Biogen shares rose 3.2% following first-quarter results, as investors welcomed the 12% growth in the company's key growth products and positive updates on both the LEQEMBI program and the high-dose SPINRAZA launch. The market reaction suggests upside surprise relative to expectations, with attention on stabilization after years of decline and a promising integration roadmap for the pending Apellis acquisition.

• Growth products delivered $850 million in revenue for Q1, up 12% year-over-year, offsetting continued declines from legacy MS and SPINRAZA.
• High-dose SPINRAZA gained approvals in the U.S., Japan, and Europe; early patient feedback is positive, with reports of switchbacks due to enhanced efficacy profile.
• The LEQEMBI franchise is progressing, with expanded maintenance use and a May 24 PDUFA date for the subcutaneous induction regimen, supporting easier patient access.
• Management emphasized the expected accretion from the pending Apellis acquisition by 2027, expanding Biogen’s commercial portfolio in both ophthalmology and nephrology.
• Cost discipline remains a focus, with a shift in commercial investment away from MS toward growth brands; management notes stabilization after multiple years of revenue and profit declines.