The Experts below are selected from a list of 198 Experts worldwide ranked by ideXlab platform
Glenn D Prestwich - One of the best experts on this subject based on the ideXlab platform.
-
in situ crosslinkable hyaluronan hydrogels for tissue engineering
Biomaterials, 2004Co-Authors: Xiao Zheng Shu, Fabio Salvatore Palumbo, Yanchun Liu, Yi Luo, Glenn D PrestwichAbstract:We describe the development of an injectable, cell-containing hydrogel that supports cell proliferation and growth to permit in vivo engineering of new tissues. Two thiolated hyaluronan (HA) Derivatives were coupled to four alpha,beta-unsaturated ester and amide Derivatives of poly(ethylene glycol) (PEG) 3400. The relative chemical reactivity with cysteine decreased in the order PEG-diacrylate (PEGDA)>>PEG-dimethacrylate>PEG-diacrylamide>PEG-dimethacrylamide. The 3-thiopropanoyl Hydrazide Derivative (HA-DTPH) was more reactive than the 4-thiobutanoyl Hydrazide, HA-DTBH. The crosslinking of HA-DTPH with PEGDA in a molar ratio of 2:1 occurred in approximately 9 min, suitable for an in situ crosslinking applications. The in vitro cytocompatibility and in vivo biocompatibility were evaluated using T31 human tracheal scar fibroblasts, which were suspended in medium in HA-DTPH prior to addition of the PEGDA solution. The majority of cells survived crosslinking and the cell density increased tenfold during the 4-week culture period in vitro. Cell-loaded hydrogels were also implanted subcutaneously in the flanks of nude mice, and after immunohistochemistry showed that the encapsulated cells retained the fibroblast phenotype and secreted extracellular matrix in vivo. These results confirm the potential utility of the HA-DTPH-PEGDA hydrogel as an in situ crosslinkable, injectable material for tissue engineering.
-
in situ crosslinkable hyaluronan hydrogels for tissue engineering
Biomaterials, 2004Co-Authors: Fabio Salvatore Palumbo, Glenn D PrestwichAbstract:Abstract We describe the development of an injectable, cell-containing hydrogel that supports cell proliferation and growth to permit in vivo engineering of new tissues. Two thiolated hyaluronan (HA) Derivatives were coupled to four α,β-unsaturated ester and amide Derivatives of poly(ethylene glycol) (PEG) 3400. The relative chemical reactivity with cysteine decreased in the order PEG-diacrylate (PEGDA)⪢PEG-dimethacrylate>PEG-diacrylamide>PEG-dimethacrylamide. The 3-thiopropanoyl Hydrazide Derivative (HA-DTPH) was more reactive than the 4-thiobutanoyl Hydrazide, HA-DTBH. The crosslinking of HA-DTPH with PEGDA in a molar ratio of 2:1 occurred in approximately 9 min, suitable for an in situ crosslinking applications. The in vitro cytocompatibility and in vivo biocompatibility were evaluated using T31 human tracheal scar fibroblasts, which were suspended in medium in HA-DTPH prior to addition of the PEGDA solution. The majority of cells survived crosslinking and the cell density increased tenfold during the 4-week culture period in vitro. Cell-loaded hydrogels were also implanted subcutaneously in the flanks of nude mice, and after immunohistochemistry showed that the encapsulated cells retained the fibroblast phenotype and secreted extracellular matrix in vivo. These results confirm the potential utility of the HA-DTPH-PEGDA hydrogel as an in situ crosslinkable, injectable material for tissue engineering.
-
hyaluronic acid n hydroxysuccinimide a useful intermediate for bioconjugation
Bioconjugate Chemistry, 2001Co-Authors: Glenn D PrestwichAbstract:Hyaluronic acid (HA) is an abundant nonsulfated glycosaminoglycan component of synovial fluid and the extracellular matrix. HA is an important building block for biocompatible and biointeractive materials with applications in drug delivery, tissue engineering, wound repair, and viscosupplementation. Herein we describe the synthesis and characterization of HA-N-succinimide, an activated ester of the glucuronic acid moiety. This HA-active ester intermediate is a precursor for fluorescent probes, drug−polymer conjugates, and cross-linked hydrogels. As a demonstration, we used HA-NHS to prepare HA-BODIPY by coupling with the Hydrazide Derivative of the fluor. Intracellular uptake of HA-BODIPY into human ovarian cancer cells, which overexpress cell-surface HA receptors, was visualized using confocal microscopy.
