Development of radiolabeled tetramer that targeting fibroblast activation protein and theranostic research in tumor xenografts / 中华核医学与分子影像杂志

Objective:To develop a tetramer probe targeting fibroblast activation protein (FAP), named 1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid (DOTA)-4P(FAP inhibitor (FAPI)) 4, evaluate its biodistribution and PET image in FAP-positive-tumor bearing nude mice, and explore its feasibility as a novel radio-regent for treatment of FAP-positive tumor. Methods:FAP tetramer probe was constructed on the FAPI-46 motif with four mini-polyethylene glycol (PEG)(PEG 3) spacers between the four FAPI motifs, denoted as 4P(FAPI) 4. DOTA was used as the chelator for radiolabeling with 68Ga and 177Lu. The FAP binding characteristics were test by in vitro cell competitive binding experiment. Small-animal PET, in vivo biodistribution, and radionuclide targeting therapy were performed in HT-1080-FAP tumor bearing nude mice ( n=39). Independent-sample t test was performed to analyze tumor uptake data, and two-factor repeated measures analysis of variance was utilized to compare tumor volume data in radioactive isotope therapy. Results:Cell experiment showed that FAPI-tetramer and FAPI-monomer had similar half maximal inhibitory concentration values (3.29 and 2.15 nmol/L). 68Ga/ 177Lu radiolabeled FAPI-tetramer had better tumor uptake and retention than FAPI-monomer in small-animal PET and in vivo biodistribution experiment, with the tumor uptake for 177Lu-DOTA-4P(FAPI) 4 and 177Lu-FAPI-46 at 48 h of (18.72±1.32) vs (2.72±1.20) percentage activity of injection dose per gram of tissue (%ID/g) ( t=15.55, P<0.001). 177Lu-DOTA-4P(FAPI) 4 group showed best anti-tumor efficacy compared with 177Lu-FAPI-46 and control group in radionuclide targeting therapy. On the 2nd day after the start of treatment, the tumor volume in the tetramer treatment group was significantly smaller than that in the control group (mean difference 67.19 mm 3, P=0.049); on the 14th day after the start of treatment, the tumor volume in the tetramer treatment group was significantly smaller than that in the monomer treatment group (mean difference 414.33 mm 3, P=0.005). Conclusion:FAPI-tetramer can improve tumor uptake and retention ability compared with FAPI-46, and 177Lu-DOTA-4P(FAPI) 4 can be a promising radio-agent for FAP-positive tumor therapy.

Research progress of salivary glands injury secondary to 225Ac/ 177Lu-PSMA-617 in the treatment of prostate cancer and its protection / 中华核医学与分子影像杂志

Prostate specific membrane antigen (PSMA) radioligand therapy (RLT) is effective in metastatic castration-resistant prostate cancer (mCRPC). However, PSMA RLT can cause radiation damage to salivary glands, especially 225Ac/ 177Lu-PSMA-617. Radiation-related salivary glands damage can cause xerostomia, reduce the quality of life, and even limit the dose of radiopharmaceuticals and reduce the efficacy of tumor treatment. At present, there are few literatures on PSMA RLT related salivary glands damage in China. In this article, radiation-related salivary glands damage and the related protective measures during 225Ac/ 177Lu-PSMA-617 RLT are reviewed based on domestic and foreign studies.

Comparison of preparation for 177Lu-labeled radiopharmaceutical and its preliminary clinical application / 中华核医学与分子影像杂志

Objective:To investigate the preparation methods and quality control of 177Lu-labeled radiopharmaceuticals, and conduct preliminary clinical application research. Methods:177Lu-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid (DOTA)- D-Phe1-Tyr3-octreotide (TOC) and 177Lu-prostate specific membrane antigen (PSMA)-I&T were labeled by manual labeling and automatic labeling, respectively. Factors such as the amount of precursor and nuclide, reaction temperature, pH value, reaction time, labeling yield and specific activity were investigated. Quality control of the products were carried out, such as clarity, pH value, sterility, bacterial endotoxin and stability in vitro. 177Lu-PSMA-I&T was applied to the treatment of prostate cancer patients, and the efficacy was evaluated by SPECT/CT imaging. Paired t test was used to analyze the data. Results:The amount of precursor and nuclide, reaction temperature, pH value and reaction time of the two methods were basically the same, both with high yield and specific activity. The yield of 177Lu-DOTA-TOC automatic labeling was significantly higher than that of manual labeling (99.2±0.4)% vs (95.3±1.5)% ( t=7.17, P<0.001), and the specific activity were (91.6±13.7) vs (89.1±13.2) GBq/μmol. The yield of 177Lu-PSMA-I&T automatic labeling was also significantly higher than that of manual labeling (99.6±0.3)% vs (95.7±1.3)% ( t=8.24, P<0.001), and the specific activity were (96.1±14.3) vs (93.2±13.8) GBq/μmol. The labeled products were colorless clear solution with pH value of 6.5-7.0. The sterility and bacterial endotoxin met the requirements. The radiochemical purity of the labeled products was more than 95% after 48 h, which showed good stability. The clinical application of 177Lu-PSMA-I&T in patients with prostate cancer showed that both primary and metastatic lesions had good uptake. Conclusions:The labeling of 177Lu radiopharmaceuticals is simple and has high yield and stability. The application of automatic labeling can simplify the process, improve the yield and reduce irradiation.

