{"entity":{"id":"caix-pet","kind":"technology","name":"CAIX PET (89Zr-girentuximab)","aka":[],"tldr":"CAIX PET is a scan using an antibody against a protein almost unique to clear-cell kidney cancer, to tell cancer from benign kidney lumps without a biopsy.","summary":"CAIX PET uses 89Zr-labelled girentuximab, an antibody against carbonic anhydrase IX, a HIF target expressed in more than 95% of clear-cell renal cell carcinomas because of VHL loss. Imaging 5 days after injection shows whether an indeterminate renal mass is clear-cell cancer without a biopsy. In the ZIRCON phase 3 (2023) it achieved sensitivity 86% and specificity 87%, giving histology-level specificity and whole-body staging in one scan. Telix's TLX250-CDx received an FDA complete response letter in 2025 over manufacturing, and resubmission is planned, so it is not yet approved; the five-day imaging delay and the 89Zr dose are practical limitations. The same antibody labelled with 177Lu is being tested therapeutically in the STARLITE trials, making CAIX a theranostic pair. It tells cancer from a benign kidney lump by lighting up a protein almost unique to clear-cell kidney cancer.","status":"phase-3","asOf":"2026-09-07","links":[{"label":"Shuch et al., ZIRCON: 89Zr-girentuximab PET-CT imaging of clear-cell renal cell carcinoma (Lancet Oncology 2024)","url":"https://doi.org/10.1016/S1470-2045(24)00402-9"}],"tags":[],"related":["zr-89","lu-177"],"indications":["rcc"],"sections":[],"technologies":["immuno-pet","pet"],"targets":[],"drugs":[],"companies":["telix"],"institutions":[],"pathways":["hif-vhl"],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"principle":"89Zr-labelled anti-CAIX antibody girentuximab imaged 5 days after injection; CAIX is a HIF target expressed in >95% of clear-cell RCC via VHL loss.","strengths":["Non-invasive histology-level specificity","Whole-body staging of clear-cell disease"],"limitations":["Five-day imaging delay; 89Zr dose","Not yet approved (CRL 2025)"]},"route":"/technologies/caix-pet/","neighbours":{"isotope":[{"id":"lu-177","kind":"isotope","name":"Lutetium-177","route":"/isotopes/lu-177/"},{"id":"zr-89","kind":"isotope","name":"Zirconium-89","route":"/isotopes/zr-89/"}],"indication":[{"id":"rcc","kind":"indication","name":"Renal cell carcinoma","route":"/indications/rcc/"}],"technology":[{"id":"immuno-pet","kind":"technology","name":"Immuno-PET","route":"/technologies/immuno-pet/"},{"id":"pet","kind":"technology","name":"PET (positron emission tomography)","route":"/technologies/pet/"}],"company":[{"id":"telix","kind":"company","name":"Telix Pharmaceuticals","route":"/companies/telix/"}],"pathway":[{"id":"hif-vhl","kind":"pathway","name":"VHL / HIF oxygen sensing","route":"/pathways/hif-vhl/"}],"idea":[{"id":"idea-caix-theranostics","kind":"idea","name":"CAIX theranostics: 89Zr-girentuximab PET and 177Lu/225Ac-girentuximab therapy","route":"/ideas/idea-caix-theranostics/"}],"opportunity":[{"id":"opp-caix-indeterminate-renal-mass","kind":"opportunity","name":"CAIX imaging of the indeterminate renal mass","route":"/opportunities/opp-caix-indeterminate-renal-mass/"}],"section":[{"id":"f-molecular-imaging","kind":"section","name":"Molecular imaging","route":"/fronts/f-molecular-imaging/"}],"paper":[{"id":"paper-zircon-lancet-oncol-2024","kind":"paper","name":"ZIRCON: [89Zr]Zr-girentuximab PET-CT for detecting clear-cell renal cell carcinoma","route":"/key-papers/paper-zircon-lancet-oncol-2024/"}],"target":[{"id":"caix","kind":"target","name":"CAIX (carbonic anhydrase IX)","route":"/targets/caix/"}],"trial":[{"id":"zircon","kind":"trial","name":"ZIRCON","route":"/trials/zircon/"}]}}