Search

Diffuse intrinsic pontine glioma (DIPG) is a group of predominantly pediatric brain tumors with an average age of diagnosis of 6–7 years old, and a poor prognosis (median survival of ~1 year). Given the location of DIPG in the brainstem, surgical approaches are limited. Furthermore, the tumors have limited responsivity to traditional chemotherapy or radiotherapy, ergo new therapeutic options are needed. Recently, the drug ONC201 has emerged as a potential therapeutic option with outcomes sometimes surpassing progression-free and expected survival outcomes. However, the selectivity of its effect and mechanism in DIPG is still unclear. Here, we pursue a better understanding of ONC201 and its mechanism of action directly in DIPG patient-derived cell lines. First, we demonstrate that a range of DIPG cell lines are highly sensitive to ONC201 and compare this sensitivity to other patient-derived brain tumor and normal controls. Next, we directly show that the mitochondrial protease, ClpP is the primary target of ONC201 in DIPG. Given recent literature implicating the activation of ClpP by ONC201 and dysregulation of the metabolome in other tumors, we are currently examining these downstream effects in DIPG. Ultimately we hope to elucidate whether ClpP targeting can be used to better diagnose and improve therapeutic options in DIPG

Emerging evidence from clinical and preclinical studies suggests that the imipridone ONC201 is well tolerated and may have some clinical impact in discrete diffuse intrinsic pontine glioma patients (DIPG). A primary goal of our work is to determine if DIPG are uniquely sensitive to ONC201 and if so, whether ONC201 itself can be used as a tool to illuminate novel vulnerabilities in DIPG. To accomplish this, we are utilizing a combination of patient-derived cell lines as well as mouse xenografts that dovetail with a variety of molecular, epigenetic and metabolomic tools. A central finding from our work is that ONC201 primarily activates the mitochondrial protease, ClpP in DIPG patient-derived cell lines, an effect consistent with recently described ONC201 mechanism of action in other tumors. We further demonstrate that activation of ClpP by ONC201 leads to a host of downstream effects in DIPG model systems including distinctive effects on the metabolome leading to direct alterations in the unique epigenetic signature of DIPG. By directly manipulating these metabolic and epigenetic factors we provide prospective mechanistic insight into how ONC201 as well as ClpP activity impacts DIPG growth and tumorigenicity. These preclinical research findings shed light on potential therapeutic vulnerabilities in DIPG as well as ways that these strategies may be combined to enhance their potential.