External exposure dose of 177Lu-PSMA-617 to the public in the treatment of prostate cancer / 中华核医学与分子影像杂志

Objective:To estimate the radiation dose (RD) to the public from patients undergoing 177Lu-prostate specific membrane antigen (PSMA)-617 therapy, and provide reference for the formulation of radiation protection measures. Methods:From July 2020 to January 2021, 10 patients with prostate cancer (age (71.1±5.9) years) who received 177Lu-PSMA-617 therapy in the Affiliated Hospital of Southwest Medical University were retrospectively analyzed. According to the different doses of 177Lu-PSMA-617, the patients were divided into the low-dose (5.55-6.29 GBq) group and high-dose (6.70-8.94 GBq) group. Respectively at 5, 30 min and 1, 2, 4, 24, 48, 72, 96, 144 h after intravenous injection of 177Lu-PSMA-617, whole-body initial dose-equivalent rate (DR) was measured with a radiation-survey meter at 0.3, 1.0 and 2.0 m from the patients. The statistics of ROI were analyzed by HERMES, and the corresponding equations were obtained by fitting the curve regression with double exponential function model. On the basis of human social contact model proposed by the National Council on Radiation Protection and Measurements (NCRP), the RD to the public from the patient discharged from the hospital at different times after completing the 177Lu-PSMA-617 injection was estimated. Results:All patients were discharged from the hospital at 72 h after treatment. The initial DR at 0.3, 1.0 and 2.0 m were (12.6±3.3), (4.7±1.2) and (1.6±0.4) μSv/h, respectively, and the RD to the co-sleeping partner, family members and colleagues who were in contact during the day were (999±253), (121±29) and (160±39) μSv, respectively. If the patients were discharged at 48 h after treatment, the RD to the adult family members could be controlled ≤5 mSv, and the RD to colleagues and children could be controlled ≤1 mSv. Starting from the injection of 177Lu-PSMA-617, the restriction duration for co-sleeping partner and colleagues were both 2 d and the restriction duration for children were 2 d (high-dose group) or 1 d (low-dose group). The patients needed to limit the time for public transportation from the 1st to 4th day after treatment, and there was no restriction from the 5th day. Conclusion:According to the current RD restrictions on the public, 177Lu-PSMA-617 is a relatively safe treatment modality for prostate cancer if good safety precautions are taken.

Laboratory variables as predictors of progression in gastroenteropancreatic neuroendocrine tumors in different lines of antineoplastic treatments

ABSTRACT Objective: To determine the association of red cell blood counts, and liver panel tests to predict outcomes in patients with gastroenteropancreatic neuroendocrine tumors who underwent systemic antineoplastic treatments. Methods: Patients with gastroenteropancreatic neuroendocrine tumors in systemic treatment were assessed according to laboratory tests within the same period. Progression free survival was determined by the period between the beginning of treatment and the date of progression. We used conditional models (PWP model) to verify the association between laboratory tests and tumor progression. The level of significance used was 5%. Results: A total of 30 treatments given to 17 patients in the intention-to-treat population were evaluated. Treatment included octreotide, lanreotide, everolimus, lutetium, and chemotherapy. We had statistically significant results in chromogranin A, neutrophils and platelets-to-lymphocyte ratio. The risk of progression increases by 2% with the addition of 100ng/mL of chromogranin A (p=0.034), 4% with the increase of 100 neutrophil units (p=0.006), and 21% with the addition of 10 units in platelets-to-lymphocyte ratio (p=0.002). Conclusion: Chromogranin A, neutrophils and platelets-to-lymphocyte ratio were associated with disease progression during systemic treatment in gastroenteropancreatic neuroendocrine tumors. Further prospective studies with larger cohorts are necessary to validate our findings.

Eficacia de lutecio-177 DOTATATE/TOC en pacientes con tumores neuroendocrinos bien diferenciados en estado avanzado. Ensayo clínico fase II / Efficacy of Lutetium-177 DOTATATE/TOC in Advanced Neuroendocrine Tumors