Philip R Hamann - One of the best experts on this subject based on the ideXlab platform.
-
an anti muc1 antibody calicheamicin conjugate for treatment of solid tumors choice of linker and overcoming drug resistance
Bioconjugate Chemistry, 2005Co-Authors: Philip R Hamann, Lois M Hinman, Ana T Menendez, Frederick E Durr, Delores Lindh, Carl Beyer, Lee M Greenberger, Rosalyn Wallace, Janis UpeslacisAbstract:The anti-MUC1 antibody, CTM01, has been chosen to target the potently cytotoxic calicheamicin antitumor antibiotics to solid tumors of epithelial origin that express this antigen. Earlier calicheamicin conjugates relied on the attachment of a Hydrazide Derivative to the oxidized carbohydrates that occur naturally on antibodies. This produced a “carbohydrate conjugate” capable of releasing active drug by hydrolysis in the lysosomes where the pH is low. Conjugates have now been made that are formed by reacting a calicheamicin Derivative containing an activated ester with the lysines of antibodies. This gives an “amide conjugate” that is stable to hydrolysis, leaving the disulfide that is present in all calicheamicin conjugates as the only likely site of drug release from the conjugate. As previously shown for the carbohydrate conjugate, this amide conjugate of CTM01 produces complete regressions of xenograft tumors at doses of 300 μg/kg (calicheamicin equivalents) given three times. This indicates that hydr...
-
an anti cd33 antibody calicheamicin conjugate for treatment of acute myeloid leukemia choice of linker
Bioconjugate Chemistry, 2002Co-Authors: Philip R Hamann, Lois M Hinman, Janis Upeslacis, Carl F Beyer, Delores Lindh, David A Flowers, Irwin D. BernsteinAbstract:The anti-CD33 antibody, P67.6, has been chosen to target the potently cytotoxic calicheamicin antitumor antibiotics to acute myeloid leukemia (AML) due to the presence of CD33 on >80% of patient samples and its lack of expression outside the myeloid cell lineages, especially its lack of expression on pluripotent stem cells. Previous calicheamicin conjugates relied on the attachment of a Hydrazide Derivative to the oxidized carbohydrates that occur naturally on antibodies. This results in a “carbohydrate conjugate” capable of releasing active drug by hydrolysis of a hydrazone bond in the lysozomes where the pH is low. Conjugates have now been made that are formed by reacting a calicheamicin Derivative containing an activated ester with the lysines of antibodies. This results in an “amide conjugate” that is stable to hydrolysis, leaving the disulfide that is present in all calicheamicin conjugates as the likely site of drug release from the conjugate. In this article, these two classes of calicheamicin−anti...
-
gemtuzumab ozogamicin a potent and selective anti cd33 antibody calicheamicin conjugate for treatment of acute myeloid leukemia
Bioconjugate Chemistry, 2002Co-Authors: Philip R Hamann, Ryan Holcomb, Lois M Hinman, Janis Upeslacis, Irwin Hollander, Carl F Beyer, Delores Lindh, William Hallett, Hwei Ru Tsou, Dan ShochatAbstract:CD33 is expressed by acute myeloid leukemia (AML) cells in >80% of patients but not by normal hematopoietic stem cells, suggesting that elimination of CD33+ cells may be therapeutically beneficial. A conjugate of a calicheamicin Hydrazide Derivative attached via hydrazone formation to the oxidized carbohydrates of the anti-CD33 murine antibody P67.6 had been chosen for use in AML prior to humanization of this antibody. However, the CDR-grafted humanized P67.6 could not be used to make the carbohydrate conjugate because of the unexpected sensitivity of this antibody to periodate oxidation. Exploration of a series of bifunctional linkers resulted in a new class of calicheamicin conjugates, termed the hybrid conjugates, that allows for the attachment of the calicheamicin to lysines but incorporates the site of hydrolytic release, a hydrazone, previously shown to be required for activity. The optimized conjugate chosen for clinical trials, gemtuzumab ozogamicin (“gem-ozo”, Mylotarg, formerly designated CMA-67...
