Measurement of Eosinophil Kinetics In Vivo.

Radiolabeled leukocyte scans are used in nuclear medicine to detect sites of infection and inflammation. We have previously demonstrated the use of clinical grade immunomagnetic beads to isolate autologous eosinophils and image their distribution in healthy volunteers. Here we describe the use of radiolabeled eosinophils coupled to single-photon emission computed tomography (SPECT) to quantify eosinophil uptake in the lungs of healthy volunteers, patients with asthma, and patients with focal eosinophilic inflammation.

Microwave assisted synthesis of Fe3O4 stabilized ZrO2 nanoparticles - Free radical scavenging, radiolabeling and biodistribution in rabbits.

AIMS: In vivo biodistribution of radio labeled ZrO2 nanoparticles is addressed for better imaging, therapy and diagnosis. Nanoparticles are synthesized by microwave assisted sol-gel technique using Fe3O4 as a stabilizer. Antioxidant assay, hemolytic activity in human blood and biodistribution in rabbits was explored to study the therapeutical as well as in vivo targeted diagnostic applications of as synthesized nanoparticles. MAIN METHODS: Fe3O4 stabilized zirconia nanoparticles are synthesized using microwave assisted sol-gel method. Microwave (MW) powers are varied in the range of 100 to 1000 W. As synthesized nanoparticles are evaluated using different characterizations such as X-ray diffractometer, scanning electron microscope, Raman spectroscopy, impedance analyzer, Vickers micro hardness indenter, FTIR, and UV-Vis spectroscopy. In vitro activity of synthesized nanoparticles is checked in freshly extracted human blood serum. To study biodistribution of Fe3O4 stabilized zirconia nanoparticles in rabbit, technetium-99 m was used for labeling purpose. The labeling efficacy and stability of labeled nanoparticles are also measured with instant thin layer chromatography (ITLC) method. Intravenous injection of 99mTc-Fe3O4 stabilized zirconia nanoparticles (0.2 ml), containing 110 MBq of radioactivity, is performed to study the biodistribution; nanoparticles are injected into the ear vein of animal (rabbit). KEY FINDINGS: Zirconia (ZrO2) nanoparticles (NPs) are stabilized using Fe3O4 that were prepared by means of microwave assisted sol-gel method. Crystallite size (~20 nm) agrees well with the values required to stabilize tetragonal zirconia (t-ZrO2). Volume shrinkage results in high value of hardness (~1369). Dielectric constant values, compatible for biomedical application, are observed for tetragonally stabilized samples. Low value of hemolytic response is observed for Fe3O4 stabilized ZrO2 NPs. 99mTc radio labeled ZrO2 NPs proved to be potential candidate to study biodistribution. Biodistribution studies show stability of radiolabeled NPs in the original suspension as well as in blood serum. CT scan of rabbit is performed for several times to check the biodistribution of NPs with time and survival of rabbit. Results suggest that these NPs can also be used as targeted nanoparticles as well as variants of drug payload carrier. SIGNIFICANCE: Results signify that Fe3O4 stabilized ZrO2 nanoparticles synthesized by microwave assisted sol-gel method may be considered as "all-rounder" nanoplatform and are safe enough to be used in diagnostic as well as therapeutic purposes.

Examination of the Association Between 3,4-Divanillyltetrahydrofuran Lignan (Urtica dioica Origin) and Prostate Cancer Cells by 131I Radiolabeling.

Background: Prostate cancer is the most common type of cancer for men in many countries. One of the various prostate cancer therapy methods is hormone therapy, and explaining the association between androgen hormones and prostate cancer is a critical role for successful prostate cancer treatment. Materials and Methods: In the current study, the behavior of 3,4-divanillyltetrahydrofuran (DTH) was examined against prostate cancer cells, which have androgen sensitivity differences [LNCaP (+), PC3 (-)]. For this aim, DTH was obtained by extraction of Urtica dioica roots. The molecular structure of isolated compound was confirmed as DTH by liquid chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy analyses. To evaluate the association of androgen sensitivity, DTH was radiolabeled with 131I, and cell uptake assay was performed by using 131I-radiolabeled DTH. Also, cytotoxicity (WST-1) assay of DTH was performed against LNCaP and PC3 cells to determinate the toxic effects of DTH on different androgen mechanisms. Results: The results of assays on cells have shown that DTH lignan behaves different like being more toxic to LNCaP cells than PC3 cells, depending on androgen sensitivity. Conclusion: The results may contribute both the research topics of phytolignan prostate cancer and androgen-sensitive prostate cancer.