Resumen Introducción: En 2009, el Instituto Nacional de Cancerología (INC) elaboró el 177Lu-DOTATATE/TOC. El propósito del estudio fue demostrar la eficacia de estos radiopéptidos en el tratamiento paliativo de pacientes con tumores neuroendocrinos (TNE) avanzados inoperables (metastásicos o localmente avanzados) y en progresión. Métodos: Ensayo clínico abierto fase II de un solo brazo en 13 pacientes adultos con TNE grado 1 o 2, con expresión de receptores de somatostatina en lesiones blanco demostrada por captación Krenning 3 o 4 en 99mTc-HYNIC TOC. Los pacientes fueron tratados con 177Lu-DOTATATE o 177Lu-DOTATOC (según disponibilidad) a una actividad acumulativa proyectada de 600-800 mCi dividida en 3-4 dosis cada 6-9 semanas comenzando siempre con una actividad fija de 200 mCi y dosimetría con la primera dosis. El desenlace primario fue la respuesta objetiva calculada 6 y 12 meses después de la última dosis del tratamiento. Resultados: Se incluyeron 13 pacientes (7 mujeres) de 63 ± 11,6 años con TNE avanzado inoperable y en progresión. La actividad final administrada fue de 800 mCi, 600 mCi, 400 mCi y 200 mCi en 4, 7, 1 y 1 pacientes, respectivamente. La tasa de control de enfermedad a 6 y 12 meses fue de 69,2% y 45,5%, respectivamente, logrando únicamente enfermedad estable. Fallecieron 7 pacientes, 2 de ellos en los primeros 6 meses. La mediana de supervivencia global a partir de la última dosis del radiopéptido fue de 15,7 meses. Conclusiones: Se corroboró la eficacia y la seguridad del tratamiento con los radiopéptidos en NETs avanzados.

Abstract Objectives: The National Cancer Institute first elaborated 177Lu-DOTATATE/TOC in 2009. The purpose of this study was to prove the efficacy of these radiopeptides in the palliative treatment of patients with progressive advanced inoperable neuroendocrine tumors (NETs). Methods: A single-phase phase II open clinical trial was conducted in 13 adult patients with grade 1 y 2 NETs, with expression of somatostatin receptors in target lesions proven by Krenning Score 3 or 4 uptake in 99mTc-HYNIC TOC. Patients were treated with 177Lu-DOTATATE or 177Lu-DOTATOC (depending upon availability) at a projected acumulative activitiy of 600-800 mCi divided into 3-4 doses every 6-9 weeks always beginning with a fixed activity of 200 mCi and dosimetry during the first dose. The primary outcome was objective response to therapy. Results: 13 patients (7 women) aged 63 ± 11.6 years with inoperable advanced NETs were included. The final therapeutic administered activity was 800 mCi, 600 mCi, 400 mCi and 200 mCi in 4, 7, 1 and 1 patients, respectively. The disease control rate at 6 and 12 months was 69.2% and 45.5%, respectively, only obtaining stable disease. Six patients died, 2 of them in the first 6 months. Median overall survival was 15.7 months from the last treatment dose. Conclusions: The efficacy of the treatment with 177Lu-DOTATATE or 177Lu-DOTATOC radiopeptides elaborated in-house was confirmed, becoming a management alternative for patients with advanced NETs.

Preparation and preliminary biological evaluation of 177Lu-NOTATATE / 中华核医学与分子影像杂志

Objective:To explore the optimal labeling conditions of 177Lu-1, 4, 7-triazacyclononane-1, 4, 7-triacetic acid (NOTA)- D-Phe1-Tyr3-Thr8-octreotide (TATE), and evaluate its biodistribution and imaging characteristics in mice. Methods:The reaction temperature, pH, reaction time and other labeling conditions were changed to realize the rapid labeling of NOTATATE by 177Lu. The optimal labeling conditions, radiochemical purity, in vitro stability, plasma protein binding rate, and lipid-water partition coefficient were determined. Twenty-four normal KM mice were divided into 6 groups by random number table method. After injected with 3.7 MBq 177Lu-NOTATATE through tail vein, they were sacrificed at 0.5, 1, 4, 24 h and 4, 6 d respectively to research the biological distribution (injection dose rate per gram of tissue percentage, %ID/g). Six normal mice were randomly divided into 2 groups and injected with 11.1 MBq 177Lu-NOTATATE and 177Lu-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid (DOTA)TATE, respectively. SPECT planar imaging was performed at 1, 2, 3 h after injection. Another 8 mice were divided into 4 groups, injected with 3.7, 7.4, 18.5 MBq 177Lu-NOTATATE and saline respectively for an acute toxicity test. Results:At pH 5 and reaction temperature between 95 ℃ and 100 ℃ for 15 min, the labeling rate could reach more than 98%. After being placed in human serum for 24 h, the radiochemical purity was still higher than 95%. The plasma protein binding rate of 177Lu-NOTATATE was (58.6±1.9)% and the lipid-water partition coefficient was 0.048±0.014. In normal mice, the concentration of radioactivity is mainly in the liver, kidney and spleen, especially in the kidney (up to (29.120±1.204) %ID/g after 0.5 h of injection), which is less distributed in the blood and excreted rapidly. Compared with 177Lu-DOTATATE, 177Lu-NOTATATE was excreted faster by the kidney. The toxicity study results revealed that no damage was observed in mice of each group, and no obvious damage or inflammatory changes were observed in organ tissue sections. Conclusions:The optimal labeling condition of 177Lu-NOTATATE were determined in this study. The physical, chemical, and biological properties of 177Lu-NOTATATE were proved to be good and safe, and it was excreted faster by the kidney than 177Lu-DOTATATE. The results of this study lay a foundation for further clinical transformation research.

