FDA delayed the Leqembi Iqlik subcutaneous initiation application to August 24, hitting Biogen and Eisai with a three-month setback after classifying their submission as a major amendment.
The original PDUFA date was May 24. The agency’s request for additional information on using subcutaneous Leqembi for treatment initiation triggered the reclassification. Biogen and Eisai had submitted data showing Leqembi Iqlik, given weekly under the skin, achieved bioequivalent drug exposure to the intravenous version given biweekly, building the scientific case for eliminating IV infusions entirely.
Leqembi Iqlik won clearance in September 2025, but only for maintenance treatments. Patients can’t skip the 18-month intravenous induction period under the existing label. A green light here would change that, making Leqembi Iqlik the first anti-amyloid therapy with at-home subcutaneous dosing from first dose through maintenance.
The competitive pressure is real. Eli Lilly’s Kisunla holds a convenience edge with once-monthly infusion versus Leqembi’s biweekly IV schedule. Biogen CEO Chris Viehbacher said in January that Kisunla’s advantage “is going to go away once we have a subcutaneous formulation.” Now that formulation is three months further away.
The delay lands at a bad moment for Biogen. The first batch of Kisunla-treated patients are ending their 18-month course, and Biogen’s head of North America says physicians are already asking what comes next.
RBC Capital Markets called the delay’s impact “limited”: reimbursements for Leqembi won’t kick in until 2027 regardless of which verdict date applies. But RBC also warned it “adds incremental risk” to Biogen and delays a growth catalyst the market had been watching.
Next decision window: August 24.
Sarah Chen