Nefrotoxicidad y hematotoxicidad un año después de cuatro ciclos de terapia con péptidos marcados con radionúclidos (PRRT) y su impacto en la planificación del tratamiento futuro. Un análisis retrospectivo / Nephrotoxicity and hematotoxicity one year after four cycles of peptide receptor radionuclide therapy (PRRT) and its impact on future treatment planning. A retrospective analysis

Introducción: La nefrotoxicidad y la hematotoxicidad después de la terapia con péptidos marcados con radionúclidos (PRRT) se han descrito en múltiples estudios usando diferentes actividades acumulativas, número de ciclos o péptidos marcados con radionúclidos. Aunque los tumores neuroendocrinos (NET) altamente diferenciados con metástasis tienen una larga supervivencia libre de progresión, pueden progresar. Analizamos los efectos secundarios a largo plazo en un esquema de tratamiento homogéneo en pacientes con PRRT y su impacto en el futuro tratamiento oncológico en caso de progresión. Métodos: De nuestra base de datos se analizaron 89 de 384 pacientes que recibieron la misma PRRT (Lu-177-DOTATATE o Y-90-DOTATOC) cuatro veces cada 10 a 12 semanas y un seguimiento a los 12 meses. Un paciente recibió tres y 11 pacientes recibieron dos veces cuatro ciclos de PRRT, lo que dio lugar a 102 casos. Se compararon el índice de filtrado glomerular estimado (FGe), la Hb, los glóbulos blancos y las plaquetas antes del primer ciclo de terapia y un año después del cuarto ciclo. La clasificación del FGe se realizó según la clasificación de la enfermedad renal crónica (ERC) y la clasificación de la hematotoxicidad según los Criterios Terminológicos Comunes para Eventos Adversos (CTCAE). También se evaluó el impacto de la edad, el sexo, la actividad acumulada y el tipo de PRRT en la toxicidad a largo plazo. Resultados: El grado 1-2 del FGe se redujo de 87/102 al inicio a 71 casos en el seguimiento (p < 0,001). Antes del tratamiento se encontró grado 3a en 13, grado 3b en 2, y en el seguimiento grado 3a en 25, grado 3b en cinco casos, y grado 4 en 1 caso. La anemia antes de la PRRT y en el seguimiento fue de grado 0 en 63 vs. 48 (p < 0,001), de grado 1 en 36 vs. 48, y de grado 2 en tres vs. seis casos. En el recuento de glóbulos blancos y plaquetas no se produjeron cambios significativos en la clasificación (AU)

Introduction: Nephro- and hematotoxicity after peptide receptor radionuclide therapy (PRRT) have been described in multiple studies with heterogeneous cumulative activities, number of cycles or radiolabelled peptides. Though highly differentiated metastasized neuroendocrine tumours (NET) have long progression free survival, they may progress. We analysed long-term side effects in a homogenous treatment schedule in PRRT-patients and their impact on future oncologic treatment in case of progression. Methods: From our database 89/384 patients receiving the same PRRT (Lu-177-DOTATATE or Y-90-DOTATOC) 4 times every 10 to 12 weeks and a follow-up at 12 months were analysed. One patient had three and 11 patients had two times four PRRT-cycles resulting in 102 cases. eGFR, Hb, WBC and platelets before the first and one year after the fourth therapy cycle were compared. eGFR-Grading was done according to chronic kidney disease classification (CKD) and grading of hematotoxicity according to Common Terminology Criteria for Adverse Events (CTCAE). Impact of age, gender, cumulative activity, type of PRRT on long-term-toxicity was also assessed. Results: eGFR grade 1-2 dropped from 87/102 at the baseline to 71 cases at follow-up (p<0.001). Before treatment grade 3a was found in 13, grade 3b in 2 cases, and at follow-up grade 3a in 25, grade 3b in 5, and grade 4 in 1 case. Anaemia prior to PRRT and at follow-up was grade 0 in 63 versus 48 (p<0.001), grade 1 in 36 versus 48, and grade 2 in three versus six cases. In white blood cell count and platelets, there were no significant changes in grading occurring. Subgroup analysis revealed that only in the age group 65 and older was there a higher incidence for anaemia (p=0.006) (AU)

Nephrotoxicity and hematotoxicity one year after four cycles of peptide receptor radionuclide therapy (PRRT) and its impact on future treatment planning. A retrospective analysis. / Nefrotoxicidad y hematotoxicidad un año después de cuatro ciclos de terapia con péptidos marcados con radionúclidos (PRRT) y su impacto en la planificación del tratamiento futuro. Un análisis retrospectivo.

