MEI suffers from the FDA’s brake on accelerated approvals

The FDA is holding an adcom next month to look at whether randomised data should be required to support approval of PI3K inhibitors – but in at least one case it has already made its decision. The surprise denial of accelerated approval to MEI’s zandelisib, based on a single-arm phase 2 trial, Tidal, in follicular or marginal zone lymphoma, has wiped out 58% of the company’s market cap. MEI must now complete the more rigorous phase 3 Coastal study to get the drug on the market, but its current cash reserves can only to stretch to completion of enrolment into Coastal, in 2024. MEI said the agency’s position on assessing PI3K inhibitors solely based on single-arm studies “appears to have evolved”, as well it might considering the series of discontinuations, withdrawals and clinical holds to which this class has been subject in recent months. Still, the FDA’s volte-face is arguably unfair to MEI: Stifel analysts point out that every PI3K-delta inhibitor greenlit so far was granted accelerated approval on efficacy and safety data notably poorer than zandelisib’s.