The US FDA has approved Tauklarify (florquinitau F 18 injection, also known as MK-6240), a radiodiagnostic positron emission tomography (PET) agent for identifying tau neurofibrillary tangle (NFT) pathology in adults with cognitive impairment being evaluated for Alzheimer's disease. The approval gives Bedford, Massachusetts-based Lantheus Holdings (Nasdaq: LNTH) its first tau imaging asset and adds a second FDA-authorized tau PET tracer to a diagnostic category that previously held only one approved agent.
Tauklarify is administered as a single intravenous dose of approximately 185 MBq (5 mCi), with scans interpreted as positive or negative for tau NFT pathology. The label carries a limitation of use: safety and effectiveness have not been established for non-Alzheimer's disease tauopathies. Clinicians are also cautioned that scan results do not independently confirm or exclude tau NFT pathology, and that performance may be lower in patients at earlier pathological stages.
Approval was supported by two blinded read studies drawing on images from more than 500 subjects across three clinical trials, encompassing individuals with mild cognitive impairment, mild Alzheimer's disease dementia, and cognitively unimpaired individuals. In Study 1 (279 subjects), positive percent agreement (PPA) across independent readers ranged from 80% to 88% and negative percent agreement (NPA) from 98% to 99%, with inter-reader agreement of κ = 0.92. In Study 2 (338 subjects), PPA ranged from 68% to 82% and NPA from 93% to 99%, with κ = 0.86. Safety data from 1,734 subjects showed a low adverse event profile; the most common reactions included headache (0.7%) and nausea (0.2%).
Florquinitau F 18 is a fluorine-18-labeled small molecule that crosses the blood-brain barrier and binds to aggregated tau paired helical filaments, enabling PET visualization of NFT distribution