LAUSR

2059Background: ONC201 is a DRD2 antagonist in Phase II trials for cancers that exhibit dysregulation of the dopamine pathway. We previously reported an objective response in the first recurrent H3 K27M midline glioma patient who received ONC201 and that H3 K27M gliomas exhibit enhanced sensitivity to the compound in vitro. Here, we report the clinical experience with ONC201 to date in adult and pediatric H3 K27M glioma. Methods: As of February 1, 2018, 14 patients with H3 K27M glioma have received single agent ONC201 and had at least one post-treatment MRI. This includes 9 adult patients (8 glioblastoma, 1 diffuse midline glioma) and 5 pediatric patients (3 DIPG, 2 other diffuse midline gliomas). All patients had recurrent disease, except for 2 DIPG patients who had completed radiotherapy. Seven patients were enrolled on a clinical trial and seven were enrolled on compassionate use protocols. ONC201 was orally administered at 625 mg to adult patients and scaled based on body weight for pediatric patients...