New Tool for Presurgical Detection of Kidney Cancers Helps to Avoid Unnecessary Surgeries

The results of a prospective multicenter phase III study demonstrate that the use of an antibody called 124I-girentuximab with positron emission tomography/computed tomography (PET/CT) imaging can help to distinguish clear cell renal-cell carcinoma (RCC), the predominant variant of kidney cancer, from other types of benign or malignant kidney masses.

If approved by the U.S. Food and Drug Administration (FDA), this will be one of the first diagnostic scans which can differentiate not only identify a tumor's origin and location, but also provide data on the type (histology) of that tumor. Armed with this information, physicians and patients will be able to make more informed treatment choices.

Kidney cancer is a radiographic diagnosis, which means treatment decisions are often made based on the findings of a solid mass on CT or magnetic resonance imaging (MRI). Unfortunately, these tests cannot distinguish the different types of kidney cancers that have variable risks. As more individuals continue to be scanned as part of their evaluation for various ailments and symptoms, the number of kidney tumors found serendipitously has increased such that now up to 70% of kidney tumors are discovered incidentally.

Kidney cancer is a surgical disease, which means that many patients with incidentally detected masses will be offered surgery. Frequently, however, the tumors are shown postsurgically to have been benign or indolent, and many would not have required immediate surgical intervention. In the absence of a definitive presurgical diagnosis, surgeons generally must opt for surgery.

Robert G. Uzzo, M.D., F.A.C.S., chairman of Fox Chase Cancer Center's (Philadelphia, PA, USA) department of surgery, presented the results of this phase III study entitled multicenter phase III REDECT trial with 124 I-girentuximab-PET/CT for the presurgical Detection of Clear Cell Renal Carcinoma (cc(RCC) study at the 2010 annual meeting of the American Urological Association, in San Francisco, CA, USA, on June 1, 2010.

124I-girentuximab is a monoclonal antibody that binds to a unique protein expressed highly on the most common and lethal type of kidney cancer (clear cell renal-cell carcinoma). When injected intravenously as part of a PET/CT scan, it gives histologic data providing useful noninvasive clinical insights to renal masses' biologic properties. The PET imaging with 124I-girentuximab (REDECTANE) is a cutting-edge type of molecular imaging tool. Researchers at Fox Chase Cancer Center have led accrual nationally to this important phase III trial.

"The ability to distinguish preoperatively between aggressive and less aggressive kidney masses is a critical clinical challenge,” said Dr. Uzzo, who is also codirector of Fox Chase's Keystone Program in Personalized Kidney Cancer Therapy. "Such information makes a direct impact on patient management, giving physicians the ability to match tumor biology to appropriate treatment strategies.”

The 124I-girentuximab PET/CT is performed similarly to any PET or CT--the antibody is injected intravenously and the patient is then imaged. In the case of kidney cancer, REDECTANE provides oncologists with superior imaging, allowing them to distinguish the aggressive RCC phenotype from other renal cell subtypes and benign tumor much better than current tests. Furthermore, the technology may aid in more precise diagnosis of tumor stage, detecting early and otherwise undetectable metastatic deposits.

Researchers identified and enrolled 226 patients in the multi-center study and found that the antibody 124I-girentuximab (cG250) binds to an aggressive phenotype, which is expressed in more than 95% of clear cell RCC--the most common form of kidney cancer, accounting for up to 90% of all kidney cancer deaths.

In this study, Dr. Uzzo and his team used PET/CT scans with 124I-girentuximab to differentiate effectively the aggressive RCC phenotype from less aggressive subtypes prior to surgery. The sensitivity and specificity of the test were 86% and 87%, respectively, with a positive predictive value of 95% for clear cell renal cancer. Such strategies potentially can help reduce the number of unnecessary surgeries and guide individualized patient management. The multicenter phase III REDECT trial was conducted at 14 centers across the United States and sponsored by Wilex AG (Munich, Germany).

The Keystone Program in Personalized Kidney Cancer Therapy, codirected by Robert G. Uzzo, M.D., FACS, Gary Hudes, M.D., and Joseph R. Testa, Ph.D., investigates the biologic processes that lead to kidney cancer metastasis and aims to uncover the molecular signals that predict how an individual patient's kidney tumor will respond to therapies.

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