Despite Leqembi's launch pains, Eisai projects Alzheimer's med will reach $8.8B in the long run

Despite weathering a host of launch challenges with Leqembi, Eisai still has big hopes for its amyloid-busting antibody in early Alzheimer’s disease.

On Thursday, the Japan-based company solidified those ambitions with new estimates for eligible patient populations worldwide and potential sales.

By Eisai’s 2026 fiscal year—which ends in March 2027—the company figures Leqembi can bring home 290 billion Japanese yen (nearly $2 billion) in global revenues. Come fiscal year 2032, those sales could potentially swell to a whopping 1.3 trillion yen ($8.8 billion), Eisai said in a new corporate update (PDF).

Last year, Eisai said it expected global Leqembi revenue to hit 1 trillion yen (currently around $6.8 billion) by 2030. 

Eisai projects there will be about 398,000 people eligible for its treatment worldwide in FY2026. The number should balloon to 3.32 million by FY2032 as diagnoses accelerate and the Leqembi treatment pathway is streamlined, the company said.

Leqembi works by removing beta amyloid in the brain, which forms once of the central theories as to what causes Alzheimer’s. In order to access the drug, patients need to be tested to confirm the presence of beta amyloid.

That said, a recent report by life sciences consultants at Spherix found that nearly half of 75 neurologists surveyed reported issues conducting the right sort of amyloid testing to get the go-ahead for Leqembi.

Regarding diagnoses, Eisai earlier this week said it would drop upwards of $15 million to re-up its investment in Alzheimer’s blood test developer C2N Diagnostics. C2N’s Precivity blood tests are designed to suss out tau and beta amyloid proteins that have made their way into the bloodstream via plaques in the brain. C2N has demonstrated that its approach is comparable to expensive brain imaging scans and uncomfortable spinal tap biopsy procedures.

Still, testing has proved just one stumbling block for Eisai’s drug, which it’s commercializing with the help of U.S. partner Biogen.

Eisai had originally set the goal to reach 10,000 patients with Leqembi by the end of March—but as of Jan. 26, just 2,000 patients in the U.S. were receiving the drug, the company explained on a February analyst call.

That level of progress made Eisai's goal “rather challenging” to achieve, the company’s global Alzheimer’s disease officer, Keisuke Naito, said at the time.

Now, Eisai aims to significantly boost its field force of neurology account specialists by some 30% in the first quarter of the 2024 fiscal calendar, the company said Thursday. The company also plans to “enhance collaboration” with Biogen, which is tackling Leqembi commercial duties in the U.S.

Nevertheless, the problems could run deeper for Leqembi, Spherix’s recent survey found. According to the poll, “few surveyed neurologists consider Leqembi to be a significant medical advance over other historical AD treatments,” the Spherix consultants said last month.

Coverage has emerged as another hurdle, with Spherix’s report noting that, on average, two-fifths of patients who should be eligible weren’t prescribed Leqembi because they couldn’t secure Medicare or other insurance approvals.

Lastly, logistics have become an issue, too. Leqembi needs to be infused at a specialist center, but three-fifths of patients, according to the Sphreix report, are receiving treatment at off-site infusion centers unrelated to the neurologists’ practice.

Eisai, for its part, has said it hopes to expand its Alzheimer’s business by rolling out maintenance dosing and a subcutaneous formulation of Leqembi, which could make the experience of receiving the medication far simpler.

In its corporate update Thursday, Eisai also said it wants to help shift medical care aware from a specialist-centric model to one in which primary care physicians also play a “major role" in addressing the disease.

In Eisai’s latest third-quarter results, which ran from October to December, Leqembi generated a slim 1.1 billion yen in U.S. sales (around $7.4 million) over the three-month stretch.

Analysts with GlobalData Healthcare have predicted Leqembi could reel in cumulative sales of $12.9 billion through 2028. At the time, another group, Evaluate Vantage, estimated that Leqembi would reach worldwide sales of $3 billion in 2028.