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1 Metabolism Branch and 2 Radiation Oncology Branch, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland; 3 Nuclear Medicine Department, Clinical Center, National Institutes of Health, Bethesda, Maryland; and 4 Laboratory of Molecular Genetics and Immunology, The Rockefeller University, New York, New York
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ABSTRACT |
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 Top ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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chain knockout (FcR–/–) mice. The ATL model was established by i.p. injection of human ATL cells (MET-1) into SCID/NOD wild-type or SCID/NOD FcR–/– mice. HAT, MAT, and 7G7/B6 were given to the leukemia-bearing mice at a dose of 100 µg weekly for 4 weeks. The three antibodies inhibited the leukemia growth significantly in SCID/NOD wild-type mice, as monitored by serum levels of human ß2-microglobulin (P < 0.01), and prolonged survival of the leukemia-bearing SCID/NOD wild-type mice (P < 0.01) as compared with the control group. However, none of the antibodies manifested efficacy on the leukemia growth and survival of the SCID/NOD FcR–/– mice bearing MET-1 leukemia. In a pharmacokinetics study, the blood concentrations of the radiolabeled antibodies decreased with time similarly in SCID/NOD wild-type and SCID/NOD FcR–/– mice. Although NK cells may play a role in humans, in this murine model FcR receptors on non-NK cells, such as polymorphonuclear leukocytes or monocytes, are required for the tumor-killing action of the antibodies directed toward CD25. |
INTRODUCTION |
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TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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, on their cell surfaces (2, 3, 4)
. There presently is no accepted curative therapy for ATL, and patients progress to death with a median survival duration of 9 months for those with acute ATL and 24 months for those with chronic ATL (1)
.
The observation that IL-2R is not expressed by normal resting cells, but is expressed by ATL and some other malignant cells, provided the rationale for the use of monoclonal antibodies directed toward IL-2R (5)
. A preclinical in vivo murine model of ATL was developed by introducing leukemic cells (MET-1) from an ATL patient into nonobese diabetic/severe combined immunodeficient (SCID/NOD) mice that lack effective T and natural killer (NK) cells (6)
, and new therapeutic approaches have been tested in this model before initiating clinical trials (6, 7, 8, 9, 10, 11)
. In initial studies, antibodies to IL-2R, including humanized anti-Tac (HAT), murine anti-Tac (MAT), and 7G7/B6, inhibited the progression of the leukemia and prolonged the survival of the leukemia-bearing mice (6)
. Furthermore, some partial and rare complete remissions were obtained in patients with ATL treated in clinical trails with HAT, MAT, and these intact antibodies armed with 90Y used in an effort to develop yet more effective IL-2R-directed agents (12
, 13)
. However, the mechanism underlying the tumor-killing action mediated by the unmodified antibodies directed toward CD25 remains unclear. Several mechanisms theoretically could be involved in the action of anti-IL-2R in the MET-1 ATL model. These include the blockade of IL-2 interaction with its growth factor receptor IL-2R with consequent cytokine deprivation mediated cell death, complement-dependent cytotoxicity, and antibody-dependent cellular cytotoxicity. Because there were no IL-2 mRNA expression and IL-2 production by the MET-1 leukemic cells (6)
and because 7G7/B6 did not block the IL-2 binding site on the IL-2R (14)
, the prevailing view of a sole mechanism for anti-IL-2R action that is the blockade of the interaction of IL-2 with its receptor was not supported. We also have presented evidence that excluded complement-dependent cytotoxicity (6)
. Classical antibody-dependent cellular cytotoxicity mediated by NK cells that may be important in immunologically intact humans also does not appear to be a likely mode of action in this model because the SCID/NOD mice used as the recipients of the ATL in our study virtually lacked functional NK cells. Nevertheless, we showed that the F(ab')2 fragment of HAT in contrast to intact antibody was not effective in this model (6)
. Because the F(ab')2 fragment of HAT lacks the Fc segment that is required for complement-dependent cytotoxicity and other Fc-mediated cytotoxicity, we considered the possibility that Fc-dependent antibody-mediated cytotoxicity involving FcRI- or FcRIII-expressing cells, such as monocytes or polymorphonuclear leukocytes, was a potential mechanism of action of these anti-CD25 antibodies in this model and, by inference, that FcRIII-mediated killing might play a role in the therapeutic efficacy observed in the IL-2-independent phase of ATL patients. To address this hypothesis, we evaluated the therapeutic efficacy of HAT, MAT, and 7G7/B6 in our ATL model in SCID/NOD wild-type and SCID/NOD Fc receptor common chain knockout (FcR–/–) mice. We showed that the three antibodies evaluated in this study had therapeutic efficacy on the MET-1 leukemia in SCID/NOD wild-type mice, whereas this efficacy was lost in SCID/NOD FcR–/– mice, indicating that the expression of the Fc receptors FcRI and FcRIII that involve the Fc chain is required for the effective action of the antibodies directed toward CD25 in vivo.
