Biogen discontinues Aduhelm to focus on Leqembi for Alzheimers

On 31 January 2024, Biogen announced that it will discontinue the development and commercialisation of Aduhelm (aducanumab), its anti-amyloid beta (Aβ) monoclonal antibody (mAb). Aduhelm received FDA-accelerated approval for the treatment of mild Alzheimer’s disease (AD) and mild cognitive impairment (MCI) in June 2021. The approval was considered to be a major milestone at the time, as it made Aduhelm the first disease-modifying therapy (DMT) to be approved for AD.

However, the approval and launch of Aduhelm were surrounded by controversy, and ultimately the drug has failed to have a significant impact in the market, with sales revenue falling flat. Biogen reported Aduhelm’s revenue to be $4.8 million in the US in 2022. In 2023, specific Aduhelm sales were not reported as the drug’s sales were included as “other product” revenue. By discontinuing Aduhelm, Biogen can now fully focus on the continued commercialisation of Eisai-partnered Leqembi (lecanemab), an anti-Aβ mAb that received full FDA approval for the treatment of mild AD and mild cognitive impairment in July 2023, as Biogen cannot afford to have two high-profile AD drugs fail.

Leqembi has already overcome many of the hurdles that Aduhelm faced and which led to its failure. Leqembi’s approval was based on positive clinical trial results in which the drug demonstrated a clinical improvement in cognitive decline. In comparison, Aduhelm’s approval was based on the surrogate endpoint of Aβ clearance as it failed to demonstrate significant clinical effects in its clinical trials. Biogen had to halve the initial launch price of $56,000 per year for Aduhelm in the US following significant backlash, whereas Leqembi is priced at slightly less than the reduced price for Aduhelm, at $26,500 per year in the US.

As a result, the US Centers for Medicare and Medicaid Services (CMS) limited the Medicare re-imbursement of Aduhelm, and subsequent similar drugs, to AD patients participating in randomised controlled trials only, which has resulted in low uptake and poor sales for the drug. While this restriction applied to Leqembi when it initially received accelerated approval in January 2023, the CMS’s decision for Leqembi was revoked following its full approval in July 2023, allowing for much broader coverage and greater access compared with Aduhelm.

Despite this, uptake of Leqembi has been slower than expected given its status as a DMT for a disease with extremely limited treatment options. This was reflected in the financial results reported by Eisai which were published on 6 February 2024 as well as in Biogen’s financial results, which were published on 13 February. Eisai and Biogen are co-promoting Leqembi. In 2023, Leqembi’s sales revenue was only around $10 million in the US. This is almost half of the forecasted US sales of $19.3 million from GlobalData’s Alzheimer’s Disease: Eight-Market Drug Forecast and Market Analysis – Update report published in May 2023.

The goal had been for 10,000 patients to be on Leqembi by the end of March 2024, but only 2,000 patients had received the drug as of 26 January. As the anti-Aβ mAbs are a new and very different class of drug for treating AD, a new treatment pathway is needed to aid access to the drug. Before treatment can be initiated, magnetic resonance imaging is required, and scheduling this has been a key limiting factor for the uptake of Leqembi. Additionally, not all medical practices have the facilities for administering a drug intravenously. Before this point is reached, there is also a bottleneck in diagnosis, as the current gold standard requires a positron emission tomography scan to assess levels of amyloid in the brain.

The success of Leqembi will likely be influenced by the success of its closest competitor, Eli Lilly’s anti-Aβ mAb donanemab. The FDA is expected to decide on donanemab by the end of the first quarter of 2024. While Leqembi does have the advantage of reaching the market before donanemab, there may be an advantage for donanemab in entering the market once a diagnosis and treatment pathway for anti-Aβ mAbs has become more established and streamlined.

One important competitive advantage that donanemab has is its once-monthly dosing schedule compared with Leqembi’s dosing of once every two weeks. However, a known side effect of these drugs is the development of amyloid-related imaging abnormalities (ARIAs), and the rates of ARIA were lower in Leqembi’s Phase III trials compared to donanemab’s Phase III trials, giving Leqembi a key advantage in its safety profile.

Regardless of any future competition, ensuring continued and better access to Leqembi will be crucial for Biogen moving forward, particularly after the lack of return from the significant investment the company put into Aduhelm.