共查询到20条相似文献,搜索用时 31 毫秒
1.
D. C. Blakey B. E. Valcaccia S. East A. F. Wright F. T. Boyle C. J. Springer P. J. Burke R. G. Melton K. D. Bagshawe 《Cell biochemistry and biophysics》1993,22(1-3):1-8
The F(ab’)2 fragment of the antitumor monoclonal antibody, A5B7, was covalently linked to the bacterial enzyme carboxypeptidase G2 (CPG2). The resulting conjugate was used in combination with a prodrug of a benzoic acid mustard alkylating agent to treat human colon tumor xenografts in a two-step targeting strategy, antibody-directed enzyme produrug therapy (ADEPT). The prodrug, 4-[(2-chloroethyl) (2-mesyloxyethyl) amino]-benzoyl-l-glutamic acid is rapidly converted by CPG2 to a drug that is at least 15x more toxic in vitro against LS174T colorectal tumor cells than the prodrug. Optimal tumor/ blood ratios of the A5B7-CPG2 were achieved 72 h after administration of the conjugate to athymic mice bearing established LS174T tumor xenografts. Significant antitumor activity was seen in LS174T tumor-bearing mice treated with the conjugate followed 3 d later by the prodrug. In contrast, prodrug, conjugate, or active drug alone did not result in any antitumor activity in this tumor model. These studies demonstrate the advantage of a two-step ADEPT system for the treatment of colorectal cancer. 相似文献
2.
Springer C. J. Poon G. K. Sharma S. K. Bagshawe K. D. 《Cell biochemistry and biophysics》1994,24(1-3):193-207
Antibody-directed enzyme prodrug therapy (ADEPT) separates the cytotoxic function from the targeting function (5). An antibody-carboxypeptidase
G2 (CPG2) enzyme is delivered prior to the nontoxic prodrug, CMDA, which is converted to a cytotoxic drug by the action of
the localized conjugate at the tumor site. An indirect in vitro assay was developed to detect the presence of functional CPG2
in the plasma of patients in an ADEPT clinical trial. Compounds in the plasma of patients were characterized using liquid
chromatography-mass spectrometry. Plasma at three different time points (prior to treatment, post-antibody-enzyme conjugate,
and post-galactosylated anti-enzyme antibody clearing agent) was added to the CMDA prodrug and analyzed. Conversion of the
CMDA prodrug to its active drug indicates that CPG2-conjugate remains in the plasma. This technique will provide essential
data for the timing of prodrug administration in ADEPT. 相似文献
3.
Surinder K. Sharma Kenneth D. Bagshawe Roger G. Melton Roger F. Sherwood 《Cell biochemistry and biophysics》1992,21(1-3):109-120
The human immune response to monoclonal antibody-enzyme conjugates has been studied in patients included in the pilot clinical
trial of ADEPT. Each patient received murine monoclonal anti-CEA antibody fragments (A5B7-F(ab')2, conjugated to bacterial
enzyme, carboxypeptidase G2 (CPG2) followed by a galactosylated monoclonal anti-CPG2 antibody (SB43), 36–48 h after the conjugate.
Some patients were also given a dose of131I-labeled conjugate (4–8 mg, 7–15 mCi) for blood clearance and gamma camera image studies. All patients studied developed
human antimouse antibodies (HAMA) and anti-CPG2 antibodies within 10 d after a single course of treatment with the conjugate.
In most cases, IgM response was detected at 7 d after the conjugate followed by the IgG response 14 d later. In one patient,
HAMA and anti-CPG2 antibodies of the IgG type could still be detected at 10 mo after treatment. Anti-CPG2 antibodies in serum
of one patient were found to inhibit CPG2 activity in vitro.
Generation of neutralizing antibodies limits the use of repeat cycles of ADEPT in patients. Use of immunosuppressive agents
may allow a useful time window for several ADEPT cycle treatments by delaying the appearance of HAMA and anti-CPG2 antibodies.
Patients given cyclosporin A before and during ADEPT are currently being studied for HAMA and anti-CPG2 response. 相似文献
4.
