Here is the design of a clinical trial:

Official Title: Regorafenib Plus FOLFIRI With Irinotecan Dose Escalated According to UGT1A1 Genotyping Versus Regorafenib Monotherapy in Patients With Previously Treated Metastatic Colorectal Cancer: A Prospective, Randomized, Controlled Study

Included conditions:
- Metastatic Colorectal Cancer

Study Armgroups:
- {'label': 'Regorafenib plus FOLFIRI', 'type': 'EXPERIMENTAL', 'description': 'Regimen for treatment consists of irinotecan (180 mg/m2 as a 120-min IV infusion for UGT1A1 genotyping (TA6/TA6) and UGT1A1 genotyping (TA6/TA7); 120 mg/m2 as a 120-min IV infusion for UGT1A1 genotyping (TA7/TA7)), followed by Leucovorin (400 mg/m2 IV infusion over 2 hours), and fluorouracil (5-FU) (2800 mg/m2 IV infusion over a 46-hour period), repeated every 2 weeks.\n\nAfter every 2 cycles of each different dose of irinotecan, if adverse events (AEs) are under the grade 2, we will escalate the dose of 30 mg/m2. The estimated maximal dose of irinotecan is 260 mg/m2 for UGT1A1 genotyping (TA6/TA6); 240 mg/m2 for UGT1A1 genotyping (TA6/TA7); 180 mg/m2 for UGT1A1 genotyping (TA7/TA7).\n\nRegorafenib is administered at adjusted dosage of 120 mg daily for 3 weeks in a 4-week cycle.', 'interventionNames': ['Drug: Regorafenib', 'Genetic: UGT1A1 genotyping (TA6/TA6)', 'Genetic: UGT1A1 genotyping (TA6/TA7)', 'Genetic: UGT1A1 genotyping (TA7/TA7)', 'Drug: Leucovorin and 5-FU']}
- {'label': 'Regorafenib', 'type': 'ACTIVE_COMPARATOR', 'description': 'Regorafenib is administered at adjusted dosage of 120 mg daily for 3 weeks in a 4-week cycle.', 'interventionNames': ['Drug: Regorafenib']}

Interventions:
- {'type': 'DRUG', 'name': 'Regorafenib', 'description': 'Regorafenib is administered at dose of 120 mg daily for 3 weeks in a 4-week cycle', 'armGroupLabels': ['Regorafenib', 'Regorafenib plus FOLFIRI'], 'otherNames': ['stivarga']}
- {'type': 'GENETIC', 'name': 'UGT1A1 genotyping (TA6/TA6)', 'description': 'The dosage of irinotecan in FOLFIRI is escalated from 180mg/m2 to 260 mg/m2', 'armGroupLabels': ['Regorafenib plus FOLFIRI']}
- {'type': 'GENETIC', 'name': 'UGT1A1 genotyping (TA6/TA7)', 'description': 'The dosage of irinotecan in FOLFIRI is escalated from 180mg/m2 to 240 mg/m2', 'armGroupLabels': ['Regorafenib plus FOLFIRI']}
- {'type': 'GENETIC', 'name': 'UGT1A1 genotyping (TA7/TA7)', 'description': 'The dosage of irinotecan in FOLFIRI is escalated from 120mg/m2 to180 mg/m2', 'armGroupLabels': ['Regorafenib plus FOLFIRI']}
- {'type': 'DRUG', 'name': 'Leucovorin and 5-FU', 'description': 'Leucovorin (400 mg/m2 IV infusion over 2 hours), and 5-FU (2800 mg/m2 IV infusion over a 46-hour period)', 'armGroupLabels': ['Regorafenib plus FOLFIRI']}

Primary Outcomes:
- {'measure': 'Progression-free survival', 'description': 'Time from treatment to disease progresses and lives', 'timeFrame': 'From date of initiation of treatment until the date of first documented progression, assessed up to 23 months'}

Please estimate the sample size based on the assumption: 
Two-sided α of 0.025, 90% power, overall probability of events is 0.77, and a 20% drop-rate.
Sample size estimation
        Using a per-protocol two-sided Î± of 0.025, a 2:1 randomization between regorafenib plus FOLFIRI dose escalation and regorafenib, and a median PFS of 3.2âmonths in the regorafenib group [9], the study would have 90% power to detect assumed median PFS of 7.0âmonths with regorafenib plus FOLFIRI [3]. The assumption of overall probability of events is 0.77 (10 progressions at the end of the study out of 13 in total) [9]. The calculated sample size is 121 patients. Considering a 20% drop-rate, a total of 153 patients should be enrolled into the study, with 102 assigned to the study group (FOLFIRI plus regorafenib group) and 51 to the control group (regorafenib monotherapy group).