The FDA guidance document “Severely Debilitating or Life-Threatening Hematologic Disorders: Nonclinical Development of Pharmaceuticals” was finalized in March of 2019. This guidance is intended to streamline the development of pharmaceuticals used to treat patients with serious noncancer hematologic disorders such as sickle cell disease, hemophilia, and aplastic anemia. The guidance notes scenarios when use of animal studies can be reduced by eliminating or delaying certain nonclinical studies.