Immunotherapy in the neoadjuvant chemoradiotherapy for locally advanced rectal cancer / 中华放射肿瘤学杂志

Long-course concurrent chemoradiotherapy (CCRT) or short-course radiotherapy (SCRT) prior to surgery and postoperative chemotherapy is one of the main standard therapies for patients with locally advanced rectal cancer (LARC). On this basis, total neoadjuvant therapy (TNT) has been shown to improve disease-free survival, distant metastasis-free survival and complete response rates, whereas the 3-year distant recurrence rate is still above 20% and pathological complete response (pCR) is less than 30%. Long-term survival and adverse reactions remain to be improved. Currently, significant achivement has been obtained in immunotherapy. Application of immunotherapy in the treatment of rectal cancer remains to be urgently validated. In recent years, immunotherapy combined with preoperative chemoradiotherapy has been adopted for LARC in clinical trials. Besides, immunotherapy alone, especially programmed death-1 (PD-1) / programmed death ligand-1 (PD-L1) inhibitor, has also been utilized to treat colon rectal cancer. Relevant research progress was reviewed in this article.

Radioimmunotherapy (RIT) in Brain Tumors / 대한핵의학회잡지

Annually, the incidence of brain tumors has slightly increased and also the patient prognosis is still disappointing, especially for high-grade neoplasms. So, researchers seek methods to improve therapeutic index as a critical aim of treatment. One of these new challenging methods is radioimmunotherapy (RIT) that involves recruiting a coupling of radionuclide component with monoclonal antibody (mAb) which are targeted against cell surface tumor–related antigens or antigens of cells within the tumor microenvironment. In the context of cancer care, precision medicine is exemplified by RIT; precision medicine can offer a tailored treatment to meet the needs for treatment of brain tumors. This review aims to discuss the molecular targets used in radioimmunotherapy of brain tumors, available and future radioimmunopharmaceutics, clinical trials of radioimmunotherapy in brain neoplasms, and eventually, conclusion and future perspective of application of radioimmunotherapy in neurooncology cancer care.

Measurement of Tumor Pressure and Strategies of Imaging Tumor Pressure for Radioimmunotherapy / 대한핵의학회잡지

Tumor interstitial pressure is a fundamental feature of cancer biology. Elevation in tumor pressure affects the efficacy of cancer treatment and results in the heterogenous intratumoral distribution of drugs and macromolecules. Monoclonal antibodies (mAb) play a prominent role in cancer therapy and molecular nuclear imaging. Therapy using mAb labeled with radionuclides—also known as radioimmunotherapy (RIT)—is an effective form of cancer treatment. RIT is clinically effective for the treatment of lymphoma and other blood cancers; however, its clinical use for solid tumor was limited because their high interstitial pressure prevents mAb from penetrating into the tumor. This pressure can be decreased using anti-cancer drugs or additional external therapy. In this paper, we reviewed the intratumoral pressure using direct tumor-pressure measurement strategies, such as the wick-in-needle and pressure catheter transducer method, and indirect tumor-pressure measurement strategies via magnetic resonance.

Novel biological strategies to enhance the radiation therapeutic ratio

Successful anticancer strategies require a differential response between tumor and normal tissue (i.e., a therapeutic ratio). In fact, improving the effectiveness of a cancer therapeutic is of no clinical value in the absence of a significant increase in the differential response between tumor and normal tissue. Although radiation dose escalation with the use of intensity modulated radiation therapy has permitted the maximum tolerable dose for most locally advanced cancers, improvements in tumor control without damaging normal adjacent tissues are needed. As a means of increasing the therapeutic ratio, several new approaches are under development. Drugs targeting signal transduction pathways in cancer progression and more recently, immunotherapeutics targeting specific immune cell subsets have entered the clinic with promising early results. Radiobiological research is underway to address pressing questions as to the dose per fraction, irradiated tumor volume and time sequence of the drug administration. To exploit these exciting novel strategies, a better understanding is needed of the cellular and molecular pathways responsible for both cancer and normal tissue and organ response, including the role of radiation-induced accelerated senescence. This review will highlight the current understanding of promising biologically targeted therapies to enhance the radiation therapeutic ratio.

