The invention relates to crystalline forms of the bis-HCI salt of a compound represented by Structural Formula 1, and pharmaceutical compositions comprising crystalline forms of the bis-HCL salt of a compound represented by Structural Formula 1 described herein. The crystalline forms of the bis-HCl salt of a compound of Structural Formula 1 and compositions comprising the crystalline forms of the compound of Structural Formula 1 provided herein, in particular, crystalline Form I, crystalline Form J, crystalline Form A, and crystalline Form B, or mixtures thereof, can be incorporated into pharmaceutical compositions, which can be used to treat various disorders. Also described herein are methods for preparing the crystalline forms (e.g., Forms I, J, B and A) of the bis-HCI salt of a compound represented by Structural Formula 1.