In fact, in humans, the Pfizer compound PF‐02545920 (ie, PDE10A inhibitor) is the only one that has currently completed a 6‐month multicenter phase 2 study (AMARYLLIS) investigating two doses (5 and 20 mg) versus placebo and failed to meet its primary end point (ie, the total motor score of the Unified Huntington's Disease Rating Scale) as publicly announced by Pfizer in a press release.53 The gene discussed is PDE10A; the disease is Huntington disease.