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Multimodal Imaging of 2-Cycle PRRT with ¹⁷⁷Lu-DOTA-JR11 and ¹⁷⁷Lu-DOTATOC in an Orthotopic Neuroendocrine Xenograft Tumor Mouse Model.

ABSTRACT: Peptide receptor radionuclide therapy (PRRT) using radiolabeled somatostatin receptor (SSTR) analogs is a common approach in advanced neuroendocrine neoplasms. Recently, SSTR antagonists have shown promising results for imaging and therapy due to a higher number of binding sites than in commonly used agonists. We evaluated PRRT with SSTR agonist ¹⁷⁷Lu-DOTATOC and antagonist ¹⁷⁷Lu-DOTA-JR11 longitudinally in an orthotopic murine pancreatic neuroendocrine neoplasm model expressing human SSTR2. Morphologic and metabolic changes during treatment were assessed using multimodal imaging, including hybrid PET/MRI and SPECT/CT. Methods: In vitro radioligand binding and internalization assays and cell-cycle analysis were performed. SSTR2-transfected BON cells (BON-SSTR2) were used for in vivo experiments. Tumor-bearing mice received 2 intravenous injections of 100 μL of saline, 30 MBq of ¹⁷⁷Lu-DOTATOC, or 20 MBq of ¹⁷⁷Lu-DOTA-JR11 with an interval of 3 wk. Weekly T2-weighted MRI was performed for tumor monitoring. Viability of the tumor tissue was assessed by ¹⁸F-FDG PET/MRI once after PRRT. Tumor and kidney uptake of the respective radiopharmaceuticals was measured 24 h after injection by SPECT/CT. Results: Compared with ¹⁷⁷Lu-DOTATOC, ¹⁷⁷Lu-DOTA-JR11 treatment resulted in an increased accumulation of cells in G2/M phase. Animals treated with the SSTR antagonist showed a significant reduction in tumor size (P < 0.001) and an increased median survival (207 d; interquartile range [IQR], 132-228) compared with ¹⁷⁷Lu-DOTATOC (126 d; IQR, 118-129). SPECT/CT revealed a 4-fold higher median tumor uptake for the antagonist and a 3-fold higher tumor-to-kidney ratio in the first treatment cycle. During the second therapy cycle, tumor uptake of ¹⁷⁷Lu-DOTATOC was significantly lower (P = 0.01) whereas ¹⁷⁷Lu-DOTA-JR11 uptake remained stable. Imaging of tumor morphology indicated comparatively larger necrotic fractions for ¹⁷⁷Lu-DOTA-JR11 despite further tumor growth. These results were confirmed by ¹⁸F-FDG PET, revealing the least amount of viable tumor tissue in ¹⁷⁷Lu-DOTA-JR11-treated animals, at 6.2% (IQR, 2%-23%). Conclusion: ¹⁷⁷Lu-DOTA-JR11 showed a higher tumor-to-kidney ratio and a more pronounced cytotoxic effect than did ¹⁷⁷Lu-DOTATOC. Additionally, tumor uptake was more stable over the course of 2 treatment cycles.

SUBMITTER: Albrecht J

PROVIDER: S-EPMC8049340 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:PurposeAfter peptide receptor radionuclide therapy (PRRT), renal toxicity may occur, particular in PRRT with (90)Y-labelled somatostatin analogues. Risk factors have been identified for increased probability of developing renal toxicity after PRRT, including hypertension, diabetes and age. We investigated the renal function over time, the incidence of nephrotoxicity and associated risk factors in patients treated with PRRT with [(177)Lu-DOTA(0),Tyr(3)]-Octreotate ((177)Lu-Octreotate). Also, radiation dose to the kidneys was evaluated and compared with the accepted dose limits in external beam radiotherapy and PRRT with (90)Y-radiolabelled somatostatin analogues.MethodsThe annual decrease in creatinine clearance (CLR) was determined in 209 Dutch patients and the incidence of grade 3 or 4 renal toxicity (according to CTCAE v4.03) was evaluated in 323 patients. Risk factors were analysed using a nonlinear mixed effects regression model. Also, radiation doses to the kidneys were calculated and their association with high annual decrease in renal function were analysed.ResultsOf the 323 patients, 3 (1 %) developed (subacute) renal toxicity grade 2 (increase in serum creatinine >1.5 - 3.0 times baseline or upper limit of normal). No subacute grade 3 or 4 nephrotoxicity was observed. The estimated average baseline CLR (± SD) was 108 ± 5 ml/min and the estimated average annual decrease in CLR (± SD) was 3.4 ± 0.4 %. None of the risk factors (hypertension, diabetes, high cumulative injected activity, radiation dose to the kidneys and CTCAE grade) at baseline had a significant effect on renal function over time. The mean absorbed kidney dose in 228 patients was 20.1 ± 4.9 Gy.ConclusionNephrotoxicity in patients treated with (177)Lu-octreotate was low. No (sub)acute grade 3 or 4 renal toxicity occurred and none of the patients had an annual decrease in renal function of >20 %. No risk factors for renal toxicity could be identified. Our data support the idea that the radiation dose threshold, adopted from external beam radiotherapy and PRRT with (90)Y-labelled somatostatin analogues, does not seem valid for PRRT with (177)Lu-octreotate.

