A real-world study found that most patients receiving the anti-amyloid therapy Leqembi (lecanemab) remained clinically stable after 17 months, with 75.9% remaining at the same stage and 6.6% improving by one disease stage, for an overall 82.5% stable or improved, reports Medical News Today.
Clinical stability was reported regardless of sex, race, ethnicity, or APOE e4 genetic status, suggesting consistent real-world effectiveness across a diverse patient population.
Nearly 87% of participants continued Leqembi treatment, indicating that most patients remained on therapy in routine clinical practice.
Safety was consistent with previous studies, with adverse events occurring in 12.3% of people, with most cases reported as mild and asymptomatic, aligning with the drug’s established safety profile from clinical trials.
At present, there is no cure for Alzheimer’s. And although anti-amyloid therapy aims to reduce the build-up of beta amyloid plaques in the brain, a hallmark of the disease, recent research has questioned the effectiveness of these medications.
While receiving treatment for the condition, maintaining clinical stability is an important goal, allowing an individual to preserve cognitive function, independence, and quality of life for as long as possible.
This latest real-world study, presented at the Alzheimer’s Association International Conference (AAIC) 2026, noted that more than three-quarters of people with early Alzheimer’s who received Leqembi remained at the same stage of disease after an average of 17 months of treatment.
The data have not yet undergone peer review or been published in a scientific journal.
What is the LEADER study?
Eisai and Biogen released press statements highlighting findings from the LEADER (Lecanemab in Early Alzheimer’s Disease) study, an ongoing retrospective analysis evaluating how lecanemab performs in routine clinical practice across multiple healthcare centres in the United States.
As an antibody intravenous infusion therapy, Leqembi has FDA approval for treating early Alzheimer’s. This includes people with mild cognitive impairment (MCI) or mild dementia due to Alzheimer’s with elevated beta-amyloid in the brain
Earlier this month, the FDA also approved a supplemental Biologics Licence Application (sBLA) for a once‑weekly LEQEMBI IQLIK subcutaneous injection as an at-home starting dose for early Alzheimer’s disease.
Unlike randomised clinical trials, which test treatments under carefully controlled conditions, the LEADER study was a real-world study examining outcomes in patients receiving treatment as part of standard medical care.
Study findings
The interim analysis included 432 participants who had received at least seven Leqembi infusions and had sufficient follow-up data to assess changes in disease stage.
Researchers reported that treatment outcomes appeared broadly consistent across sex, race, ethnicity, and APOE e4 genetic status, a gene variant associated with an increased risk of Alzheimer’s.
The investigators said 75.9% of patients remained clinically stable over the treatment period, while an additional 6.6% improved by one disease stage. This means that nearly 83% of evaluable participants were either stable or showed improvement after receiving Leqembi for an average of 17 months.
Dung Trinh, MD, an internist at MemorialCare Medical Group and chief medical officer of Healthy Brain Clinic in Irvine, California, who was not involved in the study, told Medical News Today that the most important takeaway was that lecanemab appears feasible to deliver and monitor in routine clinical practice, with 75.9% of evaluable patients remaining in the same broad disease stage and another 6.6% moving from mild dementia to the MCI category after an average of 17 months.
“These findings are encouraging, but stability in this study meant remaining within the same broad clinical stage, not necessarily experiencing no cognitive or functional decline,” Trinh said.
The investigators also found that nearly 87% elected to continue treatment, suggesting a high level of treatment persistence in routine clinical practice.
“Remaining in an earlier stage of Alzheimer’s for longer can be meaningful to patients and families because it may preserve independence, communication, participation in family life, and the ability to make decisions and plans,” Trinh said.
“However, the term clinically stable should be interpreted carefully because patients may still decline within the MCI or mild-dementia stage without progressing to the next category. The finding is therefore an encouraging real-world signal rather than a guarantee of individual benefit, and the patients who moved from mild dementia to MCI should not be described as having experienced a cure or reversal of Alzheimer’s.”