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MATERIALS AND METHODS |
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TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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. 7G7/B6 is a mouse IgG2a directed toward an epitope of the IL-2R peptide other than that identified by anti-Tac (14)
. The 7G7/B6 was purified from supernatants of a hybridoma (American Type Culture Collection, Manassas, VA) using ImmunoPure Protein A columns (Pierce, Rockford, IL).
Mouse Model of ATL.
SCID/NOD mice were purchased from The Jackson Laboratory (Bar Harbor, ME), and SCID/NOD FcR–/– mice were generated in the laboratory of Jeffrey Ravetch (Rockefeller University, New York, NY). The ATL cell population, MET-1, was established from the peripheral blood of a patient with acute ATL, and the leukemic cells were maintained by serial transfer in SCID/NOD mice. MET-1 cells have a distinct phenotype elucidated by fluorescence-activated cell sorter analysis: CD3 dim, CD4 positive/negative, CD7, CD20 negative, and CD25 positive. The ATL model was established by i.p. injection of 1.5 x 107 MET-1 cells into SCID/NOD wild-type or SCID/NOD FcR–/– mice as described previously (6
, 8)
. The therapy experiment was performed on the ATL-bearing mice when their serum-soluble IL-2R (sIL-2R) levels were >1000 pg/ml, which occurs 
10–14 days after tumor inoculation. All of the animal experiments were performed in accordance with NIH Animal Care and Use Committee guidelines.
Therapy Study.
Therapeutic studies were performed in MET-1 leukemia-bearing SCID/NOD wild-type and SCID/NOD FcR–/– mice. The leukemia-bearing mice were randomly assigned to groups that had comparable levels of the surrogate tumor marker, sIL-2R (Fig. 1A)
. Groups of 15 mice were injected i.v. with 100 µg of HAT, MAT, or 7G7/B6 or with 200 µl of PBS weekly for 4 weeks. An additional group received 100 µg of HAT and 100 µg of 7G7/B6 weekly for 4 weeks. Throughout the experiment, tumor progression was monitored by serum levels of soluble ß2-microglobulin (ß2µ), a surrogate tumor marker, and by Kaplan-Meier analysis of the survival of the mice.
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and/or soluble human ß2µ were performed using ELISA. ß2µ, which was used as a surrogate tumor marker, was measured after therapy to monitor the growth of the leukemia. The ELISA kits were purchased from R&D System (soluble Tac, catalogue no. DR2A00; soluble ß2µ, catalogue no. DBM200; Minneapolis, MN). The ELISAs were performed as indicated in the manufacturer’s kit inserts.
Radiolabeling and Radioimmunoreactivity of Antibodies.