Radioimmunotherapy in Head and Neck Cancer / 대한이비인후과학회지

Radioimmunotherapy (RIT) is a therapy that takes advantage of the “cross-fire” effect of emitted radiation by radionuclides conjugated to tumor-directed monoclonal antibodies (mAb) (including those fragments) or peptides. While RIT has been successfully employed for the treatment of lymphoma, mostly with radiolabeled antibodies against CD20 [⁹⁰yttrium (⁹⁰Y)-ibritumomab tiuxetan; Zevalin® and (131)iodine ((131)I)-tositumomab; Bexxar®], its use in solid tumors is more challenging, so far. Immuno-PET, a tool for tracking and quantification of mAbs with PET in vivo, is an exciting novel option to improve diagnostic imaging and guide mAbbased therapy. RIT in solid tumors including head and neck cancer may be an alternative treatment with advances in various biological, chemical, and treatment procedures, and it may help to reduce unnecessary exposure and enhance the therapeutic efficacy. Also, immuno-PET based on RIT might play an important role in cancer staging, in patients or targets selection of targeted therapeutics and in monitoring the response of targeted therapeutics as precision medicine. In this review, fundamentals of RIT/immune-PET and current knowledge of the preclinical/clinical trials in RIT for solid tumor including head and neck cancer are reviewed.

Radioimmunotherapy in solid tumors / 中华核医学与分子影像杂志

Radioimmunotherapy (RIT) is often used as an adjuvant therapy or consolidation therapy for cancer due to its relative high specificity and minimized radiation damage to non-targeted organs.The progress of RIT in solid tumors was slow,however,it has been developed quickly recently especially in elimination of residual micro-tumor lesions due to the application of α radionuclide,the progress in antibody preparation,and the implementation of new therapeutic strategies.

Transcatheter hepatic arterial infusion with 131I-anti-CD147-monoclonal-antibody on treating liver cancer in a rabbit model / 中华放射学杂志

Objective To evaluate the efficacy and safety of treating liver cancer using 131I-anti-CD147-monoclonal-antibody (131I-anti- CD147-McAb) by transcatheter hepatic arterial infusion (TAI) in a rabbit liver cancer model. Methods Forty-five rabbit models were randomly divided into three groups evenly. Transcatheter hepatic artery infusion under general anesthesia were performed in all three groups. Group A:control group, saline. Group B:pure 131I solution. Group C: 131I-anti-CD147-McAb solution. About 2 ml blood sample was obtained from all rabbits for liver, kidney,and thyroid function at pre-TAI and post-TAI 1 day, 3 days ,7 days, 14 days, 21 days. The rabbits were scanned by single photon emission computed tomographic (SPECT) to monitor radionuclide bio-distribution and tumor size on 1 day, 7 days, 14 days, 21days after procedures in group B and C. On 14 days after procedure, five rabbits were randomly selected to be sacrificed in each group for pathological and immunological investigations. The remaining rabbits continued to be fed, and survival rates were measured. Results The TAI and SPECT-CT/CT procedures were successfully performed in all rabbits. Test results showed that AST and ALT levels tended to increase transiently 1 day after TAI (P 0.05) 7 days after TAI. FT3 and FT4 mean values of rabbits in group B and C continued to decline 7 days after TAI, while thyroid stimulating hormone (TSH) showed corresponding increase (P0.05). SPEC-CT imaging of rabbits shows that most of the radionuclide was gathered in the gastrointestinal tract and thyroid in Group B, however, radionuclide was mainly concentrated in the tumor lesions in Group C. Fourteen days after procedures, radionuclide imaging of all rabbits disappeared in group B and C. The VX2 liver tumors increased rapidly after treatment in group A and B;but the tumors gradually reduced their size in group C. At 14 days after TAI: The proportion of tumor necrosis in group C was significantly greater than that in groups A and B (P<0.05). The microvessel density (MVD) number of residual tumor in group C was less than groups A or B (P<0.05).TUNEL analysis suggested that more apoptosis bodies was displayed in the residual tumor tissue in group C than that in groups A and B, but the expression of MMP-2 and vessel endothelial grouth factor (VEGF) was significantly reduced in group C than group A and group B. Median survival time of the rabbits in groups A, B, C was 22 days, 26 days and 54 days respectively. Survival time of the rabbits in group C was significantly prolonged than other two groups (P<0.01). Conclusions Radioimmunotherapy with 131I-anti-CD147-McAb by TAI can inhibit the growth and metastasis of liver cancer, and prolong the survival of experimental animals. The method is effective and safe in this animal study.

