A tale of two tracers - amyloid imaging with investigational radiotracers iodine (124I) evuzamitide and 99mTc-p5+14 (AT-05).

Systemic amyloidosis is a complex disorder, making early and accurate diagnosis challenging. The most common types are associated with misfolded transthyretin or immunoglobulin light chains, where cardiac and renal amyloidosis portend the worst prognosis. Peptide p5+14 can bind all types of amyloid via multivalent electrostatic interactions. When radiolabeled with either iodine-124 or technetium-99m, it can be used to detect cardiac and extracardiac amyloid deposits using positron emission tomography/computed tomography (PET/CT) or single-photon emission computed tomography/CT (SPECT/CT) imaging, respectively. 124I-p5+14 (124I-evuzamitide) has been evaluated in eight investigator-initiated studies and is now in a pivotal Phase 3 study (REVEAL) for the detection of cardiac amyloidosis. Both radiotracers image cardiac transthyretin (ATTR) and immunoglobulin light chain (AL) amyloidosis; however, due to the characteristics of the radionuclides, the images and image data are similar but uniquely different and complementary. Using data collected from the University of Tennessee Medical Center experiences, herein, we summarize and contrast characteristics of 124I-evuzamitide and 99mTc-p5+14 as radiotracers for amyloid detection.