhibiting elevated values. The porcine model has proven to be efficient in mimicking human tissue responses to light, enabling the potential to optimize future protocols. ConclusionThe porcine mandible cadaver is a novel model to understand the complex interactions between light and tissue. This study provides a foundation for future investigations into dosimetry optimization for PDT and PBM.

Photodynamic Therapy-Induced Anti-Tumor Immunity: Influence Factors and Synergistic Enhancement Strategies.

Photodynamic therapy (PDT) is an approved therapeutic procedure that exerts cytotoxic activity towards tumor cells by activating photosensitizers (PSs) with light exposure to produce reactive oxygen species (ROS). Compared to traditional treatment strategies such as surgery, chemotherapy, and radiation therapy, PDT not only kills the primary tumors, but also effectively suppresses metastatic tumors by activating the immune response. However, the anti-tumor immune effects induced by PDT are influenced by several factors, including the localization of PSs in cells, PSs concentration, fluence rate of light, oxygen concentration, and the integrity of immune function. In this review, we systematically summarize the influence factors of anti-tumor immune effects mediated by PDT. Furthermore, an update on the combination of PDT and other immunotherapy strategies are provided. Finally, the future directions and challenges of anti-tumor immunity induced by PDT are discussed.

The photosensory function of Zmphot1 differs from that of Atphot1 due to the C-terminus of Zmphot1 during phototropic response

The role of phot1 in triggering hypocotyl phototropism and optimizing growth orientation has been well-characterized in Arabidopsis, whereas the role of Zmphot1 in maize remains largely unclear. Here, we show that Zmphot1 is involved in blue light-induced phototropism. Compared with Atphot1, Zmphot1 exhibited a weaker phototropic response to very low-fluence rates of blue light (< 0.01 μmol m−2 s−1), but stronger phototropic response to high-fluence rates of blue light (> 10 μmol m−2 s−1) than Atphot1. Notably, blue light exposure induced Zmphot1-green fluorescent protein (GFP), but not Atphot1-GFP, to form the aggregates in the cytoplasm of Nicotiana benthamiana cells. Furthermore, by generating the chimeric phot1 proteins, we found that the serine-threonine kinase (STK) domain at the C-terminus is responsible for a more volatile membrane association of Zmphot1. Consistently, the chimeric phot1 protein fusing the STK domain of Zmphot1 with other domains of Atphot1 responded similarly as Zmphot1 to both low and high fluence rates of blue light. Interestingly, although both Zmphot1 and Atphot1 interact with AtNPH3, Zmphot1 induced weaker dephosphorylation of NON-PHOTOTROPIC HYPOCOTYL 3 (NPH3) than Atphot1. Together, our findings indicate that Zmphot1 and Atphot1 exhibit different photosensory function during phototropic response and that the STK domain may play a key role in determining their properties.

Shade-Induced Leaf Senescence in Plants.

Leaf senescence is a vital developmental process that involves the orderly breakdown of macromolecules to transfer nutrients from mature leaves to emerging and reproductive organs. This process is essential for a plant's overall fitness. Multiple internal and external factors, such as leaf age, plant hormones, stresses, and light environment, regulate the onset and progression of leaf senescence. When plants grow close to each other or are shaded, it results in significant alterations in light quantity and quality, such as a decrease in photosynthetically active radiation (PAR), a drop in red/far-red light ratios, and a reduction in blue light fluence rate, which triggers premature leaf senescence. Recently, studies have identified various components involved in light, phytohormone, and other signaling pathways that regulate the leaf senescence process in response to shade. This review summarizes the current knowledge on the molecular mechanisms that control leaf senescence induced by shade.

A Monte Carlo simulation for Moving Light Source in Intracavity PDT.