-
gemtuzumab ozogamicin a potent and selective anti cd33 antibody calicheamicin conjugate for treatment of acute myeloid leukemia
Bioconjugate Chemistry, 2002Co-Authors: Philip R Hamann, Ryan Holcomb, Lois M Hinman, Janis Upeslacis, Irwin Hollander, Carl F Beyer, Delores Lindh, William Hallett, Hwei Ru Tsou, Dan ShochatAbstract:CD33 is expressed by acute myeloid leukemia (AML) cells in >80% of patients but not by normal hematopoietic stem cells, suggesting that elimination of CD33(+) cells may be therapeutically beneficial. A conjugate of a calicheamicin Hydrazide Derivative attached via hydrazone formation to the oxidized carbohydrates of the anti-CD33 murine antibody P67.6 had been chosen for use in AML prior to humanization of this antibody. However, the CDR-grafted humanized P67.6 could not be used to make the carbohydrate conjugate because of the unexpected sensitivity of this antibody to periodate oxidation. Exploration of a series of bifunctional linkers resulted in a new class of calicheamicin conjugates, termed the hybrid conjugates, that allows for the attachment of the calicheamicin to lysines but incorporates the site of hydrolytic release, a hydrazone, previously shown to be required for activity. The optimized conjugate chosen for clinical trials, gemtuzumab ozogamicin ("gem-ozo", Mylotarg, formerly designated CMA-676), was significantly more potent and selective than the carbohydrate conjugate it replaced. It was selectively cytotoxic to HL-60 leukemia cells in tissue culture with an IC(50) in the low to sub-pg cal/mL range (cal = calicheamicin equivalents). Doses of gem-ozo as low as 50 microg cal/kg given three times to mice bearing HL-60 xenografts routinely resulted in long-term, tumor-free survivors, while a nonbinding control conjugate was relatively inactive. Gem-ozo at a concentration of 2 to 10 ng cal/mL selectively inhibited leukemia colony formation by marrow cells from a significant proportion of AML patients. Gem-ozo has also shown significant activity against AML in Phase II trials and is the first antibody-targeted chemotherapeutic agent approved by the FDA.
-
an anti cd33 antibody calicheamicin conjugate for treatment of acute myeloid leukemia choice of linker
Bioconjugate Chemistry, 2002Co-Authors: Philip R Hamann, Lois M Hinman, Janis Upeslacis, Carl F Beyer, Delores Lindh, David A Flowers, Irwin D. BernsteinAbstract:The anti-CD33 antibody, P67.6, has been chosen to target the potently cytotoxic calicheamicin antitumor antibiotics to acute myeloid leukemia (AML) due to the presence of CD33 on >80% of patient samples and its lack of expression outside the myeloid cell lineages, especially its lack of expression on pluripotent stem cells. Previous calicheamicin conjugates relied on the attachment of a Hydrazide Derivative to the oxidized carbohydrates that occur naturally on antibodies. This results in a "carbohydrate conjugate" capable of releasing active drug by hydrolysis of a hydrazone bond in the lysozomes where the pH is low. Conjugates have now been made that are formed by reacting a calicheamicin Derivative containing an activated ester with the lysines of antibodies. This results in an "amide conjugate" that is stable to hydrolysis, leaving the disulfide that is present in all calicheamicin conjugates as the likely site of drug release from the conjugate. In this article, these two classes of calicheamicin-antibody conjugates are compared for potential use in AML with the anti-CD33 antibody P67.6. Conjugates of P67.6 are shown to require the site of hydrolytic release afforded by the carbohydrate conjugates in order to retain good potency and selectivity in vitro, in vivo, and ex vivo. The P67.6 carbohydrate conjugate of calicheamicin is selectively cytotoxic at <0.006 ng/mL of calicheamicin equivalents (cal equiv) toward HL-60 promyelocytic leukemia cells in tissue culture. Long-term, tumor-free survivors are seen in xenograft models when mice bearing HL-60 subcutaneous tumors are treated with the P67.6 carbohydrate conjugate at a dose of 300 microg/kg cal equiv given three times. This conjugate also selectively inhibits the formation of colonies from AML marrow samples at 2 ng/mL cal equiv. The P67.6 carbohydrate conjugate of calicheamicin therefore appears to have promise as an antibody-targeted chemotherapeutic agent for CD33-positive diseases such as AML.
