Speaker
Description
Particle minibeam radiation therapy (PMBT) is a novel therapeutic approach offering great promise for
the treatment of radioresistant tumors based on the spatial fractionation of the dose and the combination
with particle therapy. PMBT offers a high dose modulation consisting of high doses (peaks) deposited in
the paths of millimetric planar beams and low doses (valleys) in the rest of the tissue. As a result, PMBT
has demonstrated in several preclinical experiments to lead to remarkable normal tissue sparing, while
experiments with proton minibeams (pMBRT) showed a superior tumor control compared to conventional
proton therapy.
This distinct dose delivery method suggests a differential radiobiological effect in the targeted tissue
underlying the tumor killing capacity and normal tissue sparing associated to this technique, based on
bystander cell communication, vascular sparing, and immune response. Indeed, the pivotal role of the
immune system in the anti-tumor response of X-ray minibeam radiation therapy was recently shown,
centered on T and B cells from the adaptive immunity system that conferred long-term anti-tumor
immunity to the cancerous cells [1]. The advances in single cell analysis and next-generation sequencing
have allowed us to further understand the immunogenic role of pMBRT in a preclinical rat glioblastoma
model, and point towards a significant acute inflammatory response in the tumor via specific signaling
pathways. During this talk, we will discuss the latest evidence in proton minibeam radiobiology and its
relationship with immune response in order to shed light on the elusive radiobiological mechanisms
underlying this innovative technique.
[1] Bertho A. & Iturri L. et al., IJROBP 2022
