Peptide receptor radionuclide therapy in gastroenteropancreatic NEN G3:a multicenter cohort study

Peptide receptor radionuclide therapy (PRRT) is an established treatment of metastatic neuroendocrine tumors grade 1–2 (G1–G2). However, its possible benefit in high-grade gastroenteropancreatic (GEP) neuroendocrine neoplasms (NEN G3) is largely unknown. We therefore aimed to assess the benefits and side effects of PRRT in patients with GEP NEN G3. We performed a retrospective cohort study at 12 centers to assess the efficacy and toxicity of PRRT in patients with GEP NEN G3. Outcomes were response rate, disease control rate, progression-free survival (PFS), overall survival (OS) and toxicity. We included 149 patients (primary tumor: pancreatic n = 89, gastrointestinal n = 34, unknown n = 26). PRRT was first-line (n = 30), second-line (n = 62) or later-line treatment (n = 57). Of 114 patients evaluated, 1% had complete response, 41% partial response, 38% stable disease and 20% progressive disease. Of 104 patients with documented progressive disease before PRRT, disease control rate was 69%. The total cohort had median PFS of 14 months and OS of 29 months. Ki-67 21–54% (n = 125) vs Ki-67 ≥55% (n = 23): PFS 16 vs 6 months (P < 0.001) and OS 31 vs 9 months (P < 0.001). Well (n = 60) vs poorly differentiated NEN (n = 62): PFS 19 vs 8 months (P < 0.001) and OS 44 vs 19 months (P < 0.001). Grade 3–4 hematological or renal toxicity occurred in 17% of patients. This large multicenter cohort of patients with GEP NEN G3 treated with PRRT demonstrates promising response rates, disease control rates, PFS and OS as well as toxicity in patients with mainly progressive disease. Based on these results, PRRT may be considered for patients with GEP NEN G3.acceptedVersio

Semi-automatic tumor delineation for evaluation of 64Cu-DOTATATE PET/CT in patients with neuroendocrine neoplasms:prognostication based on lowest lesion uptake and total tumor volume

Patients with neuroendocrine neoplasms (NENs) have heterogeneous somatostatin receptor expression, with highly differentiated lesions having higher expression. Receptor expression of the total tumor burden may be visualized by somatostatin receptor imaging, such as with (64)Cu-DOTATATE PET/CT. Assessment of maximal lesion uptake is associated with progression-free survival (PFS) but not overall survival (OS). We hypothesized that the lesion with the lowest, rather than the highest, (64)Cu-DOTATATE uptake would be more prognostic, and we developed a semiautomatic method for evaluating this hypothesis. Methods: Patients with NENs underwent (64)Cu-DOTATATE PET/CT. A standardized semiautomatic tumor delineation method was developed and used to identify the lesion with the lowest uptake, that is, with the lowest SUV(mean). Additionally, we assessed total tumor volume derived from the semiautomatic tumor delineation. Kaplan–Meier and Cox regression analyses were used to determine whether there was any association with OS and PFS. Results: In 116 patients with NENs, median PFS (95% CI) was 23 mo (range, 20–31 mo) and median OS was 85 mo (range, 68–113 mo). Minimum SUV(mean) and total tumor volume were significantly associated with PFS and OS in univariate Cox regression analyses, whereas SUV(max) was significant only for PFS. In multivariate Cox analyses, both minimum SUV(mean) and total tumor volume remained statistically significant. Minimum SUV(mean) and total tumor volume were then dichotomized by their median, and patients were categorized into 4 groups: high or low total tumor volume and high or low minimum SUV(mean). Patients with a low total tumor volume and high minimum SUV(mean) had a hazard ratio of 0.32 (95% CI, 0.20–0.51) for PFS and 0.24 (95% CI, 0.13–0.43) for OS, both with P values of less than 0.001 (reference: high total tumor volume and low minimum SUV(mean)). Conclusion: We propose a standardized semiautomatic tumor delineation method to identify the lesion with the lowest (64)Cu-DOTATATE uptake and total tumor volume. Assessment of the lowest, rather than the highest, lesion uptake greatly increases prognostication by (64)Cu-DOTATATE PET/CT. Combining lesion uptake and total tumor volume, we derived a novel prognostic classification system for patients with NENs

