A Study Of The Selective PKC-β Inhibitor MS- 553

DLT are defined as any of the following treatment-emergent events occurring during the DLT evaluation period. 1. Death 2. Hematologic toxicities: • Grade 4 neutropenia for ≥ 7 days • Grade 3 febrile neutropenia: absolute neutrophil count (ANC) 38.3°C (101°F) or a sustained temperature ≥38°C (100.4°F) for \> 1 hour • Grade 4 thrombocytopenia ≥ 14 days (patients with baseline platelet count of ≥ 50 x 109 /L) • Grade 4 thrombocytopenia ≥ 28 days (patients with baseline platelet count \< 50 x 10 9 /L) • ≥ Grade 3 thrombocytopenia associated with ≥ Grade 2 hemorrhage • New ≥ Grade 3 anemia requiring transfusion in a patient previously transfusion independent. 3. Nonhematologic toxicities: • Any other ≥ Grade 3 toxicity not reversed to any one of the following three conditions in 7 days with appropriate intervention: a) baseline; b) \< Grade 1; or c) a status considered to be controlled by the SRC. • Any TEAE requiring \>25% of doses of scheduled study drug to be withheld during the DLT period

Time frame: Assessments for DLT and TEAE will occur during Cycle 1 (28 days) for A1 Cohort and B1 Cohort and Cycles 1-4 (up to 112 days) for C1 Cohort.

Population: DLT evaluable population (Phase 1 only) included all participants who had completed at least 75% of their planned doses during Cycle 1 or the DLT period, unless missed doses were due to adverse events.

This will be assessed according to the 2008 International Workshop on Chronic Lymphocytic Leukemia (IWCLL) Response Criteria with modifications for treatment-related lymphocytosis. Any patient who receives at least one cycle of study therapy is evaluable for response.

Time frame: Evaluation of the efficacy endpoints related to response will incorporate the data from the first 9 cycles (up to 252 days) of treatment.

Population: Consisting of all patients who received at least one dose of study therapy of MS-553 and had at least one post-baseline efficacy evaluation.