ESTRO 2023 - Abstract Book

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ESTRO 2023

No enhanced RBE was observed for natural BSH exposed V79 cells when irradiated with protons. However, should nuclear reactions be the main mechanism of the previously postulated increase in RBE, then the n+10B would be the main contributor to production of high-LET particles, rather than the p+11B reaction. [1] - Cirrone et al., Sci.rep 8; 2018

PO-2228 Biodegradable nanomedicine for imaging-guided RT enhancement

C. de Faria 1 , A. Spinelli 2 , R. Vago 3 , M. Bissoli 1 , V. Amendola 1

1 University of Padua, Department of Chemical Sciences, Padua, Italy; 2 San Raffaele Scientific Institute, Experimental Imaging Centre, Milan, Italy; 3 San Raffaele Scientific Institute, Urological Research Institute, Milan, Italy Purpose or Objective This study approaches one of the challenges in cancer treatment: enhancing tumour sensitivity to radiotherapy while sparing normal tissue from its side effects using a nanosensitizer. Its innovation lies on the unique transformable features of its gold-iron composition that provide biodegradable properties while increasing tumour accumulation, in addition to acting as a contrast agent for Resonance Magnetic Imaging and Computed X-ray Tomography. The proposed nanomedicine enables more localised and precise dose deposition within tumours and greater sparing of adjacent normal tissues by image-guided radiation therapy and integration of MRI with treatment planning and its spontaneous reduction and biodegradation in the physiological environment after use allows clearance from the body on the short/medium term. Materials and Methods Nanoparticles were characterised in terms of their physico-chemical properties prior to the biological experiments. Formulations of different gold-iron proportions were tested (90/10, 25/75, 100/0) with different coatings. PC3 cell line was used as a prostate cancer model while primary fibroblasts were used as a normal cell line control. ROS experiments were performed using DCFDA assay and radiation experiments were performed using an X-rays preclinical irradiator (SmART, Precision XRay) at 225 kV, with a current of 13mA. Results Several formulations of this nanomedicine were tested in prostate cancer and normal cells (fibroblasts) in terms of toxicity, radiosensitization efficacy, ROS production and DNA damage. In Figure 1 it is shown the toxicity of NPs at 48h of incubation as well as the survival fraction relative to the control at 2 and 4 Gy for the AuFe 25/75 and Au NPs. We demonstrate that even at the highest concentration tested the toxicity of AuFe 25/75 is low in fibroblasts. Interestingly, it is higher in PC3 cancer cells, reaching about 40% at 300 ⲙ g/mL. In the clonogenic assay, we observe a dose-dependent decrease in survival for both Au and AuFe NPs, as expected, and a radiosensitization effect for the latter.

Figure 1. Toxicity of AuFe 25/75 and Au NPs at 48h of incubation in PC3 and fibroblasts (top). Relative survival from clonogenic assay in PC3 cells (bottom).