Tumor neuroendocrino y terapia con lutecio / Neuroendocrine tumor and lutetium therapy / Tumor neuroendócrino e terapia com lutecio

Resumen: Introducción: los tumores neuroendocrinos gastroenteropancreáticos (GEP-NET) son un grupo diversos de tumores de origen en las células neuroendocrinas, la mayoría son esporádicos. Se clasifican según origen, secreción hormonal y diferenciación celular. El tratamiento con péptidos radiomarcados o Peptide Receptor Radionuclide Therapy (PRRT) con lutecio 177-DOTATATE fue aprobado por la FDA en el 2018, ya que ha mostrado buenos resultados en tumores avanzados comparado con otras terapias. Presentamos un caso de una paciente con tumor neuroendocrino pancreático con secundarismo hepático tratada con este fármaco. Caso clínico: paciente de sexo femenino de 65 años, portadora de un tumor neuroendocrino pancreático con secundarismo hepático diagnosticado por biopsia y con expresión de receptores de somatostatina. Por su extensión lesional se indica tratamiento médico con análogos de somatostatina que son mal tolerados, tras lo cual se plantea quimioterapia (QT), con progresión tumoral bajo tratamiento. Dada la mala evolución se inicia tratamiento con PRRT como es lutecio 177-DOTATATE. Se observó que los ciclos con lutecio 177-DOTATATE lograron una disminución mínima del tamaño y de la captación tumoral a nivel pancreático, las metástasis hepáticas no presentaron cambios, y la paciente persistió clínicamente estable. Conclusión: El tratamiento con lutecio 177-DOTATATE en una paciente con un tumor neuroendocrino no funcionante con metástasis, irresecable quirúrgicamente, produjo una respuesta aceptable para un tratamiento paliativo, ya que no se produjo progresión tumoral. La paciente persiste clínicamente estable, asintomática, con un seguimiento a 8 años. El tratamiento con lutecio 177-DOTATATE es una opción efectiva con efectos adversos limitados en tumores GEP-NET irresecables o con metástasis.

Summary: Introduction: gastroenteropancreatic neuroendocrine neoplasms (GEP-NET) are a group of several tumors originated in neuroendocrine cells, most of which are sporadic. These tumors are classified according to hormone secretion and cell differentiation. Treatment with radiomarked peptides or Peptide Receptor Radio- nuclide Therapy (PRRT) with lutetium 177-DOTATATE was approved by the FDA in 2018, since it has evidenced good results in advanced tumors compared to other therapies. The study presents the case of a patient with a pancreatic neuroendocrine tumor with secondary hepa tic disease who was treated with this drug. Clinical case: 65-year-old female patient carrier of a pancreatic neuroendocrine tumor with secondary hepatic disease who was diagnosed with a biopsy and presented somatostatin receptor (SSTR) expression. Given the extension of the lesion, medical treatment is indicated with somatostatin analogues that are poorly tolerated. Consequently, chemotherapy is indicated, with low performance tumor progression. Given the poor outcome, PRRT treatment as lutetium 177-DOTATATE is initiated. Cycles with lutetium 177-DOTATATE were observed to cause a minimum reduction in size and tumor uptake in the liver. Liver metastases evidenced no change and the patient remained clinically stable. Conclusion: lutetium 177-DOTATATE therapy in a patient with a metastatic nonfunctioning neuroendocrine tumor, that could not be surgically resected produced an acceptable response for palliative treatment, since the tumor failed to progress. The patient continues to be clinically stable, asymptomatic, after 8 years of follow-up. Lutetium 177-DOTATATE therapy constitutes an effective option with limited side effects in unresectable GEP-NET tumors, or in the presence of metas tases.

Resumo: Introdução: os tumores neuroendócrinos gastroenteropancreáticos (GEP-NET) são um grupo diverso de tumores de origem em células neuroendócrinas, a maioria das quais esporádicos. São classificados de acordo com a origem, secreção hormonal e diferenciação celular. O tratamento com peptídeos radiomarcados ou terapia com radionuclídeos com receptor de peptídeos (PRRT) com 177 Lutecio-Dotatate foi aprovado pela FDA em 2018, pois mostrou bons resultados em tumores avançados em comparação com outras terapias. Apresentamos o caso de um paciente com tumor neuroendócrino pancreático com secundarismo hepático tratado com esse medicamento. Caso clínico: paciente do sexo feminino, 65 anos, portadora de tumor neuroendócrino pancreático com doença hepática secundária diagnosticada por biópsia e com expressão de receptores de somatostatina. Devido à extensão da lesão, o tratamento clínico é indicado com análogos da somatostatina que são pouco tolerados, após o que se considera a quimioterapia (TC), com progressão do tumor em tratamento. Dada a má evolução, foi iniciado tratamento com PRRT, como o 177 Lutecio-Dotatate. Observou-se que os ciclos com 177 Lutecio-Dotatate obtiveram diminuição mínima no tamanho e captação do tumor em nível pancreático, as metástases hepáticas não apresentaram alterações e o paciente manteve-se clinicamente estável. Conclusão: o tratamento com 177Lutecio-Dotatate em um paciente com tumor neuroendócrino não funcionante com metástases, não ressecável cirurgicamente, produziu uma resposta aceitável para o tratamento paliativo, uma vez que não ocorreu progressão do tumor. O paciente permanece clinicamente estável, assintomático, com seguimento de 8 anos. O tratamento com 177Lu-Dotatate é uma opção eficaz com efeitos adversos limitados em tumores GEP-NET não ressecáveis ou metastáticos.