131I-labeled metuximab for the treatment of hepatocellular carcinoma: recent progress in research / 介入放射学杂志

Hepatocellular carcinoma (HCC) is one of the highly malignant tumors in the world.Clinically,its onset is occult,its progression is rapid and its prognosis is poor.At present,radical surgery and other adjuvant therapies,such as percutaneous hepatic artery chemoembolization and molecular targeted therapy,are the primary therapeutic means.Although these treatments have certain curative effect,the overall survival rate of HCC patients is still unsatisfactory.Using monoclonal antibody as its carrier,131I-labeled metuximab (Licartin) is a radioactive isotope immune drug;it can specifically conjugate with the surface antigen of HCC cell,then,through both immune blocking and β ray radiation ways,produce dual targeted killing effect on HCC cells.Therefore,Licartin provides a new choice for the treatment of HCC.This paper aims to make a comprehensive review concerning the clinical application and research progress of 131I-labeled metuximab in treating HCC.

Preparation & in vitro evaluation of 90Y-DOTA-rituximab.

Background & objectives: Radioimmunotherapy is extensively being used for the treatment of non-Hodgkin’s lymphoma (NHL). Use of rituximab, a chimeric anti-CD20 antibody directed against the CD20 antigen in combination with suitable beta emitters is expected to result in good treatment response by its cross-fire and bystander effects. The present work involves the conjugation of p-isothiocyanatobenzyl DOTA (p-SCN-Bn-DOTA) to rituximab, its radiolabelling with 90Y and in vitro and in vivo evaluation to determine its potential as a radioimmunotherapeutic agent. Methods: Rituximab was conjugated with p-SCN-Bn-DOTA at 1:1 antibody: DOTA molar ratio. The number of DOTA molecules linked to one molecule of rituximab was determined by radioassay and spectroscopic assay. Radiolabelling of rituximab with 90Y was carried out and its in vitro stability was evaluated. In vitro cell binding studies were carried out in Raji cells expressing CD20 antigen. Biodistribution studies were carried out in normal Swiss mice. Results: Using both radioassay and spectroscopic method, it was determined that about five molecules of DOTA were linked to rituximab. Radiolabelling of the rituximab conjugate with 90Y and subsequent purification on PD-10 column gave a product with radiochemical purity (RCP) > 98 per cent which was retained at > 90 per cent up to 72 h when stored at 37°C. In vitro cell binding experiments of 90Y-DOTA-rituximab with Raji cells exhibited specific binding of 20.7 ± 0.1 per cent with 90Y-DOTA-rituximab which reduced to 15.5 ± 0.2 per cent when incubated with cold rituximab. The equilibrium constant Kd for 90Y-DOTA-Rituximab was determined to be 3.38 nM. Radiolabelled antibody showed clearance via hepatobiliary and renal routes and activity in tibia was found to be quite low indicating in vivo stability of 90Y-DOTA-rituximab. Interpretation & conclusions: p-SCN-Bn-DOTA was conjugated with rituximab and radiolabelling with 90Y was carried out. In vitro studies carried out in Raji cells showed the specificity of the radiolabelled conjugate suggesting the potential uitability of the formulation as a radiopharmaceutical for therapy of NHL.

