The present invention is directed to compositions and methods that target the PI3K signaling pathway for the treatment or prevention of cancer. In one aspect, there is provided a pharmaceutical formulation comprising Polymorph E of N-(3-{[(2Z)-3-[(2-chloro-5-methoxyphenyl)amino]quinoxalin-2(1H)-ylidene]sulfamoyl}phenyl)-2-methylalaninamide.L'invention concerne des méthodes de traitement du cancer chez un patient nécessitant un tel traitement, comprenant l'administration d'un inhibiteur de la PI3K.