TLR5 is a new reporter for triple-negative breast cancer indicated by radioimmunoimaging and fluorescent staining.

Triple-negative breast cancer (TNBC) is a highly aggressive tumour that lacks marker for targeted diagnosis. Recently, it was reported that toll-like receptor 5 (TLR5) was associated with some kind of tumours, especially in TNBC, but whether it could be used as a non-invasive monitoring target is not fully understood. Here, we established TLR5- 4T1 cell line with lentivirus-shRNA-TLR5 knock-down transfection (with tag GFP, green fluorescent protein, TLR5- 4T1) and control TLR5+ 4T1 cell line with negative control lentivirus transfection. The effect of TLR5 down-regulation was detected with qPCR and Western blot. 125 I-anti-TLR5 mAb and control isotype 125 I-IgG were prepared and injected to TLR5+/- 4T1-bearing mice models, respectively. Whole-body phosphor-autoradiography, fluorescence imaging and biodistribution were performed. Furthermore, ex vivo tumour TLR5 expression was proved through immunohistochemistry staining. We found that 125 I-anti-TLR5 mAb could bind to TLR5+ 4T1 with high affinity and specificity. Whole-body phosphor-autoradiography after 125 I-anti-TLR5 mAb injection showed TLR5+ 4T1 tumour images in 24 hours, more clearly in 48 hours. Radioactivities in tumour tissues were positively related with TLR5 expression. Biodistribution assay showed that 125 I-anti-TLR5 mAb was mainly metabolized through the liver and kidney, and 125 I-anti-TLR5 mAb was much more accumulated in TLR5+ 4T1 tumour than TLR5- 4T1. In vivo fluorescence imaging successfully showed tumour tissues clearly both in TLR5+ and TLR5- 4T1 mice compared with lentivirus untreated 4T1 tumour. Immunohistochemistry staining showed that TLR5 expression in tumours was indeed down-regulated in TLR5- 4T1 mice. Our results indicated that 125 I-antiTLR5 mAb was an ideal agent for non-invasive imaging of TLR5+ tumours; TLR5 may be as a novel molecular target for TNBC non-invasive diagnosis.

Evaluation of novel highly specific antibodies to cancer testis antigen Centrin-1 for radioimmunoimaging and radioimmunotherapy of pancreatic cancer.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) accounts for >90% of pancreatic malignancies, and has median survival of <6 months. There is an urgent need for diagnostic and therapeutic options for PDAC. Centrin1 (CETN1) is a novel member of Cancer/Testis Antigens, with a 25-fold increase of CETN1 gene expression in PDX from PDAC patients. The absence of selective anti-CETN1 antibodies is hampering CETN1 use for diagnosis and therapy. Here we report the generation of highly specific for CETN1 antibodies and their evaluation for radioimmunoimaging and radioimmunotherapy (RIT) of experimental PDAC. METHODS: The antibodies to CETN1 were generated via mice immunization with immunogenic peptide distinguishing CETN1 from CETN2. Patient tumor microarrays were used to evaluate the binding of the immune serum to PDAC versus normal pancreas. The antibodies were tested for their preferential binding to CETN1 over CETN2 by ELISA. Mice bearing PDAC MiaPaCa2 xenografts were imaged with microSPECT/CT and treated with 213 Bi- and 177 Lu-labeled antibodies to CETN1. RESULTS: Immune serum bind to 50% PDAC cases on patient tumor microarrays with no specific binding to normal pancreas. Antibodies demonstrated preferential binding to CETN1 versus CETN2. Antibody 69-11 localized to PDAC xenografts in mice in vivo and ex vivo. RIT of PDAC xenografts with 213 Bi-labeled antibodies was effective, safe, and CETN1-specific. CONCLUSIONS: The results demonstrate the ability of these novel antibodies to detect CETN1 both in vitro and in vivo; as well, the RIT treatment of experimental PDAC when radiolabeled with 213 Bi is highly efficient and safe. Further evaluation of these novel reagents for diagnosis and treatment of PDAC is warranted.

