Comparative uptakes and biodistributions of internalizing vs. noninternalizing copper-64 radioimmunoconjugates in cell and animal models of colon cancer (original) (raw)
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Development of a two-antibody model for the evaluation of copper-64 radioimmunotherapy
Veterinary and Comparative Oncology, 2004
Copper-64 emits b þ and bparticles suitable for positron emission tomography and radioimmunotherapy (RIT) of cancer. Copper-64-labelled antibodies have caused complete responses in laboratory animal RIT studies at far lower radiation doses than traditionally prescribed. The intracellular localization of copper radioisotopes may lead to cytotoxic effects by mechanisms beyond ionizing radiation damage. The purpose of this research was to develop a model using both internalizing and non-internalizing antibodies for direct comparison in future RIT studies using the same animal model of cancer. The monoclonal antibodies, cBR96 and cT84.66, were conjugated with N-hydroxysulfosuccinimidyl DOTA. All conjugates retained high immunoreactivity and labelled efficiently with 64 Cu with high specific activity and radiochemical purity. Twenty-four hour biodistributions determined in LS174T tumour-bearing nude mice demonstrated low organ and high tumour uptakes for both monoclonal antibodies. This model constitutes a promising system for elucidating whether internalization of 64 Cu is responsible for an enhanced tumour cytotoxicity in vivo.
Radioimmunotherapy with a 64 Cu-labeled monoclonal antibody : A comparison with 67 Cu JUDITH
2005
67Cu (tl2 = 62 h) has demonstrated potential as a radionuclide for radioimmunotherapy, but limited availability severely restricts its widespread use. 6"Cu (t1l2 = 12.8 h) has been shown to have comparable effectiveness in vitro and in vivo. The present study was undertaken to examine the therapeutic potential of 64Cuand 67Cu-bromoacetamidobenzyl-1,4,8,1 1-tetraazacyclotetradecane-N,N',N",N'"-tetraacetic acid (BAT)-2-iminothiolane (2IT)-1A3 (1A3 is a mouse anti-human colorectal cancer mAb) for treatment of GW39 human colon carcinoma carried in hamster thighs. Hamsters were injected with 64Cuor 67Cu-BAT-21T-1A3 or Cu-labeled nonspecific IgG (MOPC) or saline. Hamsters were killed 6-7 months after therapy or when tumors were 210 g. Of the hamsters with small tumors (mean weight 0.43 ± 0.25 g), 87.5% were disease-free 7 months after treatment with 2 mCi (1 Ci = 37 GBq) of 64Cu-BAT-21T-1A3 or 0.4 mCi of 67CuBAT-2IT-1A3. The mean tumor doses at these activities of 6...
Monoclonal antibodies for copper-64 PET dosimetry and radioimmunotherapy
Cancer Biology & Therapy, 2011
Copper-64 emits b þ and bparticles suitable for positron emission tomography and radioimmunotherapy (RIT) of cancer. Copper-64-labelled antibodies have caused complete responses in laboratory animal RIT studies at far lower radiation doses than traditionally prescribed. The intracellular localization of copper radioisotopes may lead to cytotoxic effects by mechanisms beyond ionizing radiation damage. The purpose of this research was to develop a model using both internalizing and non-internalizing antibodies for direct comparison in future RIT studies using the same animal model of cancer. The monoclonal antibodies, cBR96 and cT84.66, were conjugated with N-hydroxysulfosuccinimidyl DOTA. All conjugates retained high immunoreactivity and labelled efficiently with 64 Cu with high specific activity and radiochemical purity. Twenty-four hour biodistributions determined in LS174T tumour-bearing nude mice demonstrated low organ and high tumour uptakes for both monoclonal antibodies. This model constitutes a promising system for elucidating whether internalization of 64 Cu is responsible for an enhanced tumour cytotoxicity in vivo.
