Psilocybin, the psychoactive core of magic mushrooms, could be headed toward late-stage trials in treatment-resistant depression (TRD), pending the results of a soon-to-start phase IIb study. London-based Compass Pathways Ltd. has received permission from the FDA and additional regulators to run a dose-ranging study in up to 216 patients across Europe and North America. The trial, which seeks to enroll 216 patients at 12 to 15 research sites, will begin in the U.K. later this month and is expected to read out toward the end of 2019.