Synthesis and preliminary evaluation of 99mTc-Hynic-fragments [F(ab')2 and F(ab')] of Rituximab as radioimmunoscintigraphic agents for patients with Non-Hodgkin's lymphoma.

This study was to evaluate the potential of 99mTc-Hynic-fragments of Rituximab as radioimmunoscintigraphic agents for diagnosis of patients with Non-Hodgkin's Lymphoma (NHL). Rituximab was digested with immobilized pepsin and papain to yield F(ab')2-Rituximab and F(ab')-Rituximab fragments respectively. Purified fragments were characterized by SE-HPLC and SDS-PAGE and subsequently radiolabeled with technetium-99m using Hynic as bifunctional chelator. The 99mTc-Hynic-F(ab')2-Rituximab and 99mTc-Hynic-F(ab')-Rituximab exhibited good in-vitro stability and specificity to Raji cells. Biodistribution studies demonstrated rapid pharmacokinetics and clearance predominantly through renal route.

Radiolabeled F(ab')2-cetuximab for theranostic purposes in colorectal and skin tumor-bearing mice models.

PURPOSE: This study aimed to investigate theranostic strategies in colorectal and skin cancer based on fragments of cetuximab, an anti-EGFR mAb, labeled with radionuclide with imaging and therapeutic properties, 111In and 177Lu, respectively. METHODS: We designed F(ab')2-fragments of cetuximab radiolabeled with 111In and 177Lu. 111In-F(ab')2-cetuximab tumor targeting and biodistribution were evaluated by SPECT in BalbC nude mice bearing primary colorectal tumors. The efficacy of 111In-F(ab')2-cetuximab to assess therapy efficacy was performed on BalbC nude mice bearing colorectal tumors receiving 17-DMAG, an HSP90 inhibitor. Therapeutic efficacy of the radioimmunotherapy based on 177Lu-F(ab')2-cetuximab was evaluated in SWISS nude mice bearing A431 tumors. RESULTS: Radiolabeling procedure did not change F(ab')2-cetuximab and cetuximab immunoreactivity nor affinity for HER1 in vitro. 111In-DOTAGA-F(ab')2-cetuximab exhibited a peak tumor uptake at 24 h post-injection and showed a high tumor specificity determined by a significant decrease in tumor uptake after the addition of an excess of unlabeled-DOTAGA-F(ab')2-cetuximab. SPECT imaging of 111In-DOTAGA-F(ab')2-cetuximab allowed an accurate evaluation of tumor growth and successfully predicted the decrease in tumor growth induced by 17-DMAG. Finally, 177Lu-DOTAGA-F(ab')2-cetuximab radioimmunotherapy showed a significant reduction of tumor growth at 4 and 8 MBq doses. CONCLUSIONS: 111In-DOTAGA-F(ab')2-cetuximab is a reliable and stable tool for specific in vivo tumor targeting and is suitable for therapy efficacy assessment. 177Lu-DOTAGA-F(ab')2-cetuximab is an interesting theranostic tool allowing therapy and imaging.

64Cu, a powerful positron emitter for immunoimaging and theranostic: Production via natZnO and natZnO-NPs.

64Cu is one of the most beneficial radionuclide that can be used as a theranostic agent in Positron Emission Tomography (PET) imaging. In this current work, 64Cu was produced with zinc oxide nanoparticles (natZnONPs) and zinc oxide powder (natZnO) via the 64Zn(n,p)64Cu reaction in Tehran Research Reactor (TRR) and the activity values were compared with each other. The theoretical activity of 64Cu also was calculated with MCNPX-2.6 and the cross sections of this reaction were calculated by using TALYS-1.8, EMPIRE-3.2.2 and ALICE/ASH nuclear codes and were compared with experimental values. Transmission Electronic Microscopy (TEM), Scanning Electronic Microscopy (SEM) and X-Ray Diffraction (XRD) analysis were used for samples characterizations. From these results, it's concluded that 64Cu activity value with nanoscale target was achieved more than the bulk state target and had a good adaptation with the MCNPX result.

