Single- and multiple-dose pharmacokinetics, potential for CYP3A inhibition, and food effect in patients with cancer and healthy subjects receiving ipatasertib.

Purpose: To examine the single- and multiple-dose pharmacokinetics (PK), CYP3A inhibition potential of ipatasertib, and effect of food on PK of ipatasertib in patients with refractory solid tumors and a dedicated food effect assessment in healthy subjects.

Methods: The Phase I dose-escalation study enrolled patients with solid tumors in a standard 3 + 3 design with a 1 week washout after the first dose, followed by once-daily dosing on a 3-week-on/1-week-off schedule. In the expansion cohort, the effect of ipatasertib on CYP3A substrate (midazolam) was assessed by examining the change in midazolam exposure when dosed in the absence and presence of steady-state ipatasertib at 600 mg. The effect of food on ipatasertib PK was studied with ipatasertib administered in fed or fasted state (6 patients from Phase I patient study and 18 healthy subjects from the dedicated food effect study).

Results: Ipatasertib was generally well tolerated at doses up to 600 mg given daily for 21 days. Ipatasertib showed rapid absorption (t, 0.5-3 h), was dose-proportional over a range of 200-800 mg, had a median half-life (range) of 45.0 h (27.8-66.9 h), and had approximately two-fold accumulation following once-daily dosing. Midazolam exposure (AUC) increased by 2.2-fold in the presence of ipatasertib. PK was comparable in subjects administered ipatasertib in a fed or fasted state.

Conclusion: Ipatasertib exhibited rapid absorption and was dose-proportional over a broad dose range. Ipatasertib appeared to be a moderate CYP3A inhibitor when administered at 600 mg and could be administered with or without food in clinical studies.

Trail Registration: NCT01090960 (registered March 23, 2010); NCT02536391 (registered August 31, 2015).