Project description:PurposeGastroenteropancreatic -neuroendocrine tumours (GEP-NETs) are commonly treated with surgical resection or long-term therapies for tumour growth control. Lutetium [177Lu]-DOTA-TATE was approved for the treatment of GEP-NETs after the phase III NETTER 1trial demonstrated improved progression free survival, objective response rates and health-related quality of life (HRQoL) compared to high-dose somatostatin analogues. No real-world data exist on prescribing habits and clinically significant endpoints for [177Lu]Lu-DOTA-TATE treatment in Italy. REAL-LU is a multicentre, long-term observational study in patients with unresectable/metastatic GEP-NETs progressing on standard therapies in Italian clinical practice. A pre-specified interim analysis was performed at the end of the enrolment period, data from which are described herein.MethodsOverall duration of REAL-LU will be approximately 48 months, with 12- and 36-month recruitment and follow-up periods, respectively. The primary objective is to evaluate [177Lu]Lu-DOTA-TATE effectiveness in terms of progression-free survival. Secondary objectives include safety, impact on HRQoL, and identification of prognostic factors. This pre-specified interim analysis describes patient profiles, at the end of enrollment, of those prescribed [177Lu]Lu-DOTA-TATE for GEP-NETs in Italy.ResultsAmong 161 evaluable patients, mean age was 64.7 ± 10.3 years at study entry, 83.8% presented with no clinical signs of disease at physical examination, and most had minor disease symptoms. All patients had metastatic disease, most commonly in the liver (83.9%) with a median of two metastatic sites. In 90.7% of patients, the disease was stage IV, and 68.3% had ≥ 1 target lesion. [177Lu]Lu-DOTA-TATE was prescribed mainly as second-line therapy (61.6%) and following surgery (58.4%). HRQoL assessments revealed high levels of functioning and low levels of symptoms at baseline; 50.0% of patients were symptom-free at study entry.ConclusionThe characteristics of patients who received [177Lu]Lu-DOTA-TATE in Italy are similar to those of the GEP-NET population of NETTER 1 with trial but with a higher proportion of patients with a grade 2 (71%). With regard to the tumor grade profile, our study cohort appears to be closer to that of NETTER-2 study population which included patients with G2 or G3 advanced GEP-NETs (i.e. Ki-67 ≥ 10% and ≤ 55%). Further analysis of effectiveness and safety can be anticipated as REAL-LU data mature.Study registrationClinicalTrials.gov, NCT04727723; Study Registration Date: 25 January, 2021; https://clinicaltrials.gov/study/NCT04727723?cond=NCT04727723&rank=1.