Initial Experience with 64Cu-DOTATATE Digital PET of Patients with Neuroendocrine Neoplasms: Comparison with Analog PET

The recent introduction of solid-state detectors in clinical positron emission tomography (PET) scanners has significantly improved image quality and spatial resolution and shortened acquisition time compared to conventional analog PET scanners. In an initial evaluation of the performance of our newly acquired Siemens Biograph Vision 600 PET/CT (digital PET/CT) scanner for 64Cu-DOTATATE imaging, we compared PET/CT acquisitions from patients with neuroendocrine neoplasms (NENs) grades 1 and 2 and stable disease on CT who were scanned on both our Siemens Biograph 128 mCT PET/CT (analog PET/CT) and digital PET/CT within 6 months as part of their routine clinical management. Five patients fulfilled the criteria and were included in the analysis. The digital PET acquisition time was less than 1/3 of the analog PET acquisition time (digital PET, mean (min:s): 08:20 (range, 07:59–09:45); analog PET, 25:28 (24:39–28:44), p &lt; 0.001). All 44 lesions detected on the analog PET with corresponding structural correlates on the CT were also found on the digital PET performed 137 (107–176) days later. Our initial findings suggest that digital 64Cu-DOTATATE PET can successfully be performed in patients with NENs using an image acquisition time of only 1/3 of what is used for an analog 64Cu-DOTATATE PET

First-in-Human Study of [68Ga]Ga-NODAGA-E[c(RGDyK)]2 PET for Integrin &alpha;v&beta;3 Imaging in Patients with Breast Cancer and Neuroendocrine Neoplasms: Safety, Dosimetry and Tumor Imaging Ability

Arginine-Glycine-Aspartate (RGD)-recognizing cell surface integrins are involved in tumor growth, invasiveness/metastases, and angiogenesis, and are therefore an attractive treatment target in cancers. The subtype integrin &alpha;v&beta;3 is upregulated on endothelial cells during angiogenesis and on tumor cells. In vivo assessment of integrin &alpha;v&beta;3 is possible with positron emission tomography (PET). Preclinical data on radiochemical properties, tumor uptake and radiation exposure identified [68Ga]Ga-NODAGA-E[c(RGDyK)]2 as a promising candidate for clinical translation. In this first-in-human phase I study, we evaluate [68Ga]Ga-NODAGA-E[c(RGDyK)]2 PET in patients with neuroendocrine neoplasms (NEN) and breast cancer (BC). The aim was to investigate safety, biodistribution and dosimetry as well as tracer uptake in tumor lesions. A total of 10 patients (5 breast cancer, 5 neuroendocrine neoplasm) received a single intravenous dose of approximately 200 MBq [68Ga]Ga-NODAGA-E[c(RGDyK)]2. Biodistribution profile and dosimetry were assessed by whole-body PET/CT performed at 10 min, 1 h and 2 h after injection. Safety assessment with vital parameters, electrocardiograms and blood tests were performed before and after injection. In vivo stability of [68Ga]Ga-NODAGA-E[c(RGDyK)]2 was determined by analysis of blood and urine. PET images were analyzed for tracer uptake in tumors and background organs. No adverse events or pharmacologic effects were observed in the 10 patients. [68Ga]Ga-NODAGA-E[c(RGDyK)]2 exhibited good in vivo stability and fast clearance, primarily by renal excretion. The effective dose was 0.022 mSv/MBq, equaling a radiation exposure of 4.4 mSv at an injected activity of 200 MBq. The tracer demonstrated stable tumor retention and good image contrast. In conclusion, this first-in-human phase I trial demonstrated safe use of [68Ga]Ga-NODAGA-E[c(RGDyK)]2 for integrin &alpha;v&beta;3 imaging in cancer patients, low radiation exposure and favorable uptake in tumors. Further studies are warranted to establish whether [68Ga]Ga-NODAGA-E[c(RGDyK)]2 may become a tool for early identification of patients eligible for treatments targeting integrin &alpha;v&beta;3 and for risk stratification of patients

