The SMART is not an adaptive trial design. In an adaptive trial design, the trial itself changes over time (i.e., is adapted) based on interim data. For example, accumulating study data may suggest the opportunity/need to change the study’s total sample size. Or, as a second example, interim study data may suggest that one of the treatments is clearly superior to the other, and the study can be terminated ahead of schedule.
SMARTs, on the other hand, are designed to inform the development of an adaptive intervention. For example, the set of available intervention options at each decision point in a SMART will typically remain the same from the beginning to the end of the trial.