Cytotoxicity of Anti-CD64-Ricin A Chain Immunotoxin Against Human Acute Myeloid Leukemia Cells In Vitro and in SCID Mice

Zhong, Rui-kun; Winkel, Jan G. J. van de; Thepen, Theo; Schultz, Lori; Ball, ED

doi:10.1089/152581601750098318

Cited by 27 publications

(26 citation statements)

References 20 publications

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“…Additionally, based on the work of Zhong et al (22), who worked with H22 coupled to Ricin A, we could show that Gb-H22(scFv) induced apoptosis in primary CD64 + AML cells, whereas CD64 À AML cells were unaffected. However, the susceptibility of cancer cells toward a granzyme B-based immunotoxin is likely to vary between patients and cell types.…”

Section: Discussionmentioning

confidence: 83%

“…In case of the immunoconjugates targeting CD33 (8), which is a cell adhesion molecule, or receptors such as interleukin-3 receptor (5) and granulocyte-macrophage colony-stimulating factor receptor (6, 7), which are signal transduction receptors, presumably only a small portion of the administered immunotoxin becomes internalized, whereas CD64 internalizes very efficiently (36). Furthermore, the expression pattern of the receptor is limited, and normal, nonactivated CD64-expressing cells are not affected by immunoconjugates (19,22,37). Therefore, CD64 can be considered as beneficial for the targeted delivery of cytotoxic or immunomodulating drugs.…”

Section: Discussionmentioning

confidence: 99%

“…H22 and its derivatives have been used in a variety of applications including as fusion proteins with antibodies (39 -41) and toxic components such as calicheamicin (42), Pseudomonas ETA ¶ (21) and Ricin A (19,20,22,37). Both Ricin A and ETA ¶ fusions to H22 have been used as therapeutic agents against AML cells (21,22). Although both fusion proteins proved to be effective, the nonhuman fusion partners could prevent repetitive administration due to the likelihood of an undesired immune response.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, CD64 might also be an effective target in the therapy of AML. Indeed, anti-CD64 immunofusions with Ricin A as well as with Pseudomonas exotoxin A (ETA ¶) proved to be potent triggers of apoptosis in CD64 + AML cells (21,22). However, protein domains of nonhuman origin can provoke undesirable immune responses.…”

Section: Introductionmentioning

confidence: 99%

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Granzyme B-H22(scFv), a human immunotoxin targeting CD64 in acute myeloid leukemia of monocytic subtypes

Stahnke

Thepen

Stöcker³

et al. 2008

Molecular Cancer Therapeutics

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Acute myeloid leukemia (AML) cells of subtypes M4 and M5 show enhanced expression of CD64 (Fc;RI), the highaffinity receptor for IgG, which is normally expressed at high levels only on activated cells of the myeloid lineage. CD64 is therefore a prime target for the specific delivery of cytotoxic agents. A promising toxin candidate is granzyme B, a human serine protease originating from cytotoxic granules of CD8 + T lymphocytes and natural killer cells. After evaluating the sensitivity of the AML-related cell line U937 toward cytosolic granzyme B, we genetically fused granzyme B to H22, a humanized single-chain antibody fragment (scFv) specific for CD64, to obtain Gb-H22(scFv), a fusion protein lacking the immunogenic properties of nonhuman immunofusions. Gb-H22(scFv) was successfully expressed in human 293T cells, secreted, and purified from cell culture supernatants. The purified protein bound specifically to CD64 + U937 cells. Despite linkage to the binding domain, the proteolytic activity of functional Gb-H22(scFv) was identical to that of free granzyme B. Target cell-specific cytotoxicity was observed with a half-maximal inhibitory concentration (IC 50 ) between 1.7 and 17 nmol/L. In addition, the induction of apoptosis in U937 cells was confirmed by Annexin A5 staining and the detection of activated caspase-3 in the cytosol. Finally, apoptosis was observed in primary CD64 + AML cells, whereas CD64 À AML cells were unaffected. This is the first report of a completely human granzyme B-based immunotoxin directed against CD64, with activity against an AML-related cell line and primary AML cells. [Mol Cancer Ther 2008;7(9):2924 -32]

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Section: Discussionmentioning

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Granzyme B-H22(scFv), a human immunotoxin targeting CD64 in acute myeloid leukemia of monocytic subtypes

