A Study of KW-2478 in Combination With Bortezomib in Subjects With Relapsed and/or Refractory Multiple Myeloma

The purpose of this study is to assess the safety and benefits of the investigational study drug, KW-2478, when given with bortezomib (Velcade®), a drug approved for the treatment of Multiple Myeloma (MM). The primary objectives: * To establish the safety, tolerability, and recommended Phase II dose (RP2D) of KW-2478 in combination with bortezomib (Phase I); * To assess the overall response rate (ORR) when subjects with advanced MM are treated (Phase II). The secondary objectives: * To characterize the Pharmacokinetic (PK) and Pharmacodynamic (PD) of KW-2478 with bortezomib (Phase I only); * To evaluate for preliminary evidence of efficacy (Phase I); * To determine progression free survival (PFS) and duration of response of KW-2478 with bortezomib (Phase II).