Relative Bioavailability of Dordaviprone (ONC201) is Not Affected by Co‐Administration of the Proton‐Pump Inhibitor Rabeprazole

Abstract Dordaviprone (ONC201) is a novel, orally administered, anti‐cancer, small molecule imipridone with demonstrated antitumor effects in patients with glioma. Dordaviprone in vitro solubility is significantly reduced at pH >4.5. Concomitant use of acid reducing agents (ARAs) may therefore impact dordaviprone solubility and bioavailability. This open‐label, single‐sequence, three‐period crossover study evaluated the effect of proton‐pump inhibitor rabeprazole on dordaviprone pharmacokinetics (PK). Periods were consecutive and comprised of period 1 (days 1–3), period 2 (days 4–9), and period 3 (days 10–13). In period 1, participants received a single oral 625 mg dose of dordaviprone on day 1. In period 2, participants received six consecutive days of QD 20 mg rabeprazole alone. In period 3, patients received one oral dose of 20 mg rabeprazole (the seventh consecutive daily dose), followed 2 h later by a single 625 mg dordaviprone oral dose. PK blood samples were collected and analyzed from pre‐dose 72 h following dordaviprone administration in periods 1 and 3. Dordaviprone exposure PK parameters were similar following administration of dordaviprone alone or with rabeprazole. Geometric mean ratios and 90% CIs for dordaviprone exposure parameters with and without rabeprazole following dordaviprone administration fell within bioequivalence limits of 80.00%–125.00% for Cmax (97.19% [86.43–109.28]), AUClast (102.21% [95.19–109.75]), and AUCinf (102.27% [95.21–109.86]), indicating no effect of multiple oral doses of rabeprazole on dordaviprone relative bioavailability. Six of the 16 participants reported treatment‐emergent adverse events (TEAEs); dordaviprone‐related TEAEs were reported by three participants and were limited to mild nausea and dizziness. No dordaviprone dose adjustment or ARA treatment modification is warranted.