The latest development comes after the companies received guidance from a meeting held with the US Food and Drug Administration (FDA) in November.
Based on findings from the MIRAGE and Tidal trials, the company also plans to make a submission seeking marketing authorisation from the health authorities in Japan.
The companies reported the outcome of a Phase II meeting with the FDA in March, where the regulator discouraged submission based on the single-arm Phase II TIDAL trial of zandelisib in relapsed or refractory (r/r) follicular lymphoma patients.
Additionally, the agency said that a randomised trial should support the preliminary registration of zandelisib in indolent non-Hodgkin lymphoma patients.
As a result, the findings from the single-arm trials such as the Phase II TIDAL trial were inadequate to properly evaluate the PI3K inhibitors’ risk/benefit for indolent non-Hodgkin lymphoma.
The FDA noted that the randomised Phase III COASTAL trial underway in r/r follicular or marginal zone lymphoma patients could continue.
In the follow-up meeting in November, the regulatory agency offered guidance on the COASTAL trial’s design and statistical assessment.
Following this meeting, MEI and Kyowa Kirin concluded that a trial in line with the latest guidance from the FDA, including trial modification, may be unlikely to be completed within a duration that would back additional investment.
The firms, therefore, decided to discontinue zandelisib’s global development for indolent kinds of non-Hodgkin lymphoma, excluding Japan.
A selective inhibitor of PI3Kδ, zandelisib is under development for oral, once-a-day administration in B-cell malignancy patients.
MEI Pharma president and CEO Daniel Gold said: “We are very disappointed to share this decision in light of our belief in the potential of zandelisib to benefit patients and meet the ongoing need for new options to treat relapsed or refractory indolent non-Hodgkin lymphomas.
“However, in light of FDA’s guidance, we 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.”