Pharmacokinetics of vandetanib in subjects with renal or hepatic impairment

Abstract

Background and objective: Vandetanib, an oncology drug being evaluated in phase III clinical trials, undergoes significant renal and hepatic excretion. The objective of these two studies was to investigate the single-dose pharmacokinetics of vandetanib in subjects with renal or hepatic impairment in comparison with healthy subjects.

Subjects and methods: Two open-label, parallel-group studies were conducted at a single centre in Germany. Subjects aged 18-75 years with a body mass index of 18-32 kg/m2 were eligible. The renal impairment study recruited subjects with normal renal function and mild, moderate and severe renal impairment according to creatinine clearance calculated from a 24-hour urine collection pre-dose. The hepatic impairment study recruited subjects with normal hepatic function and mild, moderate and severe hepatic impairment according to the Child-Pugh classification. All subjects received a single 800 mg oral vandetanib dose. Blood samples for measurement of vandetanib, N-desmethylvandetanib and vandetanib N-oxide were collected before and at various timepoints after vandetanib administration for up to 63 days. Pharmacokinetic parameters were determined using noncompartmental methods.

Results: Thirty-two subjects were recruited for the renal impairment study (ten with normal renal function and six, ten and six with mild, moderate and severe impairment, respectively). Thirty subjects were recruited for the hepatic impairment study (eight with normal hepatic function and eight, eight and six with mild, moderate and severe impairment, respectively). The area under the plasma concentration-time curve from time zero to infinity (AUC(infinity)) values of free vandetanib increased by approximately 46%, 62% and 79% in subjects with mild, moderate and severe renal impairment, respectively. These increases were statistically significant, with the increase in the severe renal impairment group having the possibility of being double the value observed in subjects with normal renal function (geometric least squares [GLS] mean ratio [renal impairment : normal renal function] of 1.79; 90% CI 1.39, 2.31). Peak plasma concentrations of free vandetanib increased slightly by approximately 7%, 9% and 11% in subjects with mild, moderate and severe renal impairment, respectively. Total plasma clearance of free vandetanib decreased with all degrees of renal dysfunction. Hepatic impairment did not have a statistically significant effect on the AUC(infinity) of total vandetanib. Peak plasma concentrations of total vandetanib were reduced in subjects with all classifications of hepatic impairment compared with normal hepatic function, with a statistically significant effect in the severe hepatic impairment group (GLS mean ratio 0.71; 90% CI 0.53, 0.96). Increased exposure to both metabolites was seen in subjects with renal impairment. Exposure to N-desmethylvandetanib was reduced in subjects with hepatic impairment, while exposure to vandetanib N-oxide was increased in subjects with severe hepatic impairment. Vandetanib was well tolerated and had a similar tolerability profile in subjects with renal or hepatic impairment compared with healthy subjects.

Conclusion: Exposure to vandetanib was increased by about 46%, 62% and 79% in subjects with mild, moderate and severe renal impairment, respectively. A doubling in exposure could be ruled out in subjects with mild or moderate renal impairment but not for those with severe renal impairment. The possibility of dose reductions in patients with severe renal impairment will need to be assessed when the safety and tolerability profile is fully defined. Exposure to vandetanib was not altered in subjects with hepatic impairment, and no dose adjustment would be expected in patients with hepatic impairment.