FDA Accepts New Drug Application for Tau PET Imaging Agent MK-6240 in Alzheimer Disease

According to a new announcement, the FDA has accepted Lantheus’ new drug application (NDA) for MK-6240, a PET imaging agent designed to target aggregated tau protein in patients with suspected Alzheimer disease (AD). The FDA has set a PDUFA date of August 13, 2026, for the imaging agent, which has received fast track designation and is currently being used in nearly 100 active clinical trials.¹

MK-6240, considered a PET imaging tracer, may be potentially used to visualize and quantify tau burden in vivo, as well as help select patients based on tau pathology for targeted trials. In non-AD tau disorders, negative MK-6240 does not exclude tau pathology, rather, it may reflect mismatch between tracer specificity and tau confirmation. As anti-tau therapies continue to emerge in the coming years, the belief is that imaging agents like MK-6240 could serve as biomarkers for target engagement, disease progression, and treatment effect.

The NDA submission is backed by pivotal data from 2, phase 3 studies, both of which met their co-primary end points of sensitivity and specificity to detect tau neurofibrillary tangles (NFTs). Data from the studies, announced earlier this year, reinforced the potential of MK-6240 as a diagnostic tool for patients with AD.

"We’re pleased the FDA has accepted our Fast Track application for MK-6240, highlighting the urgent need for innovative Alzheimer’s diagnostic tools and the potential of MK-6240 to meet that need by enabling direct visualization of tau pathology," Brian Markison, chief executive officer at Lantheus, said in a statement.¹ "With over 100 disease-modifying therapies in development, including about 30 targeting tau and 40 targeting beta amyloid, imaging plays a critical role in diagnosis and treatment selection. If approved, MK-6240 would complement beta-amyloid PET imaging and emerging blood-based diagnostics, helping guide treatment strategies for providers and patients.”

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To date, Tauvid is the only FDA-approved F-18 tau-targeted PET imaging agent for estimating the density and distribution of aggregated tau NFTs in adults with cognitive impairment being evaluated for AD. A 2021 comparison study of MK-6240 vs Tauvid showed that both are quite capable of quantifying signal in a common set of brain regions that develop tau pathology in AD, but that MK-6240 showed greater dynamic range in SUVR estimates. Investigators concluded that this may be advantageous for detecting very early signal or in longitudinal studies designed to detect small interval changes.³

MK-6240 first demonstrated its promise as a PET tracer in a preclinical model published in 2016. In vitro binding studies using H-MK-6240 demonstrated a pattern consistent with phosphorylated tau distribution in AD brain tissue, showing high affinity for NFT-rich cortical regions and minimal binding in amyloid plaque–rich, NFT-poor areas. The tracer exhibited no displaceable binding in subcortical or non-AD brain regions, and in monkey PET studies, ^18F-MK-6240 displayed rapid and uniform brain distribution, supporting its potential for imaging tau pathology in vivo.⁴

In March 2024, Lantheus announced a new National Institutes of Health (NIH)-funded study, dubbed CLARiTI, testing MK-6240 in AD and other related dementias. The multi-site, 5-year trial is expected to span across all 37 AD Research Centers in the U.S. and is designed to collect data on imaging and blood-based biomarkers to generate etiologic profiles for cases of mixed dementia.⁵

The CLARiTI initiative leverages the National Alzheimer’s Coordinating Center (NACC) infrastructure to streamline MRI and PET data collection from Alzheimer’s Disease Research Centers (ADRCs) and share imaging results through the NACC Data Front Door. The study includes a neuropathological core with digital pathology resources to support image analysis and strengthen existing NIH efforts. Additional components focus on improving recruitment of underrepresented groups, developing PET disclosure workflows for participating sites, and establishing a foundation for standardized plasma biomarker characterization across ADRCs.

REFERENCES
1. Lantheus Announces FDA Acceptance of New Drug Application for MK-6240, a PET Imaging Agent Targeting Tau in Alzheimer’s Disease. News release. Lantheus. October 28, 2025. Accessed October 28, 2025. https://www.globenewswire.com/news-release/2025/10/28/3175415/0/en/Lantheus-Announces-FDA-Acceptance-of-New-Drug-Application-for-MK-6240-a-PET-Imaging-Agent-Targeting-Tau-in-Alzheimer-s-Disease.html
2. Lantheus Announces Alzheimer’s Disease Radiodiagnostic MK-6240 Meets Co-Primary Endpoints in Two Pivotal Studies. News release. April 30, 2025. Accessed October 28, 2025. https://lantheusholdings.gcs-web.com/news-releases/news-release-details/lantheus-announces-alzheimers-disease-radiodiagnostic-mk-6240
3. Gogola A, Minhas DS, Villemagne V. Direct comparison of the tau PET tracers [¹⁸F]flortaucipir and [¹⁸F]MK-6240 in human subjects. Journal of Neuromuscl Med. April 2021. doi.org/10.2967/jnumed.120.254961
4. Hostetler ED, Walji AM, Zeng Z, et al. Preclinical characterization of 18F-MK-6240, a promising PET tracer for in vivo quantification of human neurofibrillary tangles. Journ of Nuclear Med. 2016;57(10);1599-1606. doi:10.2967/jnumed.115.171678.
5. Latheus announces collaboration to provide novel tau imaging agent for large consortium clinical trial sponsored by the National Institute on Aging. News release. Lantheus. February 13, 2024. Accessed October 28, 2025. https://finance.yahoo.com/news/lantheus-announces-collaboration-novel-tau-133000553.html