First in human (FIH) studies are the key translational studies from preclinical to further clinical development processes. The goal of FIH studies is to investigate pharmacokinetics (PK) and pharmacodynamics (PD), determine appropriate dosing, and document safety and tolerability. These studies serve as the basis for further efficacy studies in the targeted patient populations. Nariné Baririan at SGS examines the key considerations to consider when deciding whether to run a standard FIH in HVs or a hybrid clinical trial.