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Potential Biomarkers for Radiation-Induced Renal Toxicity following 177Lu-Octreotate Administration in Mice.

ABSTRACT: UNLABELLED:The kidneys are one of the main dose-limiting organs in peptide receptor radionuclide therapy and due to large inter-individual variations in renal toxicity, biomarkers are urgently needed in order to optimize therapy and reduce renal tissue damage. The aim of this study was to investigate the transcriptional, functional, and morphological effects on renal tissue after 177Lu-octreotate administration in normal mice, and to identify biomarkers for radiation induced renal toxicity. METHODS:C57BL/6N mice were i.v. injected with 0, 30, 60, 90, 120, or 150 MBq 177Lu-octreotate (0, 16, 29, 40, 48, and 54 Gy to the kidneys). At 4, 8, and 12 months after administration, radiation-induced effects were evaluated in relation to (a) global transcriptional variations in kidney tissues, (b) morphological changes in the kidneys, (c) changes in white and red blood cell count as well as blood levels of urea, and (d) changes in renal function using 99mTc-DTPA/99mTc-DMSA scintigraphy. RESULTS:In general, the highest number of differentially regulated transcripts was observed at 12 months after administration. The Cdkn1a, C3, Dbp, Lcn2, and Per2 genes displayed a distinct dose-dependent regulation, with increased expression level with increasing absorbed dose. Ifng, Tnf, and Il1B were identified as primary up-stream regulators of the recurrently regulated transcripts. Furthermore, previously proposed biomarkers for kidney injury and radiation damage were also observed. The functional investigation revealed reduced excretion of 99mTc-DTPA after 150 MBq, an increased uptake of 99mTc-DMSA at all dose levels compared with the controls, and markedly increased urea level in blood after 150 MBq at 12 months. CONCLUSION:Distinct dose-response relationships were found for several of the regulated transcripts. The Cdkn1a, Dbp, Lcn2, and Per2 genes are proposed as biomarkers for 177Lu-octreotate exposure of kidney. Correlations to functional and morphological effects further confirm applicability of these genes as markers of radiation damage in kidney tissue.

SUBMITTER: Schuler E

PROVIDER: S-EPMC4546116 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Potential Biomarkers for Radiation-Induced Renal Toxicity following 177Lu-Octreotate Administration in Mice.

Schüler Emil E Larsson Maria M Parris Toshima Z TZ Johansson Martin E ME Helou Khalil K Forssell-Aronsson Eva E

PloS one 20150819 8

<h4>Unlabelled</h4>The kidneys are one of the main dose-limiting organs in peptide receptor radionuclide therapy and due to large inter-individual variations in renal toxicity, biomarkers are urgently needed in order to optimize therapy and reduce renal tissue damage. The aim of this study was to investigate the transcriptional, functional, and morphological effects on renal tissue after 177Lu-octreotate administration in normal mice, and to identify biomarkers for radiation induced renal toxici ...[more]

PMID: 26287527

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Project description:BACKGROUND:177Lu-octreotate is used for therapy of somatostatin receptor expressing neuroendocrine tumors with promising results, although complete tumor remission is rarely seen. Previous studies on nude mice bearing the human small intestine neuroendocrine tumor, GOT1, have shown that a priming injection of 177Lu-octreotate 24 h before the main injection of 177Lu-octreotate resulted in higher 177Lu concentration in tumor, resulting in increased absorbed dose, volume reduction, and time to regrowth. To our knowledge, the cellular effects of a priming treatment schedule have not yet been studied. The aim of this study was to identify transcriptional changes contributing to the enhanced therapeutic response of GOT1 tumors in nude mice to 177Lu-octreotate therapy with priming, compared with non-curative monotherapy. RESULTS:RNA microarray analysis was performed on tumor samples from GOT1-bearing BALB/c nude mice treated with a 5 MBq priming injection of 177Lu-octreotate followed by a second injection of 10 MBq of 177Lu-octreotate after 24 h and killed after 1, 3, 7, and 41 days after the last injection. Administered activity amounts were chosen to be non-curative, in order to facilitate the study of tumor regression and regrowth. Differentially regulated transcripts (RNA samples from treated vs. untreated animals) were identified (change ≥ 1.5-fold; adjusted p value < 0.01) using Nexus Expression 3.0. Analysis of the biological effects of transcriptional regulation was performed using the Gene Ontology database and Ingenuity Pathway Analysis. Transcriptional analysis of the tumors revealed two stages of pathway regulation for the priming schedule (up to 1 week and around 1 month) which differed distinctly from cellular responses observed after monotherapy. Induction of cell cycle arrest and apoptotic pathways (intrinsic and extrinsic) was found at early time points after treatment start, while downregulation of pro-proliferative genes were found at a late time point. CONCLUSIONS:The present study indicates increased cellular stress responses in the tumors treated with a priming treatment schedule compared with those seen after conventional 177Lu-octreotate monotherapy, resulting in a more profound initiation of cell cycle arrest followed by apoptosis, as well as effects on PI3K/AKT-signaling and unfolded protein response.

