Characterization of the cellular mechanisms of radiation induced brain necrosis for clinical intervention

Project Summary/Abstract Cure rates for childhood cancers have improved. Unfortunately, many survivors now live with life-long side effects from treatment itself. Radiation therapy, used for brain tumors, is particularly damaging. The most serious side effect is necrosis which can result in weakness, paralysis or even death. Proton therapy is an increasingly popular radiation modality. Proton therapy reduces exposure to normal tissues and the reby may decrease the incidence of cognitive deficits following radiation. However, recent studies, including our own suggest that certain areas of proton beams may be more damaging to brain tissue than others potentially leading to higher rates of necrosis. Here we will develop high accuracy models to correlate necrosis with the physical parameters of proton beams. These models will include multi-cell type human brain “organoids” as well as rodent animal models. Using these models as well as clinical data, we will identify the physical factors of proton therapy which may lead to necrosis. This is significant in that this data may be used to design safer proton therapy treatments in which the most biologically effective portions of beams are solely placed within the tumor. This should reduce necrosis and improve disease control. In a second component of our study, we will examine the molecular mechanisms of necrosis. Rather than being simple dis-organized death, we will determine if radiation induces an orderly programmed cell death pathway. We will conduct the following aims; (1) relate the physical factors of proton beams with biological response, (2) explore the cellular and molecular mechanisms of radiation induced brain damage and (3) validate the clinical consequences of variability in the effectiveness of proton beams. The knowledge gained will quickly influence the treatment of brain tumor patients and expedite the clinical introduction of agents and approaches to combat the negative effects of radiation on the brain.