Perspective on B-cell lymphoma treatment / 中国肿瘤临床

B-cell lymphoma is a heterogeneous group of disorders involving malignant proliferation of B lymphocytes, accounting for approximately 85%of non-Hodgkin lymphoma. Combined use of rituximab and chemotherapy remarkably improves the survival of pa-tients with B-cell lymphoma. Despite the increase in treatment response, some patients suffer relapsed or refractory lymphoma. Nu-merous novel treatment options have been developed in pre-clinical and clinical practice, including targeted therapies, auto-hemato-poietic stem cell transplantation, cellular immunotherapy, and radioimmunotherapy. This review describes recent advances in B-cell lymphoma treatment and discusses future perspectives.

Transcatheter Arterial Chemoembolization Plus ¹³¹I-Labelled Metuximab versus Transcatheter Arterial Chemoembolization Alone in Intermediate/Advanced Stage Hepatocellular Carcinoma: A Systematic Review and Meta-Analysis

OBJECTIVE: The aim of the study was to compare transcatheter arterial chemoembolization (TACE) plus ¹³¹I-labelled metuximab with TACE alone for hepatocellular carcinoma (HCC). MATERIALS AND METHODS: A comprehensive search was conducted in PubMed, Embase, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and Chinese BioMedical Literature Database with published date from the earliest to February 29th, 2016. No language restrictions were applied, but only prospective randomized controlled trials (RCTs) or non-RCTs were eligible for a full-text review. The primary outcome was the overall survival (OS) and effective rate (the rate of partial atrophy or complete clearance of the tumor lesion). The odds ratios (ORs) were combined using either the fixed-effects model or random-effects model. RESULTS: Eight trials (3 RCTs and 5 non-RCTs) were included, involving a total of 1121 patients. Patients receiving combined therapy of TACE plus ¹³¹I-labelled metuximab showed significant improvement in effective rate {OR = 4.00, (95% confidence interval [CI]: 2.40–6.66), p < 0.001}, 1-year OS (OR = 2.03 [95% CI: 1.55–2.67], p < 0.001) and 2-year OS (OR = 2.57 [95% CI: 1.41–4.66], p = 0.002]. CONCLUSION: TACE plus ¹³¹I-labelled metuximab is more beneficial for treating advanced HCCs than TACE alone in terms of tumor response and OS. Large, multi-center, and blinded randomized trials are required to confirm these findings.

Current status of radioimmunoimaging and radioimmunotherapeutic antibody drugs / 中华核医学与分子影像杂志

Radiolabeled monoclonal antibodies can specifically bind to tumor-associated antigens.On this immune basis,RIT and RII have therefore been used in the diagnosis and treatment of cancer.Many RIT and RII pharmaceuticals were applied in trials of preclinical and clinical phases,and excellent results had been achieved.This paper reviews on the current status of RIT and RII pharmaceuticals.

Synergism effect of 131 I-Herceptin and high-energy X-ray on HER2 overexpressed breast cancer cells / 中国生化药物杂志

Objective To study the synergism effect of 131 I-Herceptin and high-energy X-ray on HER2 overexpressed breast cancer SK-BR-3 cells.Methods The protein expression and gene amplification of human epidermal growth factor receptor-2 ( HER2 ) in SK-BR-3 cells were identified by immunohistochemistry and fluorescence in situ hybridization ( FISH ) method, 131 I-Herceptin was prepared by iodogen method, and the IC15 concentration of 131 I-Herceptin on SK-BR-3 cell were selected by MTT method.The cells were divided into control group and drug group according to 131 I-Herceptin used or not, and were delivered five different doses of external irradiation (0,2,4 and 6Gy), and the synergism effect was detected by colonogenic assay.The cells were divided into blank group, drug group(131I-Herceptin), X-ray group(2 Gy external irradiation) and combination group (131I-Herceptin+2 Gy external irradiation), the apoptosis rate and death rate were detected by AO/EB method and cell cycle were detected by flow cytometry.Results The labling rate, radiochemical purity and specific radioactivity of 131 I-Herceptin were 86.8%, 93.9% and 868.3 μci/mg, respectively.The IC15 of 131 I-Herceptin was 15.625μci/mL.131 I-Herceptin and high-energy X-ray significantly reduced surviving fraction ( SF) ( F=628.888,F=964.97,P<0.05) and there were interactions between them (F=113.046,P<0.05).There were significant differences in apoptosis rate and death rate among blank group, drug group, X-ray group and combination group(F=103.324,F=13.33,all P<0.05),and there were significant differences of pairwise comparison (P<0.05).After irradiation and 131I-Herceptin administration, the cell cycle changed obviously from G1-phase to G2-and S-phase.Conclusion 131 I-Herceptin combined with high-energy X-ray has the synergism effect on HER2 overexpressed breast cancer SK-BR-3 cells.

