Improved Estrogen Receptor Assessment by PET Using the Novel Radiotracer <sup>18</sup>F-4FMFES in Estrogen Receptor–Positive Breast Cancer Patients: An Ongoing Phase II Clinical Trial
Bibliographic record
Abstract
After encouraging preclinical and human dosimetry results for the novel estrogen receptor (ER) PET radiotracer 4-fluoro-11β-methoxy-16α-<sup>18</sup>F-fluoroestradiol (<sup>18</sup>F-4FMFES), a phase II clinical trial was initiated to compare the PET imaging diagnostic potential of <sup>18</sup>F-4FMFES with that of 16α-<sup>18</sup>F-fluoroestradiol (<sup>18</sup>F-FES) in ER-positive (ER+) breast cancer patients. <b>Methods:</b> Patients diagnosed with ER+ breast cancer (<i>n</i> = 31) were recruited for this study, including 6 who underwent mastectomy or axillary node dissection. For each patient, <sup>18</sup>F-FES and <sup>18</sup>F-4FMFES PET/CT scans were done sequentially (within a week) and in random order. One hour after injection of either radiotracer, a head-to-thigh static scan with a 2-min acquisition per bed position was obtained. Blood samples were taken at different times after injection to assess each tracer metabolism by reverse-phase thin-layer chromatography. The SUV<sub>mean</sub> of nonspecific tissues and the SUV<sub>max</sub> of the tumor were evaluated for each detected lesion, and tumor-to-nonspecific organ ratios were calculated. <b>Results:</b> Blood metabolite analysis 60 min after injection of the tracer showed a 2.5-fold increase in metabolic stability of <sup>18</sup>F-4FMFES over <sup>18</sup>F-FES. Although for most foci <sup>18</sup>F-4FMFES PET had an SUV<sub>max</sub> similar to that of <sup>18</sup>F-FES PET, tumor contrast improved substantially in all cases. Lower uptake was consistently observed in nonspecific tissues for <sup>18</sup>F-4FMFES, notably a 4-fold decrease in blood-pool activity as compared with <sup>18</sup>F-FES. Consequently, image quality was considerably improved using <sup>18</sup>F-4FMFES, with lower overall background activity. As a result, <sup>18</sup>F-4FMFES successfully identified 9 more lesions than <sup>18</sup>F-FES. <b>Conclusion:</b> This phase II study with ER+ breast cancer patients showed that <sup>18</sup>F-4FMFES PET achieves a lower nonspecific signal and better tumor contrast than <sup>18</sup>F-FES PET, resulting in improved diagnostic confidence and lower false-negative diagnoses.
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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 | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 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 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".