Radiosynthesis and Preclinical Evaluation of <sup>18</sup>F-Fluoroglycosylated Octreotate for Somatostatin Receptor Imaging
Bibliographic record
Abstract
Short synthetic octapeptide analogs derived from the native somatostatin peptides SST-14 and SST-28, namely, octreotate (TATE) or octreotide (TOC), bind with high affinity to somatostatin receptors (sstr), mainly to subtypes 2 and 5, which are expressed in high density on neuroendocrine tumors (NET). Therefore, radiolabeled TATE or TOC derivatives represent highly valuable imaging probes for NET diagnosis by positron emission tomography (PET). The aim of our study was the development of an 18 F-labeled octreotate analog as an alternative radiotracer for the clinically established 68 Ga-DOTATOC and 68 Ga-DOTATATE. We applied our previously developed method based on copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) to the radiosynthesis of 18 F-fluoroglycosylated TATE ([ 18 F]FGlc-TATE). [ 18 F]FGlc-TATE was obtained in high yields of 19–22% (non-decay-corrected, referred to [ 18 F]fluoride) and in high specific activities of 32–106 GBq/μmol. [ 18 F]FGlc-TATE showed high affinity to sstr expressed on AR42J cells (IC 50 = 4.2 nM) with fast and high internalization, and a beneficial logD 7.4 of −1.8. In AR42J tumor bearing nude mice, [ 18 F]FGlc-TATE showed high and specific tumor uptake of 5.6%ID/g at 60 min post-injection, as determined by blocking experiments using octreotide, and fast clearance from other organs, resulting in excellent tumor-to-blood ratios increasing from 9 to 17 from 30 to 60 min post-injection. Small animal PET studies revealed high uptake of [ 18 F]FGlc-TATE in the tumor which could be blocked with octreotide by >99%. Overall, [ 18 F]FGlc-TATE revealed excellent in vitro and in vivo properties and is therefore a viable alternative 18 F-labeled radiopeptide for imaging somatostatin receptor-positive tumors by PET.
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How this classification was reachedexpand
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 | 0.001 | 0.004 |
| 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) | 0.001 | 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".