Pharmacokinetics (PK) of PF-562271, a focal adhesion kinase (FAK) inhibitor, and its effect on CYP3A in patients with advanced nonhematologic malignancies.

Abstract

2553 Background: FAK transduces signaling from integrins and growth factors to modulate tumor cell invasion, proliferation, and survival. PF-562271, a potent FAK inhibitor, is under development as an anticancer agent. Preclinical studies demonstrated that PF-562271 is an inhibitor of its primary metabolizing enzyme, CYP3A. PF-562271 PK and its effect on CYP3A were investigated in a dose-escalation trial in patients with nonhematologic malignancies. Methods: Escalating doses of PF-562271 were administered orally to a total of 67 patients twice a day (BID) or once a day (QD), with or without food. Serial serum samples were collected after the first dose and at steady state to determine PK of PF-562271. To evaluate the effect of PF-562271 on CYP3A activity, plasma PK of orally administered midazolam were determined prior to PF-562271 administration and after repeated PF-562271 dosing to steady state in 8 patients who received the recommended phase 2 dose of 125 mg BID. Serum PF-562271 and plasma midazolam concentrations were determined using validated HPLC-MS/MS methods. The concentration-time data for PF-562271 and midazolam were analyzed by noncompartmental methods. Results: After a single oral dose, PF-562271 was readily absorbed with the maximum serum concentration achieved in 0.5 to 6 hours. The increases in systemic exposure (AUCinf) were dose proportional over the 5 to 25 mg range, but greater than dose proportional from 35 to 225 mg. After multiple oral doses, PF-562271 demonstrated nonlinear accumulation in exposure; the mean ratio of steady state AUC during a dose interval to AUCinf after the first dose ranged from 1.3 to 5.3, indicating time-dependent PK. Similar PK parameters for PF-562271 were observed at comparable doses given with or without food. When co-administered, PF-562271 (125 mg BID) increased total midazolam plasma exposure approximately 5.9-fold. Conclusions: PF-562271 displayed time- and dose-dependent nonlinear PK, and is a potent CYP3A inhibitor. The nonlinear PK of PF-562271 likely resulted from auto-inhibition of CYP3A. In the limited number of subjects evaluated, food did not substantially alter the PK of PF-562271. Author Disclosure Employment or Leadership Position Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Pfizer Pfizer