ESTRO 2020 Abstract book

S1059 ESTRO 2020

be achieved at different times during the RT treatment according to the number of fractions the dose/fraction and type of radiation.

Results Irradiated mice treated with PM014 showed a significant improvement in collagen deposition, normal lung volume, and functional lung parameters, and these therapeutic effects were better than those of amifostine. PM104 reduced fibrosis in an irradiated orthotopic mouse lung tumor model and increased the efficacy of the radiation therapy. PM014 attenuated the activation of the NF-kB promoter and the nuclear translocation of NF-kB induced by IR. These results suggest that inhibition of NF-kB activation by PM014 leads to reduced expression of downstream molecules, thereby inhibiting epithelial- mesenchymal transition progression. PM014 also inhibited radiation-induced p65 translocation, ROS production, and DNA damage. Conclusion Our results suggest that PM014 may be effectively and safely used as a therapeutic drug for use in combination with radiotherapy to treat lung cancer and could also act as a radioprotector for lung tissue by attenuating pneumonitis and fibrosis. * This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea PO‐1806 Early radio‐induced bladder wall thickening in rats: optimizing the methodology and first evidences A. Spinelli 1 , A. Bresolin 2 , S. Zuppone 3 , G. Fallara 3 , R. Vago 3 , C. Fiorino 2 , C. Cozzarini 4 1 San Raffaele Scientific Institute, Experimental Imaging Centre, Milano, Italy ; 2 San Raffaele Scientific Institute, Medical Physics, Milan, Italy ; 3 San Raffaele Scientific Institute, Urological Research Institute, Milan, Italy ; 4 San Raffaele Scientific Institute, Radiation Oncology, Milan, Italy Purpose or Objective The main goal of this work is to present a non-invasive imaging method based on ultrasounds (US) to investigate radiation induced changes of bladder wall thickness (BWT) using a rat model. First step consisted in the assessment of the relationship between BWT and bladder filling in order to assess the best filling conditions for reproducible measurements. The approach was then applied to irradiated rats to quantify this effect early after irradiation. Material and Methods Three groups of three female Fischer rats were treated with a single radiation dose of 25, 30 and 35 Gy respectively, using a micro-irradiator (X-RAD SmART) with micro-CBCT guidance. The radiation beam was conveyed to the bladder by a 3-fields overlap as delineated on micro- CT. 3D and longitudinal scans (Vevo 2100) were acquired at different bladder fullness conditions before and 4 days after radiation. Empty, half-filled and full-filled bladder volumes were determined for four not-irradiated rats of the sample by measuring transverse and longitudinal bladder axes from 3D US image and applying the ellipsoid volume formula. Mean BWT was estimated for both ventral and dorsal bladder sides throughout the measurement of the bladder wall area along a segment of 4-mm in the central longitudinal scan for the different filling conditions; similarly, the area inside bladder was measured in order to estimate the mean diameter of the organ. This procedure was intended to minimize the dependence on contour delineation and on vessels that locally thickened the wall. Mean BWT against volume and mean diameter were plotted and fitted. Mean BWT and diameter were quantified to highlight a possible bladder wall thickening due to acute radiation effects. Image analysis was performed using ImageJ. Results government. (NRF-2017M2A2A7A02019612, 2017R1D1A1B03027881, 2019R1A2C2086448)

Conclusion The study represents a first step towards the challenging objective of understanding, and describing in a mechanistic way the effect of radiation on the vascular microenvironment. The code is already able to model a realistic 3D network. Shift to 3D network will be performed after the tuning of the parameters which will be accomplished through in vitro (microfluidic chip) and in vivo (sublingual microscope in head&neck cancer patients) measurements. Simulations can be also extended to deal with an already impaired vasculature (e.g. hypertension, smoke, diabetes). PO‐1805 PM014 improves radiotherapy in an orthotopic lung cancer mouse model by alleviating fibrosis S. Park 1 , J. Kim 1 , J. Kim 1 , J. Cho 1 1 Yonsei Cancer Center- Yonsei University College of Medicine, Department of Radiation Oncology, Seoul, Korea Republic of Purpose or Objective Radiation therapy is the mainstay in the treatment of lung cancer, and lung fibrosis is a radiotherapy-related major side effect that seriously reduces patient’s quality of life. Nevertheless, effective strategies for protecting against radiation therapy-induced fibrosis have not been developed. Hence, we investigated the radioprotective effects and the underlying mechanism of the standardized herbal extract PM014 on radiation-induced lung fibrosis Material and Methods A radiation dose of 75 Gy was focally delivered to the left lung of mice for 6 weeks. We evaluated the effects of PM014 on radiation-induced lung fibrosis in vivo and in an in vitro cell model. Lung volume and functional changes were evaluated using the Micro-CT and Flexivent system. Fibrosis-related molecules were evaluated by immunohistochemistry, western blot, and real-time PCR. A orthotopic lung tumor mouse model was established using LLC1 cells. This abs ract has b en withdrawn