Radiation plays a central role in the management of the most lethal central nervous system malignancy, glioblastoma (GBM), yet local control rates, and hence survival, remain dismal for this disease. Even novel therapies, such as immunotherapy, have not shown efficacy in the treatment of GBM. Meanwhile, radiation dose escalation studies have demonstrated improved local control. However, dose escalated treatments are hindered by the increased incidence of radiation induced brain necrosis in surrounding tissues. High LET particle therapy holds the potential to both increase tumor cell kill and decrease normal tissue toxicity, yet the data required to develop models for clinical treatments regarding the biological effectiveness of high LET beams on normal brain tissue and GBM cells is sparse. This fact is especially true when considering results reported utilizing the appropriate environment for the origination and growth of GBM cells ? the human brain. We have implemented recently developed high accuracy models which are truly beginning to recapitulate the native GBM niche in order to correlate both necrosis induction and progression and tumor cell response with the physical parameters of particle beams. These models include multi-cell type human brain organoids (cerebral organoids) as well as immune-competent orthotopic rodent models. Using these models, we will identify the physical factors of particle beams which may lead to necrosis. This is significant in that this data will aid the design of safer treatments by reducing necrosis and improving disease control. In the second component of our study, we will examine the molecular mechanisms of necrosis and neuroinflammation. Rather than being a simple accidental, disorganized death, we will determine if radiation induces an orderly programmed cell death pathway. Overall, we will conduct the following aims; (1) identify the optimal particle and fractionation for treatment of GBM, (2) explore the cellular and molecular mechanisms of radiation induced brain damage, and (3) develop biological effect models for clinical use. The knowledge gained will quickly influence the treatment of brain tumor patients and expedite the clinical introduction heavy ion therapy for glioblastoma.
The proposed research is relevant to public health in that the discovery of novel models of radiation necrosis and glioma response are expected to transform our understanding of the effects of high LET radiation and reveal novel avenues for treatment. Thus the proposed studies are relevant to the National Cancer Institute and its mission to support research to improve cancer treatment and rehabilitation.