We developed a simulation method for modeling the light fluence delivery in intracavity Photodynamic Therapy (icav-PDT) for pleural lung cancer using a moving light source. Due to the large surface area of the pleural lung cavity, the light source needs to be moved to deliver a uniform dose around the entire cavity. While multiple fixed detectors are used for dosimetry at a few locations, an accurate simulation of light fluence and fluence rate is still needed for the rest of the cavity. We extended an existing Monte Carlo (MC) based light propagation solver to support moving light sources by densely sampling the continuous light source trajectory and assigning the proper number of photon packages launched along the way. The performance of Simphotek GPU CUDA-based implementation of the method - PEDSy-MC - has been demonstrated on a life-size lung-shaped phantom, custom printed for testing icav-PDT navigation system at the Perlman School of Medicine (PSM) - calculations completed under a minute (for some cases) and within minutes have been achieved. We demonstrate results within a 5% error of the analytic solution for multiple detectors in the phantom. PEDSy-MC is accompanied by a dose-cavity visualization tool that allows real-time inspection of dose values of the treated cavity in 2D and 3D, which will be expanded to ongoing clinical trials at PSM. PSM has developed a technology to measure 8-detectors in a pleural cavity phantom using Photofrin-mediated PDT that has been used during validation.

Evaluation of Fractionated Photofrin-mediated Photodynamic Therapy Using Different Light Fluences with Reactive Oxygen Species Explicit Dosimetry (ROSED).

Photodynamic therapy (PDT) is an established modality for cancer treatment, and reactive oxygen species explicit dosimetry (ROSED), based on direct measurements of in-vivo light fluence (rate), in-vivo photofrin concentration, and tissue oxygenation concentration, has been proved to provide the best dosimetric quantity which can be used to predict non-fractionated PDT outcome. This study performed ROSED for Photofrin-mediated PDT for mice bearing radiation-induced fibrosacorma (RIF) tumor. As demonstrated by our previous study, fractionated PDT with a 2-hour time interval can significantly improve the long-term cure rate (from 15% to 65% at 90 days), and it tends to increase as the light dose for the first light fraction gets larger. This study focused on further improving the long-term cure rate without introducing apparent toxicity using combinations of different first light fraction lengths and total light fluences. Photofrin was injected through the mouse tail vein at a concentration of 5 mg/kg. After 18~24 hours, treatment was delivered with a collimated laser beam of 1 cm diameter at 630 nm. Mice were treated using two fractions of light fluences with a 2-hour dark interval. Different dose metrics were quantified, including light fluence, PDT dose, and [ROS]rx. In addition, the total reacted [ROS]rx and treatment outcomes were evaluated and compared to identify the optimal light fraction length and total light fluence.

Multispectral singlet oxygen luminescent dosimetry (MSOLD) for Photofrin-mediated Photodynamic Therapy.

Direct detection of singlet-state oxygen ([1O2]) constitutes the holy grail dosimetric method for type II PDT, a goal that can be quantified using multispectral singlet oxygen dosimetry (MSOLD). However, the short lifetime and extremely weak nature of the singlet oxygen signal produced has given rise to a need to improve MSOLD signal-to-noise ratio. This study examines methods for optimizing MSOLD signal acquisition, specifically employing an orthogonal arrangement between detection and PDT treatment light, consisting of two fiber optics - connected to a 632-nm laser and an InGaAs detector respectively. Light collected by the InGaAs detector is then passed through a filter wheel, where spectral emission measurements are taken at 1200 nm, 1240 nm, 1250 nm, 1270 nm, and 1300 nm. The data, after fitting to the fluorescence background and a gaussian-fit for the singlet oxygen peak, is established for the background-subtracted singlet oxygen emission signal. The MSOLD signal is then compared with the singlet oxygen explicit dosimetry (SOED) results, based on direct measurements of in-vivo light fluence (rate), in-vivo Photofrin concentration, and tissue oxygenation concentration. This study focuses on validating the sensitivity and minimum detectability of MSOLD signal in various in-vitro conditions. Finally, the MSOLD device will be tested in Photofrin-mediated PDT for mice bearing Radiation-Induced Fibrosarcoma (RIF) tumors.

BBX24 Interacts with JAZ3 to Promote Growth by Reducing DELLA Activity in Shade Avoidance.

