Preclinical Evaluation of a High-Affinity <sup>18</sup>F-Trifluoroborate Octreotate Derivative for Somatostatin Receptor Imaging
Why this work is in the frame
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Bibliographic record
Abstract
UNLABELLED: Recent studies have highlighted the high sensitivity of PET imaging with (68)Ga-labeled octreotide derivatives for the detection and staging of neuroendocrine tumors. A somatostatin receptor ligand that is easily radiolabeled with (18)F-fluoride could improve the availability of PET imaging of neuroendocrine tumors. We report an alkyltrifluoroborate-octreotate conjugate that is radiolabeled in a 1-step (18)F exchange reaction in high yield and with high specific activity. METHODS: We conjugated a new alkyltrifluoroborate to octreotate to obtain AMBF3-TATE, which was stored in 50-nmol aliquots for radiolabeling. (18)F labeling was performed by (18)F-(19)F isotope exchange with (18)F-fluoride, and the tracer was purified by C18 cartridge separation. The radiochemical yield was 20%-25%. PET imaging and biodistribution were performed on mice bearing AR42J tumor xenografts. RESULTS: AMBF3-TATE bound the somatostatin receptor subtype 2 with high affinity (inhibition constant, 0.13 ± 0.03 nM). Starting with 29.6-37 GBq (0.8-1 Ci) of (18)F-fluoride, more than 7.4 GBq (>200 mCi) of (18)F-AMBF3-TATE were obtained in 25 min (n = 5) with greater than 99% radiochemical purity at high specific activity (>111 GBq [3 Ci]/μmol). (18)F-AMBF3-TATE was stable in plasma. PET imaging and biodistribution showed rapid renal excretion with low liver activity. High tumor uptake (10.11% ± 1.67% injected dose/g, n = 5) was detected at 60 min after injection. Bone uptake was negligible. Tumor-to-liver, tumor-to-blood, tumor-to-muscle, and tumor-to-bone ratios (at 60 min) were 26.2 ± 0.8, 25.1 ± 1.0, 89.0 ± 3.1, and 21.3 ± 3.6, respectively. CONCLUSION: (18)F-AMBF3-TATE was radiolabeled in high yield and at high specific activity, did not require high-performance liquid chromatography purification, exhibited unexpectedly high binding affinity to somatostatin receptor subtype 2, and showed excellent pharmacokinetic properties in vivo, with high tumor uptake and high contrast ratios.
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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 | 0.004 | 0.021 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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