Cardiac amyloidosis, often referred to as the "Alzheimer’s disease of the heart," is a progressive and incurable condition characterized by abnormal protein accumulation in the body's tissues and organs. Approximately 20% of patients with amyloid deposits in their hearts suffer premature mortality. Although recent advancements in treatment have significantly improved patient outcomes, the median survival rate for those affected is still only about three to five years. Existing therapies are effective in slowing amyloid buildup but do not benefit patients with advanced-stage disease. Early detection of cardiac amyloidosis is therefore essential, yet no imaging agents specifically approved by the Food and Drug Administration (FDA) are currently available for this purpose.

In response to this issue, researchers at the University of Tennessee Graduate School of Medicine (Knoxville, TN, USA) have developed a new radiotracer, a technetium-99m labeled version of the pan-amyloid reactive peptide p5+14 (99mTc-p5+14). This radiotracer produces high-quality, easily interpretable images of cardiac amyloidosis. In an initial human study, five healthy volunteers and 30 patients newly diagnosed with light chain or transthyretin amyloidosis underwent imaging with 99mTc-p5+14 using standard planar gamma scintigraphy and SPECT/CT. Alongside this, blood samples were collected for serum biomarkers analysis, and transthoracic echocardiograms were performed. Most patients also received standard 99mTc-pyrophosphate imaging 72 hours post-99mTc-p5+14 imaging.

The planar and SPECT/CT images generated using 99mTc-p5+14 at one and three hours after injection were of high quality and clearly interpretable. Notably, significant uptake of 99mTc-p5+14 was observed in the hearts of patients with amyloid cardiomyopathy, while no cardiac uptake was detected in healthy volunteers. The 99mTc-p5+14 radiotracer is now being further evaluated in early-stage clinical trials to determine its safety and effectiveness both in patients with cardiac amyloidosis and in healthy subjects. These studies aim to gather data to support a pivotal Phase 3 study and future FDA approval submissions.

“Early and accurate diagnosis of cardiac amyloidosis is crucial to ensure the most positive outcomes for patients,” said Jonathan Wall, PhD, director of the Amyloidosis and Cancer Theranostics Program and professor at the University of Tennessee Graduate School of Medicine. “Imaging with 99mTc-p5+14 could provide an easy to use and interpret technology that could be employed in the community cardiology setting, where SPECT imaging is common, as a rapid screen for amyloid cardiomyopathy in the future.”  

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