MEI Pharma Reaches Response Milestone in Phase II Clinical Trial of Pracinostat in Refractory Myelodysplastic Syndrome

SAN DIEGO, Dec. 22, 2014 /PRNewswire/ -- MEI Pharma, Inc. (Nasdaq: MEIP), an oncology company focused on the clinical development of novel therapies for cancer, today announced that the clinical response milestone has been reached in the Company's ongoing Phase II study of its investigational drug candidate Pracinostat in combination with a hypomethylating agent (HMA) in patients with myelodysplastic syndrome (MDS) who previously failed treatment with single-agent HMA.

Of the first 28 patients who received Pracinostat in combination with azacitidine (marketed as Vidaza^®) or decitabine (marketed as Dacogen^®) after progressing while being treated with the same HMA alone, three have now achieved clinical responses, one partial response (PR) and two marrow complete responses (mCR), exceeding the pre-specified clinical improvement rate for expansion of study enrollment.

"A year ago we set out to execute a comprehensive development program for Pracinostat in order to determine the most efficient registration path forward," said Daniel P. Gold, Ph.D., President and Chief Executive Officer of MEI Pharma. "The primary objective of this refractory MDS study was to determine if the addition of Pracinostat to a hypomethylating agent can result in clinical benefit following disease progression with a HMA alone. Observing clinical responses in this most difficult to treat patient population only reinforces our confidence in the activity of Pracinostat. Now we will complete enrollment in this study and continue to follow patients for response and survival. Meanwhile we eagerly await the unblinding of our randomized, placebo-controlled Phase II study in front line MDS in March 2015 as we prepare for the initiation of our Phase III study in front line AML in June 2015."

The primary endpoint of the refractory MDS study is clinical improvement rate, defined as the proportion of patients with CR, mCR, PR and hematologic improvement. Secondary endpoints include overall response rate, duration of response, transfusion independence, progression-free survival and overall survival. The combination of Pracinostat and azacitidine or decitabine has been generally well-tolerated in the study, with no unexpected toxicities. The most common treatment-emergent adverse events include anemia, fatigue and gastrointestinal disorders.

About Pracinostat

Pracinostat is an oral histone deacetylase (HDAC) inhibitor that has been tested in a number of Phase I and Phase II clinical trials in advanced hematologic disorders and solid tumor indications in both adult and pediatric patients. Pracinostat has been generally well tolerated in more than 300 patients to date, with manageable side effects often associated with drugs of this class, including fatigue, myelosuppresion and gastrointestinal toxicity. In a Phase I dose-escalation trial, Pracinostat demonstrated evidence of single-agent activity in elderly acute myeloid leukemia (AML) patients, including two out of 14 (14%) who achieved a CR, with durable responses persisting 206+ and 362 days, respectively. In addition, results from a pilot study of Pracinostat in combination with azacitidine in patients with advanced MDS showed an overall response rate of 90% (nine out of 10), including six patients who achieved a CR.

Earlier this month, significant clinical activity from a Phase II study of Pracinostat in combination with azacitidine in elderly patients with newly diagnosed AML were reported at the American Society of Hematology (ASH) Annual Meeting. According to the presentation, 15 of 33 evaluable patients (45%) achieved the primary endpoint of CR plus complete response with incomplete blood count recovery (CRi) plus morphologic leukemia-free state. No patient who achieved a clinical response has progressed. The Company plans to report full top line data from all 50 patients enrolled in the study in June 2015.

MEI Pharma owns exclusive worldwide rights to Pracinostat.

About MEI Pharma

MEI Pharma, Inc. (Nasdaq: MEIP) is a San Diego-based oncology company focused on the clinical development of novel therapies for cancer. The Company's lead drug candidate is Pracinostat, a potential best-in-class, oral HDAC inhibitor currently being developed for MDS and AML. In August 2014, the Company completed enrollment in a randomized, placebo-controlled Phase II study of Pracinostat in combination with azacitidine in patients with previously untreated intermediate-2 or high-risk MDS. The Company plans to unblind the study and report topline data in March 2015. MEI Pharma is also developing ME-344, a mitochondrial inhibitor currently in a Phase Ib study in combination with topotecan in patients with small cell lung or ovarian cancer who failed initial therapy. In addition, the Company expects to initiate a first-in-human study of PWT143, a highly selective PI3K delta inhibitor, in the first half of 2015.

Under U.S. law, a new drug cannot be marketed until it has been investigated in clinical trials and approved by the FDA as being safe and effective for the intended use. Statements included in this press release that are not historical in nature are "forward-looking statements" within the meaning of the "safe harbor" provisions of the Private Securities Litigation Reform Act of 1995. You should be aware that our actual results could differ materially from those contained in the forward-looking statements, which are based on management's current expectations and are subject to a number of risks and uncertainties, including, but not limited to, our failure to successfully commercialize our product candidates; costs and delays in the development and/or FDA approval, or the failure to obtain such approval, of our product candidates; uncertainties or differences in interpretation in clinical trial results; our inability to maintain or enter into, and the risks resulting from our dependence upon, collaboration or contractual arrangements necessary for the development, manufacture, commercialization, marketing, sales and distribution of any products; competitive factors; our inability to protect our patents or proprietary rights and obtain necessary rights to third party patents and intellectual property to operate our business; our inability to operate our business without infringing the patents and proprietary rights of others; general economic conditions; the failure of any products to gain market acceptance; our inability to obtain any additional required financing; technological changes; government regulation; changes in industry practice; and one-time events. We do not intend to update any of these factors or to publicly announce the results of any revisions to these forward-looking statements.

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SOURCE MEI Pharma, Inc.