Immunotoxins

Frankel, Arthur E.; Kreitman, Robert J.; Pastan, Ira; Murphy, John R.

doi:10.1007/978-94-017-2757-0_11

Cited by 4 publications

(6 citation statements)

References 430 publications

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“…BL22 has been evaluated in a phase I clinical trial at the NCI, National Institutes of Health, in patients with hematological malignancies. Sixteen patients with purine analogue-resistant hairy cell leukemia (HCL) 1 were treated with BL22 and 11 (86%) achieved complete remissions (11). BL22 is the first agent that is able to induce a high complete remission rate in patients with purine analogue-resistant HCL and confirms the concept that immunotoxins can produce clinical benefit to patients with advanced malignancies.…”

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confidence: 61%

“…Immunotoxins are composed of antibodies or their Fv biochemically or genetically linked to toxins, toxin subunits, or ribosome-inactivating proteins from bacteria, plants, or fungi (reviewed in Refs. [1][2][3]. The antibody portion binds to the antigen expressed on the target cell, and the toxin is internalized and causes cell death by arresting protein synthesis and inducing apoptosis.…”

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confidence: 99%

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In Vitro Antibody Evolution Targeting Germline Hot Spots to Increase Activity of an Anti-CD22 Immunotoxin

Kreitman

Onda

et al. 2005

Journal of Biological Chemistry

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102

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Recombinant immunotoxin BL22, containing the Fv portion of an anti-CD22 antibody, produced complete remissions in most patients with drug-resistant hairy cell leukemia but had less activity in leukemias with low CD22 expression. Complementarity-determining region (CDR) mutagenesis is used to increase antibody affinity but can be difficult to perform successfully. We previously showed that antibodies with increased affinity and immunotoxins with increased activity could be obtained by directing mutations at specific DNA residues called hot spots. Because hot spots can arise either by somatic mutation or be present in the germline, we examined which type of hot spot is preferred for increasing antibody affinity. Initially, a second generation antibody phage-display library targeting a germline hot spot (Ser 30 -Asn 31 ) within CDR1 of the antibody light chain was mutated. Substitution of serine 30 or asparagine 31 with arginine produced mutant immunotoxins with an affinity (0.8 nM) increased 7-fold over BL22 (5.8 nM) and 3-fold over the first generation mutant HA22 (2.3 nM). More importantly, a 10-fold increase in activity over BL22 and a 2-3-fold increase over HA22 were observed in various B lymphoma cell lines including WSU-CLL that contains only 5500 CD22 sites per cell. For comparison, two phage-display libraries targeting non-germline hot spots in heavy chain CDR1 and CDR3 were generated but did not produce Fv with increased affinity. Our results demonstrate that germline hot spots but not non-germline hot spots are effective for in vitro antibody affinity maturation.

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confidence: 61%

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confidence: 99%

In Vitro Antibody Evolution Targeting Germline Hot Spots to Increase Activity of an Anti-CD22 Immunotoxin

Kreitman

Onda

et al. 2005

Journal of Biological Chemistry

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102

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“…The toxins are also used as components in targeted drug treatment, for instance in cancer therapy. Since the toxins block protein synthesis very efficiently (about 2000 ribosomes are destroyed per minute after entry of one ricin molecule), directing toxins to cells for selective destruction is being tried, and promising clinical trials are being performed [11,12]. Also, a number of the protein toxins have been used as vectors to bring into cells proteins or epitopes that are then presented at the cell surface by MHC class I [13–17].…”

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confidence: 99%

Transport of protein toxins into cells: pathways used by ricin, cholera toxin and Shiga toxin

2002

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Ricin, cholera, and Shiga toxin belong to a family of protein toxins that enter the cytosol to exert their action. Since all three toxins are routed from the cell surface through the Golgi apparatus and to the endoplasmic reticulum (ER) before translocation to the cytosol, the toxins are used to study di¡er-ent endocytic pathways as well as the retrograde transport to the Golgi and the ER. The toxins can also be used as vectors to carry other proteins into the cells. Studies with protein toxins reveal that there are more pathways along the plasma membrane to ER route than originally believed. ß 2002 Published by Elsevier Science B.V. on behalf of the Federation of European Biochemical Societies.

