FDA Approves Tauklarify, Adding a New Way to Track Tau Protein in Alzheimer’s Assessment

Alzheimer’s disease imaging assessment is moving beyond the question of whether amyloid has accumulated toward a more complete pathological picture. The U.S. Food and Drug Administration (FDA) has approved Lantheus’ Tauklarify (florquinitau F 18, also known as MK-6240) for adults with cognitive impairment who are being evaluated for Alzheimer’s disease, enabling physicians to use positron emission tomography (PET) to identify tau neurofibrillary tangles associated with the disease.

Tauklarify is an injectable radioactive diagnostic agent. Participants undergo a brain PET scan after receiving an intravenous injection of approximately 185 MBq, equivalent to 5 mCi. Signals associated with the tracer’s binding to abnormal tau deposits can indicate the distribution of pathology in the images. Compared with amyloid imaging, tau imaging provides another layer of information, helping depict a pathological profile more closely associated with neurodegeneration and cognitive symptoms.

The approval was based on two blinded image-reading studies using images from more than 500 participants across three clinical trials, including cognitively normal individuals, patients with mild cognitive impairment, and patients with mild Alzheimer’s disease dementia. Independent readers received image interpretation training in advance and, without knowing the participants’ clinical information or amyloid PET results, classified the scans as positive or negative for tau pathology.

Depending on the study and reader, Tauklarify’s positive percent agreement with the prespecified reference standard ranged from 68% to 88%, while negative percent agreement ranged from 93% to 99%. However, this reference standard combined cognitive status with amyloid PET rather than using brain tissue pathology as a direct comparison. These figures therefore describe the degree of agreement in interpretation and cannot be directly regarded as diagnostic sensitivity and specificity.

The FDA approval does not turn a single scan into a definitive judgment on Alzheimer’s disease. A positive image does not necessarily confirm that a patient has tau pathology, and a negative result cannot completely rule it out. In addition, its safety and effectiveness have not been established for non-Alzheimer’s tauopathies. The images must still be interpreted together with medical history, cognitive testing, other biomarkers, and clinical judgment.

Tau PET is currently used more often in research, participant selection, and drug development than in routine outpatient testing, and no currently approved therapies directly target tau. Lantheus said it will continue supporting Alzheimer’s treatment programs through its pharmaceutical services business, but it has not committed to immediate large-scale availability and is still evaluating commercialization pathways.

This also limits the approval’s near-term impact on clinical practice. Reuters cited analysts who estimated that the current tau imaging market is worth less than $100 million annually and forecast that Tauklarify sales would remain below $50 million in 2030. For now, its clearest value may lie not in replacing existing tests, but in bringing the tau piece of the pathological puzzle into more clinical trials and more refined assessments.