Search

Dacomitinib (PF-00299804) is a small-molecule inhibitor of the tyrosine kinases human epidermal growth factor receptor-1 (HER1; epidermal growth factor receptor, EGFR), HER2, and HER4 currently being developed for the treatment of lung cancer with sensitizing mutations in EGFR or refractory to EGFR-directed treatment. Dacomitinib is largely metabolized by the liver through oxidative and conjugative metabolism; therefore, determination of the impact of varying degrees of hepatic impairment on the pharmacokinetics (PK) of dacomitinib was warranted to ensure patient safety. In this phase I, open-label, parallel-group study, a single dose of dacomitinib was administered to healthy volunteers and to subjects with mild or moderate liver dysfunction, as determined by Child-Pugh classification. The primary goal of this study was to evaluate the effects of mild and moderate hepatic impairment on the single-dose PK profile of dacomitinib, as well as to assess the safety and tolerability in these subjects. Plasma protein binding and impact of hepatic function on the PK of the active metabolite PF-05199265 was also investigated. Twenty-five male subjects received dacomitinib 30 mg, with 8 subjects in the healthy- and mild-impairment cohorts and 9 subjects in the moderate-impairment cohort. Compared with healthy volunteers, there was no significant change in dacomitinib exposure in subjects with mild or moderate liver dysfunction and no observed alteration in plasma protein binding. No serious treatment-related adverse events were reported in any group, and dacomitinib was well tolerated. A dose adjustment does not appear necessary when administering dacomitinib to patients with mild or moderate hepatic impairment. [ABSTRACT FROM AUTHOR]

Crizotinib (Xalkori®) is an orally administered, selective, small-molecule, ATP-competitive inhibitor of the anaplastic lymphoma kinase (ALK) and mesenchymal epithelial transition factor/hepatocyte growth factor receptor tyrosine kinases, and has recently been approved for the treatment of ALK-positive non-small cell lung cancer. The absolute bioavailability of crizotinib, effect of a high-fat meal on crizotinib pharmacokinetics (PK), and bioequivalence of several oral formulations (powder in capsule [PIC], immediate-release tablet [IRT], and commercial formulated capsule [FC]) were evaluated in two phase I clinical studies involving healthy volunteers who received single doses of crizotinib. PK parameters for crizotinib and its metabolite, PF-06260182, were determined using non-compartmental methods. The absolute oral bioavailability of crizotinib was approximately 43%, with a slight decrease in crizotinib exposures (area under the plasma concentration-time profile and maximum plasma concentration) following a high-fat meal that was not considered clinically meaningful. The FC was bioequivalent to the clinical development IRT and PIC formulations. No serious adverse events were observed during either study and the majority of adverse events were mild, the most common being diarrhea. Single-dose crizotinib could be safely administered to healthy subjects. [ABSTRACT FROM AUTHOR]

Dacomitinib is currently in development for the treatment of non-small cell lung cancer. Formation of the major circulating metabolite (PF-05199265) is mediated by cytochrome P450 (CYP) 2D6 and CYP2C9. This phase I, single fixed-sequence, two-period study evaluated the effect of paroxetine, a CYP2D6 inactivator, on dacomitinib pharmacokinetics in healthy volunteers who were extensive CYP2D6 metabolizers. Subjects received a single 45-mg dacomitinib dose alone and in combination with paroxetine (30 mg/day for 10 consecutive days, with dacomitinib administered on day 4) at steady-state levels. Blood samples were collected through 240 hours post-dacomitinib dosing. Dacomitinib exposure (area under the concentration-time curve from 0 to infinity; AUCinf) increased 37%; however a reduction in PF-05199265 AUCinf of approximately 90% was observed during the paroxetine treatment period. The maximum concentration of dacomitinib changed minimally. Adverse events reported with single-dose dacomitinib administered alone or in the presence of steady-state levels of paroxetine were mostly mild, and no serious adverse events were reported. While paroxetine significantly inhibited CYP2D6-mediated metabolism of a single dose of dacomitinib, the modest effect on dacomitinib exposure is unlikely to be clinically relevant when dacomitinib is given daily. Dose adjustment of dacomitinib may therefore not be required upon coadministration with a CYP2D6 inhibitor. [ABSTRACT FROM AUTHOR]