Proteus syndrome (PS) is caused by a mutation in the AKT1 gene. This gene makes a protein that communicates with other proteins in the body to make cells grow. The AKT1 mutation changes chemical signals in the body and causes overgrowth. PS can be fatal. The drug ARQ 092 reduces signals from the AKT1 protein. This may reduce or stabilize some of the overgrowth in people with PS. Researchers want to find the best dose of ARQ 092 based on its effect on tissues in people with PS.