Eisai is presenting significant clinical effectiveness data on lecanemab this weekend at the Alzheimer’s Association International Conference (AAIC) 2026 in London, with presentations running from July 12-15. The company will unveil real-world evidence spanning three years after the medication’s initial approval, including unprecedented data on home-based subcutaneous administration and long-term treatment persistence. For example, results from the LEADER study—tracking over 10,000 patients across diverse US clinical settings—will show how lecanemab performs when given in real-world conditions rather than controlled trials, with evidence that patients maintain the treatment at high rates over extended periods. The clinical data being unveiled addresses critical questions that have emerged since lecanemab’s approval: how do patients actually tolerate this treatment outside of clinical trials, what happens when they switch to maintenance dosing, and does the newer subcutaneous formulation work as expected in home settings? These presentations represent the first large-scale, real-world effectiveness evidence for anti-amyloid monoclonal antibodies in Alzheimer’s disease, moving beyond Phase III trial data to show what actually happens in everyday clinical practice.
Table of Contents
- What Clinical Data on Lecanemab Is Being Presented at AAIC 2026?
- Real-World Evidence from Three Years of Lecanemab Use
- Subcutaneous Lecanemab and At-Home Administration
- Treatment Continuation Rates and Patient Persistence with Lecanemab
- Limitations and Considerations in the Real-World Evidence
- The AHEAD 3-45 Prevention Trial and Preclinical Alzheimer’s Disease
- Maintenance Dosing Every Four Weeks and Practical Treatment Planning
What Clinical Data on Lecanemab Is Being Presented at AAIC 2026?
Eisai will present multiple layers of clinical evidence across the conference weekend. On Sunday, July 12, emerging evidence on the subcutaneous formulation takes center stage, with presentations covering clinical trial results and patient experience data from those receiving at-home injections.
The most substantial presentation comes Tuesday, July 14, at 4:15-5:45pm BST, when LEADER study results will be detailed—this real-world analysis includes data from 10,763 individuals who met criteria for continuous healthcare encounters, drawn from 13,388 total patients who received at least one intravenous lecanemab treatment between January 6, 2023, and November 30, 2025. The presentations will focus on practical treatment questions: maintenance dosing schedules with intravenous administration every four weeks, and the first reported findings of subcutaneous lecanemab administration in home settings. This represents a shift in how anti-amyloid therapy is being studied—moving from asking “does it work” to asking “how do patients use it, and how often do they stay on it?” The real-world nature of the LEADER data means it includes patients from diverse clinical settings and includes the full spectrum of tolerability issues, adherence challenges, and practical barriers that don’t always appear in controlled trials.
Real-World Evidence from Three Years of Lecanemab Use
The LEADER study’s 10,763-patient analysis population offers an important reality check on how lecanemab performs outside the controlled trial environment. These patients were selected from a larger group of 13,388 who received at least one IV treatment, meaning the analysis represents those with continuous healthcare engagement—a meaningful distinction, as patients who drop out of healthcare systems entirely aren’t captured. This limitation should be noted: the LEADER cohort may skew toward patients with more stable living situations, access to regular medical appointments, and fewer comorbidities that might interrupt their care.
The three-year timeframe—from January 6, 2023, when lecanemab gained approval, through November 30, 2025—means this data spans the medication’s first full years in clinical use, capturing early prescribing patterns, dosing adjustments, and patient discontinuations. Real-world studies reveal tolerability issues that don’t always emerge at trial scale; for example, amyloid-related imaging abnormalities (ARIA)—brain changes visible on MRI that can include microhemorrhages or microinfarcts—may show different frequencies or severities when given to unselected patient populations compared to carefully screened trial participants. The maintenance dosing regimen of IV treatment every four weeks will be examined across this diverse population, offering evidence on whether this less frequent schedule improves adherence compared to more frequent dosing.
Subcutaneous Lecanemab and At-Home Administration
The introduction of a subcutaneous formulation represents a major practical shift for patients and caregivers. Lecanemab as a subcutaneous injection allows administration at home rather than requiring infusion center visits, potentially reducing treatment burden and improving accessibility for patients with mobility limitations or those living far from specialized Alzheimer’s clinics. Sunday’s presentations will detail clinical trial evidence on this formulation and, importantly, the first real-world patient experience data from those receiving injections at home.
Home administration carries different considerations than infusion center treatment. Patients or caregivers must administer the injection themselves or arrange in-home nursing, and monitoring for injection site reactions or systemic adverse events becomes distributed across home environments rather than centralized in clinics. The data being presented on Sunday will address key questions: are adverse events comparable to IV treatment, and do patients report better adherence or quality of life with home-based administration? The inclusion of “practical use considerations” in Sunday’s session title suggests the presentations will go beyond efficacy to discuss real-world implementation challenges and patient preferences.
