68Ga-satoreotide trizoxetan is a novel somatostatin receptor antagonist associated with high sensitivity and reproducibility in neuroendocrine tumor (NET) detection and localization. But the optimal peptide mass and radioactivity ranges for 68Ga-satoreotide trizoxetan had not been established in a multi-center setting with more than 1 PET scanner. Establishing them was the objective of a study recently reported in the Journal of Nuclear Medicine.
TBG’s own Colin G. Miller was one of the article’s authors. This post aims to summarize the key points of the article.
Patients in the study received 68Ga-satoreotide trizoxetan at a peptide mass of 5–20 µg on day 1 and of 30–45 µg on days 16–22, at one of three gallium-68 radioactivity ranges (40–80, 100–140, or 160–200 MBq). Whole-body PET/CT imaging was performed 50–70 minutes after each injection. The primary endpoint was the detection rate of NET lesions imaged by 68Ga-satoreotide trizoxetan relative to contrast-enhanced CT (CECT) (for each of the six peptide mass/radioactivity range combinations).
Twenty-four patients were evaluated in the per-protocol analysis. The median number of lesions detected by 68Ga-satoreotide trizoxetan PPET/CT or PET only was at least twice as high as the number detected by CECT across the six studied peptide mass dose/radioactivity range combinations. There were no differences between the two peptide mass ranges and between the three radioactivity ranges in the number of identified lesions. However, there was a trend toward a lower relative lesion count in the liver for the 40–80 MBq range.
Researchers saw no relationship between the radioactivity range per patient’s body weight (MBq/kg) and the number of lesions detected by 68Ga-satoreotide trizoxetan. Median diagnostic sensitivity of 68Ga-satoreotide trizoxetan PET/CT, based on the number of lesions per patient, ranged from 85% to 87% across the different peptide mass and radioactivity ranges. Almost all reported adverse events were mild and self-limiting.
A radioactivity of 100–200 MBq with a peptide mass up to 50 μg were confirmed as the optimal dosing regimen for 68Ga-satoreotide trizoxetan to be used in future phase III studies.
Reach out to TBG
Since Colin was one of the authors, if you have questions about this article, or medical imaging in general, you can turn to The Bracken Group (Bracken) with confidence. Medical imaging is a core competency for TBG, and the team is always ready to help.