Emerging PET/CT Imaging Agent Shows Promise for Diagnosing Clear Cell Renal Cell Carcinoma

Findings from a recent multinational phase III trial demonstrated that the investigational agent TLX250-CDx had an 86 percent sensitivity rate for detecting clear cell renal cell carcinoma via positron emission tomography/computed tomography (PET/CT).

The urgency of timely diagnosis is critical for clear cell renal cell carcinoma. Researchers have reported five-year mortality rates that range from 50 to 70 percent but this rate plummets to 10 percent with subsequent metastasis.1 However, the findings from a new multinational phase III trial suggest that an emerging imaging agent may change the standard of care for diagnosing clear cell renal cell carcinoma.

In a recent multicenter prospective study, researchers assessed the use of the imaging agent 89Zr-DFO-girentuximab (TLX250-CDx, Telix Pharmaceuticals) in positron emission tomography/computed tomography (PET/CT) imaging.2 The study cohort consisted of 300 patients who previously had a single indeterminate renal mass (less than or equal to 7 cm in diameter) detected via computed tomography (CT) or magnetic resonance imaging (MRI).

The researchers found that TLX250-CDx had an 86 percent sensitivity rate, an 87 percent specificity rate and a 93 percent positive predictive value for diagnosing clear cell renal cell carcinoma, according to Telix Pharmaceuticals.2

The company noted that TLX250-CDx has a high affinity for carbonic anhydrase IX (CAIX), a tumor-associated antigen reportedly expressed in up to 95 percent of clear cell renal cell carcinoma. The agent, which previously received a breakthrough designation from the Food and Drug Administration (FDA), has significant potential as a non-invasive alternative for detecting and facilitating improved staging of clear cell renal cell carcinoma, according to Francoise Kraeber-Bodere, M.D., Ph.D., head of the Nuclear Medicine Department at the University Hospital of Nantes in France.

“Results from the phase III ZIRCON study of TLX250-CDx should represent a major milestone in the management of small renal lesions and the diagnosis of clear cell renal cell carcinoma,” noted Dr. Kraeber-Bodere. “There is so much potential in optimal targeting of CAIX, paving the way for better staging of this neoplasia and a theragnostic approach.”

In light of the study findings, Telix Pharmaceuticals said it plans to file a Biologics License Application for TLX250-CDx with the FDA. The company added that future research may examine the use of TLX250-CDx in surveillance, surgical staging, and assessment of treatment response for clear cell renal cell carcinoma.


1. Padala SA, Kallam A. Clear Cell Renal Carcinoma. StatPearls. StatPearls Publishing; 2022.T

2. Telix announces topline results of ZIRCON phase III kidney cancer imaging study. Cision PR Newswire. Available at: https://www.prnewswire.com/news-releases/telix-announces-positive-topline-results-of-zircon-phase-iii-kidney-cancer-imaging-study-301669685.html . Published November 6, 2022. Accessed November 8, 2022.