Janis Upeslacis - One of the best experts on this subject based on the ideXlab platform.
-
an anti muc1 antibody calicheamicin conjugate for treatment of solid tumors choice of linker and overcoming drug resistance
Bioconjugate Chemistry, 2005Co-Authors: Philip R Hamann, Lois M Hinman, Ana T Menendez, Frederick E Durr, Delores Lindh, Carl Beyer, Lee M Greenberger, Rosalyn Wallace, Janis UpeslacisAbstract:The anti-MUC1 antibody, CTM01, has been chosen to target the potently cytotoxic calicheamicin antitumor antibiotics to solid tumors of epithelial origin that express this antigen. Earlier calicheamicin conjugates relied on the attachment of a Hydrazide Derivative to the oxidized carbohydrates that occur naturally on antibodies. This produced a “carbohydrate conjugate” capable of releasing active drug by hydrolysis in the lysosomes where the pH is low. Conjugates have now been made that are formed by reacting a calicheamicin Derivative containing an activated ester with the lysines of antibodies. This gives an “amide conjugate” that is stable to hydrolysis, leaving the disulfide that is present in all calicheamicin conjugates as the only likely site of drug release from the conjugate. As previously shown for the carbohydrate conjugate, this amide conjugate of CTM01 produces complete regressions of xenograft tumors at doses of 300 μg/kg (calicheamicin equivalents) given three times. This indicates that hydr...
-
an anti cd33 antibody calicheamicin conjugate for treatment of acute myeloid leukemia choice of linker
Bioconjugate Chemistry, 2002Co-Authors: Philip R Hamann, Lois M Hinman, Janis Upeslacis, Carl F Beyer, Delores Lindh, David A Flowers, Irwin D. BernsteinAbstract:The anti-CD33 antibody, P67.6, has been chosen to target the potently cytotoxic calicheamicin antitumor antibiotics to acute myeloid leukemia (AML) due to the presence of CD33 on >80% of patient samples and its lack of expression outside the myeloid cell lineages, especially its lack of expression on pluripotent stem cells. Previous calicheamicin conjugates relied on the attachment of a Hydrazide Derivative to the oxidized carbohydrates that occur naturally on antibodies. This results in a “carbohydrate conjugate” capable of releasing active drug by hydrolysis of a hydrazone bond in the lysozomes where the pH is low. Conjugates have now been made that are formed by reacting a calicheamicin Derivative containing an activated ester with the lysines of antibodies. This results in an “amide conjugate” that is stable to hydrolysis, leaving the disulfide that is present in all calicheamicin conjugates as the likely site of drug release from the conjugate. In this article, these two classes of calicheamicin−anti...
-
gemtuzumab ozogamicin a potent and selective anti cd33 antibody calicheamicin conjugate for treatment of acute myeloid leukemia
Bioconjugate Chemistry, 2002Co-Authors: Philip R Hamann, Ryan Holcomb, Lois M Hinman, Janis Upeslacis, Irwin Hollander, Carl F Beyer, Delores Lindh, William Hallett, Hwei Ru Tsou, Dan ShochatAbstract:CD33 is expressed by acute myeloid leukemia (AML) cells in >80% of patients but not by normal hematopoietic stem cells, suggesting that elimination of CD33+ cells may be therapeutically beneficial. A conjugate of a calicheamicin Hydrazide Derivative attached via hydrazone formation to the oxidized carbohydrates of the anti-CD33 murine antibody P67.6 had been chosen for use in AML prior to humanization of this antibody. However, the CDR-grafted humanized P67.6 could not be used to make the carbohydrate conjugate because of the unexpected sensitivity of this antibody to periodate oxidation. Exploration of a series of bifunctional linkers resulted in a new class of calicheamicin conjugates, termed the hybrid conjugates, that allows for the attachment of the calicheamicin to lysines but incorporates the site of hydrolytic release, a hydrazone, previously shown to be required for activity. The optimized conjugate chosen for clinical trials, gemtuzumab ozogamicin (“gem-ozo”, Mylotarg, formerly designated CMA-67...
