PET Imaging of Carbonic Anhydrase IX Expression of HT-29 Tumor Xenograft Mice with <sup>68</sup>Ga-Labeled Benzenesulfonamides
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
Carbonic anhydrase IX (CA-IX) is a HIF-1-inducible enzyme that is overexpressed in many cancer subtypes to promote survival and invasion in hypoxic niches. Pharmacologic inhibition of CA-IX is achievable through sulfonamide-based inhibitors and has been shown to reduce primary growth of cancers and distant metastasis in preclinical models. We explored a multivalent approach for targeting CA-IX in vivo, noninvasively, with positron emission tomography. Three (68)Ga-polyaminocarboxylate chelator complex-conjugated tracers containing one, two, or three 4-(2-aminoethyl)benzenesulfonamide moieties were synthesized and evaluated for protein binding and imaging properties. Binding affinity to CA-I, -II, -IX, and -XII were determined using a stopped-flow CA catalyzed CO2 hydration assay. Biodistribution and PET/CT imaging were performed using immunocompromised mice bearing CA-IX expressing HT-29 colorectal tumors. Compounds demonstrated good binding affinity to CA-IX (Ki: 7.7-25.4 nM). (68)Ga-labeled sulfonamides were obtained in 64-91% decay-corrected average radiochemical yields with 50-536 GBq/μmol specific activity and >97% average radiochemical purity. All three tracers allowed for the visualization of tumor xenografts at 1 h postinjection, with the monomer displaying the highest contrast. Tumor uptake of the monomer was blockable in the presence of acetazolamide, confirming target specificity. The monomer was excreted predominantly through the kidneys, while the dimer and trimer were cleared by both renal and hepatobiliary pathways. According to biodistribution analysis, tumor uptake (%ID/g) of the monomeric, dimeric, and trimeric tracers were 0.81 ± 0.15, 1.93 ± 0.26, and 2.30 ± 0.53 at 1 h postinjection. This corresponded to tumor-to-muscle ratios of 5.02 ± 0.22, 4.07 ± 0.87, and 4.18 ± 0.84, respectively. Our data suggest that (68)Ga-polyaminocarboxylate chelator-conjugated sulfonamides can be used to noninvasively image CA-IX. These CA-IX targeting PET tracers may be used to identify patients who can benefit from treatments targeting this protein or serve as surrogate imaging agents for tumor hypoxia.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it