INTRODUCTION: Nephro- and hematotoxicity after peptide receptor radionuclide therapy (PRRT) have been described in multiple studies with heterogeneous cumulative activities, number of cycles or radiolabelled peptides. Though highly differentiated metastasized neuroendocrine tumours (NET) have long progression free survival, they may progress. We analysed long-term side effects in a homogenous treatment schedule in PRRT-patients and their impact on future oncologic treatment in case of progression. METHODS: From our database 89/384 patients receiving the same PRRT (Lu-177-DOTATATE or Y-90-DOTATOC) 4 times every 10 to 12 weeks and a follow-up at 12 months were analysed. One patient had three and 11 patients had two times four PRRT-cycles resulting in 102 cases. eGFR, Hb, WBC and platelets before the first and one year after the fourth therapy cycle were compared. eGFR-Grading was done according to chronic kidney disease classification (CKD) and grading of hematotoxicity according to Common Terminology Criteria for Adverse Events (CTCAE). Impact of age, gender, cumulative activity, type of PRRT on long-term-toxicity was also assessed. RESULTS: eGFR grade 1-2 dropped from 87/102 at the baseline to 71 cases at follow-up (p<0.001). Before treatment grade 3a was found in 13, grade 3b in 2 cases, and at follow-up grade 3a in 25, grade 3b in 5, and grade 4 in 1 case. Anaemia prior to PRRT and at follow-up was grade 0 in 63 versus 48 (p<0.001), grade 1 in 36 versus 48, and grade 2 in three versus six cases. In white blood cell count and platelets, there were no significant changes in grading occurring. Subgroup analysis revealed that only in the age group 65 and older was there a higher incidence for anaemia (p=0.006). CONCLUSIóN: In roughly 20% of cases an increase in grading of nephro- or hematotoxicity is observed. In those patients, except in one, toxicity findings were mild or moderate one year after completion of four cycles of PRRT with either Y-90- or Lu-177-SST-analogues. In terms of safety, PRRT has no critical impact on further oncologic treatment options in the case of disease progression.

68Ga-DOTATOC PET/CT in the localization of metastatic extra-adrenal paraganglioma and pheochromocytoma compared with 18F-DOPA PET/CT. / Comparación entre la PET/TC con 18F-DOPA y la PET/TC con 68Ga-DOTATOC para la localización del paraganglioma maligno extra-adrenal y el feocromocitoma.

OBJECTIVE: 18F-Fluoro-L-dihydroxyphenylalanine (18F-DOPA) PET offers high sensitivity and specificity in the imaging of non-malignant extra-adrenal paraganglioma (PGL) and pheochromocytoma (PHEO) but lower sensitivity in metastatic disease. These tumours are of neuroendocrine origin and can be detected by 68Ga-DOTA-Tyr3-octreotide (68Ga-DOTA-TOC) PET. Therefore, we compared 68Ga-DOTA-TOC and 18F-DOPA as radiolabels for PET/CT imaging for the diagnosis of metastatic extra-adrenal PGL and PHEO. Combined cross-sectional imaging was the reference standard. METHODS: A total of 6 men and 4 women (age range 22-72 years) with anatomical and/or histologically proven metastatic PGL and PHEO were included in this study. Of these patients, 2 male patients suffered from PHEO, while the remaining 8 patients were diagnosed as metastatic extra-adrenal PGL disease. Comparative evaluation included morphological imaging with CT and functional imaging with 68Ga-DOTA-TOC and 18F-DOPA PET. The imaging results were analyzed on a per-lesion basis. The maximum standardized uptake value (SUVmax) of each functional imaging modality in concordant tumour lesions was measured. RESULTS: Compared with anatomical imaging, the per-lesion detection rate of 68Ga-DOTA-TOC was 100% (McNemar, P<0.01), and that of 18F-DOPA PET was 82.3% (McNemar, P<0.8) in metastatic extra-adrenal PGL and PHEO. Overall, 68Ga-DOTA-TOC PET identified 67 lesions; anatomical imaging identified 62 lesions, and 18F-DOPA PET identified 56 lesions. The SUVmax (mean±SD) of all concordant lesions was 29.3±19.9 for 68Ga-DOTA-TOC PET and 12.3±9.1 for 18F-DOPA PET (Mann-Whitney U test, P<0.0001). CONCLUSION: 68Ga-DOTA-TOC PET offers the highest detection rate in metastatic extra-adrenal PGL and PHEO compared to 18F-DOPA PET and even to diagnostic CT, particularly in bone lesions. Combined functional/anatomical imaging (68Ga-DOTA-TOC PET/CT) enables exact tumour extension to be detected in these rare tumour entities, especially in the case of unclear anatomical correlation.

