Update on FDA Priority Review of LEQEMBI® IQLIK™ (lecanemab-irmb) Subcutaneous Injection as a Starting Dose for Early Alzheimer's Disease
Rhea-AI Summary
Biogen (NASDAQ: BIIB) and Eisai said the FDA extended the PDUFA action date for the sBLA for once‑weekly LEQEMBI IQLIK subcutaneous starting dose by three months to August 24, 2026 after the agency deemed submitted materials a major amendment.
The FDA has not identified approvability concerns to date; companies cite a comprehensive clinical data package and note prior FDA approval of subcutaneous maintenance dosing on August 26, 2025.
AI-generated analysis. Not financial advice.
Positive
- PDUFA action date set to August 24, 2026
- Companies cite a comprehensive clinical data package for subcutaneous dosing
- Subcutaneous maintenance dosing previously approved on August 26, 2025
- LEQEMBI approved by more than 50 regulatory authorities
Negative
- FDA classified submitted materials as a major amendment, delaying review by three months
- Symptomatic ARIA occurred in 3% and serious ARIA in 0.7% with LEQEMBI
- ARIA (radiographic) observed in 21% of LEQEMBI patients versus 9% placebo
- Intracerebral hemorrhage >1 cm reported in 0.7% with LEQEMBI versus 0.1% placebo
News Market Reaction – BIIB
On the day this news was published, BIIB gained 1.08%, reflecting a mild positive market reaction.
Data tracked by StockTitan Argus on the day of publication.
Key Figures
Market Reality Check
Peers on Argus
BIIB is modestly higher (+0.37%) while key large-cap peers like GSK, BMY, AMGN, PFE, and SNY show small declines between about -0.11% and -0.90%, and no peers appear in the momentum scanner. This points to a company-specific reaction to the LEQEMBI update rather than a sector-wide move.
Historical Context
| Date | Event | Sentiment | Move | Catalyst |
|---|---|---|---|---|
| May 05 | Leadership appointments | Neutral | +1.0% | Jeito Capital announced senior hires supporting business development and talent strategy. |
| Apr 30 | Conference call | Neutral | -1.2% | Stoke Therapeutics scheduled a webcast to discuss Q1 2026 updates. |
| Apr 20 | Asset acquisition deal | Positive | +3.4% | Biogen agreed to acquire felzartamab rights in Greater China with up to $850M consideration. |
| Apr 08 | Conference presentation | Neutral | -1.6% | Stoke Therapeutics announced a presentation at the Needham Virtual Healthcare Conference. |
| Apr 07 | Board appointment | Neutral | +2.4% | Stoke Therapeutics added an experienced drug development executive to its board. |
Recent Biogen-specific deal and pipeline news (e.g., felzartamab agreement) have been met with positive price reactions, while more routine or third-party items show smaller, mixed moves.
Recent disclosures for Biogen highlight active business development and a strengthening financial base. An April 20, 2026 agreement to acquire felzartamab rights in Greater China (potential consideration up to $850 million) saw shares rise about 3.38%. Regulatory filings on April 29, 2026 reported Q1 revenue of $2.48 billion, GAAP EPS of $2.15, and growth driven in part by LEQEMBI. Against this backdrop of expanding neurology and immunology assets, today’s FDA review extension for subcutaneous LEQEMBI fits into an ongoing Alzheimer’s-focused strategy.
Market Pulse Summary
This announcement details a three‑month FDA review extension for LEQEMBI IQLIK, moving the PDUFA date to August 24, 2026, while noting no current approvability concerns. It adds granular safety information, including ARIA in 21% of treated patients vs 9% on placebo and ICH >1 cm in 0.7% vs 0.1%. In context of Biogen’s recent growth in LEQEMBI revenue and broader pipeline investments, investors may watch how regulators balance efficacy with these safety signals.
Key Terms
supplemental biologics license application regulatory
prescription drug user fee act regulatory
pdufa regulatory
cerebral amyloid angiopathy medical
AI-generated analysis. Not financial advice.
