The Food and Drug Administration (FDA or Agency) is announcing the availability of a final guidance for industry entitled “Developing Targeted Therapies in Low-Frequency Molecular Subsets of a Disease.” This final guidance incorporates public comments to the draft guidance published in the Federal Register of December 18, 2017.

The pharmacological effect of a targeted therapy is often related to a particular molecular alteration, and many diseases are caused by a range of different molecular alterations (some of which may be rare). Therefore, a targeted therapy may have differential effects among patients with the same disease who have different molecular alterations. The purpose of this guidance is to describe general approaches to evaluating the benefits and risks of targeted therapeutics within a clinically defined disease where some molecular alterations may occur at low frequencies.