HAT, MAT, and 7G7/B6 were labeled with 125I at specific activities of 74–111 kBq/µg by using the chloramine-T method. Kit225IG3, a leukemic T-cell line that expresses CD25 on the cell surface, was maintained in RPMI 1640 containing 10% heat-inactivated fetal bovine serum, 100 units/ml penicillin, and 100 µg/ml streptomycin in an atmosphere containing 5% CO2. Immunoreactivity of 125I-HAT and 125I-7G7/B6 was evaluated as described previously (16)
. Briefly, 125I-HAT or 125I-7G7/B6 (5 ng/100 µl) was incubated with an increasing number of Kit225IG3 cells (1 x 104–1 x 107) with or without unlabeled HAT or 7G7 (25 µg/tube) inhibition at 4°C for 1 h. After centrifugation, the supernatant was aspirated, and the radioactivity bound to the cells was counted in a gamma counter.
Pharmacokinetics of HAT, MAT, and 7G7/B6.
To define the clearance rate of infused antibodies from the blood in SCID/NOD wild-type and SCID/NOD FcR–/– mice, 100 µg (the same dose as that used in the therapeutic study) of 125I-labeled HAT, MAT, or 7G7 were injected into SCID/NOD wild-type or SCID/NOD FcR–/– mice (n = 5). Serial blood samples were taken at different time points after injection and counted in a gamma counter. To determine the area under the curve (AUC), the percentage of the injected dose per gram of blood (%ID/g) was calculated and integrated using the trapezoidal rule method (GraphPad Prism version 4p; GraphPad Software, San Diego, CA.).
Statistical Analysis.
The serum levels of ß2µ at different time points for the different treatment groups and AUCs of each antibody between SCID/NOD wild-type and SCID/NOD FcR–/– mice groups were analyzed using the Student’s t test for unpaired data. Statistical significance of differences in survival of the mice in different treatment groups was determined by the log-rank test using StatView program (Abacus Concepts Inc., Berkeley, CA).
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RESULTS |
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TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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–/– mice. In the therapeutic study, the HAT, MAT, and 7G7/B6 monoclonal antibodies, all of which are directed toward the IL-2R on the leukemic cells, were injected i.v. weekly for 4 weeks at a dose of 100 µg in 200 µl. All of the antibodies manifested therapeutic efficacy in SCID/NOD wild-type mice bearing MET-1 leukemia as shown by their effects on the serum levels of ß2µ, a surrogate tumor marker that was indicative of the tumor load of ATL in the murine model (Fig. 1B)
, and by the survival of the mice (Fig. 2A)
. When compared with the serum concentration of ß2µ in the control group on days 14 and 25 after therapy, there was a significant reduction of the ß2µ levels in the HAT, MAT, and 7G7/B6 treatment groups (P < 0.0001; Fig. 1B
). Furthermore, there was a significant prolongation of survival of the mice in all of the antibody treatment groups when compared with that in the control group (P < 0.01; Fig. 2A
). The mean survival duration of the control group was 27 days, whereas it was extended to 49 days in the HAT group, 47 days in the MAT group, and >64 days in the 7G7/B6 group (Fig. 2A)
. All of the mice in the control group had died by day 31 after therapy, whereas 14 of 15 of the HAT-treated and all of the MAT- and 7G7/B6-treated mice were alive at that time. In contrast, all of the antibodies used administered at the same dosing schedule as that in MET-1-bearing SCID/NOD wild-type mice did not show any therapeutic efficacy in SCID/NOD FcR–/– mice that were bearing the same quantity of MET-1 leukemic cells (Fig. 1A)
as seen by the demonstration that there were no differences in the serum levels of the surrogate marker, ß2µ (Fig. 1C)
, and no difference in the survival of the leukemia-bearing mice (Fig. 2B)
when compared with the control group.
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. The combination of these two antibodies for the management of ATL theoretically could manifest additive or synergistic efficacy. However, in this study, administration of 100 µg of HAT and 100 µg of 7G7/B6 weekly for 4 weeks did not show more benefit than that of 100 µg of 7G7/B6 alone for the treatment of MET-1-bearing SCID/NOD wild-type mice as seen by the observation that there were no differences in the serum levels of ß2µ (Fig. 1B)
and no difference in the survival of the mice between the 7G7/B6 and combination therapy groups (Fig. 2A)
.
