MTOR and plasma cell myeloma: During the past few years, several other novel classes of drugs have been shown to have activity in myeloma in early-stage clinical trials, including the histone deacetylase (HDAC) inhibitors, heat shock protein (HSP) inhibitors, mammalian target of rapamycin (mTOR) inhibitors, phosphoinositide 3-kinase (PI3k)/AKT inhibitors, and monoclonal antibodies8, 9.