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 2007
64 Cu radiopharmaceuticals have shown tumor growth inhibition in tumor-bearing animal models with a relatively low radiation dose that may be related to nuclear localization of the 64 Cu in tumor cells. Here we address whether the nuclear localization of 64 Cu from a 64 Cu-labeled chelator-somatostatin conjugate is related to the dissociation of the radio-copper from its chelator. The 64 Cu complex of has demonstrated instability in vivo, whereas 64 Cu-CB-TE2A (CB-TE2A is 4,11-bis(carboxymethyl)-1,4,8,11-tetraazabicyclo[6.6.2]hexadecane) was highly stable. Methods: Receptor binding, nuclear uptake, internalization, and efflux assays were performed to characterize the interaction with the somatostatin receptor and the intracellular fate of 64 Cu-labeled chelator-peptide conjugates in A427-7 cells. From these data, the absorbed dose to cells was calculated. Results: 64 Cu-TETA-Y3-TATE ( 64 Cu-[1]) and 64 Cu-CB-TE2A-Y3-TATE ( 64 Cu-[2]) had high affinity for somatostatin receptor subtype 2 (SSTr2) in A427-7 cells. After 3 h, 64 Cu-[2] showed greater internalization (.30%) compared with 64 Cu-[1] (;15%). There was uptake of 64 Cu-[1] in nuclei of 427-7 cells (9.4% 6 1.7% at 24 h), whereas 64 Cu-[2]
Pharmaceutical Biology, 1995
biological behavior (Mausner, 1993). Physical properties that are important to consider include the radionuclide half-life, the type, energy and branching ratio of particulate radiation and the gamma-ray energies and abundances. The physical half-life should be matched with the in vivo pharmacokinetics of the molecule under consideration. Time-dose fractionation is also an important criterion . For equal radioactivity concentrations in the target, radionuclides with long half lives will produce a lower absorbed dose rate than those with short half lives. The type of particulate emission also must be considered. Although Auger and low-energy conversion electrons can be potentially lethal , this effect can best be realized with intranuclear localization of the radionuclide, which does not generally occur with radiolabeled MAbs. Beta particles are less densely ionizing and have a range longer than a's or the Auger and conversion electrons so that the distribution requirements are less restrictive for RIT of bulky disease or for macrometastases. The gamma-ray energies and abundances are also important physical properties, because the presence of gamma rays allows the possibility of external imaging.
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1995
Antibody fragments labeled with a radiometal using bifunctional chelates generally undergo renal clearance followed by trapping of the metabolites, leading to high radiation doses to the kidneys. Copper-64-labeled BAT-2IT-1A3-F(ab')2 was recently reported to accumulate in colorectal tumors in an animal model, however, kidney uptake was also high. In this study, the preparation of 64Cu-BAT-2IT-1A3-F(ab')2 was optimized to reduce the renal uptake. The bifunctional chelate 6-bromoacetamidobenzyl-1,4,8,11-tetraazacyclotetradecane-N,N ',N",N'"-tetraacetic acid (BAT) was conjugated to 1A3-F(ab')2 using the linking agent 2-iminothiolane (2IT). The conjugation reaction produced 20% of a lower molecular weight (molecular wieght) impurity found to be TETA-1A3-Fab'. The conjugation procedure was optimized to include FPLC purification of the BAT-2IT-1A3-F(ab')2 from TETA-1A3-Fab' after conjugation prior to labeling with 64Cu. The biodistribution of 64Cu...
Bioconjugate Chemistry, 1996
The bifunctional chelating agents (BFCs), 6-[p-(bromoacetamido)benzyl]-1, , 6-[p-(isothiocyanato)benzyl]-1, methyl]benzoic acid (CPTA), and 1- [(1,4,7,10,13-pentaazacyclopentadec-1-yl)methyl]benzoic acid (PCBA), were synthesized and conjugated to the anti-colorectal monoclonal antibody (mAb), 1A3, and antibody fragments, 1A3-F(ab′) 2 , for radiolabeling with 64,67 Cu and comparison in animal models. In vivo metabolism studies were carried out in liver and kidneys in order to correlate the nature of the metabolites formed to the uptake and retention of the radiolabel in each organ. Animal biodistribution studies were performed in Golden Syrian hamsters bearing the GW39 human colon cancer tumors and in normal Sprague-Dawley rats. All conjugates showed good tumor uptake in hamsters. Biodistribution in rats showed that 64 Cu-BAT-2IT-1A3 had the lowest liver and kidney uptake of the intact 1A3 conjugates (p < 0.03), whereas in hamsters, there were no significant differences in liver and kidney uptake between the four intact BFC-1A3 conjugates. Tumor-bearing hamsters injected with 64 Cu-CPTA-1A3-F(ab′) 2 and 64 Cu-PCBA-1A3-F(ab′) 2 had from 3 to 7 times greater uptake in the kidneys than hamsters given 64 Cu-labeled BAT and SCN-TETA 1A3-F(ab′) 2 conjugates, while rats injected with 64 Cu-CPTA-1A3-F(ab′) 2 and 64 Cu-PCBA-1A3-F(ab′) 2 had nearly twice the uptake. The in vivo metabolism of the mAbs 1A3 and 1A3-F(ab′) 2 radiolabeled with 67 Cu through the SCN-TETA, CPTA, and PCBA BFCs was investigated by excising the livers and kidneys of normal rats from 1-5 days post-injection of the radiolabeled conjugates. Liver and kidney homogenates were analyzed by size exclusion chromatography and thin layer chromatography (TLC). The size exclusion chromatography data showed that all of the 67 Cu-labeled 1A3-F(ab′) 2 conjugates were >85% degraded in the kidneys to small molecular weight metabolites by 1 day post-injection. In contrast, in the liver at 1 day post-injection, greater than 70% of the 67 Cu-labeled 1A3 conjugates were unmetabolized. By day 5, a 35 kDa peak appeared in the liver of rats injected with the 67 Cu-labeled 1A3 conjugates, possibly due to transchelation of the 67 Cu to proteins. Superoxide dismutase chromatographically elutes at the same retention time as this 67 Cu-labeled metabolite. The TLC data indicate that the low molecular weight metabolite (<5 kDa) of both 67 Cu-CPTA-1A3 and 67 Cu-CPTA-1A3-F(ab′) 2 conjugates co-chromatographed with a 67 Cu-CPTA--lysine standard. Our data suggest that chelate charge and lipophilicity play a large role in kidney retention of 64/67 Cu-labeled BFC-1A3-F(ab′) 2 conjugates, while transchelation of the copper label appears to be the major factor for liver accumulation of 64/67 Cu-labeled BFC-1A3 conjugates.
