Clinical trial 1: Inhibitor Prevention Trial schema. Schema for the Inhibitor Prevention Trial, in which ELOCTATE prophylaxis is compared with emicizumab prophylaxis to reduce inhibitor formation in PUPs with severe hemophilia A. The sample size indicates 1:3 preferential randomization of ELOCTATE/emicizumab, as a result of the incorporation of subjects on the ELOCTATE arm, borrowed from the Bayesian prior (supplemental Methods).