TLX250-CDx Advances Towards FDA Approval With Completed BLA Submission


Pending FDA review, TLX250-CDx awaits consideration following the successful outcomes of the phase 3 ZIRCON trial in clear cell renal cell carcinoma.

  • The biologics license application (BLA) submission of TLX250-CDx (Zircaix, 89Zr-DFO-girentuximab) for the FDA has been completed.
  • TLX250-CDx is an investigational radiodiagnostic PET being developed for the characterisation of renal masses as clear cell renal cell carcinoma (ccRCC).
  • Results of the phase 3 ZIRCON study in ccRCC (NCT03849118) support the BLA.

The BLA submission for TLX250-CDx, an investigational radiodiagnostic PET agent being developed to characterize renal masses as ccRCC, has been completed for FDA review.1

The rolling BLA submission began in December 2023, with timelines pre-agreed with the FDA, based on the results of the phase 3 ZIRCON study in ccRCC (NCT03849118). In the study, all coprimary and secondary end points were met.

Specifically, the agent demonstrated a sensitivity of 86%, a specificity of 87%, and a positive predictive value of 93% for ccRCC. This included lesions that were small and difficult to detect.

Renal cell carcinoma: © -

Renal cell carcinoma: © -

"Completing the BLA submission for TLX250-CDx represents a significant milestone for Telix as we bring our breakthrough investigational kidney cancer imaging agent closer to market as a noninvasive diagnostic for patients. We believe TLX250-CDx is a natural follow-on product to Illuccix as it is targeted at the same clinical stakeholders, the urologist and urologic oncologist, and leverages the proven commercial and distribution infrastructure developed through the launch of Illuccix,” said James Stonecypher, chief development officer at Telix, in a press release.

Priority review has been requested as part of the BLA submission process under the eligibility criteria of the breakthrough therapy designation. If granted, review time may be expedited.

If approved, TLX250-CDx would become the first commercially available targeted radiopharmaceutical imaging agent for kidney cancer in the US.

About the Phase 3 ZIRCON Trial

The ZIRCON study included 371 patients who were screened, 332 who were enrolled, and 300 who patients made up the safety analysis set with 284 in the full analysis set. The agent was given at a dose of 37 MBq (1 mCi)/10 mg on day 0.2

Enrollment in the study was open to patients with a single indeterminate renal mass 7 cm or smaller in diameter (cT1) on CT or MRI that was suspicious for ccRCC and scheduled for surgical removal.

The coprimary end points were sensitivity and specificity of the agent vs central histology, or surgical resection, in the detection of ccRCC. Key secondary end points included sensitivity and specificity of TLX250-CDx in a cT1a (≤4 cm) subgroup.

Safety findings from the study showed there to be minimal adverse events (AEs) linked with TLX250-CDx, and no unexpected safety signals were observed. A total of 18 patients (6%) had grade 3 or higher treatment-emergent AEs.3

1. Telix completes TLX250-CDx (Zircaix®) BLA submission for kidney cancer imaging. News release. Telix Pharmaceuticals Limited. June 2, 2024. Accessed June 5, 2024.
2. 89Zr-TLX250 for PET/CT imaging of ccRCC- ZIRCON study (89ZR-TLX250). Updated May 17, 2024. Accessed June 5, 2024.
3. Shuch BM, Pantuck AJ, Bernhard J-C, et al. Results from phase 3 study of 89Zr-DFO-girentuximab for PET/CT imaging of clear cell renal cell carcinoma (ZIRCON). J Clin Oncol. 2023;41(suppl 6; abstr LBA602). doi:10.1200/JCO.2023.41.6_suppl.LBA602
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