Provided herein are compositions of 7-(6-(2-hydroxypropan-2-yl)pyridin-3-yl)-1-((trans)-4-methoxycyclohexyl)-3,4-dihydropyrazino[2,3-b]pyrazin-2(1H)-one, solid forms, isotopologs and metabolites thereof, and methods of their use for the treatment of a disease, disorder, or condition.