MEI Pharma completes patient enrollment in Pracinostat Phase II trial for treatment of MDS

MEI Pharma, Inc. (Nasdaq: MEIP), an oncology company focused on the clinical development of novel therapies for cancer, announced today that it has completed enrollment in a randomized Phase II clinical trial of its lead investigational drug candidate Pracinostat in combination with azacitidine in patients with previously untreated intermediate-2 or high-risk myelodysplastic syndrome (MDS). The multi-center, placebo-controlled, double-blind study enrolled a total of 108 patients with a one-to-one randomization. The Company plans to unblind the study approximately six months after the last patient was enrolled and report topline data in Q1 2015.

"The achievement of this important milestone is the culmination of months of diligence and collaboration," said Daniel P. Gold, Ph.D., President and Chief Executive Officer of MEI Pharma. "Following the very high response rate reported in our MDS pilot study, we set out to execute a comprehensive development program in order to better elucidate the clinical benefit of Pracinostat plus azacitidine in this patient population. Now we look forward to unblinding this study early next year and determining the most efficient registration path forward for Pracinostat."

The randomized Phase II study is designed to evaluate the safety and efficacy of Pracinostat compared to placebo when combined with azacitidine¹, a drug approved by the U.S. Food and Drug Administration for the treatment of MDS. The primary endpoint of the study is rate of complete remission (CR). Secondary endpoints include overall response rate, hematologic improvement, duration of response, progression-free survival, rate of leukemic transformation, overall survival and safety.

Results from an earlier pilot study of Pracinostat in combination with azacitidine in patients with intermediate-2 or high-risk MDS presented at the American Society of Hematology Annual Meeting in December 2012 reported an overall response rate of 89% (eight out of nine), including seven patients who achieved either a CR or a complete remission with incomplete blood count recovery (CRi). Combined with the results from an additional patient treated at the University of Wisconsin-Madison who also achieved a CR, the trial's overall response rate was 90% (nine out of 10). The combination of Pracinostat and azacitidine was well tolerated in the study; the most frequent side effects were nausea and fatigue.

In June 2014, MEI Pharma announced preliminary data from its ongoing Phase II study of Pracinostat plus azacitidine in elderly patients with newly diagnosed AML. Of the first nine patients enrolled in the multicenter study, three achieved a CR or CRi, each following one or two treatment cycles. In addition, three patients achieved a partial response (PR) or a partial response with incomplete blood count recovery (PRi) after their initial or second treatment evaluation, for an overall response rate of 67%. The combination of Pracinostat and azacitidine has been generally well tolerated in the study, with no new or more severe adverse events than previously reported. The Company expects to report additional data from this open-label study at a scientific conference later this year.