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“…Among the many advances in the development of HER2-targeted cancer therapy over the past decade (4 -7), antibody-based strategies (e.g. herceptin (trastuzumab) (8 -10), intracellular antibody (11,12), and fusion proteins for targeted delivery of various classes of therapeutic agents (13)(14)(15)(16)(17)) are especially notable. Our previous studies exploited the in vitro and in vivo cytotoxicity of immunotoxins by generating a new class of antigen-specific killer cells (18,19), but this approach may well be limited in its clinical applications because of antigenicity of heterogeneous toxin protein.…”

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Secreted Antibody/Granzyme B Fusion Protein Stimulates Selective Killing of HER2-overexpressing Tumor Cells

Zhao

Zhang

Jia

et al. 2004

Journal of Biological Chemistry

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HER2/ErbB2, an epidermal growth factor receptor-related tyrosine kinase, is overexpressed on the surface of a variety of tumors of epithelial origin, such as breast tumors, ovarian carcinomas, and gastric tumors, and therefore constitutes an ideal therapeutic target (1-3). Among the many advances in the development of HER2-targeted cancer therapy over the past decade (4 -7), antibody-based strategies (e.g. herceptin (trastuzumab) (8 -10), intracellular antibody (11, 12), and fusion proteins for targeted delivery of various classes of therapeutic agents (13-17)) are especially notable. Our previous studies exploited the in vitro and in vivo cytotoxicity of immunotoxins by generating a new class of antigen-specific killer cells (18,19), but this approach may well be limited in its clinical applications because of antigenicity of heterogeneous toxin protein. Hence, our attention turned to human endogenous proteins, especially those acting as executioners during apoptosis, which in principle should be optimal candidates for triggering the death of tumor cells in an intrinsic physiological manner.Granzymes are a family of granular serine proteinases produced by cytotoxic T lymphocytes and natural killer cells, with a triad of key residues, histidine, aspartate, and serine, conserved at the catalytic site (20, 21). One member of the family, granzyme B (GrB), 1 plays an essential role in granule-mediated killing. GrB is originally synthesized as zymogen and activated by removal of the amino-terminal signal peptide and an acidic dipeptide after lymphocyte receptor recognition (21). The active GrB (GrBa) is then released from leukocyte granules by exocytosis, entering target cells to cause extensive proteolysis at specific amino acid residues (22, 23). GrB-mediated apoptosis involves the caspase-dependent pathway, direct nuclear entry, and caspase-independent pathways (24 -28). The potential of GrB therapy to induce multiple apoptotic pathways makes this approach to tumor cell killing especially attractive.In our most recent previous study, chimeric immunocasp-3 protein was shown to have a potent selective antitumor effect both in vitro and in vivo (29). This result led us to another targeted pro-apoptotic fusion protein, designated immunoGrB, which consisted of a single-chain anti-HER2 antibody, e23sFv (30, 31), a Pseudomonas exotoxin A (PE) translocation domain (32-35), and active GrB (GrBa) (21). The recombinant immunoGrB molecule was predicted to bind to tumor cells overexpressing HER2 and be internalized, such that endosomal cleavage would give rise to the active granzyme B domain that would consequently translocate into the cytosol to induce tumor cell death (18,19,29). Here we evaluate the antitumor activity of immunoGrB and immunoGrB-secreting lymphocytes in both in vitro and in vivo models. EXPERIMENTAL PROCEDURESConstruction of Expression Plasmids-The human GrB gene was obtained by reverse-transcription PCR from total RNA derived from healthy human peripheral blood mononuclear cells (PBMCs) following stimulatio...

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Immunotoxins

Cited by 4 publications

References 430 publications

In Vitro Antibody Evolution Targeting Germline Hot Spots to Increase Activity of an Anti-CD22 Immunotoxin

In Vitro Antibody Evolution Targeting Germline Hot Spots to Increase Activity of an Anti-CD22 Immunotoxin

Transport of protein toxins into cells: pathways used by ricin, cholera toxin and Shiga toxin

Secreted Antibody/Granzyme B Fusion Protein Stimulates Selective Killing of HER2-overexpressing Tumor Cells

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