The antibody BIIB092 (gosuranemab), a humanized version of a murine antibody raised to target tau released from induced pluripotent stem cells from a familial patient with Alzheimer's disease,7 has been shown to strikingly reduce the concentration of free tau in the cerebrospinal fluid8 but failed to slow down the progression of clinical disease severity in a phase 2 trial.9 The gene discussed is MAPT; the disease is Alzheimer disease.