A new class of Alzheimer's treatments has proven a commercial disappointment over the past two years, but the Japanese pharmaceutical firm Eisai reported new data late Wednesday that analysts say could boost uptake of the drug it sells with Biogen.
In a scientific presentation at an Alzheimer's disease conference, Eisai (ticker: ESAIY) said that a new version of its Alzheimer's therapy Leqembi, which is injected under the skin, cleared 14% more of the amyloid brain plaques thought to be associated with Alzheimer's disease than the currently approved medicine, which is administered via intravenous infusion.
Wall Street analysts said that the data might be good enough to secure Food and Drug Administration approval of the new subcutaneous version, which could ease some of the barriers to taking the drug.
Patients currently on Leqembi must travel twice monthly to infusion centers for an hourlong infusion, which can be a challenge for Alzheimer's patients suffering from cognitive impairment or dementia. A subcutaneously injected version of Leqembi could theoretically be administered at home.
Questions about the drug's safety, however, continue to loom large. Drugs like Leqembi carry the risk of a condition known as ARIA, a potentially dangerous form of brain swelling. Patients who received the new subcutaneous version of Leqembi developed ARIA at slightly higher rates than those in an earlier trial who had received the infused version of the drug, though Eisai said that the sample size of patients on the injected version was too small for exact comparisons to be made.
ARIA rates among patients who received the injected Leqembi remained lower than in patients in Eli Lilly's (LLY) trial of its similar infused Alzheimer's drug, called donanemab, which does not yet have FDA approval.
"In our opinion these results suggest that [subcutaneous] Leqembi is viable," TD Cowen analyst Phil Nadeau wrote late Wednesday. He said that the biggest risk was that regulators might ask Eisai for an additional trial testing a lower dose of the new injection to try to achieve lower ARIA rates. He rates Biogen stock at Outperform with a $305 target price.
Biogen stock (BIIB) is down 0.5% in Thursday trading, while Eisai's American depositary receipts are up 0.2%.
The two companies received FDA approval in mid-2021 for an earlier Alzeimer's therapy called Aduhelm, which was a commercial failure due to significant questions about its efficacy. Leqembi appears to work far better, and slowed cognitive decline in early-stage Alzheimer's patients by 27% over 18 months in a Phase 3 trial. Leqembi received accelerated approval from the FDA in January of this year, and full approval in July. Medicare has offered broader coverage of the drug since the summer.
Wall Street has remained skeptical, and peak sales expectations are nowhere near the $20 billion per year that analysts in 2021 projected Aduhelm would eventually hit.
Analysts have pointed to the hurdles that face Eisai and Biogen, including the safety concerns, the logistics of administering the drug, and the significant testing requirements for patients on the drug, who must receive MRIs both before and during treatments.
A subcutaneous version of Leqembi could ease some of those challenges. In a note late Wednesday, Leerink Partners analyst Mark Goodman wrote that a subcutaneous formulation "would circumvent the need to build up infrastructure around infusion centers and greatly increase ease of administration." He rates Biogen stock at Outperform with a $365 target price.
William Blair analyst Myles Minter wrote that he expects Leqembi global revenue to peak at $8 billion in 2030. He has an Outperform rating on Biogen stock.
In addition to the subcutaneous data, Eisai also on Wednesday reported other data on its Alzheimer's program, including new longer-term data on its Phase 3 Lecanemab trial. The company said that patients on intravenous Leqembi continued to see a benefit in the six months after the 18 month trial ended.