[18F]2a

[18F]2a is a fluorine-18 labeled, urea-based small molecule radiotracer developed for positron emission tomography (PET) imaging of prostate cancer. It belongs to a class of Lys-Urea-Glu-based oxime derivatives designed to target the prostate-specific membrane antigen (PSMA), a protein highly overexpressed in prostate adenocarcinoma. Developed by researchers at the National Institutes of Health (NIH) as an optimization of the FDA-approved tracer [18F]DCFPyL, [18F]2a incorporates a lipophilic oxime linkage to alter its pharmacokinetic profile. Preclinical evaluations in PC3(+) tumor xenografts demonstrated that [18F]2a maintains high binding affinity and tumor-targeting efficacy comparable to [18F]DCFPyL, but with significantly reduced renal uptake and a shift toward hepatobiliary clearance. This altered biodistribution potentially improves the detection of lesions in the pelvic region by reducing interfering background radioactivity from the kidneys and urinary tract.