The FDA approved Leqembi IQLIK as a once-weekly subcutaneous injection that patients can start with on day one, rather than beginning treatment with IV infusions. For people already diagnosed with mild cognitive impairment (MCI) or mild dementia due to Alzheimer's, this approval changes several decisions about how to start, continue, or switch delivery methods for lecanemab.
The FDA approved LEQEMBI IQLIK (lecanemab-irmb) on July 13, 2026, specifically for adults with MCI or mild dementia caused by Alzheimer's disease. Lecanemab is an anti-amyloid antibody that targets the protein buildup associated with Alzheimer's progression. Before this approval, every patient had to begin treatment through IV infusions at an infusion center; now a prescriber can start a newly diagnosed patient on at-home subcutaneous injections from the very first dose.
Medical information disclaimer: This article is for general educational purposes only and does not provide medical advice, diagnosis, or treatment. Always consult a physician or other qualified health professional about symptoms, medications, tests, or treatment decisions.
Table of Contents
- What Changed With the Day-One Approval
- Switching Between IV and Subcutaneous Mid-Treatment
- Weighing the Side-Effect Tradeoff Before Switching
- Required Testing Before Starting or Switching
- The Maintenance Decision at 18 Months
- Frequently Asked Questions
What Changed With the Day-One Approval
The new regimen delivers 500 mg once weekly as two consecutive 250 mg injections, each taking about 15 seconds. According to NeurologyLive/PharmaTimes, this replaces the prior requirement that every patient begin treatment on IV infusions before ever qualifying for subcutaneous dosing. The commercial rollout in the United States began in late August 2026.
Biogen and Eisai's press release describes the drug as dispensed through specialty pharmacy, not through infusion-center administration, which means a newly diagnosed patient can potentially avoid infusion-center visits entirely during the initiation phase. This is a change in logistics and access, not a change in who qualifies for lecanemab. The diagnostic requirements for starting treatment — confirmed amyloid pathology and a diagnosis of MCI or mild dementia due to Alzheimer's — remain the same regardless of which delivery method a patient chooses.
Switching Between IV and Subcutaneous Mid-Treatment
Patients do not have to commit to one delivery method for the entire course of treatment. Biogen and Eisai confirm that patients may switch between IV and subcutaneous administration at any point, so someone who started on IV infusions is not required to finish induction that way. This matters for people currently partway through IV induction who find the infusion schedule difficult to maintain — because of travel distance to an infusion center, time off work, or simple preference for at-home dosing.
A caregiver managing someone else's appointments may find switching to weekly at-home injections considerably easier to coordinate than recurring infusion-center visits. Data presented at AAIC 2026 give some basis for expecting comparable results across the two delivery methods. The fixed 500 mg weekly subcutaneous dose produced drug exposure at 104% of the IV lecanemab dose given at 10 mg/kg every two weeks, according to Eisai's AAIC 2026 presentation, supporting the expectation that efficacy should be similar between routes.
Weighing the Side-Effect Tradeoff Before Switching
One of the clearest differences between the two delivery methods is the rate of injection-related reactions. The same AAIC 2026 presentation reported that about 26% of IV-treated patients experienced systemic infusion reactions, compared with under 2% of subcutaneous-treated patients, according to Eisai's data.
A separate real-world observational study, LEADER, found that 72.5% of IV-treated patients remained clinically stable over a mean follow-up of 520 days, compared with 85.7% of subcutaneous-treated patients, as reported by Healio. Because this is an observational comparison rather than a randomized trial, it should be read as a signal worth discussing with a prescriber rather than a guarantee of better outcomes on the subcutaneous route. Patients weighing a switch should raise both pieces of evidence with their care team: the lower reaction rate on subcutaneous dosing, and the real-world stability data, alongside their own tolerance for infusion visits versus weekly self-injections or caregiver-administered injections.
Required Testing Before Starting or Switching
Regardless of which delivery method a patient uses, the prescribing information requires two steps before starting treatment: ApoE ε4 genotype testing and a baseline brain MRI. According to the U.S.
prescribing information, this is because ApoE ε4 homozygotes face a higher risk of ARIA (amyloid-related imaging abnormalities), a boxed-warning risk that can be serious or fatal. Anyone considering a switch from IV to subcutaneous dosing, or a newly diagnosed patient choosing subcutaneous initiation, should confirm with their prescriber that genotype testing and baseline MRI timing are already documented or scheduled. The Epocrates launch summary notes that patients should also confirm specialty-pharmacy logistics before switching routes, since the drug is now dispensed differently than IV formulations administered at infusion centers.
The Maintenance Decision at 18 Months
The new initiation approval does not change what happens after 18 months of treatment. Patients on either IV or subcutaneous initiation move to maintenance dosing at that point: 360 mg subcutaneous weekly, approved August 29, 2025, or IV infusion once every four weeks, according to FDA and Biogen's announcement.
People currently approaching the 18-month mark on IV induction should know this maintenance choice was already available before the day-one subcutaneous approval and remains unchanged by it. The new approval affects only how someone starts treatment, not the maintenance dosing options available once induction is complete.
- Confirm ApoE ε4 genotype testing and baseline MRI are complete before starting or switching delivery methods.
- Ask about specialty-pharmacy dispensing logistics if switching from infusion-center IV dosing.
- Discuss the AAIC 2026 reaction-rate data (26% IV versus under 2% subcutaneous) with a prescriber when weighing a switch.
- Remember that the 18-month maintenance decision (360 mg weekly subcutaneous or IV every four weeks) is unaffected by this approval.
Frequently Asked Questions
Can someone already partway through IV infusions switch to subcutaneous injections?
Yes. Biogen and Eisai confirm patients may switch between IV and subcutaneous administration at any point in treatment, so finishing IV induction is not required.
Does starting on subcutaneous dosing skip the required safety testing?
No. The prescribing information requires ApoE ε4 genotype testing and a baseline brain MRI before starting treatment by any route, because of ARIA risk.
Is the subcutaneous dose as effective as the IV dose?
AAIC 2026 data showed the subcutaneous initiation dose produced drug exposure at 104% of the IV dose, supporting comparable efficacy expectations.
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