 20. While not an exclusion criterion, unless considered clinically indicated, patients should avoid taking other additional non-study medications that may interfere with the study medication. In particular, patients should avoid medications that are known to either induce or inhibit the activity of hepatic microsomal isoenzymes CYP1A2, CYP2C19 and CYP3A4, as this may interfere with the metabolism of selumetinib. 