
Biogen’s unexpectedly successful new rare-disease drug, Spinraza, delivered another surprise in the first quarter: flat sales.
The drug, which treats spinal muscular atrophy, ran off to an impressive start last year, topping analyst estimates and beating even Biogen’s projections. But everything leveled off between the fourth quarter, when revenue hit $363 million, and the first three months of 2018, when Biogen booked $364 million in Spinraza sales. Analysts had expected first-quarter sales of about $383 million.