At EAU26: 41st Annual EAU Congress, held 13–16th March 2026 in London, Professor Dickon Hayne (Fiona Stanley Hospital, University of West Australia, Perth, WA, Australia) presented early findings from the ZiPUP study. This is a phase I trial exploring a novel PET imaging approach in urothelial cancer. In this interview, he discusses the unmet need in staging, the study’s design and what the preliminary data might mean for clinical practice.
The key issue is sensitivity. Conventional CT imaging remains the standard, but it’s not particularly good at detecting small-volume or oligometastatic disease. We also use FDG PET, which has improved detection in some settings, but it’s limited by urinary excretion of the tracer. That makes visualizing tumours in the urinary tract – particularly the bladder and upper tracts – more challenging. So overall, we’re still lacking a truly reliable staging modality that performs well both locally and systemically.
ZiPUP is an open-label, single-centre phase I feasibility study investigating zirconium-89–labelled girentuximab PET imaging. We enrolled 20 patients with urothelial cancer: 13 were surgical candidates undergoing resection with lymph node dissection, and seven had known metastatic disease.
All participants received a single dose of the tracer, followed by imaging approximately five days later, reflecting the relatively long half-life of zirconium-89. The primary objective was feasibility and safety, but we also assessed diagnostic performance – particularly sensitivity and specificity for lymph node metastases in those undergoing surgery, using histopathology as the gold standard.
Overall, the technique proved feasible, safe and well tolerated. We saw some adverse events, including one serious event, but none were attributed to the tracer itself. In terms of imaging performance, there was concordance between FDG PET and ZiPUP PET in 17 out of 20 cases. However, FDG PET detected more metastatic sites – 12 compared with eight – and demonstrated higher uptake, with a greater SUV max ratio.
Interestingly, in the surgical cohort, ZiPUP PET showed slightly better concordance with histopathology for lymph node involvement, although the number of positive nodes was small. Detection of primary bladder tumours was similar between the two modalities, despite FDG’s known urinary limitations.
The main takeaway is that this is a safe and technically feasible imaging approach, but it doesn’t yet outperform FDG PET – particularly for detecting metastatic disease. The lower SUV max suggests reduced sensitivity in that setting.
That said, there may still be a niche role. The slightly improved concordance for nodal disease is interesting, and the lack of urinary excretion remains a theoretical advantage. But at this stage, it’s not practice-changing – we need more data before considering broader clinical adoption.
Carbonic anhydrase IX (CAIX) is an intriguing target. Its expression varies across tumour types and is often linked to hypoxia in urothelial cancer, which may explain the more heterogeneous uptake we observed. That’s quite different from renal cell carcinoma, where expression is more uniform and imaging has been more successful.
Future work will likely focus on alternative CAIX-targeting agents – such as peptides or minibodies – that may offer improved imaging characteristics. There’s also interest in theranostic applications, but before we get there, we need to demonstrate strong concordance between this modality and existing standards like FDG PET.
So yes, further studies are certainly planned – but refining the biology and patient selection will be key to unlocking the full potential of this approach.
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Cite: ZiPUP PET in Focus: Can CAIX-Targeted Imaging Improve Urothelial Cancer Staging? touchONCOLOGY. March 25th, 2026
Disclosure: Dickon Hayne has received travel and research funding from Telix Pharmaceuticals. This short article was prepared by touchONCOLOGY in collaboration with Prof Dickon Hayne. Views expressed are the author’s own and do not necessarily reflect the views of Touch Medical Media.
Editor: Sophie Nickelson (Editorial Director)
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