The study described in this protocol is a Phase 1, single center clinical trial to evaluate
the safety and potential of [18F]GEH121224 as a PET radiotracer for the diagnostic imaging of
HER2 positive breast cancer lesions. A group of 6 patients will be selected to perform a
dosimetry study with [18F]GEH121224 followed by another group of 6 patients in a test-retest
study. The results of this study will provide crucial information to guide the development of
[18F]GEH121224 for the detection of HER2 status in advanced breast cancer patients. This
study will use established methods for characterizing the radiation dosimetry,
biodistribution and basic pharmacokinetics of a radiotracer.