The phase 3 ZIRCON trial is assessing TLX250-CDx as a noninvasive tool to identify clear cell renal cell carcinoma in patients with indeterminate renal masses.

The first US patients have been dosed in the phase 3 ZIRCON trial exploring TLX250-CDx (89Zr-girentuximab), a novel PET imaging radiopharmaceutical for clear cell renal cell carcinoma (RCC).

The goal of the ZIRCON trial (NCT03849118) is to establish the efficacy of TLX250-CDx as a noninvasive tool to identify clear cell RCC in patients with indeterminate renal masses. The primary outcome measures are sensitivity and specificity. The first patients were dosed at the University of California, Los Angeles, and the Seattle Cancer Care Alliance.
The FDA granted a Breakthrough Therapy Designation to TLX250-CDx in July 2020 for the diagnosis and staging of indeterminate renal masses. The designation is intended to expedite the development and regulatory review of the imaging radiopharmaceutical in this setting.
“We are pleased to have commenced the phase 3 ZIRCON clinical trial in North America and wish to express our gratitude to Dr Allan Pantuck and Dr Delphine Chen, principal investigators at UCLA and SCCA, respectively, as well as their clinical research teams and patients, who have made this important milestone possible,” Colin Hayward, MD, chief medical officer at Telix, stated in a press release.
TLX250-CDx uses the anti-CAIX monoclonal antibody girentuximab to target the cell-surface antigen CAIX. The antigen is found on over 90% of clear cell RCC cells, but is not found in normal kidney cells. CAIX is also expressed in metastatic disease, and Telix suggests this might enhance the accuracy of staging patients with clear cell RCC.
The prospective, international, open-label, single-group assignment, phase 3 ZIRCON trial is exploring TLX250-CDx in patients with indeterminate renal masses scheduled for partial or total nephrectomy. The indeterminant renal mass must be a maximum of 7 cm in largest diameter (tumor stage cT1) and the nephrectomy must occur within 90 days of the administration of TLX250-CDx. The efficacy of TLX250-CDx will be determined through a comparison with histologic results with surgical resection as the “standard of truth.”
The study is being conducted at 36 locations in Europe, Australia, Turkey, Canada, and the United States. The targeted enrollment is 252 patients and the estimated primary completion date is May 31, 2021.

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