Are randomized trials obsolete or more important than ever in the genomic era?

Th e genomic era has raised the possibility of major changes in the design, conduct, and even the existence of randomized trials as we know them [1­3]. Randomized trials are often seen as a slow, laborious, expensive, and diffi cult step in the translational process and are associated with a high attrition rate for drugs. Indeed, most tests that are in use for the screening, diagnosis, prognosis, monitoring or management of patients have never been scrutinized by a randomized trial. Th is has largely been due to a failure to realize that tests can do as much harm and as much good as drugs or devices; thus, a rigorous appraisal of their clinical utility, including both the possible benefi ts and the possible harms, is necessary. Moreover, numerous new omics­based tests are continu­ ally being proposed, especially in the context of targeted preventive or therapeutic interventions. Given rapid develop ment of these new biomarkers, can we make ran­ dom ized trials more adaptable to a changing land scape? Furthermore, do we still need randomized trials at all? Our answers to these two questions are: yes, to some extent; and yes, defi nitely. We will explain our reasoning in this article. Revolutionizing randomized trials in the genomic era Genomic applications in medicine are highly diverse. Th ey range from diagnostic and carrier tests for many rare Mendelian conditions to complex biomarkers that inform preventive or therapeutic interventions. One relatively new area is the explicit linkage of a treatment and a companion diagnostic test (a molecular assay to indicate the likelihood of a patient responding to this specifi c treatment or reacting adversely). With this in mind, at least three types of potentially informative