Gene signatures for determining whether a neoplasm (such as a multiple myeloma neoplasm) is sensitive to mTORi/HDACi combination therapy and/or for determining the prognosis of a neoplasm in a subject are described. Some embodiments include determining whether a neoplasm is sensitive to mTORi/HDACi combination therapy by predicting whether mTORi/HDACi combination therapy will successfully treat the neoplasm, for example increasing survival of the subject with the neoplasm. In some embodiments, determining the prognosis includes predicting the outcome (such as chance of survival) of the subject with a neoplasm. Also disclosed are reagents, for example arrays, for use with the disclosed methods, as well as computer implementation of the disclosed methods.