The clinical appropriateness of co-prescribing these medications has not been assessed. Coadministration has not been studied but based on metabolism and clearance a clinically significant pharmacokinetic interaction is unlikely. Apalutamide is metabolized by CYP2C8 and CYP3A4 and is a strong inducer of CYP3A4. Lenvatinib does not inhibit or induce CYPs or UGTs. Concentrations of lenvatinib may slightly decrease due to induction of CYP3A4 and P-gp. After coadministration with rifampicin, a strong CYP3A4 and P-gp inducer, lenvatinib AUC decreased by 18%. A similar effect may occur after coadministration with apalutamide. Therefore, no clinically relevant effect on lenvatinib exposure is expected. However, androgen deprivation treatment may prolong the QT interval.  Thus, if apalutamide is coadministered with lenvatinib, an additive or synergistic effect on QT-prolongation cannot be excluded. If coadministration is necessary, clinical monitoring including ECG assessment is recommended. Lenvatinib should be withheld in the event of a QT interval >500 ms and resumed at a reduced dose when QT-prolongation is <480 ms.