New Radiotracer Deemed Safe and Effective for Imaging Early Rheumatoid Arthritis

New research shows that a novel PET tracer that targets inflammation is safe and can clearly identify early stages of rheumatoid arthritis. The promising PET tracer, ⁶⁸Ga-DOTA-Siglec-9, rapidly clears from blood circulation, has a low radiation dose, and can be easily produced. This first-in-human study was published in the April issue of The Journal of Nuclear Medicine.

Inflammation is a significant part of several chronic diseases, including rheumatoid arthritis and its related issues. While PET imaging with ¹⁸F-FDG is a valuable tool for the diagnosis and monitoring of the effects of treatments, it is not specific enough to assess inflammation.

“It’s important to detect inflammation early so that patients can receive the best treatment,” says Anne Roivainen, PhD, professor of preclinical imaging and drug research at Turku PET Centre at the University of Turku and Turku University Hospital in Finland. “Our institution has worked for several years to develop an imaging agent that targets areas of inflammation, and in this study, tested its effectiveness in humans for the first time.”

To evaluate the radiotracer’s safety and biodistribution characteristics, six healthy study participants underwent whole body ⁶⁸Ga-DOTA-Siglec-9 PET/CT scans. ⁶⁸Ga-DOTA-Siglec-9 was well-tolerated and cleared quickly from the blood, and its radiation dose was similar to other ⁶⁸Ga tracers. In one additional study participant with rheumatoid arthritis, the tracer was able to clearly detect joints with arthritis.

“We have proven that the characteristics of ⁶⁸Ga-DOTA-Siglec-9 are favorable for use in patient imaging studies,” says Roivainen. “Future studies will clarify whether ⁶⁸Ga-DOTA-Siglec-9 PET imaging has the potential to detect other inflammatory diseases early. It could also help to evaluate the effectiveness of treatments and promptly identify patients who are unlikely respond to therapy.”

Featured image: The inflamed joints of a patient with rheumatoid arthritis are clearly visible in the PET/CT images with the novel ⁶⁸Ga-DOTA-Siglec-9 radiopharmaceutical.