A Drug-Drug Interaction Study On The Combination Of Cabazitaxel With Enzalutamide In Patients With Metastatic Castration-Resistant Prostate Cancer.

188Background: Cabazitaxel and enzalutamide are effective single agent treatment options for metastatic castration resistant prostate cancer (mCRPC). Preclinical studies suggest enhanced efficacy of the combination of a taxane with enzalutamide. Recently, Morris et al. (CCR 2016) reported on an interaction study between docetaxel and enzalutamide: docetaxel mean exposure decreased by 12% during a short period of co-treatment with enzalutamide, probably due to enzyme (CYP3A4) induction. Since cabazitaxel is a CYP3A4 substrate, we investigated the influence of enzalutamide on cabazitaxel pharmacokinetics (PK) and toxicity during 3 chemotherapy cycles. Methods: We performed a cross-over study in 14 evaluable mCRPC patients who were treated with i.v. cabazitaxel Q3W (25 mg/m2). PK-sampling (over 24h) was conducted on day 1 of each cycle during 3 consecutive cabazitaxel cycles. From day 8 (±1) of the first cycle until day 8 (±1) of the third cycle, enzalutamide (160 mg/day) was administered concomitantly. Prim...