Following the news that the FDA has approved Eli Lilly’s anti-amyloid beta (Aβ) monoclonal antibody (mAb) Kisunla (donanemab) for the treatment of patients with mild cognitive impairment (MCI) or mild Alzheimer’s disease (AD);

Philippa Salter, Managing Neurology Analyst at GlobalData, a leading data and analytics company, offers her view:

“After facing several delays, Lilly’s Kisunla is the second disease-modifying therapy (DMT) to reach the AD market in the US, providing competition for Eisai/Biogen’s Leqembi (Lecanemab), which received full FDA approval in July 2023.

“GlobalData forecasts that Leqembi and Kisunla could generate global (US, France, Germany, Italy, Spain, UK, Japan, and China) sales of approximately $3.5 billion and $2.0 billion in 2030, respectively.

“Despite gaining approval nearly a year ago, uptake of Leqembi has been slow. While the approval of Kisunla will provide further confidence in the anti-Aβ mAbs, which could help drive uptake of both drugs, many of the challenges faced by Leqembi will also apply to Kisunla.

“Both drugs require the presence of amyloid pathology to be confirmed prior to initiation via a positron emission tomography (PET) scan to assess levels of amyloid in the brain. Additionally, a magnetic resonance imaging (MRI) scan is required before treatment, with further MRIs recommended prior to subsequent infusions with earlier MRIs recommended for Kisunla. Access to PET and MRI scans is a key limiting factor for the uptake of these drugs.

“The MRIs help monitor for a known side effect of these drugs, the development of amyloid-related imaging abnormalities (ARIAs). The rates of ARIA were lower in Leqembi’s Phase III trials compared to Kisunla’s Phase III trials, giving Leqembi a key advantage in its safety profile.

“However, an important competitive advantage for Kisunla is its once-monthly dosing schedule compared with Leqembi’s dosing of once every two weeks. Further, despite having a higher annual cost of therapy of $32,000 for Kisunla compared with $26,500 per year for Leqembi, Lilly states that in the long term Kisunla will be cheaper and more convenient for patients since they won’t have to take the drug indefinitely, something that was included in the FDA label, which states that once amyloid plaques have been reduced to minimal levels on PET imaging, stopping treatment can be considered.

“While there are clear advantages in not having to take a drug indefinitely, many questions have been raised about what happens once donanemab therapy is stopped. Further real-world evidence and clinical trial data will be key for physicians to feel confident in stopping treatment with Kisunla and therefore vital for the success of the drug.”