Evaluation of HER2-specific peptide ligand for its employment as radiolabeled imaging probe.

HER2 transmembrane receptor is an important target in immunotherapy treatment of breast and gastroesophageal cancer. Molecular imaging of HER2 expression may provide essential prognostic and predictive information concerning disseminated cancer and aid in selection of an optimal therapy. Radiolabeled low molecular weight peptide ligands are particularly attractive as probes for molecular imaging, since they reach and bind to the target and clear from non-target organs and blood stream faster than bulky antibodies. In this study, we evaluated a potential HER2-imaging probe, an A9 nonapeptide, derived from the trastuzumab-Fab portion. Its cellular uptake was investigated by mass spectrometry analysis of the cytoplasmic cellular extracts. Moreover, based on in-silico modeling, DTPA chelator was conjugated to N-terminus of A9. 111In-labeled A9 demonstrated nanomolar affinity to HER2-expressing BT474 cells and favorable biodistribution profile in NMRI mice. This study suggests that the peptide A9 represents a good lead candidate for development of molecular probe, to be used for imaging purposes and for the delivery of cytotoxic agents.

New insights into the pretargeting approach to image and treat tumours.

Tumour pretargeting is a promising strategy for cancer diagnosis and therapy allowing for the rational use of long circulating, highly specific monoclonal antibodies (mAbs) for both non-invasive cancer radioimmunodetection (RID) and radioimmunotherapy (RIT). In contrast to conventional RID/RIT where the radionuclides and oncotropic vector molecules are delivered as presynthesised radioimmunoconjugates, the pretargeting approach is a multistep procedure that temporarily separates targeting of certain tumour-associated antigens from delivery of diagnostic or therapeutic radionuclides. In principle, unlabelled, highly tumour antigen specific mAb conjugates are, in a first step, administered into a patient. After injection, sufficient time is allowed for blood circulation, accumulation at the tumour site and subsequent elimination of excess mAb conjugates from the body. The small fast-clearing radiolabelled effector molecules with a complementary functionality directed to the prelocalised mAb conjugates are then administered in a second step. Due to its fast pharmacokinetics, the small effector molecules reach the malignant tissue quickly and bind the local mAb conjugates. Thereby, corresponding radioimmunoconjugates are formed in vivo and, consequently, radiation doses are deposited mainly locally. This procedure results in a much higher tumour/non-tumour (T/NT) ratio and is favourable for cancer diagnosis and therapy as it substantially minimises the radiation damage to non-tumour cells of healthy tissues. The pretargeting approach utilises specific non-covalent interactions (e.g. strept(avidin)/biotin) or covalent bond formations (e.g. inverse electron demand Diels-Alder reaction) between the tumour bound antibody and radiolabelled small molecules. This tutorial review descriptively presents this complex strategy, addresses the historical as well as recent preclinical and clinical advances and discusses the advantages and disadvantages of different available variations.

Immuno-PET Using Anticarcinoembryonic Antigen Bispecific Antibody and 68Ga-Labeled Peptide in Metastatic Medullary Thyroid Carcinoma: Clinical Optimization of the Pretargeting Parameters in a First-in-Human Trial.

