Journal of nuclear medicine : official publication, Society of Nuclear Medicine最新文献

In several malignancies, only a limited number of patients respond to immune checkpoint inhibitors. Predicting and monitoring responses to these inhibitors represent an unmet clinical need. Here, we developed a PET/CT probe targeting granzyme B, [⁶⁸Ga]Ga-NOTA-Gly-Gly-Gly-Ile-Glu-Pro-Asp-CHO (GSI), and aimed to investigate whether it can be used to monitor the effects of immune checkpoint inhibitors early in the course of therapy. Methods: Seventy-two patients with gastric cancer (stages III-IV) were recruited for [⁶⁸Ga]Ga-NOTA-GSI PET/CT imaging after 2 or 3 cycles of the immunotherapy, and 40 patients were included in the final analysis. The SUV_max of primary tumors (SUV_max-t), SUV_max of metastatic lymph nodes (SUV_max-LN), and SUV_max of normal tissues (liver and blood pool) were measured, and their target-to-liver background ratio (TLR) and target-to-blood background ratio (TBR) were denoted for primary tumors as TLR_tumor and TBR_tumor and for metastatic lymph nodes as TLR_LN and TBR_LN, respectively. The treatment responses were assessed within 1 wk after full-course treatment according to RECIST version 1.1. Wilcoxon rank-sum tests were used to compare the PET/CT parameters between responders and nonresponders. Receiver operating characteristic curve analysis was used to assess the diagnostic efficacy of [⁶⁸Ga]Ga-NOTA-GSI PET/CT parameters in identifying responders. Two-tailed P value of less than 0.05 was considered statistically significant. Results: We found that SUV_max-t, TLR_tumor, TBR_tumor, SUV_max-LN, and TBR_LN were higher in responders than in nonresponders (2.49 ± 0.58 vs. 1.55 ± 0.48, P = 0.000; 2.24 ± 0.48 vs. 1.74 ± 0.67, P = 0.007; 1.38 ± 0.43 vs. 0.90 ± 0.23, P = 0.000; 2.24 ± 0.99 vs. 1.42 ± 0.55, P = 0.003; and 1.28 ± 0.68 vs. 0.83 ± 0.32, P = 0.012, respectively). According to receiver operating characteristic curve analysis, the area under the curve for SUV_max-t, TBR_tumor, TLR_tumor, SUV_max-LN, TLR_LN, and TBR_LN was 0.886, 0.866, 0.746, 0.772, 0.648, and 0.731, respectively. The threshold of SUV_max-t was 2.05, and its sensitivity and specificity were 81.0% and 84.2%, respectively. In addition, multivariate logistic regression indicated that TBR_tumor was an independent predictor of treatment response (P = 0.03). Conclusion: Our results indicated that [⁶⁸Ga]Ga-NOTA-GSI PET/CT is a promising tool for predicting early response to combined immunotherapy in gastric cancer patients.

The role of somatostatin receptor (SSTR) PET/CT, using ⁶⁸Ga-based tracers or [⁶⁴Cu]Cu-DOTATATE (⁶⁴Cu-DOTATATE), in the management of patients with neuroendocrine neoplasm (NEN) is guided by appropriate use criteria (AUC). In this study, we performed systematic analyses of referral patterns and image findings of routine ⁶⁴Cu-DOTATATE PET/CT scans to support AUC development. Methods: We included all clinical routine ⁶⁴Cu-DOTATATE PET/CT scans performed between April 10, 2018 (start of clinical use), and May 2, 2022, at Copenhagen University Hospital-Rigshospitalet. We reviewed the referral text and image report of each scan and classified the indication according to clinical scenarios as listed in the AUC. Results: In total, 1,290 patients underwent 2,249 ⁶⁴Cu-DOTATATE PET/CT scans. Monitoring of patients with NEN seen both on conventional imaging and on SSTR PET without clinical evidence of progression was the most common indication (defined as "may be appropriate" in the AUC) and accounted for 703 (31.3%) scans. Initial staging after NEN diagnosis ("appropriate" in the AUC) and restaging after curative-intent surgery ("may be appropriate" in the AUC) accounted for 221 (9.8%) and 241 (10.7%) scans, respectively. Selection of patients eligible for peptide receptor radionuclide therapy ("appropriate" in the AUC) and restaging after peptide receptor radionuclide therapy completion ("appropriate" in the AUC) accounted for 95 (4.2%) and 115 (5.1%) scans, respectively. The number of scans performed for indications not defined in the AUC was 371 (16.5%). Image result analysis revealed no disease in 669 scans (29.7%), stable disease in 582 (25.9%), and progression in 461 (20.5%). In 99 of the 461 (21.5%) scans, progression was detected on PET but not on CT. Conclusion: Our study provided real-life data that may contribute to support development of ⁶⁴Cu-DOTATATE/SSTR PET/CT guidelines including AUC. Some scenarios listed as "may be appropriate" in the current AUC were frequent in our data. Monitoring of patients with NEN without clinical evidence of progression was the most frequent indication for ⁶⁴Cu-DOTATATE PET/CT, in which disease progression was detected in more than one third, and a large proportion was visible by PET only. We therefore conclude that this scenario could potentially be classified as appropriate.

