ERBB2 and plasma cell myeloma: Successful examples for the use of PDX does not only apply to GBM, but is extended to other tumor types, such as the use of Herceptin for adjuvant therapy with paclitaxel and doxorubin against breast cancer overexpressing the human epidermal growth factor receptor 2 (Her2/Neu) protein [72,73], and in non-solid tumors such as multiple myeloma, using the proteasome inhibitor Bortezomib/Velcade [74,75,76].