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–/– mice, we performed a pharmacokinetics experiment with 125I-labeled HAT, MAT, and 7G7/B6 in SCID/NOD wild-type and SCID/NOD FcR–/– mice. The blood clearance rates for each of the three antibodies evaluated in this study were similar in SCID/NOD wild-type and SCID/NOD FcR–/– mice (Fig. 4)
. The AUCs of the various 125I-radiolabeled antibodies administered at a dose of 100 µg were 2120 versus 1997%IDh/g for 125I-HAT, 1598 versus 1651%IDh/g for 125I-MAT, and 1085 versus 1227%IDh/g for 125I-7G7/B6, respectively, for SCID/NOD wild-type versus SCID/NOD FcR–/– mice. There was no difference in AUC for each antibody between SCID/NOD wild-type and SCID/NOD FcR–/– mice (Fig. 4
; P > 0.1). These results excluded the possibility of an exceptionally short survival of the monoclonal antibodies in SCID/NOD FcR–/– mice as the explanation for the failure to eliminate the tumor.
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DISCUSSION |
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TopABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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) with HAT, MAT, and 7G7/B6 monoclonal antibodies. The scientific basis for this strategy is that IL-2R is not expressed by the majority of normal resting cells of the body but is expressed by malignant cells in select patients with ATL, cutaneous T-cell lymphoma, hairy cell B-cell leukemia, and Hodgkin’s disease (5)
. In a clinical trial, 6 of 19 patients with ATL treated with the unmodified MAT developed a partial or complete remission lasting from 1 month to >11 years (13)
. In our laboratory, a preclinical in vivo murine model of ATL (MET-1) was developed to test new therapeutic agents and to define their mode of action before initiating patient trials (6, 7, 8, 9, 10, 11)
. In initial studies, antibodies to IL-2R, including HAT, MAT, and 7G7/B6, inhibited the progression of leukemia and prolonged the survival of the mice (6)
. The present study was designed to define the mode of action of the anti-CD25 monoclonal antibodies in this model. Several mechanisms theoretically could be involved in the action of anti-IL-2R in the MET-1 ATL model. These include blockade of the interaction of IL-2 with its growth factor receptor IL-2R with the consequent cytokine deprivation-mediated cell death. This may be a major mode of action in patients with ATL because the majority of such patients responding to unmodified anti-CD25 antibodies manifest an autocrine IL-2/IL-2R self-stimulatory loop. However, this mechanism does not provide an adequate explanation for the response of patients who are no longer in the IL-2-dependent phase of their leukemia and whose malignant cells no longer express IL-2 mRNA. Furthermore, cytokine deprivation does not represent an explanation for the efficacy in the MET-1 ATL model because the MET-1 leukemic cells do not express IL-2 mRNA and do not respond to murine IL-2 (6)
. The therapeutically effective 7G7/B6 monoclonal antibody also does not bind to the IL-2 binding site of IL-2R and thus does not block IL-2 interaction with its receptor (14)
. Although antibody-dependent cellular cytotoxicity mediated by NK cells may dominate in humans, such classical antibody-dependent cellular cytotoxicity mediated by NK cells also does not appear to be the mode of action of the monoclonal antibodies in this model because the SCID/NOD mice used in our study lack T and functional NK cells. Nevertheless, the antibodies appear to act through an FcR-dependent antibody-mediated mechanism. That is, although the three antibodies used showed significant inhibition of the MET-1 ATL growth in SCID/NOD wild-type mice, they showed no efficacy on the leukemia growth or animal survival in the ATL-bearing SCID/NOD FcR–/– mice. The lack of efficacy in the ATL-bearing SCID/NOD FcR–/– mice indicates that the expression of the receptor FcRIII that requires the FcR chain probably is required for effective action of these antibodies directed toward CD25 in this in vivo model of ATL. This efficacy may represent a form of antibody-dependent cellular cytotoxicity requiring FcR receptors that are expressed on other cells, such as polymorphonuclear leukocytes and monocytes. Alternatively, the multimerization of the antibodies presented by the FcR on such cells may lead to aggregation of IL-2R with consequent IL-2R-mediated apoptotic cell death. In this regard, it should be noted that activation-induced cell death, a form of T-cell lymphocyte suicide, has as a required element the interaction of IL-2 with its private IL-2R receptor, the target of the CD25-directed antibodies used in this study. IL-2R-deficient mice do not manifest activation-induced cell death (20)
.
