[68Ga] Pentixafor

While magnetic resonance imaging (MRI) remains the gold standard for morphological imaging, its ability to differentiate between tumor tissue and treatment-induced changes on the cellular level is insufficient. Notably, glioma cells, particularly glioblastoma multiforme (GBM), demonstrate overexpression of chemokine receptor-4 (CXCR4). This study aims to evaluate the feasibility of non-invasive ⁶⁸Ga-Cixafor™ PET/CT as a tool to improve diagnostic accuracy in patients with high-grade glioma.

In this retrospective analysis, a database of histopathology-confirmed glioma patients with MRI findings consistent with high-grade gliomas was utilized. Within 2 weeks of their MRI, these patients underwent ⁶⁸Ga-Cixafor™ PET/CT scans to assess CXCR4 expression. Both visual scoring based on established criteria and semi-quantitative measures including maximum standardized uptake value (SUV_max) and tumor-to-background ratios (TBR) were calculated to analyze the PET/CT data.

Our retrospective study enrolled 29 histologically confirmed glioma patients with MRI findings consistent with high-grade gliomas. All patients underwent ⁶⁸Ga-Cixafor™ PET/CT scans within 2 weeks of their MRI, specifically at one-hour post-injection time point. Visual assessment based on a standardized scoring system identified 27 positive scans out of 29 (93.1%). Median SUV_max was 2.31 (range: 0.49-9.96) and median TBR was 20 (range: 6.12-124.5). Pathological analysis revealed 5 grade III (17.24%) and 24 grade IV (82.75%) lesions among the 29 patients. Notably, the median SUV_max of grade IV lesions (2.85) was significantly higher than grade III lesions (1.27) (P=0.02). Conversely, there was no significant difference in median TBR between grade IV (20) and grade III (22.37). These findings support the correlation between high CXCR4 expression, particularly in high-grade gliomas, and elevated uptake of ⁶⁸Ga-Pentixafor. While areas with high uptake showed CXCR4 expression, areas with low uptake did not exhibit noticeable expression (data not shown).

This study demonstrated that ⁶⁸Ga-Cixafor™ PET exhibits a TBR with minimal cortical uptake, significantly enhancing glioma detection compared to conventional imaging methods. This, combined with the potential therapeutic capabilities of CXCR4-targeting radiopharmaceuticals, highlights the promise of ⁶⁸Ga-Cixafor™ as a valuable tool for not only improved glioma diagnosis but also personalized treatment strategies.

Purpose: To establish the extent, distribution and frequency of in-vivo vessel wall [⁶⁸Ga]Ga-PentixaFor uptake and to determine its relationship with calcified atherosclerotic plaque burden (CAP) and cardiovascular risk factors (CVRF). Methods: 65 oncological patients undergoing [⁶⁸Ga]Ga-PentixaFor PET/CT were assessed. Radiotracer uptake (target-to-background ratio [TBR]) and CAP burden (including number of CAP sites, calcification circumference and thickness) in seven major vessel segments per patient were determined. We then investigated associations of vessel wall uptake with CAP burden, cardiovascular risk (CVRF and European Society of Cardiology [ESC] SCORE2/SCORE2-OP risk chart) and image noise (determined by coefficient of variation [CoV] from unaffected liver parenchyma). Results: We identified 1292 sites of high focal [⁶⁸Ga]Ga-PentixaFor uptake (PentixaFor+ sites) in the vessel wall in 65/65 (100%) patients, with concomitant calcification in 385/1292 (29.8%) sites. There were no significant associations between vessel wall uptake and CAP burden (number of PentixaFor+ sites: r ≤ 0.18, P ≥ 0.14; PentixaFor+ TBR: r ≤ 0.08, P ≥ 0.54). The number of PentixaFor+ sites showed a moderate correlation with cardiovascular risk (ESC SCORE2/SCORE2-OP, r = 0.30; number of CVRF, r = 0.26; P = 0.04, respectively), but failed to reach significance for PentixaFor+ TBR (r ≤ 0.18, P ≥ 0.22). In univariable regression analysis, body mass index (odds ratio [OR] 1.08, 95%-confidence interval [CI] 1.02-1.14) and CoV (OR, 1.07; CI, 1.05-1.10) were linked to TBR and the number of PentixaFor+ sites (P < 0.01, respectively), while injected activity was only associated with the latter imaging parameter (OR, 0.99; CI, 0.98-1.00; P = 0.04). In multivariable regression, injected activity (OR, 1.00; CI, 0.99-1.00) and CoV (OR, 1.06; CI, 1.06-1.07) remained significantly associated with the number of PentixaFor+ sites (P < 0.01, respectively). CoV, however, was the only parameter significantly linked to PentixaFor+ TBR on multivariable analysis (OR, 1.02; CI, 1.01-1.03; P < 0.01). Conclusion: On a visual and quantitative level, high focal [⁶⁸Ga]Ga-PentixaFor uptake in the arterial tree was not consistently linked to vessel wall calcification or cardiovascular risk. Image noise, however, may account for a substantial portion of apparent vessel wall uptake.