Project description:BACKGROUND:Peptide receptor radionuclide therapy (PRRT) utilizes somatostatin receptor (SSR) overexpression on neuroendocrine tumors (NET) to deliver targeted radiotherapy. Intensity of uptake at imaging is considered related to efficacy but has low sensitivity. A pretreatment strategy to determine individual PRRT response remains a key unmet need. NET transcript expression in blood integrated with tumor grade provides a PRRT predictive quotient (PPQ) which stratifies PRRT "responders" from "non-responders". This study clinically validates the utility of the PPQ in NETs. METHODS:The development and validation of the PPQ was undertaken in three independent 177Lu-PRRT treated cohorts. Specificity was tested in two separate somatostatin analog-treated cohorts. Prognostic value of the marker was defined in a cohort of untreated patients. The developmental cohort included lung and gastroenteropancreatic [GEP] NETs (n?=?72) from IRST Meldola, Italy. The majority were GEP (71%) and low grade (86% G1-G2). Prospective validation cohorts were from Zentralklinik Bad Berka, Germany (n?=?44), and Erasmus Medical Center, Rotterdam, Netherlands (n?=?42). Each cohort included predominantly well differentiated, low grade (86-95%) lung and GEP-NETs. The non-PRRT comparator cohorts included SSA cohort I, n?=?28 (100% low grade, 100% GEP-NET); SSA cohort II, n?=?51 (98% low grade; 76% GEP-NET); and an untreated cohort, n?=?44 (64% low grade; 91% GEP-NET). Baseline evaluations included clinical information (disease status, grade, SSR) and biomarker (CgA). NET blood gene transcripts (n?=?8: growth factor signaling and metabolism) were measured pre-therapy and integrated with tumor Ki67 using a logistic regression model. This provided a binary output: "predicted responder" (PPQ+); "predicted non-responder" (PPQ-). Treatment response was evaluated using RECIST criteria [Responder (stable, partial and complete response) vs Non-Responder)]. Sample measurement and analyses were blinded to study outcome. Statistical evaluation included Kaplan-Meier survival and standard test evaluation analyses. RESULTS:In the developmental cohort, 56% responded to PRRT. The PPQ predicted 100% of responders and 84% of non-responders (accuracy: 93%). In the two validation cohorts (response: 64-79%), the PPQ was 95% accurate (Bad Berka: PPQ?+?=97%, PPQ-?=?93%; Rotterdam: PPQ?+?=94%, PPQ-?=?100%). Overall, the median PFS was not reached in PPQ+ vs PPQ- (10-14 months; HR: 18-77, p?<?0.0001). In the comparator cohorts, the predictor (PPQ) was 47-50% accurate for SSA-treatment and 50% as a prognostic. No differences in PFS were respectively noted (PPQ+: 10-12 months vs. PPQ-: 9-15 months). CONCLUSION:The PPQ derived from circulating NET specific genes and tumor grade prior to the initiation of therapy is a highly specific predictor of the efficacy of PRRT with an accuracy of 95%.

Dataset Information

Potential Biomarkers for Radiation-Induced Renal Toxicity following 177Lu-Octreotate Administration in Mice.

Publications

Potential Biomarkers for Radiation-Induced Renal Toxicity following 177Lu-Octreotate Administration in Mice.

Similar Datasets

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