A rare case of a 123I-MIBG SPECT/CT positive, but 68Ga-DOTA-TOC PET/CT negative pheochromocytoma of the bladder. / Caso infrecuente de feocromocitoma vesical positivo en la SPECT/TC con 123I-MIBG, pero negativo en la PET/TC con 68Ga-DOTA-TOC.

Pheochromocytoma (PHEO) is rare and belongs to the group of neuroendocrine tumours (NETs). These tumours can be found anywhere from the neck to the pelvis associated with sympathetic ganglia. Morphological imaging, for example CT, provides excellent anatomical detail and high sensitivity but lacks specificity as difficulties may occur when distinguishing between tumours derived from the sympathetic nervous system and other tumour entities. In contrast to anatomical imaging, functional imaging (123I-MIBG, 68Ga-DOTA-TOC PET) provides high sensitivity and specificity in detecting NETs. Early detection of PHEO is crucial and has a major effect on treatment and prognosis. This case report describes the important role of anatomical and functional imaging in a patient with a neuroendocrine tumour of unusual origin.

Localization and prediction of malignant potential in recurrent pheochromocytoma/paraganglioma (PCC/PGL) using 18F-FDG PET/CT.

BACKGROUND: To our knowledge, data are lacking on the role of 18F-FDG PET/CT in the localization and prediction of neuroendocrine tumors, in particular the pheochromocytoma/paraganglioma (PCC/PGL) group. PURPOSE: To evaluate the role of 18F-FDG PET/CT in localizing and predicting the malignant potential of PCC/PGL. MATERIAL AND METHODS: Twenty-three consecutive patients with a history of PCC/PGL, presenting with symptoms related to catecholamine excess, underwent 18F-FDG PET/CT. Final confirmation of the diagnosis was made using the composite references. PET/CT findings were analyzed on a per-lesion basis and a per-patient basis. Tumor SUVmax was analyzed to predict the dichotomization of patient endpoints for the local disease and metastatic groups. RESULTS: We investigated 23 patients (10 men, 13 women) with a mean age of 46.43 ± 3.70 years. Serum catecholamine levels were elevated in 82.60% of these patients. There were 136 sites (mean SUVmax: 16.39 ± 3.47) of validated disease recurrence. The overall sensitivities for diagnostic CT, FDG PET, and FDG PET/CT were 86.02%, 87.50%, and 98.59%, respectively. Based on the composite references, 39.10% of patients had local disease. There were significant differences in the SUVmax distribution between the local disease and metastatic groups; a significant correlation was noted when a SUVmax cut-off was set at 9.2 (P<0.05). CONCLUSION: In recurrent PCC/PGL, diagnostic 18F-FDG PET/CT is a superior tool in the localization of recurrent tumors. Tumor SUVmax is a potentially useful predictor of malignant tumor potential.

68Ga-DOTA-TOC uptake in neuroendocrine tumour and healthy tissue: differentiation of physiological uptake and pathological processes in PET/CT.

