LEQEMBI (LECANEMAB) – WHAT IT IS AND HOW IT IS USED
Leqembi (generic name lecanemab) is an FDA-approved treatment for early Alzheimer’s disease and mild cognitive impairment due to Alzheimer’s. It is not a cure. Its purpose is to slow the rate of cognitive decline by reducing beta-amyloid plaque in the brain.

TYPICAL TREATMENT REGIMEN
Leqembi is given as an intravenous infusion. The standard dosing schedule is one infusion every two weeks over approximately one hour. Treatment is ongoing and long-term. After about eighteen months, some patients may transition to less frequent IV dosing or weekly under-the-skin injections. This makes the regimen cyclic with repeated infusion visits.

DIAGNOSTIC AND SAFETY SCREENING
Before starting treatment, patients are evaluated to confirm the diagnosis and determine safety. This can include cognitive testing, amyloid confirmation (PET scan or spinal fluid biomarkers), and a baseline MRI. APOE genetic testing may be used to determine risk for treatment-related complications.

WHY MRI MONITORING IS REQUIRED
Leqembi can cause ARIA (Amyloid-Related Imaging Abnormalities), which are changes visible on MRI involving brain swelling or small brain hemorrhages. Many cases have no symptoms, which is why scheduled MRI scans are built into the treatment plan.
Standard MRI monitoring includes:
A baseline MRI before the first infusion
Follow-up MRIs before the third, fifth, seventh, and fourteenth infusions
Additional MRI between the second and third infusion due to early-phase safety risk
More MRIs may be ordered if symptoms such as headaches or neurological changes occur.

INFUSION-SITE EFFECTS
Because Leqembi is administered through a peripheral IV line, usually in the hand or forearm, infusion-site bruising, mild swelling, or tenderness are common and expected with repeated access.

OTHER FOLLOW-UP TESTING
Follow-up may include:
Laboratory tests
Cognitive assessments
Physical and neurological exams

KEY POINTS
Drug name: Leqembi (lecanemab)
Mechanism: targeted removal of beta-amyloid plaque
Goal: slow cognitive decline in early disease
Modality: intravenous infusion
Interval: every two weeks
Safety monitoring: multiple scheduled MRIs
Infusion-site bruising is common