A drug-drug interaction study to assess the effect of the CYP1A2 inhibitor fluvoxamine on the pharmacokinetics of dovitinib (TKI258) in patients with advanced solid tumors.

Purpose: Dovitinib is an orally available multi tyrosine kinase inhibitor which inhibits VEGFR 1-3, FGFR 1-3, and PDGFR. This study was performed to investigate the potential drug-drug interaction of dovitinib with the CYP1A2 inhibitor fluvoxamine in patients with advanced solid tumors.
Methods: Non-smoking patients of ≥ 18 years with advanced solid tumors, excluding breast cancer, were included. Patients were treated with a dose of 300 mg in 5 days on/2 days off schedule. Steady-state pharmacokinetic assessments of dovitinib were performed with or without fluvoxamine.
Results: Forty-five patients were enrolled; 24 were evaluable for drug-drug interaction assessment. Median age was 60 years (range 30-85). At steady state the geometric mean for dovitinib (coefficient of variation%) of the area under the plasma concentration-time curve (AUC _0-72h ) and maximum concentration (C _max ) were 2880 ng/mL h (47%) and 144 ng/mL (41%), respectively. Following administration of dovitinib in combination with fluvoxamine the geometric mean of dovitinib AUC _0-72h and C _max were 8290 ng/mL h (60%) and 259 ng/mL (45%), respectively. The estimated geometric mean ratios for dovitinib AUC _0-72h and C _max (dovitinib + fluvoxamine vs. dovitinib alone) were 2.88 [90% confidence interval (CI) 2.58, 3.20] and 1.80 (90% CI 1.66, 1.95). This effect is considered a moderate drug-drug interaction.
Conclusions: Fluvoxamine co-administration resulted in a 80% increase in C _max and a 188% increase in AUC _0-72h of dovitinib. Given the increase in exposure to dovitinib observed, patients are at risk of dovitinib related toxicity. Dovitinib should, therefore, not be co-administered with moderate and strong CYP1A2 inhibitors, without dose reduction.