Consistent with previous studies
The safety profile reported in the study was generally consistent with earlier clinical trials and the FDA-approved label.
Amyloid-related imaging abnormalities (ARIA) describe a known side effect of anti-amyloid therapies that can involve brain swelling or small areas of bleeding. This adverse event occurred in 12.3% of participants, but the investigators state that most cases were asymptomatic and mild.
They also reported encouraging findings among those who transitioned to once-monthly intravenous (IV) maintenance dosing.
Of the 432 participants, 155 transitioned to once-every-four-weeks IV maintenance therapy, where 72.3% remained stable and 8.4% improved.
How do findings compare with earlier research?
The CLARITY AD clinical trial previously demonstrated that lecanemab could slow cognitive decline in people with early Alzheimer’s over 18 months compared with a placebo to help establish the drug’s possible clinical benefit.
The new LEADER data provide evidence that the treatment may be similarly effective in everyday clinical settings, where individuals are generally more diverse and may have additional health conditions that are often excluded from clinical trials.
“CLARITY AD and LEADER provide different but complementary forms of evidence,” Trinh noted.
“CLARITY AD offers randomised, placebo-controlled evidence that lecanemab slows cognitive and functional decline on average, while LEADER provides information about how treatment is being delivered in everyday practice, including treatment persistence, safety monitoring, clinical-stage patterns, and the transition to maintenance therapy.
“Randomised trials are the stronger source for determining treatment efficacy, while real-world studies help clinicians understand implementation and patient experience outside the controlled trial environment. LEADER therefore complements the CLARITY AD evidence but does not replace it.”
Cautious interpretation, say experts
Although the findings are encouraging, several study limitations should be considered.
The LEADER study is observational and retrospective rather than a randomised controlled trial. As such, there is no untreated comparison group. Therefore, it is not possible to determine how much of the observed disease stability is attributable directly to the medication.
“Clinicians should view the LEADER findings as supportive and hypothesis-generating rather than proof of a treatment effect. Without an untreated comparison group, it is impossible to determine how many similar patients would have remained in the same disease stage without lecanemab,” pointed out Trinh.
“The retrospective design, broad disease-stage categories, potential inconsistencies in medical records, and requirement that patients receive at least seven infusions may also introduce selection bias by excluding some patients who discontinued treatment earlier because of adverse events, medical issues, logistical barriers, or personal preference.
“The results are most useful as evidence about real-world feasibility, persistence, monitoring and safety,” he noted.
Additionally, disease progression was assessed using clinicians’ evaluations of disease stage rather than standardised cognitive outcome measures alone. The results also represent an interim analysis, meaning additional follow-up may provide a more complete picture of long-term effectiveness and safety.
What this means for future treatment
The researchers plan to continue following participants in the LEADER study to evaluate longer-term outcomes, including treatment persistence, maintenance dosing strategies, and the effectiveness of newer administration approaches, such as subcutaneous formulations currently under investigation.
As disease-modifying therapies for Alzheimer’s become more widely available, real-world studies like LEADER may help clinicians understand who benefits most from treatment and how these therapies perform in settings outside clinical trials.
However, randomised controlled trials remain the strongest form of evidence for determining treatment efficacy, with observational studies viewed as complementary sources of information.
“The results do not fundamentally change treatment eligibility or established safety requirements, but they may give clinicians greater confidence that lecanemab can be integrated into routine care when the necessary diagnostic, imaging, monitoring, and care-co-ordination systems are in place,” said Trinh.
“Decisions should remain individualised and should consider confirmation of amyloid pathology, the expectation that treatment slows rather than stops decline, ARIA and haemorrhage risks, APOE ε4 status, MRI monitoring, anticoagulant or antithrombotic use, treatment burden, patient goals, and caregiver support.
“The findings also reinforce the importance of a coordinated pathway that begins with primary care recognition and evaluation, uses blood-based biomarkers appropriately for triage, includes specialist confirmation and treatment-readiness assessment, and continues with shared follow-up between specialists and primary care,” he added.
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