-
gemtuzumab ozogamicin a potent and selective anti cd33 antibody calicheamicin conjugate for treatment of acute myeloid leukemia
Bioconjugate Chemistry, 2002Co-Authors: Philip R Hamann, Ryan Holcomb, Lois M Hinman, Janis Upeslacis, Irwin Hollander, Carl F Beyer, Delores Lindh, William Hallett, Hwei Ru Tsou, Dan ShochatAbstract:CD33 is expressed by acute myeloid leukemia (AML) cells in >80% of patients but not by normal hematopoietic stem cells, suggesting that elimination of CD33(+) cells may be therapeutically beneficial. A conjugate of a calicheamicin Hydrazide Derivative attached via hydrazone formation to the oxidized carbohydrates of the anti-CD33 murine antibody P67.6 had been chosen for use in AML prior to humanization of this antibody. However, the CDR-grafted humanized P67.6 could not be used to make the carbohydrate conjugate because of the unexpected sensitivity of this antibody to periodate oxidation. Exploration of a series of bifunctional linkers resulted in a new class of calicheamicin conjugates, termed the hybrid conjugates, that allows for the attachment of the calicheamicin to lysines but incorporates the site of hydrolytic release, a hydrazone, previously shown to be required for activity. The optimized conjugate chosen for clinical trials, gemtuzumab ozogamicin ("gem-ozo", Mylotarg, formerly designated CMA-676), was significantly more potent and selective than the carbohydrate conjugate it replaced. It was selectively cytotoxic to HL-60 leukemia cells in tissue culture with an IC(50) in the low to sub-pg cal/mL range (cal = calicheamicin equivalents). Doses of gem-ozo as low as 50 microg cal/kg given three times to mice bearing HL-60 xenografts routinely resulted in long-term, tumor-free survivors, while a nonbinding control conjugate was relatively inactive. Gem-ozo at a concentration of 2 to 10 ng cal/mL selectively inhibited leukemia colony formation by marrow cells from a significant proportion of AML patients. Gem-ozo has also shown significant activity against AML in Phase II trials and is the first antibody-targeted chemotherapeutic agent approved by the FDA.
-
an anti cd33 antibody calicheamicin conjugate for treatment of acute myeloid leukemia choice of linker
Bioconjugate Chemistry, 2002Co-Authors: Philip R Hamann, Lois M Hinman, Janis Upeslacis, Carl F Beyer, Delores Lindh, David A Flowers, Irwin D. BernsteinAbstract:The anti-CD33 antibody, P67.6, has been chosen to target the potently cytotoxic calicheamicin antitumor antibiotics to acute myeloid leukemia (AML) due to the presence of CD33 on >80% of patient samples and its lack of expression outside the myeloid cell lineages, especially its lack of expression on pluripotent stem cells. Previous calicheamicin conjugates relied on the attachment of a Hydrazide Derivative to the oxidized carbohydrates that occur naturally on antibodies. This results in a "carbohydrate conjugate" capable of releasing active drug by hydrolysis of a hydrazone bond in the lysozomes where the pH is low. Conjugates have now been made that are formed by reacting a calicheamicin Derivative containing an activated ester with the lysines of antibodies. This results in an "amide conjugate" that is stable to hydrolysis, leaving the disulfide that is present in all calicheamicin conjugates as the likely site of drug release from the conjugate. In this article, these two classes of calicheamicin-antibody conjugates are compared for potential use in AML with the anti-CD33 antibody P67.6. Conjugates of P67.6 are shown to require the site of hydrolytic release afforded by the carbohydrate conjugates in order to retain good potency and selectivity in vitro, in vivo, and ex vivo. The P67.6 carbohydrate conjugate of calicheamicin is selectively cytotoxic at <0.006 ng/mL of calicheamicin equivalents (cal equiv) toward HL-60 promyelocytic leukemia cells in tissue culture. Long-term, tumor-free survivors are seen in xenograft models when mice bearing HL-60 subcutaneous tumors are treated with the P67.6 carbohydrate conjugate at a dose of 300 microg/kg cal equiv given three times. This conjugate also selectively inhibits the formation of colonies from AML marrow samples at 2 ng/mL cal equiv. The P67.6 carbohydrate conjugate of calicheamicin therefore appears to have promise as an antibody-targeted chemotherapeutic agent for CD33-positive diseases such as AML.
