<qa>  How many patients are needed to show this difference?The expected median PFS in Arm A standard arm is 11 months. The minimum increase in PFS in Arm B experimental arm will be 3 months 21 hazard ratio reduction. 540 events are required for 80 power. 740 patients are needed to show this difference 0.05, 2-tailed test. To allow for ineligibility in some patients, a total of 750 patients will be included. 