Novel PET Tracer Shows Promise for More Accurate Kidney Cancer Detection and Staging

A newly developed PET imaging tracer targeting carbonic anhydrase IX (CAIX) has shown impressive results in detecting clear cell renal cell carcinoma (ccRCC), offering enhanced sensitivity and clearer imaging than conventional methods. Early clinical findings were presented at the 2026 Annual Meeting of the Society of Nuclear Medicine and Molecular Imaging.

Clear cell renal cell carcinoma is known for its high expression of CAIX, making the protein an attractive target for molecular imaging. However, previous attempts to develop CAIX-targeted tracers have been limited by high background activity in the gastrointestinal tract, which can obscure abdominal tumors and metastases.

Researchers from Wuhan, China, developed a novel cyclic peptide-based tracer called 68Ga-RCC78, designed to rapidly accumulate in tumors while clearing quickly from healthy tissues.

“Unlike conventional antibody-based tracers that can take several days to leave the body, our cyclic peptide probe enables high-contrast imaging within a much shorter timeframe,” said Sixuan Cheng, MD, of the Department of Nuclear Medicine at Union Hospital, Tongji Medical College, Huazhong University of Science and Technology.

The team synthesized 16 CAIX-targeted cyclic peptides and labeled them with gallium-68. After extensive laboratory testing in cell cultures and animal models, the most promising candidate, 68Ga-RCC78, was evaluated in a first-in-human study involving 13 patients with ccRCC.

In preclinical studies, the tracer demonstrated strong and sustained uptake in CAIX-positive tumors while rapidly clearing from surrounding tissues. Clinical imaging results showed that 68Ga-RCC78 accurately distinguished CAIX-positive tumors from CAIX-negative lesions, in agreement with biopsy findings.

The tracer also outperformed the commonly used imaging agent 18F-FDG, producing higher uptake in both primary and metastatic tumors. Low intestinal background activity enabled clearer visualization of abdominal metastases, and the improved tumor-to-background contrast allowed researchers to identify additional cancer lesions that were not detected with standard imaging approaches.

According to Dawei Jiang, PhD, professor and deputy director of the Nuclear Medicine Department at Wuhan Union Hospital, the new tracer provides a more precise molecular picture of kidney cancer.

“Our probe minimizes background interference in the abdominal cavity while maintaining exceptionally high tumor uptake, potentially representing an important advance toward personalized radiotheranostics for ccRCC,” Jiang said.

Researchers are also exploring therapeutic applications of the same molecule by labeling it with treatment-oriented radioactive isotopes that could deliver targeted radiation directly to cancer cells while limiting damage to healthy organs.

Although the technology remains in the early stages of clinical evaluation, larger trials are being planned. Access through specialized clinical studies may become available within the next one to two years, while broader clinical use will depend on future regulatory approvals.