As part of the ongoing review process, the agency requested additional information and has determined that it constituted a major amendment to the sBLA, extending the PDUFA date to allow sufficient time for a full review of the additional materials. The FDA has not raised any concerns to date regarding the approvability of LEQEMBI IQLIK as a starting dose.
Eisai and Biogen believe that the comprehensive clinical data package evaluating subcutaneous administration of LEQEMBI across multiple studies and dosing regimens strongly supports the potential use of LEQEMBI IQLIK for initiation therapy, following FDA approval of the subcutaneous maintenance dosing regimen on August 26, 2025.
LEQEMBI has been approved by more than 50 regulatory authorities worldwide, reflecting broad regulatory confidence in LEQEMBI as a treatment option for early Alzheimer's disease.
Eisai and Biogen look forward to ongoing discussions with the FDA as the review progresses and are committed to bringing this important advancement to patients and care partners as quickly as possible to provide greater flexibility and choice in how anti-amyloid treatment is delivered.
INDICATION
LEQEMBI® is indicated for the treatment of Alzheimer's disease (AD). Treatment with LEQEMBI should be initiated in patients with mild cognitive impairment (MCI) or mild dementia stage of disease, the population in which treatment was initiated in clinical trials.
IMPORTANT SAFETY INFORMATION
WARNING: AMYLOID-RELATED IMAGING ABNORMALITIES (ARIA)
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CONTRAINDICATION
Contraindicated in patients with serious hypersensitivity to lecanemab-irmb or to any of the excipients. Reactions have included angioedema and anaphylaxis.
WARNINGS AND PRECAUTIONS
Amyloid-Related Imaging Abnormalities
Medications in this class, including LEQEMBI, can cause ARIA-E, which can be observed on MRI as brain edema or sulcal effusions, and ARIA-H, which includes microhemorrhage and superficial siderosis. ARIA can occur spontaneously in patients with AD, particularly in patients with MRI findings suggestive of cerebral amyloid angiopathy (CAA), such as pretreatment microhemorrhage or superficial siderosis. ARIA-H generally occurs with ARIA-E. Reported ARIA symptoms may include headache, confusion, visual changes, dizziness, nausea, and gait difficulty. Focal neurologic deficits may also occur. Symptoms usually resolve over time.
Incidence of ARIA
Symptomatic ARIA occurred in
Incidence of ICH
ICH >1 cm in diameter was reported in
Risk Factors of ARIA and ICH
ApoE ε4 Carrier Status
Of the patients taking LEQEMBI,
Radiographic Findings of CAA
Neuroimaging findings that may indicate CAA include evidence of prior ICH, cerebral microhemorrhage, and cortical superficial siderosis. CAA has an increased risk for ICH. The presence of an ApoE ε4 allele is also associated with CAA.
The baseline presence of at least 2 microhemorrhages or the presence of at least 1 area of superficial siderosis on MRI, which may be suggestive of CAA, have been identified as risk factors for ARIA. Patients were excluded from Clarity AD for the presence of >4 microhemorrhages and additional findings suggestive of CAA (prior cerebral hemorrhage >1 cm in greatest diameter, superficial siderosis, vasogenic edema) or other lesions (aneurysm, vascular malformation) that could potentially increase the risk of ICH.
Concomitant Antithrombotic or Thrombolytic Medication
In Clarity AD, baseline use of antithrombotic medication (aspirin, other antiplatelets, or anticoagulants) was allowed if the patient was on a stable dose. Most exposures were to aspirin. Antithrombotic medications did not increase the risk of ARIA with LEQEMBI. The incidence of ICH:
Fatal cerebral hemorrhage has occurred in 1 patient taking an anti-amyloid monoclonal antibody in the setting of focal neurologic symptoms of ARIA and the use of a thrombolytic agent.
Additional caution should be exercised when considering the administration of antithrombotics or a thrombolytic agent (e.g., tissue plasminogen activator) to a patient already being treated with LEQEMBI. Because ARIA-E can cause focal neurologic deficits that can mimic an ischemic stroke, treating clinicians should consider whether such symptoms could be due to ARIA-E before giving thrombolytic therapy in a patient being treated with LEQEMBI.
