Bortezomib combination therapy in multiple myeloma.

Bortezomib was approved for the treatment of multiple myeloma (MM) in 2003. Since then several bortezomib-based combination therapies have emerged. Although some combinations have been preceded by preclinical investigations, most have followed the inevitable process in which active (or potentially active) drugs are combined with each other to create new treatment regimens. Regimens that have combined bortezomib with corticosteroids, alkylating agents, thalidomide, and/or lenalidomide have resulted in high response rates. Despite the higher and often deeper response rates and prolongation of progression-free survival with bortezomib-based multiagent regimens, an overall survival (OS) advantage has not been demonstrated with most combinations compared to the sequential approach of using anti-myeloma agents, particularly in patients less than 65 years of age with newly diagnosed myeloma. The unique properties of some of these regimens can be taken into account when choosing a particular regimen based on the clinical scenario. For example, the combination of bortezomib, thalidomide, and dexamethasone (VTD) has particular value in renal failure since none of the drugs need dose modification. Similarly, the combination chemotherapy regimen VDT-PACE (bortezomib, dexamethasone, thalidomide, cisplatin, doxorubicin, cyclophosphamide, and etoposide) is of particular value in patients presenting with aggressive disease such as extramedullary plasmacytomas or plasma cell leukemia. Ongoing clinical trials are testing combinations of bortezomib with several other classes of agents, including monoclonal antibodies, and inhibitors of deacetylases, heat shock proteins, phosphatidyl inositol 3-kinase/Akt/mammalian target of rapamycin pathway and farnesyl transferase.