Impact of P-gp inhibition on systemic exposure of pralsetinib and dosing considerations

A study to determine the impact of cyclosporine (Neoral), an inhibitor of P-gp, on the pharmacokinetics of pralsetinib (trade name GAVRETO®) was conducted in 15 healthy adult volunteers. A single 200 mg dose of pralsetinib was administered orally alone and in combination with cyclosporine with a 9-day washout between treatments. Co-administration with cyclosporine resulted in a clinically relevant increase in pralsetinib maximum plasma concentration (C_max) and area under the plasma concentration-time curve extrapolated to infinity (AUC_0-∞) with associated geometric mean ratios (GMRs) and 90% confidence intervals (CIs) of 148% (109, 201) and 181% (136, 241), respectively. These findings provide insight into concomitant dosing of pralsetinib with inhibitors of P-gp given the increases in pralsetinib exposure observed when administered with cyclosporine. Based on these results, co-administration of pralsetinib with P-gp inhibitors is not recommended. In the event that co-administration cannot be avoided, it is recommended that the dose of pralsetinib be reduced.