Earlier clinical studies reported a high sensitivity of pretargeted immunoscintigraphy using murine or chimeric anticarcinoembryonic antigen (CEA) bispecific antibody (BsMAb) and peptides labeled with 111In or 131I in medullary thyroid carcinoma (MTC). Preclinical studies showed that new-generation humanized recombinant anti-CEA × antihistamine-succinyl-glycine (HSG) trivalent BsMAb TF2 and radiolabeled HSG peptide (IMP288) present good features for PET. This study aimed at optimizing molar doses and pretargeting interval of TF2 and 68Ga-labeled IMP288 for immuno-PET in relapsed MTC patients with calcitonin serum levels greater than 150 pg/mL. METHODS: Five cohorts (C1-C5) of 3 patients received variable molar doses of TF2 and approximately 150 MBq of 68Ga-IMP288 after different pretargeting time intervals (C1: 120 nmol TF2, 6 nmol IMP288, 24 h; C2: 120 nmol TF2, 6 nmol IMP288, 30 h; C3: 120 nmol TF2, 6 nmol IMP288, 42 h; C4: 120 nmol TF2, 3 nmol IMP288, 30 h; and C5: 60 nmol TF2, 3 nmol IMP288, 30 h). TF2 and 68Ga-IMP288 pharmacokinetics were monitored. Whole-body PET was recorded 60 and 120 min after 68Ga-IMP288 injection. Tumor maximal SUV (T-SUVmax) and T-SUVmax-to-mediastinum blood-pool (MBP) SUVmean ratios (T/MBP) were determined. RESULTS: In C1, T-SUVmax and T/MBP ranged from 4.09 to 8.93 and 1.39 to 3.72 at 60 min and 5.14 to 11.25 and 2.73 to 5.38 at 120 min, respectively. Because of the high MBP, the delay was increased to 30 h in C2, increasing T-SUVmax and T/MBP. Further increasing the delay to 42 h in C3 decreased T-SUVmax and T/MBP, showing that 30 h was the most favorable delay. In C4, the TF2-to-peptide mole ratio was increased to 40 (delay 30 h), resulting in high T-SUVmax but with higher MBP than in C2. In C5, the molar dose of TF2 was reduced, resulting in lower imaging performance. Pharmacokinetics demonstrated a fast TF2 clearance and a clear relationship between blood activity clearance and the ratio between the molar amount of injected peptide to the molar amount of circulating TF2 at the time of peptide injection. CONCLUSION: High tumor uptake and contrast can be obtained with pretargeted anti-CEA immuno-PET in relapsed MTC patients, especially using optimized pretargeting parameters: a BsMAb-to-peptide mole ratio of 20 and 30 h pretargeting delay.

Evaluation of a novel type of imaging probe based on a recombinant bivalent mini-antibody construct for detection of CD44v6-expressing squamous cell carcinoma.

We have developed the CD44v6-targeting human bivalent antibody fragment AbD19384, an engineered recombinant human bivalent Fab antibody formed via dimerization of dHLX (synthetic double helix loop helix motif) domains, for potential use in antibody-based molecular imaging of squamous cell carcinoma in the head and neck region. This is a unique construct that has, to the best of our knowledge, never been assessed for molecular imaging in vivo before. The objective of the present study was to evaluate for the first time the in vitro and in vivo binding properties of radio-iodinated AbD19384, and to assess its utility as a targeting agent for molecular imaging of CD44v6-expressing tumors. Antigen specificity and binding properties were assessed in vitro. In vivo specificity and biodistribution of 125I-AbD19384 were next evaluated in tumor-bearing mice using a dual-tumor setup. Finally, AbD19384 was labeled with 124I, and its imaging properties were assessed by small animal PET/CT in tumor bearing mice, and compared with 2-deoxy-2-[18F]fluoro-D-glucose (18F-FDG). In vitro studies demonstrated CD44v6-specific binding with slow off-rate for AbD19384. A favorable biodistribution profile was seen in vivo, with tumor-specific uptake. Small animal PET/CT images of 124I-AbD19384 supported the results through clearly visible high CD44v6-expressing tumors and faintly visible low expressing tumors, with superior imaging properties compared to 18F-FDG. Tumor-to-blood ratios increased with time for the conjugate (assessed up to 72 h p.i.), although 48 h p.i. proved best for imaging. Biodistribution and small-animal PET studies demonstrated that the recombinant Fab-dHLX construct AbD19384 is a promising tracer for imaging of CD44v6 antigen expression in vivo, with the future aim to be used for individualized diagnosis and early detection of squamous cell carcinomas in the head and neck region. Furthermore, this proof-of-concept research established the feasibility of using recombinant Fab-dHLX constructs for in vivo imaging of tumor biomarkers.

