This is a safety, feasibility and pharmacokinetic phase II study to evaluate treatment with ModraDoc006/r (oral docetaxel with ritonavir) in chemotherapy naïve patients with castration-resistant metastatic prostate cancer for whom treatment with intravenous docetaxel is indicated. The primary objective of this study is to determine the recommended dose determined as the maximum tolerated dose (MTD) of docetaxel (as ModraDoc006 10 mg tablets) that can safely be administered in combination with ritonavir to patients with metastatic castration-resistant prostate cancer in a bi-daily weekly schedule without interruption and results in an adequate systemic exposure to docetaxel. On a predefined day of the first and every subsequent week, the patient will receive oral docetaxel (as ModraDoc006 10 mg tablets). This regime will be continued weekly (intake around the same time) until completion of the study, progressive disease or until adverse events, which require dose modification or discontinuation of therapy, are observed.~A dose escalation design will be used to determine the recommended dose of ModraDoc006 in combination with ritonavir that is safe and feasible and provides an adequate systemic docetaxel exposure in the target population of the projected pivotal study in patients with CRPC. Three castration-resistant metastatic prostate cancer (CRPC) patients will be assigned to the starting dose level 1A of 30-20 mg ModraDoc006 in a bi-daily weekly schedule, each intake of ModraDoc006 will be combined with 200 mg ritonavir. If no more than one DLT has occurred during the first four weeks of treatment on dose level 1A (30-20 mg ModraDoc006 and bi-daily ritonavir 200 mg) and the pharmacokinetic results are favorable, than three additional patients will be added to this dose level. If no more than 1 DLT in these first 6 patients has occurred, this will be the recommended dose and this dose level will be expanded until a total of 20 for toxicity evaluable patients have been treated on this dose level.~If 2 DLTs have occurred directly in the first 3 patients or in the first 6 patients (after the previous described addition of 3 patients), during the first four weeks of treatment on dose level 1A (30-20 mg ModraDoc006 and bi-daily 200 mg ritonavir) and the pharmacokinetic results are favorable, the dose may be de-escalated to the next lower dose-level, depending on the pharmacokinetic results and the study schedule will start again from the beginning.~If no more than one DLT has occurred in the first 6 patients during the first four weeks of treatment on dose level 1A and the pharmacokinetic results are not favorable, than the dose will be escalated depending on the pharmacokinetic results and the study schedule will start again from the beginning.~If two or more DLTs have occurred in the first 6 patients during the first four weeks of treatment on dose level 1A and the pharmacokinetic results are not favorable, the dose will be altered according to the type of DLT.
This is a safety, feasibility and pharmacokinetic study to confirm that the recommended safe dose and schedule of ModraDoc006/r (oral docetaxel with ritonavir) as determined in a previous phase I study is also safe and feasible in the target population of patients with CRPC.