Kairemo Kalevi J. A. Ljunggren Kaj Wahlström Torsten Stigbrand Torgny Strand Sven-Erik 《Cell biochemistry and biophysics》1994,24(1-3):293-300
Tumor stroma contains much fibrin and monoclonal antifibrin antibody targeting is possible in tumors. In this study, nude
mouse human ovarian carcinoma xenograft specimens were investigated after treatment with90Y-labeled monoclonal antifibrin antibody Fab fragment or with90Y-labeled OC125-monoclonal antibody F(ab′)2 fragments. The mice received the radioimmunotherapy activity either intratumorally, intraperitoneally, or intravenously.
Beta-camera imaging (BCI) is a novel device for studying activity distribution in tissue specimens and, together with immunohistochemistry
(IHC) with OC125, antifibrin, anticarcinoembryonic antigen, anti-cytokeratin, and anti-placental alkaline phosphatase antibodies,
was used for correlation of activity distribution of tissue specimens. These results were in concordance: Antigen distribution
measured with IHC and radioactivity distribution were similar with the same antibodies, antifibrin, and OC125: However, these
antigens demonstrated rather different distribution. Tissue studies revealed that activity was concentrated also in the necrotic
tumor tissue, indicating that cell death was also caused by radiation. Differences in the tumor cell morphology were observed
using different routes of administration. With BCI, it is possible to quantitate activities in frozen sections (microdosimetry),
and these results were in concordance with absolute activities as measured by tissue sampling and well-counting. Three-dimensional
reconstruction of tissue slices combined with radioactivity distribution measured with BCI allows estimation of total absorbed
radiation dose in tumor after an appropriate dose planning. 相似文献
5.
Abraham Ralph Aman Nureddin von Borstel Reid Darsley Michael Kamireddy Balreddy Kenten John Morris Geoffrey Titmas Richard 《Cell biochemistry and biophysics》1994,24(1-3):127-133
5′-O-β-d-galactosyl-5-fluorouridine is a prodrug that can be converted by the enzyme β-d-galactosidase to the potent antineoplastic drug 5-fluorouridine. The prodrug is more than 100x less toxic than the drug to
bone marrow cells in Balb/c mice. The ratio of the IC50 of the prodrug to that of the drug determined on a variety of tumor cell lines in vitro ranged from 500∶1–1000∶1. An antibody-enzyme
conjugate (AEC) was synthesized and purified. Maleimide-substituted COL-1 anti-CEA monoclonal antibody was linked to free
thiol groups of β-d-galactosidase. The conjugate was purified by size exclusion and ion exchange chromatography. It retained full immunoreactivity
and enzyme activity. After binding to antigen-positive tumor cells, the conjugate was able to activate the prodrug and specifically
kill the cells. We are continuing to investigate this model for its potential use in antibody-directed enzyme prodrug therapy
(ADEPT). 相似文献
6.
de Boisferon Marc Hillairet Manetti Corrine Raguin Olivier Gautherot Emmanuel Rostène William Barbet Jacques Gruaz-Guyon Anne 《International journal of peptide research and therapeutics》1997,4(4-6):331-339
Summary The advantages of bivalent hapten-bearing peptides for the detection of tumours pretargeted with bispecific antibodies have
been demonstrated. This technology is now considered for radioimmunotherapy and bivalent haptens designed to target131I are needed. We thus synthesised a series of tyrosine-containing peptides bearing the histamine-hemisuccinate hapten. These
molecules were tested for their ability to bind simultaneously two anti-hapten antibody molecules. One of these bivalent haptens,
AG3.0, with a lysyl-d-tyrosyl-lysine connecting chain, was found to have optimal binding characteristics and was thus selected for further investigations.
AG3.0 was shown to efficiently deliver radioactive iodine to human colorectal tumours grafted in nude mice using an anti-carcinoembryonic
antigen×anti-histamine-hemisuccinate bispecific antibody. AG3.0 was also targeted to human B lymphoma cells pretargeted with
a bispecific antibody specific for membrane IgM. In this system, bivalent ligands such as F(ab′)2 or IgG are rapidly internalised and covalently linked radioactive iodine is released from target cells as a result of intracellular
catabolism. With the pretargeted iodine-labelled bivalent hapten, a fivefold increase in the intracellular activity retention
time as compared to125I-labelled F(ab′)2 and IgG was observed. The radiolabelled hapten did not undergo any degradation after internalisation. These results have
been confirmed in vivo with an anti-BCL1 IgM idiotype bispecific antibody and131I-labelled AG3.0. These reagents injected as a single 300 μCi dose, 7 days after inoculation of 104 BCL1 lymphoma cells in BALB/c mice, cured 14/16 of the animals and the treatment was well tolerated. Comparatively, the same dose
of labelled IgG cured 13/16 of the mice but three mice died of haematologic toxicity. The same dose of labelled F(ab′)2 or Fab′ was completely inefficient.131I-labelled bivalent haptens are now used in phase I radioimmunotherapy clinical trials. 相似文献
7.
