Lilly rushes through wide-open US Alzheimer’s floodgates

The Aduhelm fallout continues with news that Lilly will, after all, file its similarly acting Alzheimer’s antibody donanemab later this year. As recently as April Lilly was saying there was no path to approval based on the phase 2 Trailblazer-Alz trial, an opinion based on FDA feedback. But Biogen’s green light for Aduhelm has moved the goalposts, with the agency now awarding donanemab breakthrough therapy designation, along with Biogen’s lecanemab. Lilly is already considered a big beneficiary of the FDA's new lenient stance in Alzheimer’s: its market cap had added $14bn since Aduhelm’s approval, and surged a further $15bn this morning. Still, while Biogen’s win was controversial the drug was backed by safety data in 3,000-plus subjects; Trailblazer-Alz recruited only 257. With a confirmatory trial due to read out in early 2023 Lilly could presumably extract safety data before that; the sellside reckons approval could happen as soon as mid-2022. This feels like a lose-lose scenario for Biogen. If Trailblazer-Alz2 succeeds donanemab will quickly become stiff competition, while failure will heap more pressure on both Biogen and the FDA to justify Aduhelm’s presence on the market. Little surprise that Biogen stock opened 6% lower.