Caution should be exercised when considering the use of LEQEMBI in patients with factors that indicate an increased risk for ICH and, in particular, patients who need to be on anticoagulant therapy or patients with findings on MRI that are suggestive of CAA.
Radiographic Severity With LEQEMBI
Most ARIA-E radiographic events occurred within the first 7 doses, although ARIA can occur at any time, and patients can have >1 episode. Maximum radiographic severity of ARIA-E with LEQEMBI was mild in
Monitoring and Dose Management Guidelines
Baseline brain MRI and periodic monitoring with MRI are recommended. Enhanced clinical vigilance for ARIA is recommended during the first 14 weeks of treatment. Depending on ARIA-E and ARIA-H clinical symptoms and radiographic severity, use clinical judgment when considering whether to continue dosing or to temporarily or permanently discontinue LEQEMBI. If a patient experiences ARIA symptoms, clinical evaluation should be performed, including MRI if indicated. If ARIA is observed on MRI, careful clinical evaluation should be performed prior to continuing treatment.
Hypersensitivity Reactions
Hypersensitivity reactions, including angioedema, bronchospasm, and anaphylaxis, have occurred with LEQEMBI. Promptly discontinue the infusion upon the first observation of any signs or symptoms consistent with a hypersensitivity reaction and initiate appropriate therapy.
Infusion-Related Reactions (IRRs)
IRRs were observed—LEQEMBI:
IRRs can occur during or after the completion of infusion. In the event of an IRR during the infusion, the infusion rate may be reduced or discontinued, and appropriate therapy initiated as clinically indicated. Consider prophylactic treatment prior to future infusions with antihistamines, acetaminophen, nonsteroidal anti-inflammatory drugs, or corticosteroids.
ADVERSE REACTIONS
- The most common adverse reactions reported in ≥
5% with LEQEMBI infusion every 2 weeks and ≥2% higher than placebo were IRRs (LEQEMBI:26% ; placebo:7% ), ARIA-H (LEQEMBI:14% ; placebo:8% ), ARIA-E (LEQEMBI:13% ; placebo:2% ), headache (LEQEMBI:11% ; placebo:8% ), superficial siderosis of central nervous system (LEQEMBI:6% ; placebo:3% ), rash (LEQEMBI:6% ; placebo:4% ), and nausea/vomiting (LEQEMBI:6% ; placebo:4% ) - Safety profile of LEQEMBI IQLIK for maintenance treatment was similar to LEQEMBI infusion. Patients who received LEQEMBI IQLIK experienced localized and systemic (less frequent) injection-related reactions (mild to moderate in severity)
LEQEMBI (lecanemab-irmb) is available:
- Intravenous infusion: 100 mg/mL
- Subcutaneous injection: 200 mg/mL
Please see full Prescribing Information for LEQEMBI, including Boxed WARNING.
MEDIA CONTACTS | |
Eisai Co., Ltd. Public Relations Department TEL: +81 (0)3-3817-5120 Eisai Inc. ( Julie Edelman +1-862-213-5915 Julie_Edelman@eisai.com | Biogen Inc. Madeleine Shin +1-781-464-3260 |
INVESTOR CONTACTS | |
Eisai Co., Ltd. Investor Relations Department TEL: +81 (0) 3-3817-5122 | Biogen Inc. Tim Power + 1-781-464-2442 |
Notes to Editors
- About lecanemab (generic name, brand name: LEQEMBI®)
Lecanemab is the result of a strategic research alliance between Eisai and BioArctic. It is a humanized immunoglobulin gamma (IgG1) monoclonal antibody directed against aggregated soluble (protofibril) and insoluble forms of amyloid-beta (Aβ).