FcRIII has been shown to be required for the action of an array of monoclonal antibodies in murine models of malignancy, including melanoma treated with antimelanoma monoclonal antibodies (21
, 22) , HER-2/neu-expressing breast tumors treated with trastuzumab (22)
, CD20-expressing B-cell lymphomas treated with rituximab (22)
, CD2-expressing T-cell malignancy, MET-1 treated with the anti-CD2 monoclonal antibody MEDI-507 (10)
, and CD52-expressing MET-1 leukemia treated with the anti-CD52 monoclonal antibody Campath-1 (11)
. However, the anti-CD30 monoclonal antibody Hefi-1 was effective in the karpas299 model of anaplastic large-cell lymphoma in SCID/NOD FcR–/– mice, suggesting in this case a direct apoptotic-inducing action of the anti-CD30 monoclonal antibody.5
The demonstration that Fc receptors presumably on granulocytes and monocytes is required for the action of the anti-CD25 antibodies examined in this study suggests that for their effective action there must be a proximity of FcR-expressing mononuclear cells to the leukemic cells, a requirement that may not be accomplished in patients with lymphomas, including ATL lymphoma.
An effort has been made to obtain synergistic improvement in the therapeutic efficacy in the MET-1 ATL murine model by combining two effective therapeutic agents (7, 8, 9)
. However, the simultaneous addition of two distinct monoclonal antibodies that require FcR expression yielded no additive effect. In particular, we saw no meaningful increased efficacy by the simultaneous administration of two distinct antibodies to CD25 in the present study or one to CD25 and a second to CD2 (10)
or one to CD25 and a second to CD52 (11)
in our previous trials. This suggests that the simultaneous administration of two antibodies that share a mode of action requiring FcR expression on effector cells does not increase the efficacy beyond that provided by saturating concentrations of a single monoclonal antibody. This observation contrasts with the synergistic efficacy observed when HAT was used in this model in concert with radioimmunotherapy or chemotherapeutic agents that have a distinct mode of action (7)
. This observation parallels those with trastuzumab and rituximab that provide additive or synergistic effects when combined with appropriate chemotherapeutic agents that have a markedly different mode of action from those of the monoclonal antibodies (23
, 24)
.
In conclusion, FcR receptors on polymorphonuclear leukocytes and monocytes are required for the cytocidal action of the three antibodies used that were directed toward CD25 in the MET-1 model of ATL. HAT is already in clinical trial for the treatment of patients with ATL or with other T-cell malignancies. The results of the present study and those previously performed with this model support the use of a combination regimen in a clinical trial involving patients with ATL using HAT in concert with effective chemotherapeutic agents or with other therapeutic approaches that have a different mode of action, such as radioimmunotherapy with monoclonal antibodies armed with radionuclides.
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FOOTNOTES |
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Requests for reprints: Thomas A. Waldmann, Metabolism Branch, NCI, NIH, Building 10, Room 4N115, 10 Center Drive, Bethesda, MD 20892-1374. Phone: 301-496-6656; Fax: 301-496-9956; E-mail: tawald{at}helix.nih.gov
Received 3/26/04. Revised 5/24/04. Accepted 6/10/04.
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REFERENCES |
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-directed monoclonal antibodies provide effective therapy in a murine model of adult T-cell leukemia by a mechanism other than blockade of IL-2/IL-2R interaction. Cancer Res, 60: 6977-84, 2000.-emitting radionuclide, bismuth 213. Blood, 100: 208-16, 2002.-expressing adult T-cell leukemia with yttrium-90-labeled anti-Tac. Blood, 86: 4063-75, 1995. chain regulates the size and content of the peripheral lymphoid compartment. Immunity, 3: 521-30, 1995.[CrossRef][Medline]
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