Background: Docetaxel IV and prednisone is a standard of care in mCRPC with demonstrated overall survival benefit. ModraDoc006 is a novel oral tablet formulation of docetaxel and to enhance bioavailability, it is co-administered with ritonavir (/r), an inhibitor of cytochrome p450 3A4 and P-glycoprotein. The oral combination, denoted as ModraDoc006/r, could be preferable due to patient convenience and elimination of infusion reactions and prophylactic steroids administration. Due to its weekly administration and exposure levels, increased efficacy may be demonstrated. Methods: The study is an open label 1:1 randomized phase 2b trial of ModraDoc006/r bi-daily QW versus docetaxel IV 75 mg/m² Q3W. Thirty (30) mg ModraDoc006 combined with 200 mg /r in morning and 20 mg ModraDoc006 with 100 mg /r in evening is administered on days 1, 8 and 15 of a 21 day cycle. Safety and preliminary efficacy of ModraDoc006/r have been established in a phase Ib trial in mCRPC pts. All patients will receive 5 mg oral prednisone twice daily. Treatment is continued until progression, unacceptable toxicity or patient wish. mCRPC pts with measurable disease per RECIST 1.1, suitable for docetaxel therapy, are eligible. No prior treatment with taxanes is allowed. Primary objective is objective response rate (ORR) as assessed by investigators. Secondary objectives include PSA response, PSA-PFS, time to skeletal related events and progression, duration of response, disease control rate and safety assessments. Patient reported outcomes and health-related quality of life will be captured with treatment satisfaction and FACT-P questionnaires. It is expected that ModraDoc006/r will be at least as effective as docetaxel IV. A sample size of 50 evaluable pts per arm will evaluate an estimated ORR of 25% in each arm, with a 5% two-sided alpha and power of 83.7%. Conclusions: ModraDoc006/r represents an advance in prostate cancer therapeutics with convenience of oral administration, reduced myelosuppressive toxicity and potential improved efficacy over IV docetaxel. Clinical trial information: NCT04028388