177Lu-PSMA-I&T automated radiolabeling and preclinical prostate cancer targeting research / 中华核医学与分子影像杂志

Objective@#To synthesis 177Lu-prostate specific membrane antigen (PSMA)-I&T with automated module, evaluate the biodistribution and pharmacokinetics in mice and study the targeting property in human prostate cancer cell line LNCaP Clone FGC.@*Methods@#The iQS-TS automated module was applied in labeling 177Lu-PSMA-I&T. Radiochemical purity and stability were determined with high performance liquid chromatography (HPLC). The biodistribution was observed in normal ICR mice and U-SPECT/CT imaging was performed in LNCaP Clone FGC tumor-bearing mice. Independent-sample t test was used to analyze the data.@*Results@#177Lu-PSMA-I&T was stable in vitro and in vivo, with the radiolabeled yield of (91.5±4.9)% and radiochemical purity >99%. The half maximal inhibitory concentration (IC50) of 177Lu-PSMA-I&T binding to LNCaP Clone FGC cells was (26.74±3.53) nmol/L. The uptake of 177Lu-PSMA-I&T by LNCaP Clone FGC cells increased with time and significantly decreased after the inhibitor addition (t values: 4.301-27.483, all P<0.05). 177Lu-PSMA-I&T was cleared from blood rapidly and predominantly excreted by kidneys. Significant radioactive uptake was observed in tumors with a long retention time.@*Conclusion@#177Lu-PSMA-I&T can be produced in a convenient and efficient procedure using iQS-TS automated module, with good biological properties and excellent affinity and targeting property towards prostate cancer cells, which making it a potential radiopharmaceutical for prostate cancer therapy.

Current Status and Growth of Nuclear Theranostics in Singapore / 대한핵의학회잡지

The concept of theranostics, where individual patient-level biological information is used to choose the optimal therapy for that individual, has become more popular in the modern era of ‘personalised’ medicine. With the growth of theranostics, nuclear medicine as a specialty is uniquely poised to grow along with the ever-increasing number of concepts combining imaging and therapy. This special report summarises the status and growth of Theranostic Nuclear Medicine in Singapore.We will cover our experience with the use of radioiodine, radioiodinated metaiodobenzylguanidine, peptide receptor radionuclide therapy, prostate specific membrane antigen radioligand therapy, radium-223 and yttrium-90 selective internal radiation therapy.We also include a section on our radiopharmacy laboratory, crucial to our implementation of theranostic principles. Radionuclide theranostics has seen tremendous growth and we hope to be able to grow alongside to continue to serve the patients in Singapore and in the region.

Dawn of Theranostics in Myanmar (Dream, Reality, and Constraint) / 대한핵의학회잡지

Prostate cancer is third common malignancy in men of old age (average 65 years) in Myanmar. Currently, serum PSA and bone scan are the markers of choice. Because of the evidence-based, promising success of ⁶⁸Ga-PSMA PET-CT and 177Lu-PSMA theranostics in prostate cancer worldwide, (99m)Tc-PSMA SPECT-CT imaging and ¹⁷⁷Lu-PSMA therapy has launched as a stepping-stone of theranostics in Myanmar with the available facilities. Twelve cases of prostate cancer patients were imaged with 600 MBq of (99m)Tc-PSMA I+S SPECT-CT. Four metastatic castration resistant prostate cancer (MCRPC) patients with abnormal result were treated with ¹⁷⁷Lu-PSMA. The protocol consists of 6–8 GBq of ¹⁷⁷Lu-PSMA, three successive doses at interval of 4–6 weeks. Post-therapy SPECT-CT imaging was done. All treated patients were improved by free of bone pain, and fall/rise in serum PSA level. Two patients with extensive skeletal metastases succumbed to complications. The results are well documented and present at the multidisciplinary conferences for clinical awareness. Theranostics in prostate cancer with available facilities is an additional boon to our health care professionals to upgrade cancer management in Myanmar. This paper provides the technology with cost effectiveness and benefit to prostate cancer patients of Myanmar.

Application progress of radionuclide imaging and therapy in neuroendocrine tumors / 中华核医学与分子影像杂志

Some subtypes of somatostatin receptors (SSTRs) are overexpressed in neuroendocrine tumors (NETs). 177Lu-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid-D-Phel-Tyr3-Thr8-octreotide (DOTATATE) is a somatostatin analogue that can be combined with somatostatin receptor specifically, which plays an important role not only in early diagnosis, clinical staging, treatment guiding, recurrence detection and metastasis of NETs, but also in the targeted radionuclide therapy of tumors. The side effect of peptide receptor radionuclide therapy is relatively mild, which is of great clinical significance for prolonging patients′ survival, improving symptoms and the quality of life.