Advantage of residualizing radiolabels for an internalizing antibody against the B-cell lymphoma antigen, CD22 总被引:1,自引:0,他引:1
Robert M. Sharkey Thomas M. Behr M. Jules Mattes Rhona Stein Gary L. Griffiths Lisa B. Shih Hans J. Hansen Rosalyn D. Blumenthal Robert M. Dunn Malik E. Juweid D. M. Goldenberg 《Cancer immunology, immunotherapy : CII》1997,44(3):179-188
LL2 is an anti-CD22 pan-B-cell monoclonal antibody which, when radiolabeled, has a high sensitivity for detecting B-cell,
non-Hodgkin’s lymphoma (NHL), as well as an antitumor efficacy in therapeutic applications. The aim of this study was to determine
whether intracellularly retained radiolabels have an advantage in the diagnosis and therapy of lymphoma with LL2. In vitro
studies showed that iodinated LL2 is intracellularly catabolized, with a rapid release of the radioiodine from the cell. In
contrast, residualizing radiolabels, such as radioactive metals, are retained intracellularly for substantially longer. In
vivo studies were performed using LL2-labeled with radioiodine by a non-residualizing (chloramine-T) or a residualizing method
(dilactitol-tyramine, DLT), or with a radioactive metal (111In). The biodistribution of a mixture of 125I (non-residualizing chloramine-T compared to residualizing DLT), 111In-labeled LL2 murine IgG2a or its fragments [F(ab′)2, Fab′], as well as its humanized, CDR-grafted form, was studied in nude mice bearing the RL human B-cell NHL cell line. Radiation
doses were calculated from the biodistribution data according to the Medical International Radiation Dose scheme to assess
the potential advantage for therapeutic applications. At all assay times, tumor uptake was higher with the residualizing labels
(i.e., 111In and DLT-125I) than with the non-residualizing iodine label. For example, tumor/blood ratios of 111In-labeled IgG were 3.2-, 3.5- and 2.8-fold higher than for non-residualizing iodinated IgG on days 3, 7 and 14, respectively.
Similar results were obtained for DLT-labeled IgG and fragments with residualized radiolabels. Tumor/organ ratios also were
higher with residualizing labels. No significant differences in tumor, blood and organ uptake were observed between murine
and humanized LL2. The conventionally iodinated anti-CD20 antibody, 1F5, had tumor uptake values comparable to those of iodinated
LL2, the uptake of both antibodies being strongly dependent on tumor size. These data suggest that, with internalizing antibodies
such as LL2, labeling with intracellularly retained isotopes has an advantage over released ones, which justifies further
clinical trials with residualizing 111In-labeled LL2 for diagnosis, and residualizing 131I and 90Y labels for therapy.
Received: 23 August 1996 / Accepted: 7 February 1997 相似文献
8.
Huston James S. Adams Gregory P. McCartney John E. Tai Mei-Sheng Hudziak Robert M. Oppermann Hermann Stafford Walter F. Liu Sen Fand Irwin Apell Gerald Laminet Axel Bookman Michael A. Houston L. L. Weiner Louis M. 《Cell biochemistry and biophysics》1994,24(1-3):267-278
This investigation has utilized novel forms of the single-chain Fv (sFv), wherein a cysteine-containing peptide has been fused
to the sFv carboxyl terminus to facilitate disulfide bonding or specific crosslinking of this sFv′ to make divalent (sFv′)2. The 741F8 anti-c-erbB-2 monoclonal antibody was used as the basis for construction of 741F8 sFv, from which the sFv′ and (sFv′)2 derivatives were prepared. Recombinant c-erbB-2 extracellular domain (ECD) was prepared in CHO cells and the bivalency of 741F8 (sFv′)2 demonstrated by its complex formation with ECD. The tumor binding properties of125I-labeled anti-c-erbB-2 741F8 sFv, sFv′, and (sFv′)2 were compared with radiolabeled antidigoxin 26-10 sFv′ and (sFv′)2 controls. Following intravenous administration of radiolabeled species to severe combined immune-deficient (SCID) mice bearing
SK-OV-3 tumors (which overexpress c-erbB-2), blood and organ samples were obtained as a function of time over 24 h. Comparative analysis of biodistribution and tumor-to-organ
ratios demonstrated the 741F8 sFv, sFv′, and (sFv′)2 had excellent specificity for tumors, which improved with time after injection. This contrasted with nonspecific interstitial
pooling in tumors observed with the 26-10 sFv, sFv′, and (sFv′)2, which decreased with time after administration. Tumor localization was significantly better for disulfide or peptide crosslinked
741F8 (sFv′)2 having Gly4Cys tails than for monovalent 741F8 sFv′ or Fab. The superior properties of the 741F8 (sFv′)2 in targeting SK-OV-3 tumors in SCID mice suggests the importance of further investigations of divalent sFv analogs for immunotargeting. 相似文献
9.
