Chimerix, Inc. announced that a peer-reviewed article entitled, “Phase 2 Study of ONC201 in Neuroendocrine Tumors including Pheochromocytoma-Paraganglioma (PC-PG) and Desmoplastic Small Round Cell Tumor (DSRCT),” has been published in the journal, Clinical Cancer Research. An interim summary of select cohorts from this study was previously presented at the annual meeting of the American Society of Clinical Oncology (ASCO) in 2021. ONC201 is an orally administered small molecule dopamine receptor D2 (DRD2) antagonist and caseinolytic protease (ClpP) agonist.

This open-label Phase 2 investigator-initiated study treated 30 patients with rare neuroendocrine tumors. Paraganglioma patients were separated in to two separate cohorts of the study receiving ONC201 either once or twice weekly. A third cohort included patients with other neuroendocrine tumors, including desmoplastic small round cell tumor (DSRCT), dosed weekly with ONC201.

The primary endpoint was radiographic response as measured by RECIST criteria. In the cohort of paraganglioma patients receiving ONC201 once weekly, 50% (5/10) of patients exhibited a partial response (PR) and two additional patients had stable disease (SD) that lasted longer than three months. Five of the 10 patients in this cohort were treated longer than one year.

Among the cohort of paraganglioma patients receiving ONC201 twice weekly one PR and seven SD were observed; this cohort includes four of eight patients who crossed over from the weekly dosing cohort. The third cohort of other neuroendocrine tumors included one PR (DSRCT) and two SD (DSRCT; neuroblastoma) that lasted longer than three months. Importantly, across all cohorts there was no decline in Karnofsky Performance Status (KPS) at week 12 for 93% of patients (28/30) and no dose modification due to treatment-related adverse events.