MEI Pharma, Inc. announced that the first patient has been dosed in a Phase II clinical trial of Pracinostat, the Company's investigational oral histone deacetylase (HDAC) inhibitor, in patients with myelodysplastic syndrome (MDS) who either failed to respond or maintain a response to a hypomethylating agent (HMA) alone. This two-stage trial of Pracinostat is expected to enroll up to a total of 76 patients into two groups: patients who have had disease progression or have relapsed following a clinical response to either Vidaza or Dacogen therapy; and patients with stable disease who failed to respond to their initial HMA therapy. If at any time two or more responses are observed in the first 29 patients of each group, that group will continue to enroll an additional nine patients in the second stage, for a total of up to 38 evaluable patients per group.

Preliminary data from this open-label trial is anticipated by December 2014. The primary endpoint of the trial is clinical improvement rate, defined as the proportion of patients with complete remission (CR), partial remission (PR) and hematologic improvement (HI). Secondary endpoints include overall response rate, CR rate, HI rate, duration of response, progression-free survival, time to progression and overall survival.

Meanwhile, MEI Pharma remains on track to fully enroll its randomized, placebo-controlled Phase II trial of Pracinostat in combination with Vidaza in patients with previously untreated intermediate-2 or high-risk MDS by June 2014, with topline data expected by December 2014. In addition, the Company continues to enroll patients in a two-stage Phase II trial of Pracinostat in combination with Vidaza in elderly patients with newly diagnosed acute myeloid leukemia (AML). If at any time three or more responses are observed in the first 27 patients, the trial will continue to enroll an additional 13 patients in the second stage, for a total of up to 40 evaluable patients.

Preliminary data from this open-label trial is also anticipated by December 2014.