Chezian Somasundaram Robert Arch Siegfried Matzku Margot Zöller 《Cancer immunology, immunotherapy : CII》1996,42(6):343-350
A bispecific F(ab′)2 antibody conjugate (BAC) was constructed against the complement receptor CR3 of macrophages and a variant CD44 (CD44v6) antigen
of rat pancreatic adenocarcinoma cells to redirect macrophage-mediated tumor cytotoxicity. The Fab′ fragments of monoclonal
antibodies (mAb) 1.1ASML and OX42, recognizing the CD44v6 and the CR3 antigens respectively, were chemically coupled at the
hinge region using 5,5′-dithiobis(2-nitrobenzoate). The BAC was characterized in vitro for its specific, dual binding capacity
to CD44v6 and CR3 antigens. Although the monovalence of the BAC resulted in lower avidities to both the antigens as expected,
it was still able to form stable cross-linkages between tumor cells and macrophages in culture leading to the formation of
“clump-like” cell aggregates. The in vitro and in vivo tumor-targeting capacity of the BAC was compared with that of the parental
antitumor mAb 1.1ASML, which mediates tumor killing by antibody-dependent cell cytotoxicity. These results showed that, even
though the bivalent mAb 1.1ASML did not mediate stable cross-linking of target and effector cells, its Fc-receptor-mediated
killing of tumor cells was more effective when compared to the BAC. Thus, this study strongly supports the hypothesis that
firm persistent binding between effector and target cells per se is not as important as the choice of trigger molecule used for macrophage activation to redirect their tumor cytotoxic potential
effectively.
Received: 2 May 1996 / Accepted: 21 May 1996 相似文献
10.
Spencer DI Robson L Purdy D Whitelegg NR Michael NP Bhatia J Sharma SK Rees AR Minton NP Begent RH Chester KA 《Proteomics》2002,2(3):271-279
Antibodies are highly specific recognition molecules which are increasingly being applied to target therapy in patients. One type of developmental antibody-based therapy is antibody directed enzyme prodrug therapy (ADEPT) for the treatment of cancer. In ADEPT, an antibody specific to a tumor marker protein delivers a drug-activating enzyme to the cancer. Subsequent intravenous administration of an inactive prodrug results in drug activation and cytotoxicity only within the locale of the tumor. Pilot clinical trials with chemical conjugates of the prodrug activating enzyme carboxypeptidase G2 (CPG2) chemically conjugated with an antibody to and carcinoembryonic antigen (CEA), have shown that CPG2-mediated ADEPT is effective but limited by formation of human antibodies to CPG2 (HACA). We have developed a recombinant fusion protein (termed MFE-CP) of CPG2 with an anti-CEA single chain Fv antibody fragment and we have developed methods to address the immunogenicity of this therapeutic. A HACA-reactive discontinuous epitope on MFE-CP was identified using the crystal structure of CPG2, filamentous phage technology and surface enhanced laser desorption/ionization affinity mass spectrometry. This information was used to create a functional mutant of MFE-CP with a significant reduction (range 19.2 to 62.5%, median 38.5%) in reactivity with the sera of 11 patients with post-therapy HACA. The techniques described here are valuable tools for identifying and adapting undesirable immunogenic sites on protein therapeutics. 相似文献
11.
