The phase 4 trial (NCT00841217) was stopped and warnings issued by the World Anti-Doping Agency,8 Health Canada,9 and, most recently in April 2018, GW501516 was classified as a poisonous substance in Australia.10 The precise role of PPARβ/δ in cancer, particularly in humans, however, remains unclear as reports continue to emerge showing that agonists may either increase or protect against different cancers.11 Here, PPARD is linked to cancer.