Safety and Tolerability of RGB-286638 in Patients With Selected, Relapsed or Refractory Hematological Malignancies

Inclusion Criteria: * Histologically/cytologically confirmed diagnosis of: * Multiple myeloma (MM) * Chronic Lymphocytic Leukemia (CLL) / Small Lymphocytic Lymphoma (SLL) * Mantle Cell Lymphoma (MCL) * Chronic Myelogenous Leukemia (CML) * Refractory to/relapsed after and/or intolerant of one or more standard therapies or for which no standard therapy exists. * ECOG performance status 0-2. * Adequate bone marrow, cardiovascular, renal and hepatic function * Recovery from all adverse events due to prior therapies * Contraception Exclusion Criteria: * Prior chemotherapy, monoclonal antibodies, investigational agents, or radiation therapy (involving ≥ 30% of the active bone marrow) within 14 days prior to the first dose (note nitrosoureas and mitomycin are not permitted for at least 42 days before the first dose of RGB-286638). * CNS involvement of the hematological malignancy. * Active or unstable cardiac disease and/or history of myocardial infarction within 6 months and/or history of clinically significant ventricular arrhythmias. * Concomitant therapies that are known to prolong the QT interval and are associated with a risk of Torsades de Pointes (TdP) are not permitted within 7 days before the first dose; however, amiodarone is not permitted within 90 days before the first dose. * Patients with uncontrolled and unstable intercurrent illness. * Concomitant therapy with inhibitors and/or inducers of CYP450 3A4 within 1 week of the first dose. * Bleeding disorder unrelated to hematological malignant disease. * HIV or HIV-related malignancy. * History of other malignancies except: (i) adequately treated basal or squamous cell carcinoma of the skin; (ii) curatively treated, a) in situ carcinoma of the uterine cervix, b) prostate cancer, or c) superficial bladder cancer; or (iii) other curatively treated solid tumor with no evidence of disease for ≥ 2 years. * Any other condition that would, in the investigator's judgment, contraindicate the patient's participation in the clinical study due to safety concerns or compliance with clinical study procedures.