Kuniyo Inouye 《Cancer immunology, immunotherapy : CII》1997,45(3-4):159-161
A bispecific F(ab′)2 fragment recognizing both human thyroid-stimulating hormone (TSH) and alkaline phosphatase (AP) was prepared by disulfide
bond exchange between F(ab′)2 fragments of IgG1 mAb against TSH and AP. AP was polymerized by glutaraldehyde, and a sandwich enzyme-linked immunosorbent
assay for TSH was developed by using the AP polymers and the bispecific F(ab′)2 fragment. In this assay, the preparation of covalently linked AP-mAb conjugates was not needed, and the interaction of mAb
with non-specific proteins was greatly reduced. The sensitivity for TSH increased in proportion to the degree of AP polymerization,
and the lower detection limit obtained with the AP trimer was 0.5 μU/ml. The use of the bispecific F(ab′)2 fragment allows us to use monomers and polymers of AP and thereby regulates the sensitivity of the assay.
Accepted: 14 October 1997 相似文献
12.
Jewett A Teruel A Romero M Head C Cacalano N 《Cancer immunology, immunotherapy : CII》2008,57(7):1053-1066
Freshly isolated untreated NK cells undergo rapid apoptosis and lose their cytotoxic function upon the addition of F(ab′)2 fragment of anti-CD16 antibodies. Loss of NK cell cytotoxic function after treatment with F(ab′)2 fragment of anti-CD16 antibody can be seen against K562 and UCLA-2 oral tumor cells when either added immediately in the
co-cultures of NK cells with the tumor cells or after pre-treatment of NK cells with the antibody before their addition to
the tumor cells. Addition of Interleukin-2 (IL-2) in combination with anti-CD16 antibody to NK cells delayed the induction
of DNA fragmentation in NK cells, and even though decreased cytotoxicity could still be observed against K562 and UCLA-2 oral
tumors when compared to IL-2 alone treated NK cells, the cytotoxicity levels remained relatively higher and approached those
obtained by untreated NK cells in the absence of antibody treatment. No increases in IFN-γ, Granzymes A and B, Perforin and
TRAIL genes could be seen in NK cells treated with anti-CD16 antibody. Neither secretion of IFN-γ nor increased expression
of CD69 activation antigen could be observed after the treatment of NK cells with anti-CD16 antibody. Furthermore, IL-2 mediated
increase in CD69 surface antigens was down-modulated by anti-CD16 antibody. Finally, the addition of anti-CD16 antibody to
co-cultures of NK cells with tumor target cells was not inhibitory for the secretion of VEGF by oral tumor cells, unlike those
co-cultured with untreated or IL-2 treated NK cells. Thus, binding and triggering of CD16 receptor on NK cells may enhance
oral tumor survival and growth by decreased ability of NK cells to suppress VEGF secretion or induce tumor cell death during
the interaction of NK cells with oral tumor cells.
This work was supported by RO1-DE18830 from NIH. 相似文献
13.
The human immune response to monoclonal antibody-enzyme conjugates has been studied in patients included in the pilot clinical trial of ADEPT. Each patient received murine monoclonal anti-CEA antibody fragments (A5B7-F(ab')2, conjugated to bacterial enzyme, carboxypeptidase G2 (CPG2) followed by a galactosylated monoclonal anti-CPG2 antibody (SB43), 36-48 h after the conjugate. Some patients were also given a dose of 131I-labeled conjugate (4-8 mg, 7-15 mCi) for blood clearance and gamma camera image studies. All patients studied developed human antimouse antibodies (HAMA) and anti-CPG2 antibodies within 10 d after a single course of treatment with the conjugate. In most cases, IgM response was detected at 7 d after the conjugate followed by the IgG response 14 d later. In one patient, HAMA and anti-CPG2 antibodies of the IgG type could still be detected at 10 mo after treatment. Anti-CPG2 antibodies in serum of one patient were found to inhibit CPG2 activity in vitro. Generation of neutralizing antibodies limits the use of repeat cycles of ADEPT in patients. Use of immunosuppressive agents may allow a useful time window for several ADEPT cycle treatments by delaying the appearance of HAMA and anti-CPG2 antibodies. Patients given cyclosporin A before and during ADEPT are currently being studied for HAMA and anti-CPG2 response. 相似文献
14.
