In the context of an investigational treatment with potential for promising benefit within a biomarker subpopulation, design strategies involving graphical gate keeping methods and adaptive Phase II/III seamless designs can be employed. Graphical gatekeeping methods are beneficial in visualizing testing strategies in an easily communicable way. This is particularly important in multiple test procedures for complex trial objectives such as assessing treatment benefit for multiple endpoints in more than one population.In the case of Phase II/III seamless designs, adaptation decisions at the end of Phase II will determine whether the subsequent conduct of the trial into Phase III will continue in the full population or enriched to focus on the biomarker sub-population to demonstrate the effectiveness of therapy. While such clinical trial designs may have attractive features including time and cost savings, clinical and operational aspects need to be considered to ensure a robust design. In this presentation, some practical considerations, flexibility offered and challenges faced by these designs are discussed with examples and simulations in the framework of group sequential design.