Acquisition protocols of quantitative 177Lu-Dotatate SPECT/CT imaging based on different energy windows and collimators / 中国医学影像技术

Objective: To explore the optimal acquisition protocols for 177Lu-Dotatate SPECT/CT imaging based on different energy windows and collimators. Methods 177Lu SPECT images of a NEMA IEC body phantom with known activity concentration ration (12:1) between filled hollow spheres and uniform background were acquired with 3 different collimators: Low energy high resolution (LEHR), medium energy general purpose (MEGP) and high energy general purpose (HEGP). Main energy window was defined around the energy peak 113 keV, 208 keV and 113 keV+208 keV with 20% width. Scatter correction was performed with applying attenuation correction and triple energy window method. Thus 9 different acquisition protocols could be produced, including LEHR_113, LEHR_208, LEHR_113+208, MEGP_113, MEGP_208, MEGP_113+208, HEGP_113, HEGP_208 and HEGP_113+208 in short. The intensity ratio between spheres and background, relative error and conversion factor were measured and corrected for partial volume effect and used to compare the performance of different methods. Results: The contrast of MEGP_208 SPECT image was the worst, whereas better visual resolution images were achieved by MEGP_208 and MEGP_113+208. The measured average intensity ratios of 9 methods were all lower than the real ratio (F=2.659, P=0.040). The relative error of intensity ratio in MEGP_113+208 was the minimum ([-1.33±6.40]%), and in LEHR_208 was the maximum ([-58.34±14.42]%). All acquisition protocols showed significant difference in conversion factor (F=4.846, P=0.003). Conclusion: Different acquisition protocols have significant effect on the results of 177Lu-Dotatate SPECT/CT quantitative imaging. Image quality of MEGP collimator combined with 113 keV+208 keV is the best, and the intensity ratio is the closest to the real ratio.

Application progress of radionuclide imaging and therapy in neuroendocrine tumors / 中华核医学与分子影像杂志

Some subtypes of somatostatin receptors ( SSTRs) are overexpressed in neuroendocrine tumors (NETs). 177Lu-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid-D-Phel-Tyr3-Thr8-octreoti-de ( DOTATATE) is a somatostatin analogue that can be combined with somatostatin receptor specifically, which plays an important role not only in early diagnosis, clinical staging, treatment guiding, recurrence de-tection and metastasis of NETs, but also in the targeted radionuclide therapy of tumors. The side effect of peptide receptor radionuclide therapy is relatively mild, which is of great clinical significance for prolonging patients' survival, improving symptoms and the quality of life.

Safety and efficacy of 177Lu-PSMA-617 therapy in metastatic castration-resistant prostate cancer / 中华核医学与分子影像杂志

Objective To investigate the safety and efficacy of 177Lu-prostate specific membrane antigen (PSMA)-617 in the treatment of metastatic castration-resistant prostate cancer (mCRPC).Methods From August 2017 to September 2018,11 patients(average age 70.6 years) with mCRPC who underwent 177Lu-PSMA-617 therapy in Nanjing First Hospital were studied.All patients underwent 68Ga-PSMA-11 PET/CT before therapy to assess the tumor radioactive uptake.Blood routine examination and renal function test results were documented before and after therapy to assess the safety.The efficacy was reflected by the changes of prostate specific antigen (PSA) levels and maximum standardized uptake value (SUVmax) on 68Ga-PSMA-11 PET/CT imaging.Paired t test and Wilcoxon's sign rank test were used to analyze the data.Results No acute side effects were observed after therapy of 177Lu-PSMA-617.There were no statistically significant differences after therapy in WBC counts,RBC counts,and PLT,as well as Hb levels (t values:-0.28-1.11,all P＞ 0.05).No kidney toxicity was found.The PSA level after 177Lu-PSMA-617 therapy was significantly lower than that before therapy (80.70 (14.29,1 538.00) μg/L vs 604.60 (88.41,3 980.00) μg/L;u =59,P =0.023).Of the 11 patients,only 2 had elevated PSA levels and disease progression,while the other 9 patients had varying decreases,of which 2/11 decreased by ＞30％ and 7/11 decreased by ＞50％.After therapy,SUVmax of metastatic lesions and metastatic lymph nodes were decreased in 9 and 2 patients respectively.Conclusions 177Lu-PSMA-617 has a good therapeutic value for mCRPC.It is safe and has no obvious side effects.