Shade avoidance syndrome (SAS) is a strategy of major adaptive significance and typically includes elongation of the stem and petiole, leaf hyponasty, reduced branching and phototropic orientation of the plant shoot toward canopy gaps. Both cryptochrome 1 and phytochrome B (phyB) are the major photoreceptors that sense the reduction in the blue light fluence rate and the low red:far-red ratio, respectively, and both light signals are associated with plant density and the resource reallocation when SAS responses are triggered. The B-box (BBX)-containing zinc finger transcription factor BBX24 has been implicated in the SAS as a regulator of DELLA activity, but this interaction does not explain all the observed BBX24-dependent regulation in shade light. Here, through a combination of transcriptional meta-analysis and large-scale identification of BBX24-interacting transcription factors, we found that JAZ3, a jasmonic acid signaling component, is a direct target of BBX24. Furthermore, we demonstrated that joint loss of BBX24 and JAZ3 function causes insensitivity to DELLA accumulation, and the defective shade-induced elongation in this mutant is rescued by loss of DELLA or phyB function. Therefore, we propose that JAZ3 is part of the regulatory network that controls the plant growth in response to shade, through a mechanism in which BBX24 and JAZ3 jointly regulate DELLA activity. Our results provide new insights into the participation of BBX24 and JA signaling in the hypocotyl shade avoidance response in Arabidopsis.

Homodyne time-of-flight acousto-optic imaging for low-gain photodetector.

Acousto-optics imaging (AOI) is a hybrid imaging modality that is capable of mapping the light fluence rate in deep tissue by local ultrasound modulation of the diffused photons. Since the intensity of the modulated photons is relatively low, AOI systems often rely on high-gain photodetectors, e.g. photomultiplier tubes (PMTs), which limit scalability due to size and cost and may significantly increase the relative shot-noise in the detected signal due to low quantum yields or gain noise. In this work, we have developed a homodyne AOI scheme in which the modulated photons are amplified by interference with a reference beam, enabling their detection with a single low-gain photodetector in reflection-mode configuration. We experimentally demonstrate our approach with a silicon photodiode, achieving over a 4-fold improvement in SNR in comparison to a PMT-based setup. The increased SNR manifested in lower background noise level thus enabling deeper imaging depths. The use of a fiber-based configuration enables the integration of our scheme in a hand-held AOI probe.

Real-time PDT Dose Dosimetry for Pleural Photodynamic Therapy.

PDT dose is the product of the photosensitizer concentration and the light fluence in the target tissue. For improved dosimetry during plural photodynamic therapy (PDT), an eight-channel PDT dose dosimeter was developed to measure both the light fluence and the photosensitizer concentration simultaneously from eight different sites in the pleural cavity during PDT. An isotropic detector with bifurcated fibers was used for each channel to ensure detected light was split equally to the photodiode and spectrometer. The light fluence rate distribution is monitored using an IR navigation system. The navigation system allows 2D light fluence mapping throughout the whole pleural cavity rather than just the selected points. The fluorescence signal is normalized by the light fluence measured at treatment wavelength. We have shown that the absolute photosensitizer concentration can be obtained by applying optical properties correction and linear spectral fitting to the measured fluorescence data. The detection limit and the optical property correction factor of each channel were determined and validated using tissue-simulating phantoms with known varying concentration of Photofrin. Tissue optical properties are determined using an absorption spectroscopy probe immediately before PDT at the same sites. The combination of 8-channel PDT dosimeter system and IR navigation system, which can calculate light fluence rate in the pleural cavity in real-time, providing a mean to determine the distribution of PDT dose on the entire pleural cavity to investigate the heterogeneity of PDT dose on the pleural cavity.

Reactive oxygen species explicit dosimetry (ROSED) for fractionated photofrin-mediated photodynamic therapy (PDT).

Photodynamic therapy (PDT) is an established modality for cancer treatment and reactive oxygen species explicit dosimetry (ROSED), based on direct measurements of in-vivo light fluence (rate), in-vivo photofrin concentration, and tissue oxygenation concentration, has been proved to be an effective dosimetric quantity which can be used to predict PDT outcome. In this study, ROSED was performed for photofrin-mediated PDT for mice bearing radiation-induced fibrosacorma (RIF) tumor. PDT treatments were performed using single or fractionated illumination to a same total fluence of 135 Jcm-2. The effects of light fractionation on the total reacted [ROS]rx and treatment outcomes were evaluated.

