Telix Pharmaceuticals Limited (ASX: TLX, NASDAQ: TLX, “Telix”) today announces the publication of a new independent analysis of Phase 3 ZIRCON trial data in European Urology1, demonstrating that TLX250-Px (Zircaix®2, 89Zr-girentuximab) PET/CT3 imaging may be highly predictive of renal malignancy across all subtypes, not limited to clear cell renal cell carcinoma (ccRCC).
Recognizing that carbonic anhydrase IX (CAIX) expression is also observed in other renal cancer subtypes4, this subsequent analysis conducted by international investigators who participated in ZIRCON Phase 3 trial5, evaluated centrally reviewed imaging and pathology data to explore whether tracer uptake in renal masses correlated with malignancy beyond ccRCC.
The analysis demonstrated that positive PET findings were highly predictive of malignancy overall, including in non-clear cell renal cell carcinoma (nccRCC), with a reported positive predictive value (PPV) of 98% (95% CI, 96–99), sensitivity of 82% (95% CI, 82–90), and specificity of 87% (95% CI, 81–93). These exploratory scientific findings suggest TLX250-Px has applications beyond the detection of ccRCC in primary renal masses and may have implications to management of nccRCC.
Aboubacar Kaba, MD, urologist at the University of California, Los Angeles and corresponding author, commented: “This analysis shows that when TLX250-Px PET/CT is positive, it is highly predictive of renal malignancy, including beyond ccRCC. Thus, the utility of this test may be important in distinguishing more hypoxic, and therefore, aggressive disease from indolent tumors with clear treatment implications. This may provide an additional tool to aid in risk stratifying or guiding patient and clinician decisions in the treatment of renal masses.”
Dr. David N. Cade, Group Chief Medical Officer at Telix, added: “Publication of these data in European Urology reflects the scientific strength of the ZIRCON trial and the robustness of its central imaging and pathology review. While ZIRCON was designed to address ccRCC, this analysis supports continued evaluation of TLX250-Px PET imaging across a broader spectrum of renal malignancies, with potential application in the management of patients with non-clear cell RCC. Furthermore, essentially all false-positives for ccRCC in the ZIRCON study have now been shown to be other malignant kidney cancer subtypes, reducing the risk of overtreatment and further supporting clinical adoption.”
The full paper is available at: https://www.europeanurology.com/article/S0302-2838(26)02037-3/fulltext.
These findings are based on exploratory analyses and were not the basis of Telix’s Biologics License Application (BLA) submission for TLX250-Px, which focuses exclusively on detection of ccRCC in primary renal masses.
About TLX250-Px
TLX250-Px is a PET imaging candidate under development for the diagnosis and characterization of ccRCC, and included in leading international guidelines for renal imaging6. It works by specifically binding to carbonic anhydrase IX (CAIX), a validated target protein expressed on >95% of ccRCC cells7, to produce images with high tumor-to-background ratio and high intra- and inter-reader consistency.
Telix's pivotal Phase 3 ZIRCON trial evaluating TLX250-Px in 300 patients, of whom 284 were evaluable, met all primary and secondary endpoints, including showing 86% sensitivity and 87% specificity and a 93% positive predictive value (PPV) for ccRCC across three independent radiology readers8. Telix believes this demonstrated the ability of TLX250-Px to reliably detect the clear cell phenotype and provide an accurate, non-invasive method for diagnosing and characterizing ccRCC.
ZIRCON-X, a noninterventional, prospective, post hoc study using imaging data from ZIRCON, found that almost half of all patients (48.6%) would have undergone a change in clinical management if imaged with TLX250-Px, compared with baseline standard-of-care (SOC) imaging, and that more than 20% could potentially have avoided an invasive biopsy9.
For more on TLX250-Px and Telix's theranostic kidney cancer program, click here.
TLX250-Px has not received a marketing authorization in any jurisdiction.
About Telix Pharmaceuticals Limited
Telix is a global biopharmaceutical company focused on the development and commercialization of radiopharmaceuticals with the goal of addressing significant unmet medical need in oncology and rare diseases. Telix is headquartered in Melbourne (Australia) with international operations in the United States, United Kingdom, Brazil, Canada, Europe (Belgium and Switzerland) and Japan. Telix is listed on the Australian Securities Exchange (ASX: TLX) and the Nasdaq Global Select Market (NASDAQ: TLX).
