SAN DIEGO, CA USA (UroToday.com) - Positron-emission tomography/computer tomography (PET/CT) with iodine-124 (124I)-Girentuximab (cG250) utilizes a chimeric immunoglobulin G monoclonal antibody that binds to carbonic anhydrase IX (CAIX), a tumor cell-surface antigen that is expressed in 90% of all clear cell renal cell carcinomas (RCC). This allows excellent targeting to primary and metastatic ccRCC. PET/CT and contrast-enhanced CTs of the abdomen were performed on patients 2 to 6 days after intravenous 124I-girentuximab administration and before undergoing nephrectomy (n=26). Imaging was able to accurately determine the presence or absence of ccRCC (sensitivity 94%, specificity 100%; PPV 60%). The test was also excellent in the targeting of metastatic disease (close to 90%), significantly greater than contrast-enhanced CT alone. At this stage, it is unclear if it can identify renal masses with poor prognosis, but it has the potential to guide surgery, guide follow-up, and carry out a metastatic work-up. The authors suggested that it could be used as a prognostic imaging biomarker and may help categorize patients by degree of risk for disease occurrence or progression. “PET/CT with 124I-girentuximab may be of value in risk stratification of patients with renal masses, and it fulfills an unmet medical need to improve appropriate patient care while minimizing the risks of invasive diagnostics and potentially unnecessary surgery,” the investigators concluded.
The authors further postulated that “patients presenting with incidentally identified T1 renal masses may benefit from the incorporation of 124I-girentuximab PET/CT to optimally inform a clinical management decision and add confidence and clarity to rational therapeutic recommendations for the surgically fragile, elderly, or comorbidly ill patient.”
Dr. Marston Linehan from the NIH then posed an interesting question: “does it differentiate VHL mutation? The CAIX mutation may not be present in patients who do not have VHL.” The authors responded that this was a fertile area for further research, but they did not specifically address that question.
Presented by Chaitanya Divgi, MD at the Society of Urologic Oncology (SUO) meeting preceding the American Urological Association (AUA) Annual Meeting - May 4 - 8, 2013 - San Diego Convention Center - San Diego, California USA
NewYork-Presbyterian/Columbia, New York, NY USA
Reported for UroToday.com by Jeffrey Tomaszewski, MD