Reflection-mode acousto-optic imaging using plane wave ultrasound pulses.

.Significance: Performance of an acousto-optic imaging system is limited by light fluence rate and acoustic pressure field distributions characteristics. In optically scattering media, the former determines the achievable contrast, whereas the latter the imaging resolution. The system parameters can be shaped by changing relative positions of ultrasound (US) transducer array and optodes. However, in the case of many potential clinical applications, optimization possibilities in this regard are limited, as a sample is accessible from one side only and using a water tank for coupling is not feasible.Aim: We investigate the possibilities of improving performance of an acousto-optic imaging system operating in reflection mode geometry with linear US array in direct contact with a sample using plane wave instead of focused US pulses.Approach: Differences in acoustic pressure field distributions for various transducer excitation patterns were determined numerically and experimentally. Acousto-optic images of phantoms with and without optically absorbing inclusions were acquired by measuring laser speckle contrast decrease due to the light modulation by plane wave and focused US pulses with different apodization patterns.Results: The residual acoustic pressure field components occupy relatively large volume and contribute to light modulation. Using nonsteered plane wave US pulses instead of focused ones allows one to mitigate their influence. It also allows one to obtain clear two-dimensional reconstructions of light fluence rate maps by shifting transducer apodization along the lateral direction.Conclusions: Using nonsteered plane wave US pulses allows one to achieve better imaging performance than with focused pulses in the assumed system geometry.

PD43-01 UPDATED TREATMENT RESULTS FROM A PHASE I STUDY OF WST11 PHOTOTHERAPY (VTP) FOR UPPER TRACT UROTHELIAL CARCINOMA

You have accessJournal of UrologyBladder Cancer: Upper Tract Transitional Cell Carcinoma I (PD43)1 Sep 2021PD43-01 UPDATED TREATMENT RESULTS FROM A PHASE I STUDY OF WST11 PHOTOTHERAPY (VTP) FOR UPPER TRACT UROTHELIAL CARCINOMA Lucas Nogueira, Andrew Tracey, Ricardo Alvim, Peter Reisz, Daniel Sjoberg, Quinlan Demac, Nicole Benfante, Karan Nagar, Jasmine Thomas, Jie Chen, Kwanghee Kim, David Solit, Avigdor Scherz, and Jonathan Coleman Lucas NogueiraLucas Nogueira More articles by this author , Andrew TraceyAndrew Tracey More articles by this author , Ricardo AlvimRicardo Alvim More articles by this author , Peter ReiszPeter Reisz More articles by this author , Daniel SjobergDaniel Sjoberg More articles by this author , Quinlan DemacQuinlan Demac More articles by this author , Nicole BenfanteNicole Benfante More articles by this author , Karan NagarKaran Nagar More articles by this author , Jasmine ThomasJasmine Thomas More articles by this author , Jie ChenJie Chen More articles by this author , Kwanghee KimKwanghee Kim More articles by this author , David SolitDavid Solit More articles by this author , Avigdor ScherzAvigdor Scherz More articles by this author , and Jonathan ColemanJonathan Coleman More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002057.01AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: The treatment of upper tract urothelial carcinoma (UTUC) presents technical challenges with endoscopic access and treatment delivery, representing a significant barrier to organ-preserving treatments in UTUC, limiting endoscopic management to small, low-grade tumors. Vascular-targeted photodynamic therapy (VTP) using intravascular photosensitizing agent padeliporfin (WST11) has demonstrated preclinical efficacy in preclinical animal models and provides an alternative to extirpative surgery in patients unable or unwilling to undergo extirpative surgery. Herein we present updated results from a phase 1 dose-finding study of WST11-VTP of the upper tract. METHODS: 18 patients with recurrent UTUC were treated with up to 2 sessions of endoscopic WST11-VTP. Eligibility included residual or recurrent urothelial carcinoma of the ureter or renal pelvis failing prior endoscopic treatment, who are unable or unwilling to undergo surgical management by resection of the involved ureter or kidney. A light dose escalation model was employed with increasing light fluence from 100mW/cm up to a maximally tolerated dose of 200mW/cm. The primary endpoint was the determination of maximally tolerated laser light fluence rate, with the secondary objective to evaluate treatment efficacy defined by absence of visible tumor and negative urine cytology following treatment. RESULTS: Complete response (CR) and tumor recurrence rates at 30 days after treatment were 67% and 28%, respectively. A second VTP treatment was performed in 8 (44%) patients, with 67% CR rate. The efficacy rates were comparable among patients who received the intermediate and highest light fluence and between the first and second treatment. Graded adverse events related to treatment are showed in table 1. No ureteral strictures were identified with the procedure. No evidence of increased toxicity was identified among patients who received a second VTP treatment. CONCLUSIONS: WST11-VTP shows promising evidence of therapeutic treatment effect in low- and high-grade upper tract urothelial tumors with limited treatment related toxicity. These early results provide support for further investigation to evaluate the curative potential for this therapy in a planned multicenter trial. Source of Funding: Steba Biotech © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e730-e730 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Lucas Nogueira More articles by this author Andrew Tracey More articles by this author Ricardo Alvim More articles by this author Peter Reisz More articles by this author Daniel Sjoberg More articles by this author Quinlan Demac More articles by this author Nicole Benfante More articles by this author Karan Nagar More articles by this author Jasmine Thomas More articles by this author Jie Chen More articles by this author Kwanghee Kim More articles by this author David Solit More articles by this author Avigdor Scherz More articles by this author Jonathan Coleman More articles by this author Expand All Advertisement Loading ...