PURPOSE: We wanted to establish the range of (68)Ga-DOTA-TOC uptake in liver and bone metastases of patients with neuroendocrine tumours (NET) and to establish the range of its uptake in pancreatic NET. This would allow differentiation between physiological uptake and tumour-related somatostatin receptor expression in the pancreas (including the uncinate process), liver and bone. Finally, we wanted to test for differences in patients with NET, either treated or not treated with peptide receptor radionuclide therapy (PRRT). METHODS: In 249 patients, 390 (68)Ga-DOTA-TOC PET/CT studies were performed. The clinical indications for PET/CT were gastroenteropancreatic NET (194 studies), nongastroenteropancreatic NET (origin in the lung and rectum; 46 studies), NET of unknown primary (111 studies), phaeochromocytoma/glomus tumours (18 studies), and radioiodine-negative metastatic thyroid carcinoma (21 studies). RESULTS: SUVmax (mean ± standard deviation) values of (68)Ga-DOTA-TOC were 29.8 ± 16.5 in 162 liver metastases, 19.8 ± 18.8 in 89 bone metastases and 34.6 ± 17.1 in 43 pancreatic NET (33.6 ± 14.3 in 30 tumours of the uncinate process and 36.3 ± 21.5 in 13 tumours of the pancreatic tail). A significant difference in SUVmax (p < 0.02) was found in liver metastases of NET patients treated with PRRT. There were significant differences in SUVmax between nonmalignant and malignant tissue for both bone and liver metastases and for pancreatic NET including the uncinate process (p < 0.0001). At a cut-off value of 17.1 the specificity and sensitivity of SUVmax for differentiating tumours in the uncinate process were 93.6 % and 90.0 %, respectively (p < 0.0001). CONCLUSION: (68)Ga-DOTA-TOC is an excellent tracer for the imaging of tumours expressing somatostatin receptors on the tumour cell surface, facilitating the detection of even small tumour lesions. The noninvasive PET/CT approach by measurement of regional SUVmax can offer important clinical information to distinguish between physiological and pathological somatostatin receptor expression, especially in the uncinate process. PRRT does not significantly influence SUVmax, except in liver metastases of patients with NET.

Comparison of (68)Ga-DOTA-Tyr(3)-octreotide and (18)F-fluoro-L-dihydroxyphenylalanine positron emission tomography in neuroendocrine tumor patients.

AIM: (68)Ga-DOTA-Tyr3-octreotide positron emission tomography ((68)Ga-DOTA-TOC PET) and (18)F-fluoro-L-dihydroxyphenylalanine PET ((18)F-DOPA PET) are emerging modalities for imaging of neuroendocrine tumors. This study reports our initial experiences with these two PET modalities on initial diagnosis, staging and restaging in NET patients. METHODS: Fifteen patients with NET underwent both (68)Ga-DOTA-TOC and (18)F-DOPA PET as well as computed tomography (CT). Image findings were compared on a patient-basis (pathological uptake: yes/no) as well as on a lesion-basis. Contrast-enhanced CT and histological follow-up served as gold standard. Furthermore, imaging results were matched with tumor marker levels and quantitative tracer uptake by the tumor lesions. RESULTS: When comparing (68)Ga-DOTA-TOC and (18)F-DOPA PET, each modality showed a sensitivity of 64% and a specificity of 100% on a patient-based analysis. (68)Ga-DOTA-TOC PET and (18)F-DOPA PET showed equal findings in 7 out of 15 patients and disagreement in 8 patients. (68)Ga-DOTA-TOC revealed more metastases than (18)F-DOPA PET in 6 patients, while (18)F-DOPA PET detected more metastases than (68)Ga-DOTA-TOC in 4 patients. By (68)Ga-DOTA-TOC PET, 208 malignant lesions were detected, while by (18)F-DOPA only 86 lesions were found, and in CT 124, respectively. CONCLUSIONS: (68)Ga-DOTA-TOC and (18)F-DOPA PET are useful tools in the detection and staging of NET lesions. Our initial results allow the conclusion that (68)Ga-DOTA-TOC PET may have a stronger clinical impact in NET patients, as it does not only offer diagnostic information, but is decisive for the further treatment management, i. e. PRRT, as well.

Individualized peptide-related-radionuclide-therapy concept using different radiolabelled somatostatin analogs in advanced cancer patients.