Peptide Receptor Radionuclide Therapy and the Treatment of Gastroentero-pancreatic Neuroendocrine Tumors: Current Findings and Future Perspectives / 대한핵의학회잡지

PURPOSE AND METHODS: Patients with inoperable andmetastasized neuroendocrine tumors (NETs), particularly those with grades 1 and 2, usually receive treatment with somatostatin analogues (SSAs). Peptide receptor radionuclide therapy (PRRT) has gained momentum over the past two decades in patients who progress on SSAs. 177Lu-DOTATATE is currently the most widely used radiopeptide for PRRT. We reviewed the recent evidence on PRRT and the treatment of gastroentero-pancreatic neuroendocrine tumors (GEP-NETs).RESULTS: ¹⁷⁷Lu-DOTATATE can be used as neoadjuvant treatment in patients with inoperable GEP-NETs, who might be candidate for surgery after treatment and as adjuvant therapy after surgical intervention. Combination treatments of PRRT with chemotherapy or targeted agents as well as combinations of radionuclides in patients with NETs have been explored over the last few years. The majority of patients with NETs experience partial response or have disease stabilization, a small percentage has complete response, while some 30% of patients, however, will have disease progression. The safety and efficacy of retreatment with extra cycles of PRRT as salvage therapy have been evaluated in small retrospective series.CONCLUSION: Overall, there is evidence that disease control and quality of life improve significantly after 117Lu PRRT therapy. Clinical trials on this therapy are scarce, and there is a need for further studies to establish proper management guidelines.

Comparative in vivo biodistributions of nanoparticles and polymers of ¹⁷⁷lutetium-labeled hyaluronic acids in mice during 28 days

Hyaluronic acid (HA) has been investigated for biomedical and pharmaceutical applications. This study was conducted to determine the distributions of HA nanoparticles (NPs; size 350–400 nm) and larger HA polymers in mice at intervals after application. ¹⁷⁷Lutetium (Lu)-labeled HA-NPs or HA polymers were intravenously injected (5 mg/kg) into male ICR mice, and radioactivity levels in blood and target organs were measured from 0.25 h to 28 days post-injection. In blood, the radioactivities of HA-NPs and HA polymer peaked at 0.5 h after injection but were remarkably decreased at 2 h; subsequently, they maintained a constant level until 6 days post-injection. HA-NPs and HA polymers were observed in the liver, spleen, lung, kidney, and heart (in ascending order) but were seldom observed in other organs. After 3 days, both the HA-NP and HA polymer levels showed similar steady decreases in lung, kidney, and heart. However, in liver and spleen, the HA-NP levels tended to decrease gradually after 1 day and both were very low after 14 days, whereas the HA polymer level accumulated for 28 days. The results indicate that HA-NPs, with their faster clearance pattern, may act as a better drug delivery system than HA polymers, especially in the liver and spleen.

Production, quality control, biodistribution assessment and preliminary dose evaluation of [177Lu]-tetra phenyl porphyrin complex as a possible therapeutic agent / Produção, controle de qualidade, avaliação de biodistribuição e avaliação da dose preliminar de [177Lu] -tetra complexo fenil porfirina como um possível agente terapêutico

Due to interesting therapeutic properties of ¹⁷⁷Lu and tumor avidity of tetraphenyl porphyrins (TPPs), ¹⁷⁷Lu-tetraphenyl porphyrin was developed as a possible therapeutic compound. ¹⁷⁷Lu of 2.6-3 GBq/mg specific activity was obtained by irradiation of natural Lu₂O₃sample with thermal neutron flux of 4 × 10¹³ n.cm^-2.s^-1. Tetraphenyl porphyrin was synthetized and labeled with ¹⁷⁷Lu. Radiochemical purity of the complex was studied using Instant thin layer chromatography (ITLC) method. Stability of the complex was checked in final formulation and human serum for 48 h. The biodistribution of the labeled compound in vital organs of wild-type rats was studied up to 7 d. The absorbed dose of each human organ was calculated by medical internal radiation dose (MIRD) method. A detailed comparative pharmacokinetic study was performed for ¹⁷⁷Lu cation and [¹⁷⁷Lu]-TPP. The complex was prepared with a radiochemical purity: >97±1% and specific activity: 970-1000 MBq/mmol. Biodistribution data and dosimetric results showed that all tissues receive approximately an insignificant absorbed dose due to rapid excretion of the complex through the urinary tract. [¹⁷⁷Lu]-TPP can be an interesting tumor targeting agent due to low liver uptake and very low absorbed dose of approximately 0.036 to the total body of human...

Devido às propriedades interessantes do ¹⁷⁷Lu e da avidez tumoral das tetrafenil porfirinas (TPP), desenvolveu-se a ¹⁷⁷Lu-tetrafenil porfirina como composto terapêutico potencial. ¹⁷⁷Lu de atividade específica de 2,6-3 GBq/mg foi obtido por irradiação de amostra de Lu₂O₃ com fluxo térmico de nêutrons de 4 × 10¹³ n.cm^-2.s^-1. Sintetizou-se a tetrafenil porfirina e marcou-se com ¹⁷⁷Lu. A pureza radioquímica do complexo foi estudada usando método de Cromatografia Instantânea de Camada Delgada ( ITLC). A estabilidade do complexo foi checada na formulação final e no ser humano por 48 h. A biodistribuição do composto marcado em órgãos vitais de ratos do tipo selvagem foi estudada por mais de 7 dias. A dose absorvida para cada órgão humano foi calculada pelo método da Dose Médica de Radiação Interna (MIRD). Estudo farmacocinético comparativo detalhado foi efetuado para o cátion ¹⁷⁷Lu e para o [¹⁷⁷Lu]-TPP. O complexo foi preparado com pureza radioquímica >97±1% e atividade específica de 970-1000 MBq/mmol. Os dados de biodistribuição e os resultados dosimétricos mostraram que todos os tecidos receberam uma dose absorvida aproximadamente insignificante devido à rápida excreção do complexo pelo trato urinário. O [¹⁷⁷Lu]-TPP pode ser um agente interessante de direcionamento do tumor devido à baixa captação pelo fígado e pela dose bem baixa absorvida, de, aproximadamente, 0,036 do corpo humano total...