A Comparison of Two Probes to Determine Rectum Optical Properties.

Tissue optical properties are crucial for determining the light dose delivered to the tumor. Two probes are compared: the two-catheter probe is based on transmittance measurement between one point source and one isotropic detector inside parallel catheters spaced at 0.5 cm along a 1-inch diameter transparent cylinder; and a 1-inch trans-rectal diffuse optical tomography (DOT) probe designed for prostate measurements, using a multiple fiber-array with source-detector separations of 1.4-10 mm. The two-catheter probe uses an empirical model for primary and scatter light fluence rates in the cylindrical cavity condition for anal PDT to determine optical properties along the source catheter using dual motors to move the source and detector along the catheters. The DOT probe uses finite element method (FEM) to obtain distribution of optical properties in 3D. Validations for the two probes were performed in liquid and solid phantoms. For each method, validation was performed in tissue-mimicking liquid phantoms for a range of known optical properties (μa between 0.05 and 0.9 cm-1 and μs' between 5.5 and 16.5 cm-1). To cross-check the two methods, solid phantoms were created of known optical properties at the University of Pennsylvania and sent for measurement to Princess Margaret Cancer Centre (PMH) to mimic realistic patient simulating conditions. Measurements were taken and optical properties were then recovered without knowing the expected values to cross-validate each probe. The results show modest agreement between the measured μa and μs'values, but high degree of agreement between the measured μeff performed independently using the two methods.

Determination of the distribution of drug concentration and tissue optical properties for ALA-mediated anal photodynamic therapy.

PDT efficacy depends on the availability and dynamic interactions of photosensitizer, light, and oxygen. Tissue optical properties influence the delivered light dose and impact PDT outcome. In-vivo measurements of tissue optical properties and photosensitizer concentration enable determination of explicit and implicit dose factors affecting PDT and helps to understand the underlying biophysical mechanism of PDT. In this study, we measure tissue optical properties (absorption μa (λ) and scattering μs' (λ) coefficients) and PpIX concentration in tissue simulating liquid phantoms with a geometry that resembles anal canal. In-vivo light fluence rate and photosensitizer fluorescence of 405nm excitation light source were acquired using a dual-motor continuous wave transmittance spectroscopy system. We characterized the tissue optical properties correction factor of fluorescence signal using a series of tissue simulating phantoms with known PpIX concentrations and with absorption coefficient between 0.1 - 0.9 cm-1 and reduced scattering coefficient between 5 - 40 cm-1. The results demonstrated that our spectroscopy system could determine the distribution of tissue optical properties and PPIX concentration during anal PDT.

