Blood biomarkers have moved from research tool to diagnostic infrastructure in Alzheimer's disease and related peptide-adjacent conditions. The dominant assays in 2026 measure phosphorylated tau fragments and cleaved amyloid peptides in plasma, allowing rule-in or rule-out of AD pathology through a standard blood draw rather than the amyloid PET imaging or lumbar puncture that older diagnostic pathways required.
Several fresh datasets anchor the 2026 landscape. Roche's Elecsys pTau217 in vitro diagnostic assay (developed with Eli Lilly) received CE Mark on May 12, 2026 as a rule-in/rule-out test for amyloid pathology with the same high and low cutoffs usable across primary and secondary care settings. Eli Lilly's Samantha Burnham, PhD presented AAIC 2026 data (July 15) showing P-tau217 blood assays performed comparably to amyloid PET for identifying AD pathology in cognitively unimpaired individuals. Eisai's etalanetug program at AAIC 2026 (July 13) featured the novel eMTBR-tau243 biomarker, a tau-tangle-specific plasma fragment reduced 78% at 3 months and greater than 90% at 9 months on treatment. NewAmsterdam Pharma's obicetrapib BROADWAY Phase 3 cardiovascular trial showed statistically significant plasma p-tau217 reductions vs placebo in the full analysis set (n=1,535, p=0.025) and ApoE4 carriers (n=367, p=0.022) at 12 months.
Stories here cover plasma biomarker assay development, regulatory milestones, and clinical use across diagnosis and treatment-response monitoring. See [[p-tau217]], [[alzheimers-disease]], and [[tau]] for adjacent threads.
Roche (SIX: ROG) presented new Elecsys plasma phosphorylated-tau 217 (pTau217) blood test performance data at AAIC 2026 in London (July 12-15, 2026) covering both primary care and secondary care settings. The Elecsys pTau217 in vitro diagnostic assay, developed in collaboration with Eli Lilly, received CE Mark certification on May 12, 2026 as an amyloid-pathology rule-in and rule-out test for adults presenting with symptoms of cognitive decline. The same high and low cutoffs of the blood test can be used across primary care (family physicians, general internists) and secondary care (memory clinics, neurology specialty practice) to rule in or rule out amyloid pathology, which simplifies the diagnostic pathway substantially compared with amyloid PET imaging or lumbar puncture. The AAIC 2026 presentations evaluated Elecsys pTau217 performance across both care settings and add real-world diagnostic evidence to the tau-blood-test infrastructure that Eli Lilly's Samantha Burnham anchored earlier in the week with the rule-in-versus-amyloid-PET data set. Roche's AAIC 2026 program spanned undiagnosed Alzheimer's pathology in cardiovascular patients, ApoE4-dependent CETP-inhibitor dose response, and Alzheimer's diagnostic-and-therapeutic integration.
Eli Lilly (NYSE: LLY) presented 16 Alzheimer's disease diagnostic and therapeutic research abstracts at AAIC 2026 in London (July 12-15), including anchor data on the P-tau217 blood biomarker assay. Samantha Burnham, PhD, senior research scientist at Eli Lilly, presented data showing that P-tau217 blood biomarker assays demonstrated strong rule-in performance for identifying Alzheimer's disease pathology, with results indicating that the assays performed comparably to amyloid PET (positron emission tomography) for identifying pathology in cognitively unimpaired individuals. P-tau217 is a phosphorylated fragment of tau protein released from the brain into the bloodstream during Alzheimer's disease pathology; the fragment can be measured with a standard blood draw rather than requiring the specialized PET imaging or lumbar puncture that current Alzheimer's diagnostics rely on. Blood biomarker tests and amyloid PET agents are not yet indicated for use in cognitively unimpaired individuals, but the results generate support for a potentially scalable, accessible alternative to imaging in future early-detection screening. Lilly's therapeutic AAIC 2026 slate also included updated data on donanemab (Kisunla) and the P-tau217-anchored diagnostic pathway that pairs with amyloid-directed treatment.
Eisai announced Monday July 13, 2026 that its investigational anti-microtubule-binding region (MTBR) tau antibody etalanetug (development code E2814) reduced levels of plasma extracellular MTBR-tau243 (eMTBR-tau243), a novel fluid biomarker of Alzheimer's disease tau tangle pathology, in findings presented during a Featured Research Session at AAIC 2026 in London. Etalanetug reduced plasma eMTBR-tau243 by 78% at 3 months and by more than 90% at 9 months. The biomarker was largely absent in healthy adults and detected only in patients with dominantly inherited Alzheimer's disease (DIAD), suggesting it reflects disease-related tau pathology at the pathological source (neurofibrillary tangle formation) rather than tau physiology broadly. eMTBR-tau243 consists of tau fragments that include amino acid residue 243 and MTBR sequences, arising during the formation of neurofibrillary tangles, and can now be measured with a blood test to track tau pathology non-invasively. Etalanetug is Eisai's second-generation Alzheimer's antibody program beyond lecanemab (LEQEMBI, amyloid protofibril-directed), extending the company's franchise from amyloid to tau.