Treatment Continuation Rates and Patient Persistence with Lecanemab
One of the most striking findings from the Phase III Clarity AD trial was that 94 percent of patients who completed 18 months of lecanemab chose to continue maintenance treatment. This continuation rate is notably high for a medication requiring regular infusions or injections, particularly given that this is treatment for a disease where cognitive decline is inevitable even on therapy—patients aren’t seeing dramatic reversal of symptoms but rather a slowing of decline. This 94 percent figure provides important context for the LEADER study: if Phase III patients continued at such high rates, the real-world LEADER population offers evidence on whether this persistence holds across a broader, less carefully selected group of patients.
The maintenance dosing schedule of IV treatment every four weeks, compared to the more frequent induction phase, likely influences continuation rates. Less frequent dosing reduces treatment burden and allows patients more time between appointments, potentially explaining why many patients opt to continue. The real-world LEADER data will show how this plays out in practice: whether patients miss maintenance doses, whether clinic visit frequency affects adherence, and whether social factors—insurance coverage, transportation, caregiver support—shape continuation rates differently than they appeared in controlled trials.
Limitations and Considerations in the Real-World Evidence
The LEADER analysis population of 10,763 out of 13,388 treated patients means approximately 4,625 individuals who received at least one lecanemab treatment are not included in the primary analysis. These excluded patients merit careful consideration: they may represent those who discontinued early due to adverse events, lack of clinical benefit, or practical barriers like difficulty accessing follow-up care. Without understanding this discontinuation population, the 94 percent continuation rate and other persistence metrics may overestimate how well patients tolerate lecanemab in everyday practice.
The requirement for “continuous healthcare encounters” in the LEADER cohort also introduces selection bias. Patients with significant cognitive decline, limited access to healthcare infrastructure, unstable housing, or complex medical comorbidities may fall out of continuous healthcare and disappear from real-world registries. Real-world evidence is sometimes cleaner but narrower than it appears; the LEADER data tells us how lecanemab works for patients who stay engaged with healthcare systems, not necessarily how it works for those who don’t. Additionally, real-world studies lack the imaging surveillance of clinical trials—ARIA rates may be systematically under- or over-reported if not all patients receive regular MRI monitoring.
The AHEAD 3-45 Prevention Trial and Preclinical Alzheimer’s Disease
Eisai will also present updates on the AHEAD 3-45 trial, a Phase 3 study examining lecanemab in preclinical Alzheimer’s disease—patients with brain amyloid pathology but no cognitive symptoms. This 216-week trial (over four years) represents a major shift in how anti-amyloid therapy is being tested: instead of treating symptomatic patients, researchers are attempting to prevent symptom onset in cognitively normal individuals. Presentations at AAIC 2026 will include updates on participant retention and engagement in this long-duration prevention trial.
Participant retention over four years is a critical metric in prevention trials, because patients have no symptoms motivating them to continue treatment, and any adverse effects directly outweigh perceived benefits. The AHEAD 3-45 updates will indicate whether preclinical patients stay enrolled and continue treatment at rates comparable to symptomatic patients in LEADER or Clarity AD. This data shapes the future of anti-amyloid therapy: if prevention trials show good retention and emerging efficacy in delaying cognitive decline onset, the treatment paradigm shifts toward identifying and treating asymptomatic amyloid-positive individuals. If retention is poor, it signals that asymptomatic individuals may not accept the burden of regular infusions or injections without symptoms driving their motivation.
Maintenance Dosing Every Four Weeks and Practical Treatment Planning
The maintenance schedule of intravenous lecanemab every four weeks represents a substantial commitment for patients and caregivers. This monthly infusion means approximately 13 clinic visits per year, requiring coordination around work schedules, transportation, and caregiver availability. The LEADER study will show whether this frequency is sustainable across diverse patient populations—whether employed patients can manage monthly clinic visits, whether patients with limited transportation access maintain their appointments, and whether insurance coverage barriers affect adherence to this schedule.
The first reported findings of at-home subcutaneous administration offer a potential solution to visit burden for some patients, though they introduce different challenges. At-home injections mean patients or caregivers must manage medication storage, injection technique, and monitoring for local or systemic reactions without immediate clinical supervision. Clinicians and patients choosing between IV maintenance every four weeks and subcutaneous at-home administration will need data on these practical trade-offs—data that Sunday’s presentations at AAIC 2026 will provide from actual patient experience.
