Emerging research suggests the positron emission tomography/computed tomography (PET/CT) imaging agent (89Zr)Zr-girentuximab may provide a viable non-invasive option for the detection of clear cell renal cell carcinoma (ccRCC).
For the prospective, multicenter phase 3 trial, recently published in Lancet Oncology, researchers assessed the use of (89Zr)Zr-girentuximab (TLX250-CDx, Zircaix®, Telix Pharmaceuticals) in 284 patients (mean age of 61) who had indeterminate renal masses < 7 cm that were suspicious for ccRCC.
The researchers found that (89Zr)Zr-girentuximab had an 85.5 percent mean sensitivity rate and an 87 percent mean specificity rate for the diagnosis of ccRCC. The PET/CT imaging agent also had a 92.9 percent mean positive predictive value (PPV) and a 75.2 percent negative predictive value (NPV), according to the study authors.
“These results establish the value of (89Zr)Zr-girentuximab PET–CT imaging as a new standard, non-invasive tool for the diagnosis and detection, (characterization), and differentiation of clear-cell renal cell carcinoma from other renal and extrarenal lesions in clinical practice, (minimizing) the risk of unnecessary invasive interventions,” wrote lead study author Brian Shuch, M.D., a professor of urology and director of the Kidney Cancer Program at the UCLA Institute of Urologic Oncology in Los Angeles, and colleagues.
The study authors also noted similar effectiveness for (89Zr)Zr-girentuximab for diagnosing ccRCC in smaller renal masses. The PET/CT agent demonstrated mean sensitivity results of 85 percent, 84.4 percent and 96.7 percent for ccRCC in indeterminate renal masses of < 4 cm, < 3 cm and < 2 cm respectively, according to the researchers. For renal masses < 2 cm, Shuch and colleagues said (89Zr)Zr-girentuximab had a mean specificity, PPV and NPV of 96.7 percent.
“ … The results observed with indeterminate renal masses with diameters up to 2, 3, and 4 cm suggest that (89Zr)Zr-girentuximab PET–CT imaging could improve detection of very small lesions. A high-quality scan for small lesions allows an earlier diagnosis of clear-cell renal cell carcinoma and could potentially improve outcomes and impact patient management,” emphasized Shuch and colleagues.
Out of 261 adverse events reported in the study, the researchers noted that 13 may have been related to the use of (89Zr)Zr-girentuximab. Those adverse events, reported in eight patients, included diarrhea, abdominal pain, dysuria, fatigue, asthenia, urinary retention, and night sweats, according to the study.
Three Key Takeaways
1. Efficacy in diagnosing ccRCC. The (⁸⁹Zr)Zr-girentuximab PET–CT imaging agent demonstrated high diagnostic accuracy for clear-cell renal cell carcinoma (ccRCC), with a mean sensitivity of 85.5 percent and specificity of 87 percent. It provides a non-invasive diagnostic tool to differentiate ccRCC from other renal lesions.
2. Effectiveness for small lesions. The imaging agent was effective in detecting smaller renal masses, showing mean sensitivity and specificity rates of 96.7 percent for ccRCC in masses < 2 cm, enhancing early detection and potentially improving patient outcomes.
3. Workflow and efficiency benefits. The five-day window between administering the imaging agent and performing the PET/CT scan offers logistical advantages, improving patient workflow and allowing more efficient imaging of patients.
The researchers added that the five-day window between administration of (89Zr)Zr-girentuximab and the subsequent PET/CT exam offers practical benefits for patients and clinicians.
“ … Imaging can be scheduled in the morning when other patients might be undergoing injections of other imaging agents (eg, prostate-specific membrane antigen (PSMA) radiotracers) and waiting for sufficient uptake, thus (optimizing) patient workflow and scanner time. Ultimately, this process (optimization) will allow a greater number of patients to be imaged per day and enhance patient workflow efficiency,” maintained Shuch and colleagues.
(Editor’s note: For related content, see “New Research Shows Viability of PET Imaging Agent for Clear Cell Renal Cell Carcinoma,” “Meta-Analysis Assesses Impact of PSMA PET/CT for Staging of Renal Cell Carcinoma” and “Multicenter CT Study Shows Benefits of Emerging Diagnostic Model for Clear Cell Renal Cell Carcinoma.”)
In regard to study limitations, the authors acknowledged limited racial diversity in the cohort. They also indicated that contrast-enhanced CT or multiparametric magnetic resonance imaging (MRI) may be necessary after negative PET/CT results with (89Zr)Zr-girentuximab to confirm the presence of benign masses or indolent renal cell carcinoma.
