After winning full FDA nod for Leqembi, Eisai touts 'promising' study on subcutaneous version

Right on the heels of an FDA approval for the closely watched Alzheimer's disease drug Leqembi in an intravenous dose, Eisai is touting "promising" findings that the company says support the case for a subcutaneous version.

During a presentation at the Alzheimer's Association International Conference 2023, researchers shared an exposure/bioavailability and modeling study comparing the two dosing forms of Leqembi. A subcutaneous dose of the Alzheimer's drug would be situated under the skin and allow for wider uptake of the drug given that it would not need to be administered at infusion centers. 

In the study, the subcutaneous formulation's "bioavailability," or the amount of active drug that enters the blood circulation, was about 50% of the intravenous form, Eisai said in a release.

The team concluded that a fixed, subcutaneous dose of 720 mg weekly "may potentially result in comparable exposure … and efficacy" as the intravenous version at the recommended 10-mg/kg dose given every other week.

Further, models have shown that a common—and sometimes serious—side effect of the drug, called amyloid-related imaging abnormalities with edema/effusion (ARIA-E), is related to elevated concentrations of the drug in the blood. This means that because the subcutaneous dose won't have similar maximum concentrations, the under-the-skin version may be associated with a "lower incidence of ARIA-E," Eisai said.

The Japanese drugmaker described the results as "promising" and said the subcutaneous dose may represent "a potential new option for administering therapy."

The company plans to release more details from the presentation on its website Thursday evening.

The findings come two weeks after Eisai and its partner Biogen scored a full FDA approval for their drug, enabling wider Medicare coverage and allowing them to start their launch at a larger scale. Before the full FDA nod, the agency had granted an accelerated approval in January, which limited the drug's reach to Medicare patients.

As for the subcutaneous version, Eisai previously said it would file for FDA approval in its current fiscal year, which started April 1.