Stahnke

Thepen

Stöcker³

et al. 2008

Molecular Cancer Therapeutics

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“…The engraftment of human AML cells in the NOD/ SCID model has subsequently facilitated development of several new treatment modalities. 4,276,[374][375][376][377][378][379][380][381][382][383] Despite the obvious advantages of the NOD/SCID model over all other immunodeficient models, there are still some inherent obstacles. While various strategies, including hu-cytokine supplementation, 364,370,[384][385][386] co-transplantation of growth factor-producing cell lines or 'accessory cells' 384,385 have been evaluated, only 70% of all AML samples exhibit detectible engraftment in NOD/SCIDs.…”

Section: Nude Modelsmentioning

confidence: 99%

Animal models of acute myelogenous leukaemia – development, application and future perspectives

2005

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From the early inception of the transplant models through to contemporary genetic and xenograft models, evolution of murine leukaemic model systems have been critical to our general comprehension and treatment of cancer, and, more specifically, disease states such as acute myelogenous leukaemia (AML). However, even with modern advances in therapeutics and molecular diagnostics, the majority of AML patients die from their disease. Thus, in the absence of definitive in vitro models which precisely recapitulate the in vivo setting of human AMLs and failure of significant numbers of new drugs late in clinical trials, it is essential that murine AML models are developed to exploit more specific, targeted therapeutics. While various model systems are described and discussed in the literature from initial transplant models such as BNML and spontaneous murine leukaemia virus models, to the more definitive genetic and clinically significant NOD/SCID xenograft models, there exists no single compendium which directly assesses, reviews or compares the relevance of these models. Thus, the function of this article is to provide clinicians and experimentalists a chronological, comprehensive appraisal of all AML model systems, critical discussion on the elucidation of their roles in our understanding of AML and consideration to their efficacy in the development of AML chemotherapeutics.

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Selective elimination of synovial inflammatory macrophages in rheumatoid arthritis by an Fcγ receptor I–directed immunotoxin

Roon¹,

Vuuren²,

Wijngaarden³

et al. 2003

Arthritis & Rheumatism

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Objective. To determine whether monocyte/macrophages from rheumatoid arthritis (RA) patients can be selectively eliminated by a toxin-conjugated antibody CD64-ricin A (CD64-RiA) directed toward the highaffinity receptor for IgG (Fc␥RI), exploiting the capacity of Fc␥RI to efficiently endocytose antibody which it has bound.Methods. Mononuclear cells from peripheral blood (PB) and synovial fluid (SF) obtained from RA patients were cultured in the presence of CD64-RiA. Cell death of monocyte/macrophages was measured by phenotypic changes (light-scatter patterns and CD14 and Fc␥RI expression) and apoptosis (nuclear DNA fragmentation). We then tested whether CD64-RiAinduced cell death of macrophages affected their capacity to stimulate antigen-induced lymphocyte proliferation and to secrete cytokines. Additionally, the capacity of CD64-RiA to inhibit proinflammatory activity and cartilage degradation by RA synovial tissue explants was evaluated.Results. Inflammatory macrophages from RA SF expressed elevated levels of Fc␥RI and were selectively eliminated by CD64-RiA via apoptotic cell death.Monocyte/macrophages from RA PB, which had lower levels of Fc␥RI expression, were much less affected. Induction of SF macrophage apoptosis was associated with efficient inhibition of antigen-induced lymphocyte proliferation and a reduction in tumor necrosis factor ␣ (TNF␣) release. Consistent with these effects on SF macrophages, CD64-RiA also inhibited TNF␣ production, interleukin-1␤ production, and cartilagedegrading activity of RA synovial tissue explants.Conclusion. Together, these data underscore the crucial role of synovial macrophages in RA joint inflammation and indicate that selective elimination of these cells through Fc␥RI-directed immunotoxins could be a novel approach to the treatment of RA.

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Cytotoxicity of Anti-CD64-Ricin A Chain Immunotoxin Against Human Acute Myeloid Leukemia Cells In Vitro and in SCID Mice

Cited by 27 publications

References 20 publications

Granzyme B-H22(scFv), a human immunotoxin targeting CD64 in acute myeloid leukemia of monocytic subtypes

Granzyme B-H22(scFv), a human immunotoxin targeting CD64 in acute myeloid leukemia of monocytic subtypes

Animal models of acute myelogenous leukaemia – development, application and future perspectives

Selective elimination of synovial inflammatory macrophages in rheumatoid arthritis by an Fcγ receptor I–directed immunotoxin

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