Some ethical implications of "adaptive" trials.

Adaptive trials are a new type of sequential trial, as yet not very widespread, in which each step can be modified on the basis of findings from the preceding step. In other words, the data accumulated during the study are used to modify the trial design. The potential of this type of trial is highly promising, especially for the development of therapies for rare diseases. The planning, conduct and management of data from adaptive trials are extremely complex processes and call for highly specialised skills. Without going into the merits of the experimental protocols, the aim of this article is to point out some ethical aspects that call for caution, as well as the need for ethics committees to be aware of the challenges posed by these trials.