Purpose: To evaluate a mitotic inhibitor, ON01910.Na, as a potential chemotherapeutic agent for brain tumors using a series of PK/PD studies, which led to the evaluation of its structural analog, ON013105, a prodrug of the more lipophilic product, ON013100.
Methods: Systemic PK characterization of ON01910 and ON013105 was completed in healthy mice. Using an orthotopic U87 glioma mouse model, brain and brain tumor distribution under steady-state conditions were evaluated for ON01910.Na and ON013105/ON013100; anticancer potential following a multiple-dose schedule of 250 mg/kg/day IP for 7 days was evaluated for ON01910.Na.
Results: ON01910 exhibited low brain and brain tumor distribution with quasi-steady-state brain/plasma (Css(brain)/Css(plasma)) and brain tumor/plasma (Css(brain tumor)/Css(plasma)) concentration ratios of 0.03 ± 0.02 and 0.14 ± 0.08, respectively. Significant antiangiogenic potential and antiproliferative capacity of ON01910 in the intracerebral model was absent. ON013100 showed high brain and brain tumor penetration with Css(brain)/Css(plasma) and Css(brain tumor)/Css(plasma) ratios of 0.92 ± 0.26 and 1.35 ± 0.40, respectively; its prodrug ON013105 showed negligible brain and brain tumor penetration.
Conclusions: ON013105, not ON01910.Na, was identified as a potential anticancer drug candidate for further investigation in brain tumor chemotherapy based on the properties of ON013100.