MEI Pharma Presents Updated Clinical Data from the ME-401 Phase 1b study in Patients with Indolent B-cell Malignancies at the 2019 International Conference on Malignant Lymphoma (ICML)

SAN DIEGO, June 22, 2019 /PRNewswire/ -- MEI Pharma, Inc. (NASDAQ: MEIP), a late-stage pharmaceutical company focused on advancing potential new therapies for cancer, today announced that updated data presented in an oral presentation at ICML 2019 from a Phase 1b study of investigational ME-401, a selective oral inhibitor of PI3K delta, demonstrate an 83% overall response rate in patients with relapsed or refractory (r/r) follicular lymphoma (FL) and r/r chronic lymphocytic leukemia or small lymphocytic lymphoma (CLL/SLL).

Additionally, the data demonstrate:

• Overall response rates of 75% to 100% across all patient groups receiving ME-401.
• 100% overall response rate in all patients with CLL/SLL.
• A lower rate of delayed, grade 3 adverse events observed in patients dosed on the intermittent schedule (IS) (e.g. 9.7% diarrhea/colitis for IS dosing).
• Durable responses in patients with FL and CLL/SLL across both CS and IS dosing groups.
• Median PFS not reached.

The ME-401 ICML 2019 presentation can be accessed on the MEI Pharma website.

"The Phase 1b interim results presented at ICML support the high level of confidence we hold in ME-401 as a potential new treatment for patients with B-cell malignancies; we were particularly excited to see continued strong and durable responses in chronic lymphocytic leukemia, especially as the majority of the patients tested expressed unmutated IGHV, which is generally  associated with a poorer prognosis," said Daniel
P. Gold, Ph.D., president and chief executive officer of MEI Pharma. "ME-401's rapid and preferential accumulation in tumor cells, among other properties, we believe enable it to be successfully administered on our intermittent dosing schedule, which results in lower toxicity while maintaining potency as presented in our data to date. Based on the pharmacological profile of ME-401, we see important opportunities to investigate various combination regimens to treat B-cell malignancies."

MEI has initiated a global Phase 2 study to evaluate the efficacy, safety and tolerability of ME-401 as a single agent in patients with follicular lymphoma after failure of at least two prior systemic therapies including chemotherapy and an anti-CD20 antibody. The Phase 2 TIDAL study (Trials of PI3K DeltA in Non-Hodgkin's Lymphoma) is intended to support an accelerated approval marketing application with the U.S. Food and Drug Administration.

ME-401 Phase 1b Clinical Study
The ongoing Phase 1b clinical study is evaluating ME-401 as a monotherapy and in combination with rituximab or with zanubrutinib in patients with r/r B-cell malignancies. Over 85 patients have been enrolled to date, of which data on 71 patients were presented today at ICML 2019 including 17 with r/r CLL/SLL and 54 patients with r/r FL.

ME-401 was administered once daily at 60 mg for two 28-day cycles and then on an intermittent schedule of once daily dosing for the first 7 days of each subsequent 28-day cycle (i.e. the intermittent schedule or IS). A previous cohort of monotherapy patients in the study was treated with ME-401 administered continuously once daily or were switched to the intermittent schedule in later cycles (i.e. the continuous schedule or CS).

The overall response rate in patients with r/r FL or r/r CLL/SLL was 83% (54/64); the overall response rate in patients with r/r FL was 80% (40/50) and it was 100% in patients with CLL/SLL (14/14). The overall response rate in patients ranged from 75% to 100% across all groups. Median progression free survival was not reached with a median follow up of approximately 9 months.

ME-401 was generally well-tolerated and no grade 4 or grade 5 adverse events have been observed in the Phase 1b study. Among drug related grade 3 adverse events of special interest, the most common are diarrhea/colitis at 9.7% (3/31) on IS dosing and 20% (8/40) on CS dosing, and rash with none on IS dosing and 10% (4/40) on CS dosing.

The rate of the development of delayed, grade 3 adverse events was improved in patients on the intermittent dosing schedule. There were no isolated grade 3 elevations in ALT and AST; such elevations were transient and in each case were associated with grade 3 diarrhea or rash.

About ME-401
ME-401 is an investigational oral phosphatidylinositol 3-kinase ("PI3K") delta inhibitor; PI3K delta is often overexpressed in cancer cells and plays a key role in the proliferation and survival of hematologic cancers. ME-401 displays high selectivity for the PI3K delta isoform and has distinct pharmaceutical properties from other PI3K delta inhibitors. It is being clinically evaluated in patients with various B-cell malignancies. An ongoing, global, Phase 2 study is evaluating the efficacy, safety, and tolerability of ME-401 as a single agent in patients with follicular lymphoma after failure of at least two prior systemic therapies including chemotherapy and an anti-CD20 antibody. The Phase 2 study is intended to support an accelerated approval new drug application with the U.S Food and Drug Administration.

About MEI Pharma
MEI Pharma, Inc. (Nasdaq: MEIP) is a late-stage pharmaceutical company focused on developing potential new therapies for cancer. Our portfolio of drug candidates contains four clinical-stage assets, including one candidate in an ongoing global registration trial and another candidate in a Phase 2 clinical trial which may support an accelerated approval marketing application with the U.S. Food and Drug Administration. Each of our pipeline candidates leverages a different mechanism of action with the objective of developing therapeutic options that are: (1) differentiated, (2) address unmet medical needs and (3) deliver improved benefit to patients either as standalone treatments or in combination with other therapeutic options. For more information, please visit www.meipharma.com.

Under U.S. law, a new drug cannot be marketed until it has been investigated in clinical studies 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.