Diabody Pretargeting with Click Chemistry In Vivo.

UNLABELLED: Radioimmunotherapy and nuclear imaging (immuno-PET/SPECT) of cancer with radiometal-labeled antibody fragments or peptides is hampered by low tumor-to-kidney ratios because of high renal radiometal retention. Therefore, we developed and evaluated a pretargeting strategy using click chemistry in vivo to reduce kidney uptake and avoid unwanted radiation toxicity. We focused on the bioorthogonal reaction between a trans-cyclooctene (TCO)-functionalized TAG72 targeting diabody, AVP04-07, and a low-molecular-weight radiolabeled tetrazine probe that was previously shown to have low kidney retention and relatively fast renal clearance. METHODS: AVP04-07 diabodies were functionalized with TCO tags, and in vitro immunoreactivity toward bovine submaxillary mucin and tetrazine reactivity were assessed. Next, pretargeting biodistribution studies were performed in LS174T tumor-bearing mice with AVP04-07-TCO(n) (where n indicates the number of TCO groups per diabody) and radiolabeled tetrazine to optimize the TCO modification grade (0, 1.8, or 4.7 TCO groups per diabody) and the (177)Lu-tetrazine dose (0.1, 1.0, or 10 Eq with respect to the diabody). Radiolabeled tetrazine was injected at 47 h after diabody injection, and mice were euthanized 3 h later. A pretargeting SPECT/CT study with (111)In-tetrazine was performed with the optimized conditions. RESULTS: Immunoreactivity for native AVP04-07 was similar to that for TCO-functionalized AVP04-07, and the latter reacted efficiently with radiolabeled tetrazine in vitro. The combination of the pretargeting component AVP04-07 functionalized with 4.7 TCO groups and 1 Eq of (177)Lu-tetrazine with respect to the diabody showed the most promising biodistribution. Specifically, high (177)Lu-tetrazine tumor uptake (6.9 percentage injected dose/g) was observed with low renal retention, yielding a tumor-to-kidney ratio of 5.7. SPECT/CT imaging confirmed the predominant accumulation of radiolabeled tetrazine in the tumor and low nontumor retention. CONCLUSION: Pretargeting provides an alternative radioimmunotherapy and nuclear imaging strategy by overcoming the high renal retention of low-molecular-weight radiometal tumor-homing agents through the separate administration of a tumor-homing agent and a radioactive probe with fast clearance.

Development and characterisation of a 3D multi-cellular in vitro model of normal human breast: a tool for cancer initiation studies.

Multicellular 3-dimensional (3D) in vitro models of normal human breast tissue to study cancer initiation are required. We present a model incorporating three of the major functional cell types of breast, detail the phenotype and document our breast cancer initiation studies. Myoepithelial cells and fibroblasts were isolated and immortalised from breast reduction mammoplasty samples. Tri-cultures containing non-tumorigenic luminal epithelial cells HB2, or HB2 overexpressing different HER proteins, together with myoepithelial cells and fibroblasts were established in collagen I. Phenotype was assessed morphologically and immunohistochemically and compared to normal breast tissue. When all three cell types were present, polarised epithelial structures with lumens and basement membrane production were observed, akin to normal human breast tissue. Overexpression of HER2 or HER2/3 caused a significant increase in size, while HER2 overexpression resulted in development of a DCIS-like phenotype. In summary, we have developed a 3D tri-cellular model of normal human breast, amenable to comparative analysis after genetic manipulation and with potential to dissect the mechanisms behind the early stages of breast cancer initiation.

Targeting arterial wall sulfated glycosaminoglycans in rabbit atherosclerosis with a mouse/human chimeric antibody.

