Lantheus Holdings announced that the U.S. Food and Drug Administration (FDA) has accepted its New Drug Application (NDA) for MK-6240. MK-6240 is an investigational PET imaging agent designed for the detection of tau neurofibrillary tangles, a key indicator of Alzheimer's disease. The application was granted Fast Track designation, and the FDA has set a Prescription Drug User Fee Act (PDUFA) target action date of August 13, 2026. The submission is supported by data from two pivotal Phase 3 trials that met their primary endpoints for sensitivity and specificity. If approved, MK-6240 could complement existing beta-amyloid PET imaging and emerging blood-based diagnostics, aiding in treatment strategies for Alzheimer's patients.