EJNMMI Research, 2018
Background: The aim of the present study is to evaluate the kinetics and dosimetry of 64 CuCl 2 in human prostate cancer (PCa) lesions. We prospectively evaluated 50 PCa patients with biochemical relapse after surgery or external beam radiation therapy. All patients underwent 64 CuCl 2-PET/CT to detect PCa recurrence/metastases. Volumes of interest were manually drawn for each 64 CuCl 2 avid PCa lesion with a diameter > 1 cm on mpMRI in each patient. Time-activity curves for all lesions were obtained. The effective and biological half-life and the standard uptake values (SUVs) were calculated. Tumour/background ratio (TBR) curves as a function of time were considered. Finally, the absorbed dose per lesion was estimated. Results: The mean effective half-life of 64 CuCl 2 calculated in the lymph nodes (10.2 ± 1.7 h) was significantly higher than in local relapses (8.8 ± 1.1 h) and similar to that seen in bone metastases (9.0 ± 0.4 h). The mean 64 CuCl 2 SUV max calculated 1 h after tracer injection was significantly higher in the lymph nodes (6.8 ± 4.3) and bone metastases (6.8 ± 2.9) than in local relapses (4.7 ± 2.4). TBR mean curve of 64 CuCl 2 revealed that the calculated TBR max value was 5.0, 7.0, and 6.2 in local relapse and lymph node and bone metastases, respectively, and it was achieved about 1 h after 64 CuCl 2 injection. The mean absorbed dose of the PCa lesions per administrated activity was 6.00E-2 ± 4.74E-2mGy/MBq. Indeed, for an administered activity of 3.7 GBq, the mean dose absorbed by the lesion would be 0.22 Gy. Conclusions: Dosimetry showed that the dose absorbed by PCa recurrences/metastases per administrated activity was low. The dosimetric study performed does not take into account the possible therapeutic effect of the Auger electrons. Clinical trials are needed to evaluate 64 Cu internalization in the cell nucleus that seems related to the therapeutic effectiveness reported in preclinical studies.
Radioimmunotherapy with a 64Cu-labeled monoclonal antibody: a comparison with 67Cu
Proceedings of the National Academy of Sciences, 1996
67Cu (t1/2 = 62 h) has demonstrated potential as a radionuclide for radioimmunotherapy, but limited availability severely restricts its widespread use. 64Cu (t1/2 = 12.8 h) has been shown to have comparable effectiveness in vitro and in vivo. The present study was undertaken to examine the therapeutic potential of 64Cu- and 67Cu-bromoacetamidobenzyl-1,4,8,11-tetraazacyclotetradeca ne-N, N',N",N"'-tetraacetic acid (BAT)-2-iminothiolane (2IT)-1A3 (1A3 is a mouse anti-human colorectal cancer mAb) for treatment of GW39 human colon carcinoma carried in hamster thighs. Hamsters were injected with 64Cu- or 67Cu-BAT-2IT-1A3 or Cu-labeled nonspecific IgG (MOPC) or saline. Hamsters were killed 6-7 months after therapy or when tumors were > or = 10 g. Of the hamsters with small tumors (mean weight 0.43 +/- 0.25 g), 87.5% were disease-free 7 months after treatment with 2 mCi (1 Ci = 37 GBq) of 64Cu-BAT-2IT-1A3 or 0.4 MCi of 67Cu-BAT-2IT-1A3. The mean tumor doses at these ac...