FDA Concerns Over P13K Inhibitors Snag MEI Pharma, Kyowa Kirin


Shares of MEI Pharma, Inc. plunged nearly 50% in premarket trading after the company announced that additional clinical research will be needed in order for the company’s phosphatidylinositol-3-kinase (PI3K) inhibitor zandelisib to be considered for regulatory approval.

MEI and its partner Kyowa Kirin hoped to seek marketing authorization for zandelisib through the accelerated approval pathway based on data from the single arm Phase II TIDAL study in follicular lymphoma (FL) patients. That study showed that zandelisib treatment demonstrated a 70.3% objective response rate in patients. However, this morning, the U.S. Food and Drug Administration recommended a randomized trial to adequately assess drug efficacy and safety of PI3K inhibitor drug candidates. 

The FDA’s decision follows plans for an advisory committee to review the use of PI3K inhibitors in blood cancers next month. Several companies, including Gilead Sciences and Incyte, have had to pull their P13K inhibitors from the market due to failures in confirmatory trials. 

It’s this concern that has caused the FDA to deny MEI and Kyowa’s attempts to enter the market early for FL. 

The FDA said that safety on the 60 mg intermittent schedule appears reasonable. It recommended continued dose exploration to further support the current dose and regimen. MEI and Kyowa Kirin have an ongoing Phase III study with zandelisib, the COASTAL trial.

Daniel P. Gold, president and chief executive officer of MEI Pharma, noted that the regulatory agency’s position on the benefit of risk with P13K inhibitors based on single arm studies has evolved. The advisory committee will determine if more randomized data is needed to show if PI3K inhibitors can demonstrate appropriate evidence of efficacy and safety.

“Clearly, the outcome of our recent FDA meeting is a disappointing development. Nonetheless, we will continue to focus on the ongoing Phase III COASTAL study as we consider options that provide the most expeditious approval pathway utilizing randomized data, and which we believe will demonstrate the potential of zandelisib to help patients,” Gold said in a statement. “Today’s announcement in no way diminishes our conviction to the development of zandelisib and the promise of its emerging clinical profile.”

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The company plans on completing the evaluation of the Phase II TIDAL study. Data is expected to be shared later this year.

Yoshifumi Torii, head of research and development at Kyowa Kirin, noted that the dialogue with the FDA has provided greater insight into the FDA’s view of the P13K inhibitor drug class. 

“With this knowledge, we can focus our efforts to advance the COASTAL program. Our teams around the world have made steady progress to enroll patients and give us important momentum. Together with MEI Pharma, we will continue to work with the investigators, patients, and advocacy organizations to drive continued progress,” Torii said. 


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