MEI Abandons PI3K Inhibitor, 30% of Staff in Strategic Shift


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Following a development setback, MEI Pharma will pivot toward two earlier clinical-stage assets and cut 30% of its workforce in a strategic realignment, the company announced Monday.

The decision to streamline its operations comes as MEI, along with its Japanese partner Kyowa Kirin Co., Ltd., discontinued the global development of its selective PI3Kδ inhibitor zandelisib outside of Japan. Zandelisib was being investigated as a once-daily oral treatment for patients with B-cell malignancies.

In a statement, MEI President and CEO Daniel Gold, Ph.D. explained that after a late November meeting with the FDA, the partners “no longer believe clinical development can be completed within a time period that would support further investment, or with sufficient certainty of the regulatory requirements to justify continued global development efforts.”

MEI’s shares fell 33.5% in reaction to the news.

With the loss of its lead candidate, MEI will now pin its hopes on two earlier clinical-stage programs. The first, voruciclib, is an oral cyclin-dependent kinase 9 (CDK9) inhibitor that is also being tested against B-cell malignancies. It is currently in Phase I studies as a combination therapy with AbbVie and Genentech’s Venclexta (venetoclax) against acute myeloid leukemia.

Preclinical studies are also ongoing for voruciclib in KRAS-mutated solid tumors.

The second candidate is ME-344, a tumor-selective mitochondrial inhibitor being investigated in solid tumors. MEI is readying a Phase Ib study of ME-344 with Genentech’s Avastin (bevacizumab) in relapsed colorectal cancer, which is expected to start enrolling early next year.

Along with the pipeline changes, MEI is implementing a staggered workforce reduction, which will involve an initial downsizing of approximately 30% of the current headcount. 

Once the layoffs and discontinuation of zandelisib have been completed, along with any future workforce reductions, MEI expects its existing cash, cash equivalents and marketable securities to see both voruciclib and ME-344 through important clinical data milestones.

Zandelisib’s Rough Road

MEI’s troubles with zandelisib began in May when the FDA said it would need additional clinical research before it could consider the drug for regulatory approval. 

MEI and Kyowa Kirin filed their application for zandelisib under the Agency’s accelerated approval pathway and submitted data from the Phase II TIDAL study, which showed the compound could elicit a 70.3% objective response rate and a 35.2% complete response rate in patients with follicular lymphoma.

In June, the partners posted follow-up data for zandelisib, showing that most responses occurred within the first two to four cycles of therapy.

Nevertheless, the FDA insisted on a randomized, controlled trial to assess the efficacy and safety of the drug more comprehensively. This decision is in line with the agency’s recent increased scrutiny of PI3K inhibitors.  

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