The progression of atherosclerosis is favored by increasing amounts of chondroitin sulfate proteoglycans in the artery wall. We previously reported the reactivity of chP3R99 monoclonal antibody (mAb) with sulfated glycosaminoglycans and its association with the anti-atherogenic properties displayed. Now, we evaluated the accumulation of this mAb in atherosclerotic lesions and its potential use as a probe for specific in vivo detection of the disease. Atherosclerosis was induced in NZW rabbits (n = 14) by the administration of Lipofundin 20% using PBS-receiving animals as control (n = 8). Accumulation of chP3R99 mAb in atherosclerotic lesions was assessed either by immunofluorescence detection of human IgG in fresh-frozen sections of aorta, or by immunoscintigraphy followed by biodistribution of the radiotracer upon administration of (99m)Tc-chP3R99 mAb. Immunofluorescence studies revealed the presence of chP3R99 mAb in atherosclerotic lesions 24 h after intravenous administration, whereas planar images showed an evident accumulation of (99m)Tc-chP3R99 mAb in atherosclerotic rabbit carotids. Accordingly, (99m)Tc-chP3R99 mAb uptake by lesioned aortic arch and thoracic segment was increased 5.6-fold over controls and it was 3.9-folds higher in carotids, in agreement with immunoscintigrams. Moreover, the deposition of (99m)Tc-chP3R99 mAb in the artery wall was associated both with the presence and size of the lesions in the different portions of evaluated arteries and was greater than in non-targeted organs. In conclusion, chP3R99 mAb preferentially accumulates in arterial atherosclerotic lesions supporting the potential use of this anti-glycosaminoglycans antibody for diagnosis and treatment of atherosclerosis.

Radioimmunoimaging of liver metastases with PET using a 64Cu-labeled CEA antibody in transgenic mice.

PURPOSE: Colorectal cancer is one of the most common forms of cancer, and the development of novel tools for detection and efficient treatment of metastases is needed. One promising approach is the use of radiolabeled antibodies for positron emission tomography (PET) imaging and radioimmunotherapy. Since carcinoembryonic antigen (CEA) is an important target in colorectal cancer, the CEA-specific M5A antibody has been extensively studied in subcutaneous xenograft models; however, the M5A antibody has not yet been tested in advanced models of liver metastases. The aim of this study was to investigate the (64)Cu-DOTA-labeled M5A antibody using PET in mice bearing CEA-positive liver metastases. PROCEDURES: Mice were injected intrasplenically with CEA-positive C15A.3 or CEA-negative MC38 cells and underwent micro-computed tomography (micro-CT) to monitor the development of liver metastases. After metastases were detected, PET/MRI scans were performed with (64)Cu-DOTA-labeled M5A antibodies. H&E staining, immunohistology, and autoradiography were performed to confirm the micro-CT and PET/MRI findings. RESULTS: PET/MRI showed that M5A uptake was highest in CEA-positive metastases. The %ID/cm(3) (16.5% ± 6.3%) was significantly increased compared to healthy liver tissue (8.6% ± 0.9%) and to CEA-negative metastases (5.5% ± 0.6%). The tumor-to-liver ratio of C15A.3 metastases and healthy liver tissue was 1.9 ± 0.7. Autoradiography and immunostaining confirmed the micro-CT and PET/MRI findings. CONCLUSION: We show here that the (64)Cu-DOTA-labeled M5A antibody imaged by PET can detect CEA positive liver metastases and is therefore a potential tool for staging cancer, stratifying the patients or radioimmunotherapy.

Immunoscintigraphy and radioimmunotherapy in Cuba: experiences with labeled monoclonal antibodies for cancer diagnosis and treatment (1993-2013).

