Two Approved Drugs, Hundreds of Trials, and a New Target: Alzheimer’s at a Turning Point

For decades, Alzheimer’s disease was defined by scientific setbacks and failed clinical trials. That narrative has begun to change. The approvals of the first disease-modifying therapies, advances in diagnostic testing, and growing evidence supporting new therapeutic targets have transformed the field from one searching for proof of concept to one focused on improving access, refining treatment strategies, and expanding the range of available options. As a new wave of clinical data emerges in 2026, researchers and industry leaders are assessing how far the field has progressed—and what challenges remain before these advances can reach patients at scale.

The Drugs That Finally Work

For most of the past thirty years, Alzheimer’s drug development meant failure. Hundreds of trials. Billions of dollars. No approved therapy that changed the course of the disease. That changed in 2023. Then again in 2024. And the pace has not slowed.

The FDA approved lecanemab (Leqembi®) in July 2023 as the first amyloid-targeting antibody to receive traditional approval. The drug, developed by Eisai and Biogen, slowed cognitive decline by 27% at 18 months in the Phase 3 CLARITY AD trial. Donanemab (Kisunla®), developed by Eli Lilly, followed with FDA approval in July 2024. Both drugs target amyloid plaques — the protein deposits in the brain long associated with Alzheimer’s disease.

Neither drug is a cure. Both carry a risk of brain swelling or micro-bleeds called ARIA, which is more common in patients carrying the APOE4 gene. And both remain limited to patients in the earliest stages of the disease. But the clinical significance of having two FDA-approved disease-modifying therapies in this space cannot be overstated: it confirms the amyloid hypothesis well enough to build commercial infrastructure around.

From Hospital to Home: The Delivery Revolution

Getting a biologic infusion every two weeks is a barrier. The field recognized this quickly, and the regulatory response came fast.

In January 2025, the FDA approved monthly IV maintenance dosing for lecanemab — allowing patients who complete 18 months of biweekly treatment to shift to a once-a-month schedule. That alone reduced clinic burden substantially.

Then came the bigger step. In August 2025, the FDA approved LEQEMBI IQLIK — a subcutaneous autoinjector that patients self-administer at home, once weekly. The injection takes approximately 15 seconds. Eisai launched it in the U.S. on October 6, 2025. For a disease that typically affects patients in their 70s and 80s — often with limited mobility and caregiver bandwidth — that shift from infusion center to living room is clinically and practically significant.

Eisai completed the rolling FDA submission in November 2025 for a subcutaneous starting dose — meaning patients could eventually begin treatment at home from day one, without the initial IV phase. That decision is pending. If approved, it removes the largest remaining friction point in lecanemab’s treatment pathway.

The Tau Moment: What Just Happened at Biogen

Amyloid was always one piece of the puzzle. Tau — the second hallmark protein that forms tangles in the Alzheimer’s brain — has been harder to target therapeutically. Until now, no tau-directed therapy had produced both biomarker impact and cognitive benefit in a randomized trial.

That changed on May 14, 2026.

Biogen released topline results from the Phase 2 CELIA study of diranersen (BIIB080), an antisense oligonucleotide (ASO) therapy that targets tau at the mRNA level — reducing tau production rather than clearing existing tangles. The results showed both a reduction in tau pathology and a slowing of clinical decline in early Alzheimer’s patients. CELIA is the first randomized Phase 2 study of a tau-directed therapy to demonstrate both effects simultaneously.

The result did not hit its primary endpoint. The Alzheimer’s Association, in its response, noted that Biogen will continue development based on the encouraging signals — specifically the slowing of cognitive decline and measurable tau reduction in the brain. Full data will be presented at the Alzheimer’s Association International Conference (AAIC) in July 2026.

The FDA granted diranersen Fast Track designation in April 2025, citing its potential to address unmet need in early Alzheimer’s. That designation accelerates review and enables rolling submissions once Phase 3 data matures.

