Safety Study of Dasatinib With Bortezomib (Velcade®) and Dexamethasone for Multiple Myeloma

Key Inclusion Criteria: * Confirmed diagnosis of multiple myeloma with measurable disease * Evidence of relapsed or refractory disease and at least 2 prior therapies for multiple myeloma * Eastern Cooperative Oncology Group Performance Status of 0 - 2 * Last treatment for multiple myeloma not within 21 days prior to study treatment initiation * Bone marrow transplant not within 3 months prior to study treatment initiation * Required baseline hematology and chemistry parameters. Key Exclusion Criteria: * Clinically significant cardiac disease (New York Heart Association Class III or IV) * Abnormal QT interval corrected for heart rate using Fridericia's formula prolonged (\>450 msec) after electrolytes have been corrected on baseline electrocardiogram * Malabsorption syndrome or uncontrolled gastrointestinal toxicities * Dementia, chronic medical or psychiatric condition, or laboratory abnormality that may increase the risk associated with study participation * Clinically significant pleural effusion in the previous 12 months or current ascites * Clinically significant coagulation or platelet function disorder * Intolerance to dasatinib and/or bortezomib * Acute diffuse infiltrative pulmonary disease * Prior or concurrent malignancy, except for adequately treated basal cell or squamous cell skin cancer, adequately treated Stage I or II cancer currently in complete remission, cervical carcinoma in situ, or any other cancer from which the participant has been disease-free for 3 years.