ESTRO 2024 - Abstract Book

S5336

Radiobiology - Tumour biology

ESTRO 2024

Conclusion:

Our results show that MYC inhibition impacts cell cycle distribution and cell survival and that MYC inhibition has a radiosensitizing effect on murine PDAC cells. Targeting MYC might provide a further potential treatment strategy for patients with radioresistant PDAC in the future.

Keywords: c-myc, radiosensitization, PDAC

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Cell survival in a helium SOBP irradiation: Monte Carlo prediction compared with experimental data

Thomas Berger 1 , Gersende Alphonse 1,2 , Caterina Monini 1 , Charbel Koumeir 3 , Flavien Ralite 3 , Noel Servagent 3 , Vincent Métivier 3 , Ferid Haddad 3 , Alexis Pereda 4 , Lydia Maigne 4 , Étienne Testa 1 , Michaël Beuve 1 1 Institut de Physique des 2 Infinis de Lyon, Université Claude Bernard Lyon 1, Lyon, France. 2 Radiobiologie Cellulaire et Moléculaire, Faculté de Médecine Lyon-Sud, Oullins, France. 3 Laboratoire SUBATECH, UMR 6457 CNRS-IN2P3, Nantes, France. 4 Laboratoire de Physique de Clermont, Université Clermont Auvergne, Aubière, France

Purpose/Objective:

While proton- and carbon-ion- therapy are the two hadron-therapy modalities employed clinically, helium-ion therapy has recently gained traction as helium ions represent a balanced compromise between protons and carbon ions.

Having an accurate relative biological effectiveness (RBE) estimation is key to precise treatment planning and is currently performed for heavy ions using the LEM and mMKM radiobiological models as they are incorporated in Treatment Planning Systems currently in clinical use. Recently an alternative model was developed which takes into account the stochastic nature of energy deposition at both the nanometric and microscopic scales. In this model called NanOx for NANo-dosimetry and OXidative stress, two types of events are considered, the local lethal events caused by one track and described in terms of nano-dosimetry, and the global events resulting from combined deleterious effects from several tracks and attributed to sublethal damage and oxidative stress. Experimental data indicates that NanOx accurately predicts survival curves as shown by Monini et al (2019 PhIRO) for three cell lines irradiated by monoenergetic ions from five different species. In hadron-therapy, homogeneous dose in the target region is achieved by combining pristine Bragg peaks to form a spread-out Bragg peak (SOBP). While irradiated tissue in all positions of this SOBP is exposed to mixed radiation field, most experiments that quantify the RBE consist in the in vitro irradiation of cells with monoenergetic beams and are therefore not carried out using mixed fields.