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.

4to Seminario Internacional y 4to Taller Nacional "Uso y desarrollo de productos de la industria isotópica para la salud" / 4th International Seminar and 4th National Workshop on "Use and Development of Health-Related Industrial Isotope Products". Scientific report

El trabajo presenta una reseña científica de los principales temas abordados en el 4to Seminario Internacional y 4to Taller Nacional "Uso y Desarrollo de Productos de la Industria Isotópica para la Salud" celebrado los días 7, 8 y 9 de diciembre de 2010 en conmemoración al XV Aniversario del Centro de Isótopos.

The paper presents an analysis of the main topics discussed at the 4th International Seminar and 4th National Workshop on "Use and Development of Health-Related Industrial Isotope Products" held on December 7th, 8th and 9th 2010 to commemorate the Fifteenth Anniversary of the Isotope Centre.

Exposición radiológica de los trabajadores y el público en la primera fase del ensayo clínico del Nimotuzumab marcado con para el tratamiento de tumores cerebrales en Cuba / Occupational and public exposures in RIT of brain tumors in Cuba

RESUMEN La primera fase del ensayo clínico del anticuerpo monoclonal humanizado h-R3 (Nimotuzumab) marcado con , para la radioinmunoterapia de tumores cerebrales malignos fue ejecutada durante el período 2002-2005 en Cuba. El objetivo del trabajo fue analizar los datos de la vigilancia radiológica realizada durante el estudio, con respecto a las dosis estimadas inicialmente. Estas últimas se calcularon para cada nivel de actividad, operación y cantidad total de pacientes, considerando el decaimiento radiactivo del y que una misma persona realizaba todas las operaciones. Se demostró que el riesgo radiológico de la práctica es aceptable. Las hipótesis conservadoras empleadas para los cálculos y el cumplimiento de los procedimientos de seguridad establecidos, determinaron que la exposición medida fuera inferior a la estimada. La realización de este trabajo constituye una referencia para la introducción y desarrollo de la radioinmunoterapia en Cuba.

ABSTRACT The first phase of the clinical trial using the humanized monoclonal antibody h-R3 (Nimotuzumab) labelled with , for radioimmunotherapy of brain malignant was performed during the period 2002-2005 in Cuba. The aim of this work was to analyze data from the radiological surveillance of this research compared to initially estimated doses. These latter were calculated for each activity level, operation and total quantity of patients, considering the radioactive decay of and taking into account that only one person carries out all of the operations. It was demonstrated that the radiation risk of the practice is acceptable. The conservative hypotheses for dose assessment and the compliance with established safety procedures during this trial showed that the measured exposure was lower than that estimated. This paper is a reference useful to introduce and develop the RIT in Cuba.

Current research of Zevalin and Bexxar in the field of radioimmunotherapy / 复旦学报（医学版）

Radioimmunotherapy using monoclonal antibodies incorporated with radionuclide has been showed to be an effective agent for refractory non-Hodgkin's lymphoma (NHL). Many anti-CD20 antibodies labeled with radionuclide, such as 90Y-ibritumomab tiuxetan (Zevalin) and 131I-tositumomab tiuxetan (Bexxar), have been reported to be effective for the treatment of patients with relapsed or refractory low-grade, follicular, or transformed NHL. This review summarizes the current advance in clinical trials and studies of Zevalin and Bexxar for the treatment of NHL patients.