Lecanemab has been approved in 53 countries and regions includingJapan ,the United States ,China ,Europe ,South Korea ,Taiwan , andSaudi Arabia , and is under regulatory review in 6 countries. Following the initial phase with treatment every two weeks for 18 months, intravenous (IV) maintenance dosing with treatment every four weeks was approved in 7 countries including theU.S. ,China , theUK , and others, and applications have been filed in 12 countries and regions. TheU.S. FDA approved Eisai's Biologics License Application (BLA) for subcutaneous maintenance dosing with LEQEMBI IQLIK in August 2025. In November 2025, an application for a subcutaneous injectable formulation inJapan was submitted. In January 2026, the Biologics License Application (BLA) for the subcutaneous formulation was accepted inChina . In December 2025, lecanemab (IV) has been included in the "Commercial Insurance Innovative Drug List", recently introduced by the National Healthcare Security Administration (NHSA) ofChina .
Since July 2020, the Phase 3 clinical study (AHEAD 3-45) for individuals with preclinical AD, meaning they are clinically normal and have intermediate or elevated levels of amyloid in their brains, is ongoing. AHEAD 3-45 is conducted as a public-private partnership between the Alzheimer's Clinical Trial Consortium that provides the infrastructure for academic clinical trials in AD and related dementias in theU.S , funded by the National Institute on Aging, part of the National Institutes of Health, Eisai, and Biogen. Since January 2022, the Tau NexGen clinical study for Dominantly Inherited AD (DIAD), that is conducted by Dominantly Inherited Alzheimer Network Trials Unit (DIAN-TU), led by Washington University School of Medicine inSt. Louis , is ongoing and includes lecanemab as the backbone anti-amyloid therapy. - About Protofibrils
Protofibrils are thought to be the most toxic Aβ species that contribute to brain damage in AD and play a major role in the cognitive decline of this progressive and devastating disease. Protofibrils can cause neuronal and synaptic damage in the brain, which can subsequently adversely affect cognitive function through multiple mechanisms. The mechanism by which this occurs has been reported not only by increasing the formation of insoluble Aβ plaques, but also by directly damaging signaling between neurons and other cells. It is believed that reducing protofibrils may reduce neuronal damage and cognitive impairment, potentially preventing the progression of AD. - About the Collaboration between Eisai and Biogen for AD
Eisai and Biogen have been collaborating on the joint development and commercialization of AD treatments since 2014. Eisai serves as the lead of lecanemab development and regulatory submissions globally with both companies co-commercializing and co-promoting the product and Eisai having final decision-making authority. - About the Collaboration between Eisai and BioArctic for AD
Since 2005, Eisai and BioArctic have had a long-term collaboration regarding the development and commercialization of AD treatments. Eisai obtained the global rights to study, develop, manufacture and market lecanemab for the treatment of AD pursuant to an agreement with BioArctic in December 2007. The development and commercialization agreement on the antibody lecanemab back-up was signed in May 2015. - About Eisai Co., Ltd.
Eisai's Corporate Concept is "to give first thought to patients and people in the daily living domain, and to increase the benefits that health care provides." Under this Concept (also known as human health care (hhc) Concept), we aim to effectively achieve social good in the form of relieving anxiety over health and reducing health disparities. With a global network of R&D facilities, manufacturing sites and marketing subsidiaries, we strive to create and deliver innovative products to target diseases with high unmet medical needs, with a particular focus in our strategic areas of Neurology and Oncology.
In addition, we demonstrate our commitment to the elimination of neglected tropical diseases (NTDs), which is a target (3.3) of the United Nations Sustainable Development Goals (SDGs), by working on various activities together with global partners.
For more information about Eisai, please visit www.eisai.com (for global headquarters: Eisai Co., Ltd.), and connect with us on X, LinkedIn and Facebook. The website and social media channels are intended for audiences outside of theUK andEurope . For audiences based in theUK andEurope , please visit www.eisai.eu and Eisai EMEA LinkedIn. - About Biogen
Founded in 1978, Biogen is a leading biotechnology company that pioneers innovative science to deliver new medicines to transform patient's lives and to create value for shareholders and our communities. We apply deep understanding of human biology and leverage different modalities to advance first-in-class treatments or therapies that deliver superior outcomes. Our approach is to take bold risks, balanced with return on investment to deliver long-term growth.
