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Researchers are looking for better ways to diagnose kidney cancer. Currently, diagnosis is made using scans, which cannot tell the difference between benign and cancerous tumours. For a more accurate diagnosis, a biopsy involving surgery may be needed. There is, therefore, an unmet need for an accurate test to diagnose kidney cancer to guide patient management.
Girentuximab is an antibody that attaches to an enzyme called carbonic anhydrase IX (CAIX). This enzyme is found in clear cell kidney cancer tumours. 89Zr-DFO-girentuximab (TLX250-CDx) is a product made from combining a weakly radioactive molecule called zirconium Zr 89 with girentuximab. When given to humans, 89Zr-DFO-girentuximab binds to carbonic anhydrase IX in kidney cancer tumours and can help to tell the difference between kidney cancer, normal tissue, and other tumours.
Findings from the phase 3 ZIRCON trial looking at TLX250-CDx (89Zr-DFO-girentuximab) in patients with a mass in their kidney that is suspicious of clear cell kidney cancer have been published in The Lancet Oncology. The company is looking to submit a biologics license application (BLA) for the imaging agent to the Food and Drug Administration (FDA) in the United States.
In the ZIRCON trial, patients who were scheduled to have a partial nephrectomy within 90 days were given 89Zr-DFO-girentuximab 10 days before surgery and then had a PET/CT scan 5 days later. The scans were assessed independently to determine whether the patient had kidney cancer. Both the sensitivity and accuracy of the scans where assessed.
There were 300 patients in the study, two thirds of whom had clear cell kidney cancer. The results were assessed independently by 3 radiographers. The average sensitivity was 86%, and the average accuracy was 87%. Positive predictive values for kidney cancer were more than 90%, including for small and difficult to detect kidney masses. These results were similar for small renal masses.
There were only two treatment-related side effects, both of which were considered to be of mild intensity.
Overall, the trial reported high accuracy of TLX250-CDx in detecting and characterising clear cell kidney cancer in patients with kidney masses.
This study confirms that 89Zr-DFO-girentuximab is well tolerated and can accurately identify kidney cancer from a PET/CT scan. This is promising for the management of kidney cancer patients.
Currently, TLX250-CDx is available through an expanded access programme in the United States, named patient programmes in Europe, and a special access scheme in Australia for patients outside of clinical trials for whom there is no comparable or satisfactory alternatives. If approved, TLX250-CDx would be the first targeted PET agent specifically for kidney cancer.
