The Effects of Monosodium Glutamate on PSMA Radiotracer Uptake in Men with Recurrent Prostate Cancer: A Prospective, Randomized, Double-Blind, Placebo-Controlled Intraindividual Imaging Study
Bibliographic record
Abstract
The prostate-specific membrane antigen (PSMA) is an excellent target for theranostic applications in prostate cancer. However, PSMA-targeted radioligand therapy can cause undesirable effects due to high accumulation of PSMA radiotracers in salivary glands and kidneys. This study assessed orally administered monosodium glutamate (MSG) as a potential means of reducing kidney and salivary gland radiation exposure using a PSMA-targeting radiotracer. Methods: This prospective, double-blind, placebo-controlled study enrolled 10 patients with biochemically recurrent prostate cancer. Each subject served as his own control. PET/CT imaging sessions using 2-(3-{1-carboxy-5-[(6-18F-fluoro-pyridine-3-carbonyl)-amino]-pentyl}-ureido)-pentanedioic acid (18F-DCFPyL) were performed 3–7 d apart, after oral administration of either 12.7 g of MSG or placebo. Data from the 2 sets of images were analyzed by placing regions of interest on lacrimal, parotid, and submandibular glands; left ventricle; liver; spleen; kidneys; bowel; urinary bladder; gluteus muscle; and malignant lesions. The results from MSG and placebo scans were compared by paired analysis of the region-of-interest data. Results: In total, 142 pathologic lesions along with normal tissues were analyzed. As hypothesized a priori, there was a significant decrease in SUVmax corrected for lean body mass (SULmax) on images obtained after MSG administration in the parotids (24% ± 14%, P = 0.001), submandibular glands (35% ± 11%, P < 0.001), and kidneys (23% ± 26%, P = 0.014). Significant decreases were also observed in the lacrimal glands (49% ± 13%, P < 0.001), liver (15% ± 6%, P < 0.001), spleen (28% ± 13%, P = 0.001), and bowel (44% ± 13%, P < 0.001). A mildly lower blood pool SULmean was observed after MSG administration (decrease of 11% ± 13%, P = 0.021). However, significantly lower radiotracer uptake in terms of SULmean, SULpeak, and SULmax was observed in malignant lesions on scans performed after MSG administration than on the placebo studies (SULmax median decrease, 33%; range, −1% to 75%; P < 0.001). No significant adverse events occurred after placebo or MSG administration, and vital signs were stable. Conclusion: Orally administered MSG significantly decreased salivary gland, kidney, and other normal-organ PSMA radiotracer uptake in human subjects, using 18F-DCFPyL as an exemplar. However, MSG caused a corresponding reduction in tumor uptake, which may limit the benefits of this approach for diagnostic and therapeutic applications.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.003 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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 source (direct Gemma or distilled Codex), 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".