Summary. Targeted diagnostic agents are expected to have a significant impact in molecular imaging of cell-surface associated markers
of proliferation, inflammation and angiogenesis. In this communication, we describe a new class of targeted polyamino acid-based
protected graft copolymers (PGC) of poly-(L-lysine) and methyl poly-(ethylene glycol) (PGC) covalently conjugated with a monoclonal
antibody fragment, F(ab′)2. We utilized targeted PGC conjugates as carriers of near-infrared indocyanine fluorophores (Cy5.5) for optical imaging of
endothelial cell populations expressing IL-1β inducible proinflammatory marker E-selectin. We compared two conjugation chemistries, involving either introduction of sulfhydryl
group to F(ab′)2, or via direct attachment of the antibody fragment directly to the chemically activated PGC. Both PGC-based targeted agents
demonstrated high binding specificity (20–30 fold over non-specific uptake) and were utilized for imaging E-selectin expression
on human endothelial cells activated with IL-1β.
Received June 29, 2001 Accepted August 8, 2001 Published online August 9, 2002 相似文献
15.
John R. Arthur Fergus Nicol Geoffrey J. Beckett 《Biological trace element research》1992,33(1-3):37-42
Selenium deficiency impairs thyroid hormone metabolism by inhibiting the synthesis and activity of the iodothyronine deiodinases,
which convert thyroxine (T4) to the more metabolically active 3,3′-5 triiodothyronine (T3). Hepatic type I iodothyronine deiodinase, identified in partially purified cell fractions using affinity labeling with [125I]N-bromoacetyl reverse triiodothyronine, is also labeled with75Se by in vivo treatment of rats with75Se-Na2SeO3. Thus, the type I iodothyronine 5′-deiodinase is a selenoenzyme. In rats, concurrent selenium and iodine deficiency produces
greater increases in thyroid weight and plasma thyrotrophin than iodine deficiency alone. These results indicate that a concurrent
selenium deficiency could be a major determinant of the severity of iodine deficiency. 相似文献
16.
The role of selenium in thyroid hormone metabolism and effects of selenium deficiency on thyroid hormone and iodine metabolism 总被引:1,自引:0,他引:1
John R. Arthur Fergus Nicol Geoffrey J. Beckett 《Biological trace element research》1992,34(3):321-325
Selenium deficiency impairs thyroid hormone metabolism by inhibiting the synthesis and activity of the iodothyronine deiodinases,
which convert thyroxine (T4) to the more metabolically active 3,3′–5 triiodothyronine (T3). Hepatic type I iodothyronine deiodinase, identified in partially purified cell fractions using affinity labeling with [125I]N-bromoacetyl reverse triiodothyronine, is also labeled with75Se by in vivo treatment of rats with75Se−Na2SeO3. Thus, the type I iodothyronine 5′-deiodinase is a selenoenzyme. In rats, concurrent selenium and iodine deficiency produces
greater increases in thyroid weight and plasma thyrotrophin than iodine deficiency alone. These results indicate that a concurrent
selenium deficiency could be a major determinant of the severity of iodine deficiency. 相似文献
17.
Sridhar Nimmagadda Mrudula Pullambhatla Ala Lisok Chaoxin Hu Anirban Maitra Martin G Pomper 《Biochemical and biophysical research communications》2014
The receptor tyrosine kinase Axl is overexpressed in and leads to patient morbidity and mortality in a variety of cancers. Axl–Gas6 interactions are critical for tumor growth, angiogenesis and metastasis. The goal of this study was to investigate the feasibility of imaging graded levels of Axl expression in tumors using a radiolabeled antibody. We radiolabeled anti-human Axl (Axl mAb) and control IgG1 antibodies with 125I with high specific radioactivity and radiochemical purity, resulting in an immunoreactive fraction suitable for in vivo studies. Radiolabeled antibodies were investigated in severe combined immunodeficient mice harboring subcutaneous CFPAC (Axlhigh) and Panc1 (Axllow) pancreatic cancer xenografts by ex vivo biodistribution and imaging. Based on these results, the specificity of [125I]Axl mAb was also validated in mice harboring orthotopic Panc1 or CFPAC tumors and in mice harboring subcutaneous 22Rv1 (Axllow) or DU145 (Axlhigh) prostate tumors by ex vivo biodistribution and imaging studies at 72 h post-injection of the antibody. Both imaging and biodistribution studies demonstrated specific and persistent accumulation of [125I]Axl mAb in Axlhigh (CFPAC and DU145) expression tumors compared to the Axllow (Panc1 and 22Rv1) expression tumors. Axl expression in these tumors was further confirmed by immunohistochemical studies. No difference in the uptake of radioactivity was observed between the control [125I]IgG1 antibody in the Axlhigh and Axllow expression tumors. These data demonstrate the feasibility of imaging Axl expression in pancreatic and prostate tumor xenografts. 相似文献
18.