INTRODUCTION The availability of monoclonal antibodies in Cuba has facilitated development and application of innovative techniques (immunoscintigraphy and radioimmunotherapy) for cancer diagnosis and treatment. Objective Review immunoscintigraphy and radioimmunotherapy techniques and analyze their use in Cuba, based on the published literature. In this context, we describe the experience of Havana's Clinical Research Center with labeled monoclonal antibodies for cancer diagnosis and treatment during the period 1993-2013. EVIDENCE ACQUISITION Basic concepts concerning cancer and monoclonal antibodies were reviewed, as well as relevant international and Cuban data. Forty-nine documents were reviewed, among them 2 textbooks, 34 articles by Cuban authors and 13 by international authors. All works published by the Clinical Research Center from 1993 through 2013 were included. Bibliography was obtained from the library of the Clinical Research Center and Infomed, Cuba's national health telematics network, using the following keywords: monoclonal antibodies, immunoscintigraphy and radioimmunotherapy. RESULTS Labeling the antibodies (ior t3, ior t1, ior cea 1, ior egf/r3, ior c5, h-R3, 14F7 and rituximab) with radioactive isotopes was a basic line of research in Cuba and has fostered their use as diagnostic and therapeutic tools. The studies conducted demonstrated the good sensitivity and diagnostic precision of immunoscintigraphy for detecting various types of tumors (head and neck, ovarian, colon, breast, lymphoma, brain). Obtaining different radioimmune conjugates with radioactive isotopes such as 99mTc and 188Re made it possible to administer radioimmunotherapy to patients with several types of cancer (brain, lymphoma, breast). The objective of 60% of the clinical trials was to determine pharmacokinetics, internal dosimetry and adverse effects of monoclonal antibodies, as well as tumor response; there were few adverse effects, no damage to vital organs, and a positive tumor response in a substantial percentage of patients. CONCLUSIONS Cuba has experience with production and radiolabeling of monoclonal antibodies, which facilitates use of these agents. Studies in Cuba conducted by the Clinical Research Center over the past 20 years have yielded satisfactory results. Evidence obtained suggests promising potential of monoclonal antibodies and nuclear medicine, with immunoscintigraphy and radioimmunotherapy techniques providing alternatives for cancer diagnosis and treatment in Cuba.

Preliminary radioimmunoimaging and biodistribution of ¹³¹iodine-labeled single-chain antibody fragment against progastrin-releasing peptide(31₋98) in small cell lung cancer xenografts.

BACKGROUND: Monoclonal antibodies (mAbs) such as DD3, raised against progastrin-releasing peptide(31-98) (ProGRP (31-98)) antigen, have been used to target small cell lung cancer (SCLC). However, as an intact mAb, DD3 is cleared slowly from the body, with an optimal radioimmunoimaging time of 72 hours. More recently, a single-chain antibody fragment has demonstrated reduced excretion time in blood and normal tissues and is increasingly used in diagnostic cancer research. Thereby, it potentially increases the radioimmunoimaging efficacy. However, there have been few studies with this antibody fragment. The aim of this study was to characterize the preliminary radioimmunoimaging and biodistribution of (131)I-anti-ProGRP(31-98) scFv in nude mice bearing SCLC xenografts. METHODS: Anti-ProGRP(31-98) scFv was used to detect ProGRP expression by flow cytometry analysis and immunohistochemistry. (131)I-anti-ProGRP(31-98) scFv was injected intravenously into healthy Kunming mice and the percentage injected dose per gram (%ID/g) in various organs was calculated. Similarly, the %ID/g and tumor/non-tumor ratio in xenograft-bearing mice was calculated. After injection of (131)I-anti-ProGRP(31-98) scFv, treated mice were imaged at 1, 24, and 30 hours. Then the tumor/base ratios were calculated. RESULTS: ProGRP was highly expressed in NCI-H446 cells and xenograft tissue. The metabolism of (131)I-anti-ProGRP(31-98) scFv in healthy mice was consistent with a first-order and two-compartment model; T1/2α and T1/2ß were 10.2 minutes and 5 hours 18 minutes, respectively. The %ID/g of (131)I-anti-ProGRP(31-98) scFv in xenografts was much higher than in healthy tissues at 12 hours after injection, reaching a maximum of (5.38±0.92) %ID/g at 24 hours. Successful imaging of xenograft tissue was achieved as early as 1 hour post-injection and persisted until 30 hours, with 24 hours proving optimal. CONCLUSION: (131)I-anti-ProGRP(31-98) scFv shows highly selective tumor uptake with low accumulation in normal tissues and rapid blood clearance, indicating that it could be a promising agent for SCLC radioimmunoimaging.