Fabio Salvatore Palumbo - One of the best experts on this subject based on the ideXlab platform.
-
in situ crosslinkable hyaluronan hydrogels for tissue engineering
Biomaterials, 2004Co-Authors: Fabio Salvatore Palumbo, Glenn D PrestwichAbstract:Abstract We describe the development of an injectable, cell-containing hydrogel that supports cell proliferation and growth to permit in vivo engineering of new tissues. Two thiolated hyaluronan (HA) Derivatives were coupled to four α,β-unsaturated ester and amide Derivatives of poly(ethylene glycol) (PEG) 3400. The relative chemical reactivity with cysteine decreased in the order PEG-diacrylate (PEGDA)⪢PEG-dimethacrylate>PEG-diacrylamide>PEG-dimethacrylamide. The 3-thiopropanoyl Hydrazide Derivative (HA-DTPH) was more reactive than the 4-thiobutanoyl Hydrazide, HA-DTBH. The crosslinking of HA-DTPH with PEGDA in a molar ratio of 2:1 occurred in approximately 9 min, suitable for an in situ crosslinking applications. The in vitro cytocompatibility and in vivo biocompatibility were evaluated using T31 human tracheal scar fibroblasts, which were suspended in medium in HA-DTPH prior to addition of the PEGDA solution. The majority of cells survived crosslinking and the cell density increased tenfold during the 4-week culture period in vitro. Cell-loaded hydrogels were also implanted subcutaneously in the flanks of nude mice, and after immunohistochemistry showed that the encapsulated cells retained the fibroblast phenotype and secreted extracellular matrix in vivo. These results confirm the potential utility of the HA-DTPH-PEGDA hydrogel as an in situ crosslinkable, injectable material for tissue engineering.
-
in situ crosslinkable hyaluronan hydrogels for tissue engineering
Biomaterials, 2004Co-Authors: Xiao Zheng Shu, Fabio Salvatore Palumbo, Yanchun Liu, Yi Luo, Glenn D PrestwichAbstract:We describe the development of an injectable, cell-containing hydrogel that supports cell proliferation and growth to permit in vivo engineering of new tissues. Two thiolated hyaluronan (HA) Derivatives were coupled to four alpha,beta-unsaturated ester and amide Derivatives of poly(ethylene glycol) (PEG) 3400. The relative chemical reactivity with cysteine decreased in the order PEG-diacrylate (PEGDA)>>PEG-dimethacrylate>PEG-diacrylamide>PEG-dimethacrylamide. The 3-thiopropanoyl Hydrazide Derivative (HA-DTPH) was more reactive than the 4-thiobutanoyl Hydrazide, HA-DTBH. The crosslinking of HA-DTPH with PEGDA in a molar ratio of 2:1 occurred in approximately 9 min, suitable for an in situ crosslinking applications. The in vitro cytocompatibility and in vivo biocompatibility were evaluated using T31 human tracheal scar fibroblasts, which were suspended in medium in HA-DTPH prior to addition of the PEGDA solution. The majority of cells survived crosslinking and the cell density increased tenfold during the 4-week culture period in vitro. Cell-loaded hydrogels were also implanted subcutaneously in the flanks of nude mice, and after immunohistochemistry showed that the encapsulated cells retained the fibroblast phenotype and secreted extracellular matrix in vivo. These results confirm the potential utility of the HA-DTPH-PEGDA hydrogel as an in situ crosslinkable, injectable material for tissue engineering.
Lois M Hinman - One of the best experts on this subject based on the ideXlab platform.