Biodistribution of iodine-131-labled chimeric monoclonal antibody in patients following intratumoral administraion in advanced lung carcinoma / 复旦学报（医学版）

Objective To investigate the biodistribution of intratumoral administerd~(131)Ⅰ-labeled human-mouse chimeric monoclonal antibody (chTNT) in patients with advanced lung carcinoma. Methods Eleven patients enrolled had cytological and histological confirmed diagnoses of either stage Ⅲ b or stage Ⅳ inoperable lung carcinoma. Intratumoral injection was directed by thoracic CT-guided catheter using a multi-holed needle. The dose for each patient was 18.5 - 37 MBq/cm~3 tumor mass. Blood samples were drawn at different time intervals for up to 13 days, and urine samples were collected for up to 11 days after injection for pharmacokinetic studies. In vivo stability was examined by HPLC by analyzing serum and urine, which were found to contain~(131)Ⅰ-chTNT. Whole body images were taken for quantitative organ and tumor biodistribution studies. Results In all 11 patients,~(131)Ⅰ-chTNT was the major component of the radiolabel in serum. Within 96 hours after administration, it was 100% stable. Plasma disappearance curves of ~(131)Ⅰ-chTNT were best fit by a two-exponential model in all patients with T_(1/2kα) of (0. 89±0. 17) h and T_(1/2β) of (86.88 ± 25.97)h. Free Ⅰ was the only metabolite of Ⅰ-chTNT that appeared in urine. A biodistribution study demonstrated excellent localization of the radioactivity in tumors. The accumulated radioactivity in urine at 264 h was (58.37 △Corresponding author E-mail:chen. shaoliang@zs-hospital. sh. cn±17.45) % of the injection dose. There was (51.05±8.41)%ID ,~(131)Ⅰ-chTNT in the tumor at 30 min after injection, and the tumor/lung (T/N) ratio was 63.87 ± 25.71. It remained (3.47 ± 3.27) %ID at 264 h,and the T/N ratio was 9. 61 ± 11.00. Among the main target organs, accumulation of the radiolabeled antibody was mainly found in lungs, liver, heart, kidneys, spleen and thyroid.Conclusions Pharmacokinietics of ~(131)Ⅰ-chTNT follows a two-exponential model. According to its long preservation in tumor tissue, intratumoral injection of~(131)Ⅰ-chTNT is good for tumor therapy.

Radioimmunotherapy of solid tumor / 肿瘤研究与临床

Radioimmunotherapy (RIT) is one kind of targeted immunotherapy. It is a better therapy of tumour treatment for its distinct advantages. Nowadays, it has been widely used to treat lymphoma, and part of solid tumors. In this review,basic research and clinical application related to solid tumor are summarized.

mage-Based Assessment and Clinical Significance of Absorbed Radiation Dose to Tumor in Repeated High-Dose (131)I Anti-CD20 Monoclonal Antibody (Rituximab) Radioimmunotherapy for Non-Hodgkin's Lymphoma / 핵의학분자영상

PURPOSE: We assessed the absorbed dose to the tumor (Dosetumor) by using pretreatment FDG-PET and whole-body (WB) planar images in repeated radioimmunotherapy (RIT) with 131I rituximab for NHL. MATERIALS AND METHODS: Patients with NHL (n=4) were administered a therapeutic dose of (131)I rituximab. Serial WB planar images after RIT were acquired and overlaid to the coronal maximum intensity projection (MIP) PET image before RIT. On registered MIP PET and WB planar images, 2D-ROIs were drawn on the region of tumor (n=7) and left medial thigh as background, and Dosetumor was calculated. The correlation between Dosetumor and the CT-based tumor volume change after RIT was analyzed. The differences of Dosetumor and the tumor volume change according to the number of RIT were also assessed. RESULTS: The values of absorbed dose were 397.7+/-646.2cGy (53.0~2853.0cGy). The values of CT-based tumor volume were 11.3+/-9.1 cc (2.9~34.2cc), and the % changes of tumor volume before and after RIT were -29.8+/-44.3% (-100.0%~+42.5%), respectively. Dosetumor and the tumor volume change did not show the linear relationship (p>0.05). Dosetumor and the tumor volume change did not correlate with the number of repeated administration (p>0.05). CONCLUSION: We could determine the position and contour of viable tumor by MIP PET image. And, registration of PET and gamma camera images was possible to estimate the quantitative values of absorbed dose to tumor.