SAN DIEGO, Dec. 9, 2013 /PRNewswire/ -- Mirati Therapeutics, Inc. ("Mirati") (NASDAQ: MRTX) today presented data at the 2013 American Society of Hematology (ASH) Annual Meeting demonstrating promising clinical response rates in patients with myelodysplastic syndromes (MDS) patients treated with mocetinostat in combination with azacitidine. Separately, Mirati announced that it has dosed the first patients in its Phase 2 dose confirmation trial of mocetinostat in combination with azacitidine for the treatment of MDS. In an analysis of an open-label, Phase 1/2 trial of 66 patients with MDS or acute myeloid leukemia (AML), researchers analyzed a subset of 22 patients with Intermediate and High Risk disease and baseline bone marrow blasts of 5 to 20 percent at screening, representing a population of patients with RAEB-1 or RAEB-2, a type of MDS that is associated with poor clinical outcomes. Of the 22 patients treated with mocetinostat plus azacitidine, 59 percent experienced an objective response. Median overall survival was 12.4 months. "Patients diagnosed with MDS have few treatment options, and, despite the advances with the standard of care treatment of azacitidine alone, there remains an unmet medical need to improve patient outcome," said Dr. Guillermo Garcia-Manero, professor in the department of leukemia, division of cancer medicine and deputy chair of translational research, department of leukemia, division of cancer medicine (co-chair) at MD Anderson Cancer Center and the principal investigator of the study. "Building upon the experience with azacitidine, our data show that the addition of mocetinostat to azacitidine results in an encouraging objective response rate, and a randomized registration trial is the next logical step." In the open-label dose confirmation trial that began dosing patients this month, Mirati's goal is to confirm the planned Phase 3 dose of mocetinostat in combination with full dose azacitidine to obtain additional information on clinical benefit of the combination. Data on dose confirmation will be available before the initiation of Phase 3, expected in the second half of 2014.