Phosphatidylserine (PS) is an attractive target for imaging agents that identify tumors and assess their response to therapy. PS is absent from the surface of most cell types, but becomes exposed on tumor cells and tumor vasculature in response to oxidative stresses in the tumor microenvironment and increases in response to therapy. To image exposed PS, we used a fully human PS-targeting antibody fragment, PGN635 F(ab’)2, that binds to complexes of PS and β2-glycoprotein I. PGN635 F(ab’)2 was labeled with the positron-emitting isotope iodine-124 (124I) and the resulting probe was injected into nude mice bearing subcutaneous or orthotopic human PC3 prostate tumors. Biodistribution studies showed that 124I-PGN635 F(ab’)2 localized with remarkable specificity to the tumors with little uptake in other organs, including the liver and kidneys. Clear delineation of the tumors was achieved by PET 48 hours after injection. Radiation of the tumors with 15 Gy or systemic treatment of the mice with 10 mg/kg docetaxel increased localization in the tumors. Tumor-to-normal (T/N) ratios were inversely correlated with tumor growth measured over 28 days. These data indicate that 124I-PGN635 F(ab’)2 is a promising new imaging agent for predicting tumor response to therapy. 相似文献
19.
Susanna M. Rybak Hennie R. Hoogenboom Dianne L. Newton Jef C. M. Raus Richard J. Youle 《Cell biochemistry and biophysics》1992,21(1-3):121-138
Members of the pancreatic ribonuclease (RNase) family have diverse activities toward RNA that could cause them to function
during host defense and physiological cell death pathways. This activity could be harnessed by coupling RNases to cell binding
ligands for the purpose of engineering them into cell-type specific cytotoxins. Therefore, the cytotoxic potential of RNase
was explored by linking bovine pancreatic ribonuclease A via a disulfide bond to human transferrin or antibodies to the transferrin
receptor. The RNase hybrid proteins were cytotoxic to K562 human erythroleukemia cells in vitro with an IC50 around 10−7
M, whereas>10−4
M of native RNase was required to inhibit protein synthesis. Cytotoxicity required both components of the conjugate since excess
transferrin or ribonuclease inhibitors added to the medium protected the cells from the transferrin-RNase toxicity. Importantly,
the RNase conjugates were found to have potent antitumor effects in vivo. Chimeric RNase fusion proteins were also developed.
F(ab′)2-like antibody-enzyme fusions were prepared by linking the gene for human RNase to a chimeric antitransferrin receptor heavy
chain gene. The antibody enzyme fusion gene was introduced into a transfectoma that secreted the chimeric light chain of the
same antibody, and cell lines were cloned that synthesized and secreted the antibody-enzyme fusion protein of the expected
size at a concentration of 1–5 ng/mL. Culture supernatants from clones secreting the fusion protein caused inhibition of growth
and protein synthesis toward K562 cells that express the human transferrin receptor but not toward a nonhuman derived cell
line. Since human ribonucleases coupled to antibodies also exhibited receptor mediated toxicities, a new approach to selective
cell killing is provided. This may allow the development of new therapeutics for cancer treatment that exhibit less systemic
toxicity and, importantly, less immunogenicity than the currently employed ligand-toxin conjugates. 相似文献
20.
《International journal of radiation applications and instrumentation. Part B, Nuclear medicine and biology》1989,16(4):405-411
The pharmacokinetics of 131I-labeled OC 125 F(ab′)2 antibody fragment were investigated in athymic mice bearing OVCAR-3 ovarian carcinoma xenografts, a model in which the CA 125 antigen is present in serum. Nine antibody doses between 0.1 and 650 μg were studied. Optimal tumor to normal tissue ratios were obtained at 100–200 μg of F(ab′)2. At most antibody doses, the pre-injection level of circulating CA 125 appeared to influence the localization of 131I activity in tumor, liver and spleen. 相似文献