AIM: Over the last decade, somatostatin (SST) receptor (R)-positive tumors have been treated using either (90)Y-DOTA-TOC, (177)Lu-DOTA-TATE or (90)Y-DOTA-LAN/(177)Lu-DOTA-LAN, at the Innsbruck Medical University. This report presents data from the evaluation of the initial 100 patients receiving receptor mediated radionuclide therapy (PRRT) according to our protocol. METHODS: One-hundred patients with SSTR-positive tumors were treated (36 female, 64 male; mean age, 58 years; range, 13 to 84 years), including 68 patients with neuroendocrine tumors (NET), and patients with other non-neuroendocrine tumors, e.g. patients with radioiodine-negative thyroid carcinoma, refractory to conventional treatment modalities. Patients were selected based on high SSTR expression as assessed by (68)Ga-DOTA-TOC as first choice tracer for patients with NET, or (68)Ga-DOTA-LAN for patients with other tumor entities, or if the (68)Ga-DOTA-TOC PET was negative. Following positron emission tomography (PET), individual dosimetry was regularly performed using (111)In-labeled compounds. Therapy cycles were repeated every 10 weeks using either (90)Y-DOTA-TOC (3.7 GBq, 3-5 cycles) or (177)Lu-DOTA-TATE (7.4 GBq, 3-4 cycles). Thirteen patients received both and 5 patients even 3 different therapeutic compounds. Each patient received an amino acid solution (arginin, lysine) to reduce the kidney dose. Between the radioactive cycles a long-acting SST analog was applied. Dosages were individually adapted depending on several disease related factors. RESULTS: Overall, following PRRT partial remission (PR) was observed in 23 patients (23 %), minor remission (MR) in 10 (10 %), stable disease (SD) in 42 patients (42 %). Although 25 patients (25 %) showed progressive disease (PD), palliative care was provided in most of these patients. In the group treated with 90Y-DOTA-TOC, 12 patients showed PR, 3 MR, 32 SD and 13 had PD. In the group of patients treated with (177)Lu-DOTA-TATE, PR was observed in 15 patients, MR in 8, SD in 19 and PD in 13 patients. Severe side effects (WHO Grad 3 and 4) were seen in only 6 % of patients. Severe long-term nephrotoxicity was observed in none of the patients. These adverse reactions were especially seen in patients who were treated with high doses per cycle, in patients pre-treated with chemotherapy and in patients with low clinical performance. CONCLUSIONS: PRRT with differently labelled tracers (Y-90 or Lu-177) and different SST-analogs is generally well tolerated without serious side effects. These results favour the combined use of radiolabeled SST analogs providing a customized tumour targeting for size reduction and improvement of quality-of-life. Extended time intervals and reduced individual doses make sense in patients with advanced tumor stages, in case of moderate SSTR-expression, and in patients with higher age.

99mTc-labelled HYNIC-minigastrin with reduced kidney uptake for targeting of CCK-2 receptor-positive tumours.

PURPOSE: Different attempts have been made to develop a suitable radioligand for targeting CCK-2 receptors in vivo, for staging of medullary thyroid carcinoma (MTC) and other receptor-expressing tumours. After initial successful clinical studies with [DTPA(0),D: Glu(1)]minigastrin (DTPA-MG0) radiolabelled with (111)In and (90)Y, our group developed a (99m)Tc-labelled radioligand, based on HYNIC-MG0. A major drawback observed with these derivatives is their high uptake by the kidneys. In this study we describe the preclinical evaluation of the optimised shortened peptide analogue, [HYNIC(0),D: Glu(1),desGlu(2-6)]minigastrin (HYNIC-MG11). METHODS: (99m)Tc labelling of HYNIC-MG11 was performed using tricine and EDDA as coligands. Stability experiments were carried out by reversed phase HPLC analysis in PBS, PBS/cysteine and plasma as well as rat liver and kidney homogenates. Receptor binding and cell uptake experiments were performed using AR4-2J rat pancreatic tumour cells. Animal biodistribution was studied in AR4-2J tumour-bearing nude mice. RESULTS: Radiolabelling was performed at high specific activities and radiochemical purity was >90%. (99m)Tc-EDDA-HYNIC-MG11 showed high affinity for the CCK-2 receptor and cell internalisation comparable to that of (99m)Tc-EDDA-HYNIC-MG0. Despite high stability in solution, a low metabolic stability in rat tissue homogenates was found. In a nude mouse tumour model, very low unspecific retention in most organs, rapid renal excretion with reduced renal retention and high tumour uptake were observed. CONCLUSION: (99m)Tc-EDDA-HYNIC-MG11 shows advantages over (99m)Tc-EDDA-HYNIC-MG0 in terms of lower kidney retention with unchanged uptake in tumours and CCK-2 receptor-positive tissue. However, the lower metabolic stability and impurities formed in the labelling process still leave room for further improvement.