The company routinely posts information that may be important to investors on its website at www.biogen.com. Follow Biogen on social media – Facebook, LinkedIn, X, YouTube.
Biogen Safe Harbor
This news release contains forward-looking statements, including about the potential clinical effects of lecanemab; the potential benefits, safety and efficacy of lecanemab; potential regulatory discussions, submissions and approvals and the timing thereof including for lecanemab-irmb (LEQEMBI IQLIK); the treatment of Alzheimer's disease; the anticipated benefits and potential of Biogen's collaboration arrangements with Eisai; the potential of Biogen's commercial business and pipeline programs, including lecanemab; and risks and uncertainties associated with drug development and commercialization. These forward-looking statements may be accompanied by such words as "aim," "anticipate," "assume," "believe," "contemplate," "continue," "could," "estimate," "expect," "forecast," "goal," "guidance," "hope," "intend," "may," "objective," "plan," "possible," "potential," "predict," "project," "prospect," "should," "target," "will," "would," and other words and terms of similar meaning. Drug development and commercialization involve a high degree of risk, and only a small number of research and development programs result in commercialization of a product. Results in early-stage clinical trials may not be indicative of full results or results from later stage or larger scale clinical trials and do not ensure regulatory approval. You should not place undue reliance on these statements. Given their forward-looking nature, these statements involve substantial risks and uncertainties that may be based on inaccurate assumptions and could cause actual results to differ materially from those reflected in such statements.
These forward-looking statements are based on management's current beliefs and assumptions and on information currently available to management. Given their nature, we cannot assure that any outcome expressed in these forward-looking statements will be realized in whole or in part. We caution that these statements are subject to risks and uncertainties, many of which are outside of our control and could cause future events or results to be materially different from those stated or implied in this document, including, among others, uncertainty of long-term success in developing, licensing, or acquiring other product candidates or additional indications for existing products; expectations, plans and prospects relating to product approvals, approvals of additional indications for our existing products, sales, pricing, growth, reimbursement and launch of our marketed and pipeline products; our ability to effectively implement our corporate strategy; the successful execution of our strategic and growth initiatives, including acquisitions; the risk that positive results in a clinical trial may not be replicated in subsequent or confirmatory trials or success in early stage clinical trials may not be predictive of results in later stage or large scale clinical trials or trials in other potential indications; risks associated with clinical trials, including our ability to adequately manage clinical activities, unexpected concerns that may arise from additional data or analysis obtained during clinical trials, regulatory authorities may require additional information or further studies, or may fail to approve or may delay approval of our drug candidates; the occurrence of adverse safety events, restrictions on use with our products, or product liability claims; and any other risks and uncertainties that are described in other reports we have filed with the
These statements speak only as of the date of this press release and are based on information and estimates available to us at this time. Should known or unknown risks or uncertainties materialize or should underlying assumptions prove inaccurate, actual results could vary materially from past results and those anticipated, estimated or projected. Investors are cautioned not to put undue reliance on forward-looking statements. A further list and description of risks, uncertainties and other matters can be found in our Annual Report on Form 10-K for the fiscal year ended December 31, 2025 and in our subsequent reports on Form 10-Q, Except as required by law, we do not undertake any obligation to publicly update any forward-looking statements whether as a result of any new information, future events, changed circumstances or otherwise.
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From time to time, we have used, or expect in the future to use, our investor relations website (investors.biogen.com), the Biogen LinkedIn account (linkedin.com/company/biogen-) and the Biogen X account (https://x.com/biogen) as a means of disclosing information to the public in a broad, non-exclusionary manner, including for purposes of the SEC's Regulation Fair Disclosure (Reg FD). Accordingly, investors should monitor our investor relations website and these social media channels in addition to our press releases, SEC filings, public conference calls and websites, as the information posted on them could be material to investors.
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SOURCE Eisai Co., Ltd.