The importance of this result runs beyond Biogen’s pipeline. A tau-directed therapy with clinical signal opens an entirely new treatment layer. Combination approaches — clearing amyloid while simultaneously suppressing tau — are now a more realistic near-term development target than they were before May 14.

The Pipeline: 192 Trials and Growing

The Alzheimer’s drug pipeline in 2026 is the largest in the field’s history. The Alzheimer’s Association’s annual pipeline review, published in early 2026, counts 192 active clinical trials evaluating 158 novel agents. That is up from 182 trials and 138 drugs in 2025. Disease-targeting therapies account for 73% of agents in trials. Cognition-enhancing symptomatic treatments make up 18%, and neuropsychiatric symptom drugs account for 10%.

Eight Phase 3 trials will reach their primary completion date in 2026. Twenty-nine Phase 2 studies will also complete this year. The volume of readouts expected creates what the Alzheimer’s Association describes as the potential for a very active year of clinical news.

The pipeline now extends well beyond amyloid and tau. Trials target neuroinflammation, synaptic function, metabolic pathways, and lifestyle interventions. The field has moved from a single-hypothesis approach to a multi-mechanism model — reflecting a growing scientific consensus that Alzheimer’s disease is heterogeneous and unlikely to respond fully to any single target.

The Diagnostic Shift: Blood Tests Replace Brain Scans

Disease-modifying therapies only work if patients receive them early. That makes diagnosis — and the speed and cost of diagnosis — a central variable in the field’s commercial and clinical trajectory.

Until recently, confirming Alzheimer’s pathology required either a PET scan (expensive, not widely covered) or a lumbar puncture (invasive, uncomfortable). Blood-based biomarkers are changing that arithmetic.

Tests measuring plasma phosphorylated tau (p-tau217) and amyloid beta ratios now achieve diagnostic accuracy that compares favorably to PET and cerebrospinal fluid assays. The global blood-based biomarker diagnostics market for Alzheimer’s stood at approximately $198.72 million in 2026 and is projected to reach $841.9 million by 2035, growing at 17.4% annually.

The Alzheimer’s Drug Discovery Foundation announced Phase 3 of its Diagnostics Accelerator program in March 2026, with an additional $50 million in funding to support next-generation biomarker development, combination therapies, and precision medicine approaches. Better diagnostics do more than improve patient access. They also enable earlier clinical trial enrollment — which accelerates the entire development cycle.

The Market: Where $10 Billion Is Heading

The commercial picture is evolving quickly. The global Alzheimer’s therapeutics market stood at approximately $5.11 billion in 2026 and is expected to reach $10.11 billion by 2034, growing at roughly 9% annually. That projection reflects the current drugs at current uptake rates. It does not fully price in an approved tau therapy, an oral disease-modifying agent, or subcutaneous starting doses expanding the eligible patient base.

Medicare now covers both lecanemab and donanemab. Private insurer coverage remains inconsistent — lecanemab’s list price sits at approximately $26,500 per year, a figure that puts access decisions firmly in the hands of payer policy. The real-world adoption curve for both drugs has been slower than peak projections, partly because the diagnostic infrastructure needed to identify eligible patients (early-stage, amyloid-confirmed) is still scaling.

That gap between approved drug and accessible patient is where the next phase of the field’s development may play out.

What 2026 Sets Up

Two years ago, the field had no approved disease-modifying therapy. Today it has two. The delivery systems are improving. The diagnostic pipeline is accelerating. And a tau-directed therapy just produced the first randomized clinical signal of its kind.

The Alzheimer’s Association pipeline report describes 2026 as potentially one of the most active years for clinical news the field has ever seen. Eight Phase 3 completions will either confirm or challenge current development directions across a range of mechanisms. AAIC in July will be the most consequential single scientific meeting for the Alzheimer’s field in recent memory.

The field is not finished. But it is no longer in the position it occupied for three decades — accumulating failure and hoping the next hypothesis holds. It is accumulating evidence.

Author

Bernice Lottering

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