Neuroendocrine tumor (NET) metastases to the heart are found in 1%-4% of NET patients and have been reported primarily in the form of individual cases. We investigated the prevalence, clinical characteristics, imaging features, and outcomes of NET patients with cardiac metastases on ⁶⁸Ga-DOTATATE PET/CT. Methods: ⁶⁸Ga-DOTATATE PET/CT of 490 consecutive patients from a single institution were retrospectively reviewed for sites of metastases. The cumulative cardiovascular event rate and overall survival of patients with cardiac NET metastases (CNMs) were compared with those of a control group of metastatic NET patients without cardiac metastases. In patients with CNMs, the cardiac SUV_max with and without normalization to the myocardial background uptake was compared with a separate cohort of 11 patients with active cardiac sarcoidosis who underwent ⁶⁸Ga-DOTATATE PET/CT for research purposes. Results: In total, 270 patients with metastatic NETs were identified, 9 (3.3%) of whom had CNMs. All 9 patients had grade 1-2 gastroenteropancreatic NETs, most commonly from the small intestine (7 patients). The control group consisted of 140 patients with metastatic grade 1-2 gastroenteropancreatic NETs. On Kaplan-Meier analysis, there was no significant difference in the risk of cardiovascular adverse events (P = 0.91 on log-rank test) or mortality (P = 0.83) between the metastatic NET patients with and without cardiac metastases. The degree of cardiac DOTATATE uptake was significantly higher in CNMs than in patients with cardiac sarcoidosis without overlap, in terms of both cardiac SUV_max (P = 0.027) and SUV_max-to-myocardial background ratio (P = 0.021). Conclusion: Routine ⁶⁸Ga-DOTATATE PET/CT can be used to identify CNMs in 3% of patients with metastatic NETs. CNMs do not confer added cardiovascular or mortality risk. A distinguishing feature of CNMs is their high degree of DOTATATE uptake compared with focal myocardial inflammation.

Identifying cancer therapy resistance is a key time-saving tool for physicians. Part of chemotherapy resistance includes senescence, a persistent state without cell division or cell death. Chemically inducing senescence with the combination of trametinib and palbociclib (TP) yields several tumorigenic and prometastatic factors in pancreatic cancer models with many potential antibody-based targets. In particular, urokinase plasminogen activator receptor (uPAR) has been shown to be a membrane-bound marker of senescence in addition to an oncology target. Methods: Here, 2 antibodies against murine uPAR and human uPAR were developed as immuno-PET agents to noninvasively track uPAR antigen abundance. Results: TP treatment increased cell uptake both in murine KPC cells and in human MiaPaCa2 cells. In vivo, subcutaneously implanted murine KPC tumors had high tumor uptake with the antimurine uPAR antibody independently of TP in young mice, yet uPAR uptake was maintained in aged mice on TP. Mice xenografted with human MiaPaCa2 tumors showed a significant increase in tumor uptake on TP therapy when imaged with the antihuman uPAR antibody. Imaging with either uPAR antibody was found to be more tumor-selective than imaging with [¹⁸F]FDG or [¹⁸F]F-DPA-714. Conclusion: The use of radiolabeled uPAR-targeting antibodies provides a new antibody-based PET imaging candidate for pancreatic cancer imaging as well as chemotherapy-induced senescence.