A convolutional neural network for total tumor segmentation in [⁶⁴Cu]Cu-DOTATATE PET/CT of patients with neuroendocrine neoplasms

BACKGROUND: Segmentation of neuroendocrine neoplasms (NENs) in [(64)Cu]Cu-DOTATATE positron emission tomography makes it possible to extract quantitative measures useable for prognostication of patients. However, manual tumor segmentation is cumbersome and time-consuming. Therefore, we aimed to implement and test an artificial intelligence (AI) network for tumor segmentation. Patients with gastroenteropancreatic or lung NEN with [(64)Cu]Cu-DOTATATE PET/CT performed were included in our training (n = 117) and test cohort (n = 41). Further, 10 patients with no signs of NEN were included as negative controls. Ground truth segmentations were obtained by a standardized semiautomatic method for tumor segmentation by a physician. The nnU-Net framework was used to set up a deep learning U-net architecture. Dice score, sensitivity and precision were used for selection of the final model. AI segmentations were implemented in a clinical imaging viewer where a physician evaluated performance and performed manual adjustments. RESULTS: Cross-validation training was used to generate models and an ensemble model. The ensemble model performed best overall with a lesion-wise dice of 0.850 and pixel-wise dice, precision and sensitivity of 0.801, 0.786 and 0.872, respectively. Performance of the ensemble model was acceptable with some degree of manual adjustment in 35/41 (85%) patients. Final tumor segmentation could be obtained from the AI model with manual adjustments in 5 min versus 17 min for ground truth method, p < 0.01. CONCLUSION: We implemented and validated an AI model that achieved a high similarity with ground truth segmentation and resulted in faster tumor segmentation. With AI, total tumor segmentation may become feasible in the clinical routine. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13550-022-00901-2

A Randomized, Factorial Phase II Study to Determine the Optimal Dosing Regimen for 68Ga-Satoreotide Trizoxetan as an Imaging Agent in Patients with Gastroenteropancreatic Neuroendocrine Tumors.

68Ga-satoreotide trizoxetan is a novel somatostatin receptor antagonist associated with high sensitivity and reproducibility in neuroendocrine tumor (NET) detection and localization. However, the optimal peptide mass and radioactivity ranges for 68Ga-satoreotide trizoxetan have not yet been established. We therefore aimed to determine its optimal dosing regimen in patients with metastatic gastroenteropancreatic NETs in a prospective, randomized, 2 × 3 factorial, multicenter phase II study. Methods: Patients received 68Ga-satoreotide trizoxetan at a peptide mass of 5-20 µg on day 1 of the study and of 30-45 µg on days 16-22, at 1 of 3 68Ga radioactivity ranges (40-80, 100-140, or 160-200 MBq). Whole-body PET/CT imaging was performed 50-70 min after each injection. The primary endpoint was the detection rate of NET lesions imaged by 68Ga-satoreotide trizoxetan relative to contrast-enhanced CT (for each of the 6 peptide mass and radioactivity range combinations). Results: Twenty-four patients were evaluated in the per-protocol analysis. The median number of lesions detected by 68Ga-satoreotide trizoxetan PET/CT or PET alone was at least twice as high as the number detected by contrast-enhanced CT across the 6 studied peptide mass and radioactivity range combinations. There were no differences between the 2 peptide mass ranges or between the 3 radioactivity ranges in the number of identified lesions. However, a trend toward a lower relative lesion count was noted in the liver for the 40- to 80-MBq range. No relationship was observed between the radioactivity range per patients body weight (MBq/kg) and the number of lesions detected by 68Ga-satoreotide trizoxetan. The 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. Conclusion: A radioactivity of 100-200 MBq with a peptide mass of up to 50 µg was confirmed as the optimal dosing regimen for 68Ga-satoreotide trizoxetan to be used in future phase III studies