-
an anti muc1 antibody calicheamicin conjugate for treatment of solid tumors choice of linker and overcoming drug resistance
Bioconjugate Chemistry, 2005Co-Authors: Philip R Hamann, Lois M Hinman, Ana T Menendez, Frederick E Durr, Delores Lindh, Carl Beyer, Lee M Greenberger, Rosalyn Wallace, Janis UpeslacisAbstract:The anti-MUC1 antibody, CTM01, has been chosen to target the potently cytotoxic calicheamicin antitumor antibiotics to solid tumors of epithelial origin that express this antigen. Earlier calicheamicin conjugates relied on the attachment of a Hydrazide Derivative to the oxidized carbohydrates that occur naturally on antibodies. This produced a “carbohydrate conjugate” capable of releasing active drug by hydrolysis in the lysosomes where the pH is low. Conjugates have now been made that are formed by reacting a calicheamicin Derivative containing an activated ester with the lysines of antibodies. This gives an “amide conjugate” that is stable to hydrolysis, leaving the disulfide that is present in all calicheamicin conjugates as the only likely site of drug release from the conjugate. As previously shown for the carbohydrate conjugate, this amide conjugate of CTM01 produces complete regressions of xenograft tumors at doses of 300 μg/kg (calicheamicin equivalents) given three times. This indicates that hydr...
-
an anti cd33 antibody calicheamicin conjugate for treatment of acute myeloid leukemia choice of linker
Bioconjugate Chemistry, 2002Co-Authors: Philip R Hamann, Lois M Hinman, Janis Upeslacis, Carl F Beyer, Delores Lindh, David A Flowers, Irwin D. BernsteinAbstract:The anti-CD33 antibody, P67.6, has been chosen to target the potently cytotoxic calicheamicin antitumor antibiotics to acute myeloid leukemia (AML) due to the presence of CD33 on >80% of patient samples and its lack of expression outside the myeloid cell lineages, especially its lack of expression on pluripotent stem cells. Previous calicheamicin conjugates relied on the attachment of a Hydrazide Derivative to the oxidized carbohydrates that occur naturally on antibodies. This results in a “carbohydrate conjugate” capable of releasing active drug by hydrolysis of a hydrazone bond in the lysozomes where the pH is low. Conjugates have now been made that are formed by reacting a calicheamicin Derivative containing an activated ester with the lysines of antibodies. This results in an “amide conjugate” that is stable to hydrolysis, leaving the disulfide that is present in all calicheamicin conjugates as the likely site of drug release from the conjugate. In this article, these two classes of calicheamicin−anti...
-
gemtuzumab ozogamicin a potent and selective anti cd33 antibody calicheamicin conjugate for treatment of acute myeloid leukemia
Bioconjugate Chemistry, 2002Co-Authors: Philip R Hamann, Ryan Holcomb, Lois M Hinman, Janis Upeslacis, Irwin Hollander, Carl F Beyer, Delores Lindh, William Hallett, Hwei Ru Tsou, Dan ShochatAbstract:CD33 is expressed by acute myeloid leukemia (AML) cells in >80% of patients but not by normal hematopoietic stem cells, suggesting that elimination of CD33+ cells may be therapeutically beneficial. A conjugate of a calicheamicin Hydrazide Derivative attached via hydrazone formation to the oxidized carbohydrates of the anti-CD33 murine antibody P67.6 had been chosen for use in AML prior to humanization of this antibody. However, the CDR-grafted humanized P67.6 could not be used to make the carbohydrate conjugate because of the unexpected sensitivity of this antibody to periodate oxidation. Exploration of a series of bifunctional linkers resulted in a new class of calicheamicin conjugates, termed the hybrid conjugates, that allows for the attachment of the calicheamicin to lysines but incorporates the site of hydrolytic release, a hydrazone, previously shown to be required for activity. The optimized conjugate chosen for clinical trials, gemtuzumab ozogamicin (“gem-ozo”, Mylotarg, formerly designated CMA-67...