Project description:BackgroundPatients with advanced neuroendocrine tumors (NETs) of the midgut are suitable candidates for 177Lu-DOTATOC therapy. Integrated SPECT/CT systems have the potential to help improve the accuracy of patient-specific tumor dosimetry. Dose estimations to target organs are generally performed using the Medical Internal Radiation Dose scheme. We present a novel Monte Carlo-based voxel-wise dosimetry approach to determine organ- and tumor-specific total tumor doses (TTD).MethodsA cohort of 14 patients with histologically confirmed metastasized NETs of the midgut (11 men, 3 women, 62.3 ± 11.0 years of age) underwent a total of 39 cycles of 177Lu-DOTATOC therapy (mean 2.8 cycles, SD ± 1 cycle). After the first cycle of therapy, regions of interest were defined manually on the SPECT/CT images for the kidneys, the spleen, and all 198 tracer-positive tumor lesions in the field of view. Four SPECT images, taken at 4 h, 24 h, 48 h and 72 h after injection of the radiopharmaceutical, were used to determine their effective half-lives in the structures of interest. The absorbed doses were calculated by a three-dimensional dosimetry method based on Monte Carlo simulations. TTD was calculated as the sum of all products of single tumor doses with single tumor volumes divided by the sum of all tumor volumes.ResultsThe average dose values per cycle were 3.41 ± 1.28 Gy (1.91-6.22 Gy) for the kidneys, 4.40 ± 2.90 Gy (1.14-11.22 Gy) for the spleen, and 9.70 ± 8.96 Gy (1.47-39.49 Gy) for all 177Lu-DOTATOC-positive tumor lesions. Low- and intermediate-grade tumors (G 1-2) absorbed a higher TTD compared to high-grade tumors (G 3) (signed-rank test, p = < 0.05). The pre-therapeutic chromogranin A (CgA) value and the TTD correlated significantly (Pearson correlation: = 0.67, p = 0.01). Higher TTD resulted in a significant decrease of CgA after therapy.ConclusionThese results suggest that Monte Carlo-based voxel-wise dosimetry is a very promising tool for predicting the absorbed TTD based on histological and clinical parameters.

Project description:This study aimed to evaluate the safety and efficacy of multiple cycles of 177Lu-DOTA-Evans blue (EB)-TATE peptide receptor radionuclide therapy (PRRT) at escalating doses in neuroendocrine tumors (NETs). Methods: Thirty-two NET patients were randomly divided into 3 groups and treated with escalating doses. Group A received 1.17 ± 0.09 GBq/cycle; group B, 1.89 ± 0.53 GBq/cycle; and group C, 3.97 ± 0.84 GBq/cycle. The treatment was planned for up to 3 cycles. Treatment-related adverse events were graded according to the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE), version 5.0. Treatment response was evaluated according to the European Organisation for Research and Treatment of Cancer criteria and modified PERCIST. Results: Administration of PRRT was well tolerated, without life-threatening adverse events (CTCAE grade 4). CTCAE grade 3 hematotoxicity was recorded in 1 patient (16.6%) in group B (thrombocytopenia) and 3 patients (21.4%) in group C (thrombocytopenia in 3, anemia in 1). CTCAE grade 3 hepatotoxicity (elevated aspartate aminotransferase) was recorded in 1 patient in group A (8.3%) and 1 patient in group C (7.1%). No nephrotoxicity was observed. According to the criteria of the European Organisation for Research and Treatment of Cancer, the overall disease response rates were similar in groups A, B, and C (50.0%, 50.0%, and 42.9%, respectively), and the overall disease control rates were higher in groups B (83.3%) and C (71.5%) than in group A (66.7%). According to modified PERCIST, a lower disease response rate but a similar disease control rate were found. When a comparable baseline SUVmax ranging from 15 to 40 was selected, the percentage change in SUVmax increased slightly in group A (2.1% ± 40.8%) but decreased significantly in groups B and C (-38.7% ± 10.0% and -14.7% ± 20.0%, respectively) after the first PRRT (P = 0.001) and decreased in all 3 groups after the third PRRT (groups A, B, and C: -6.9% ± 42.3%, -49.2% ± 30.9%, -11.9% ± 37.9%, respectively; P = 0.044). Conclusion: Dose escalations of up to 3.97 GBq/cycle seem to be well tolerated for 177Lu-DOTA-EB-TATE. 177Lu-DOTA-EB-TATE doses of 1.89 and 3.97 GBq/cycle were effective in tumor control and more effective than 1.17 GBq/cycle.

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Multimodal Imaging of 2-Cycle PRRT with ¹⁷⁷Lu-DOTA-JR11 and ¹⁷⁷Lu-DOTATOC in an Orthotopic Neuroendocrine Xenograft Tumor Mouse Model.

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Multimodal Imaging of 2-Cycle PRRT with 177Lu-DOTA-JR11 and 177Lu-DOTATOC in an Orthotopic Neuroendocrine Xenograft Tumor Mouse Model.

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OmicsDI is part of the ELIXIR infrastructure

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Multimodal Imaging of 2-Cycle PRRT with ¹⁷⁷Lu-DOTA-JR11 and ¹⁷⁷Lu-DOTATOC in an Orthotopic Neuroendocrine Xenograft Tumor Mouse Model.