Tratamento de tumores neuroendócrinos por medicina nuclear: revisão sistemática da eficácia e segurança do radiofármaco Dotatate-177Lu / Treatment of neuroendocrine tumors by nuclear medicine: a systematic review of efficacy and safety of the radiopharmaceutical 177Lu-Dotatate

O DOTATATE-177Lu é um análogo de somatostatina radiomarcado que guia a radioatividade para tumores neuroendócrinos (NETs) que superexpressam receptores de somatostatina (SSTRs), promovendo o seu tratamento por terapia radionuclídica receptor-específica (PRRT). O objetivo deste trabalho foi avaliar a eficácia e a segurança da PRRT dos NETs com o DOTATATE-177Lu, através de uma revisão sistemática da literatura. A PRRT com o DOTATATE-177Lu foi eficaz no tratamento de NETs metastáticos ou inoperáveis que expressam SSTR tipo 2. Observou-se estabilização ou até regressão da doença em 20 a 50 % dos casos. Já a prevalência de remissão total da doença, apesar de numericamente baixa, foi satisfatória, principalmente levando-se em conta o estágio avançado dos tumores. Os efeitos adversos mais comuns da PRRT foram toxicidade renal e hematológica. Apesar dos estudos evidenciarem a eficácia e a segurança da PRRT com o radiofármaco, essa terapia ainda é considerada em desenvolvimento.

The DOTATATE-177Lu is a radiolabeled somatostatin analogue that guides the radioactivity to neuroendocrine tumors (NETs) that overexpress somatostatin receptors (SSTRs), allowing their treatment by receptor- specific radionuclide therapy (PRRT). The aim of this study was to evaluate the efficacy and safety of PRRT of NETs with DOTATATE-177Lu through a systematic literature review. PRRT with 177Lu - DOTATATE was effective in the treatment of inoperable or metastatic NETs that express SSTR type 2. Stabilization or regression of the disease was observed in 20 to 50% of the cases . The prevalence of total remission, although numerically low, was satisfactory, especially taking into account the advanced tumor stage. The most common adverse events in the PRRT were hematological toxicity and renal failure. Despite studies demonstrate the efficacy and safety of PRRT with the radiotracer , this treatment modality is still considered under development.

An approach for conjugation of 177Lu- DOTA-SCN- Rituximab (BioSim) & its evaluation for radioimmunotherapy of relapsed & refractory B-cell non Hodgkins lymphoma patients.

Background & objectives: The prerequisite of radioimmunotherapy is stable binding of a radionuclide to monoclonal antibodies, which are specific to the tumour-associated antigen. Most B-cell lymphomas express CD20 antigen on the surface of the tumour cells, making it a suitable target for therapeutic radioactive monoclonal antibodies. In the present study, the immunoconjugate of biosimilar Rituximab (Reditux™) and macrocyclic chelator, p-SCN-Bz-DOTA, was prepared and radiolabelled with Lutetium-177 followed by quality control procedures. Methods: Rituximab(BioSim) was desalted with sodium bicarbonate (0.1M, pH 9.0) and incubated with DOTA-SCN (1:50). The effectiveness of the conjugation was evaluated by determining the number of chelators per antibody molecule. This conjugate was radiolabelled with Lutetium-177 and purified using PD10 column. The quality control parameters like pH, clarity, radiochemical purity, in vitro stability and sterility were studied. Immunoreactivity of 177Lu-DOTA-Rituximab (BioSim) was assessed using RAMOS cells. The radioimmunoconjugate (RIC) after stringent quality assurance was injected in three patients and the biodistribution profile was analysed. Results: An average of 4.25 ± 1.04 p-SCN-Bz-DOTA molecules could be randomly conjugated to a single molecule of Rituximab (BioSim).The radiochemical purity of the labelled antibody was >95 per cent with preserved affinity for CD20 antigen. The final preparation was stable up to about 120 h when tested under different conditions. A favourable biodistribution profile was observed with liver showing the maximum uptake of the RIC. Interpretation & conclusions: A favourable radiochemical purity, stability and biodistribution of the radiolabelled immunoconjugate indicate that clinical trials for evaluation of toxicity and efficacy of 177Lu-DOTA-antiCD20 antibody-Rituximab (BioSim) in patients of relapsed and refractory non Hodgkin’s lymphoma can be considered.