-
gemtuzumab ozogamicin a potent and selective anti cd33 antibody calicheamicin conjugate for treatment of acute myeloid leukemia
Bioconjugate Chemistry, 2002Co-Authors: Philip R Hamann, Ryan Holcomb, Lois M Hinman, Janis Upeslacis, Irwin Hollander, Carl F Beyer, Delores Lindh, William Hallett, Hwei Ru Tsou, Dan ShochatAbstract:CD33 is expressed by acute myeloid leukemia (AML) cells in >80% of patients but not by normal hematopoietic stem cells, suggesting that elimination of CD33(+) cells may be therapeutically beneficial. A conjugate of a calicheamicin Hydrazide Derivative attached via hydrazone formation to the oxidized carbohydrates of the anti-CD33 murine antibody P67.6 had been chosen for use in AML prior to humanization of this antibody. However, the CDR-grafted humanized P67.6 could not be used to make the carbohydrate conjugate because of the unexpected sensitivity of this antibody to periodate oxidation. Exploration of a series of bifunctional linkers resulted in a new class of calicheamicin conjugates, termed the hybrid conjugates, that allows for the attachment of the calicheamicin to lysines but incorporates the site of hydrolytic release, a hydrazone, previously shown to be required for activity. The optimized conjugate chosen for clinical trials, gemtuzumab ozogamicin ("gem-ozo", Mylotarg, formerly designated CMA-676), was significantly more potent and selective than the carbohydrate conjugate it replaced. It was selectively cytotoxic to HL-60 leukemia cells in tissue culture with an IC(50) in the low to sub-pg cal/mL range (cal = calicheamicin equivalents). Doses of gem-ozo as low as 50 microg cal/kg given three times to mice bearing HL-60 xenografts routinely resulted in long-term, tumor-free survivors, while a nonbinding control conjugate was relatively inactive. Gem-ozo at a concentration of 2 to 10 ng cal/mL selectively inhibited leukemia colony formation by marrow cells from a significant proportion of AML patients. Gem-ozo has also shown significant activity against AML in Phase II trials and is the first antibody-targeted chemotherapeutic agent approved by the FDA.
-
an anti cd33 antibody calicheamicin conjugate for treatment of acute myeloid leukemia choice of linker
Bioconjugate Chemistry, 2002Co-Authors: Philip R Hamann, Lois M Hinman, Janis Upeslacis, Carl F Beyer, Delores Lindh, David A Flowers, Irwin D. BernsteinAbstract:The anti-CD33 antibody, P67.6, has been chosen to target the potently cytotoxic calicheamicin antitumor antibiotics to acute myeloid leukemia (AML) due to the presence of CD33 on >80% of patient samples and its lack of expression outside the myeloid cell lineages, especially its lack of expression on pluripotent stem cells. Previous calicheamicin conjugates relied on the attachment of a Hydrazide Derivative to the oxidized carbohydrates that occur naturally on antibodies. This results in a "carbohydrate conjugate" capable of releasing active drug by hydrolysis of a hydrazone bond in the lysozomes where the pH is low. Conjugates have now been made that are formed by reacting a calicheamicin Derivative containing an activated ester with the lysines of antibodies. This results in an "amide conjugate" that is stable to hydrolysis, leaving the disulfide that is present in all calicheamicin conjugates as the likely site of drug release from the conjugate. In this article, these two classes of calicheamicin-antibody conjugates are compared for potential use in AML with the anti-CD33 antibody P67.6. Conjugates of P67.6 are shown to require the site of hydrolytic release afforded by the carbohydrate conjugates in order to retain good potency and selectivity in vitro, in vivo, and ex vivo. The P67.6 carbohydrate conjugate of calicheamicin is selectively cytotoxic at <0.006 ng/mL of calicheamicin equivalents (cal equiv) toward HL-60 promyelocytic leukemia cells in tissue culture. Long-term, tumor-free survivors are seen in xenograft models when mice bearing HL-60 subcutaneous tumors are treated with the P67.6 carbohydrate conjugate at a dose of 300 microg/kg cal equiv given three times. This conjugate also selectively inhibits the formation of colonies from AML marrow samples at 2 ng/mL cal equiv. The P67.6 carbohydrate conjugate of calicheamicin therefore appears to have promise as an antibody-targeted chemotherapeutic agent for CD33-positive diseases such as AML.
