Phase IIb trial of oral ModraDoc006/r as a tolerable and effective option in comparison with intravenous docetaxel in metastatic castration-resistant prostate cancer (mCRPC).
Authors: Ulka N. Vaishampayan, Marianne Keessen, Neal D. Shore, Elisabeth I. Heath, Robert Dreicer, Tomas Buchler, Péter Ferenc Árkosy, Tibor Csőszi, Pawel Wiechno, Evgeny Kopyltsov, Denis Kholtobin, Aleander Nosov, Sergei Varlamov, Nicholas J. Vogelzang
Journal: Journal of Clinical Oncology (2021)

132 Background: ModraDoc006 is a novel, oral tablet formulation of docetaxel. To enhance bioavailability, it is co-administered with ritonavir (r), an inhibitor of cytochrome P450 3A4 and P-glycoprotein. The oral combination, denoted ModraDoc006/r, has potential advantages in terms of patient convenience, elimination of infusion-related reactions and avoiding prophylactic steroid administration, as well as safety benefits. Safety and preliminary efficacy of ModraDoc006/r in mCRPC were established in a prior phase Ib trial. Methods: This is an open label 1:1 randomized phase IIb trial of ModraDoc006/r bi-daily once weekly (BIDW) regimen versus IV docetaxel 75 mg/m2 q day 21. Initially, BIDW 30-20 mg ModraDoc006 combined with 200-100 mg ritonavir was administered on days 1, 8 and 15 of a 21-day cycle. After 39 patients, the dose of ModraDoc006 was reduced to 20-20 mg BIDW to improve GI tolerability. All patients received 5 mg oral prednisone BID. Imaging is obtained every 8-9 weeks for the first 24 weeks, every 12 weeks thereafter. Initially mCRPC patients with RECIST 1.1 measurable disease were eligible; this was amended to evaluable disease per Prostate Cancer Working Group 3 (PCWG3) to allow for wider recruitment. No prior taxane therapy is allowed. The primary efficacy endpoint is radiographic progression free survival (rPFS) per PCWG3 criteria. Secondary objectives include objective response rate, PSA-PFS, time to skeletal related events, disease control rate, duration of response and safety. Patient reported outcomes, QoL and FACT-P questionnaires are assessed. It is expected that ModraDoc006/r will be as effective as IV docetaxel. A sample size of approximately 50 evaluable patients per arm will provide a point estimate of the primary endpoint of rPFS for this study. Results: At the data cut-off of 30 Nov 2020, 90 patients were enrolled in US and EU: 44 patients had been randomized to IV docetaxel and 46 to ModraDoc006/r, with 58 patients currently on treatment. Preliminary PSA response rates and rPFS were noted to be comparable in both treatment arms. ModraDoc006/r was mainly associated with mild and reversible GI-toxicity, of which grade and incidence were reduced at 20-20 mg compared to the initial dose-level of 30-20 mg ModraDoc006. Myelosuppression and neurotoxicity were low to negligible in the ModraDoc006/r arm, with low accompanying levels of alopecia. Conclusions: Adverse events of cytopenias and alopecia were lower with ModraDoc006/r, and preliminary efficacy appears comparable in both arms. Oral chemotherapy option has become critically important during the COVID-19 pandemic. Preliminary data reveals that ModraDoc006/r is an attractive oral option in mCRPC with favorable toxicity profile and comparable efficacy. Clinical trial information: NCT04028388.