Tangent algorithm for photogravitropic balance in plants and Phycomyces blakesleeanus: Roles for EHB1 and NPH3 of Arabidopsis thaliana

Plant organs that are exposed to continuous unilateral light reach in the steady-state a photogravitropic bending angle that results from the mutual antagonism between the photo- and gravitropic responses. To characterize the interaction between the two tropisms and their quantitative relationship we irradiated seedlings of Arabidopsis thaliana that were inclined at various angles and determined the fluence rates of unilateral blue light required to compensate the gravitropism of the inclined hypocotyls. We found the compensating fluence rates to increase with the tangent of the inclination angles (0° <γ < 90° or max. 120°) and decrease with the cotangent (90°<γ < 180° or max. 120°of the inclination angles. The tangent dependence became also evident from analysis of previous data obtained with Avena sativa and the phycomycete fungus, Phycomyces blakesleeanus. By using loss-of function mutant lines of Arabidopsis, we identified EHB1 (enhanced bending 1) as an essential element for the generation of the tangent and cotangent relationships. Because EHB1 possesses a C2-domain with two putative calcium binding sites, we propose that the ubiquitous calcium dependence of gravi- and phototropism is in part mediated by Ca2+-bound EHB1. Based on a yeast-two-hybrid analysis we found evidence that EHB1 does physically interact with the ARF-GAP protein AGD12. Both proteins were reported to affect gravi- and phototropism antagonistically. We further showed that only AGD12, but not EHB1, interacts with its corresponding ARF-protein. Evidence is provided that AGD12 is able to form homodimers as well as heterodimers with EHB1. On the basis of these data we present a model for a mechanism of early tropism events, in which Ca2+-activated EHB1 emerges as the central processor-like element that links the gravi- and phototropic transduction chains and that generates in coordination with NPH3 and AGD12 the tangent / cotangent algorithm governing photogravitropic equilibrium.

Treatment results from a phase I study of WST11 phototherapy (VTP) for upper tract urothelial carcinoma.

460 Background: Localized treatment of upper tract urothelial carcinoma (UTUC) is technically challenging which limits the ability to provide organ-sparing therapies to preserve renal function and representing a serious unmet need. Vascular-targeted photodynamic therapy (VTP) using intravascular photosensitizing agent padeliporfin (WTS11) has demonstrated preclinical safety and effective tumoricidal activity. Endoluminal application of this therapy offers a promising alternative to radical surgery for patients with upper tract cancers seeking to avoid extirpative surgery. Herein we present early results from a phase I dose-finding study of padeliporfin VTP for UTUC. Methods: Fourteen patients with recurrent UTUC were treated with up to 2 sessions of endoscopic padeliporfin VTP treatment. Eligibility included residual or recurrent urothelial carcinoma of the ureter or renal pelvis failing prior endoscopic treatment in patients who were unable or unwilling to undergo surgical management by resection of the involved ureter or kidney. WST-11 was administered at 4mg/kg and infused over 10 minutes. An intermedic diode laser was used to illuminate tumors with light at a wavelength 753 nm through a flexible ureteroscope. A light dose escalation model was employed with increasing light fluence from 100mW/cm up to a maximally tolerated dose of 200mW/cm. The primary endpoint was the determination of maximally tolerated laser light fluence rate, with the secondary objective to evaluate treatment efficacy defined by absence of visible tumor and negative urine cytology following treatment. Results: Among 14 treated patients, complete response and tumor recurrence rates at 30 days after treatment were 64% and 29%, respectively. A second VTP treatment was performed in 6 (43%) patients. The efficacy rates were comparable among patients who received the intermediate and highest light fluence and between the first and second treatment. At the last follow-up (mean: 11.5 months), 13 patients (93%) had maintained their affected kidney and renal function was not significantly affected. Graded adverse events related to treatment were rigorously evaluated prospectively as the primary endpoint of the trial to be reported separately in detail. Treatment related toxicities were limited, and no ureteral strictures were identified with the procedure. No evidence of increased toxicity was identified among patients who received a second VTP treatment. Conclusions: WST11-VTP shows promising evidence of therapeutic treatment effect in low- and high-grade upper tract urothelial tumors with limited treatment related toxicity. These early results provide support for further investigation to evaluate the curative potential for this therapy in a planned multicenter trial. Clinical trial information: NCT03617003.