Group sequential design in East

“Two Samples”, “Logrank Test Given Accrual Duration and Study Duration” in the Survival library will be used for sample size calculations.

After selecting the design option, you will initially see tabs: “Test Parameters” and “Accrual/Dropouts”. Once the “Number of Looks” is updated to greater than 1, a “Boundary” tab will appear.

Below are screenshots of each of the tabs for a group sequential design (GSD) for a progression-free survival (PFS) endpoint, which has one interim analysis for both efficacy and non-binding futility:

The results are as follows:

The results are generated with East version 6.5.4.6.