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A radiolabeled antibody targeting CD123(+) leukemia stem cells - initial radioimmunotherapy studies in NOD/SCID mice engrafted with primary human AML.

Leyton JV, Gao C, Williams B, Keating A, Minden M, Reilly RM - Leuk Res Rep (2015)

Bottom Line: Radioimmunotherapy (RIT) with anti-CD123 monoclonal antibody CSL360 modified with nuclear translocation sequence (NLS) peptides and labeled with the Auger electron-emitter, (111)In ((111)In-NLS-CSL360) was studied in the prevalent NOD/SCID mouse AML engraftment assay.Significant decreases in CD123(+) leukemic cells and impairment of leukemic stem cell self-renewal were achieved with high doses of RIT.At low non-toxic treatment doses, (111)In-NLS-CSL360 demonstrated a trend towards improved survival associated with decreased spleen/body weight ratio, an indicator of leukemia burden, and almost complete eradication of leukemia from the bone marrow in some mice.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON, Canada.

ABSTRACT
Radioimmunotherapy (RIT) with anti-CD123 monoclonal antibody CSL360 modified with nuclear translocation sequence (NLS) peptides and labeled with the Auger electron-emitter, (111)In ((111)In-NLS-CSL360) was studied in the prevalent NOD/SCID mouse AML engraftment assay. Significant decreases in CD123(+) leukemic cells and impairment of leukemic stem cell self-renewal were achieved with high doses of RIT. However, NOD/SCID mice were very radiosensitive to these doses. At low non-toxic treatment doses, (111)In-NLS-CSL360 demonstrated a trend towards improved survival associated with decreased spleen/body weight ratio, an indicator of leukemia burden, and almost complete eradication of leukemia from the bone marrow in some mice.

No MeSH data available.


Related in: MedlinePlus

Effect of treatment of NOD/SCID mice engrafted with AML specimen 090295 with radioimmunoconjugates (17–18 MBq; 20–27 μg) on leukemic cells in the bone marrow (BM). (A) Percentage of human hCD45+/CD123+ cells in the BM of primary engrafted mice at 8 weeks. Data shown for untreated mice was taken from reference 12. (B) Percentage of hCD45+ cells in the BM of secondary recipient mice engrafted with donor cells from primary AML-engrafted mice treated with radioimmunoconjugates. (C) Percentage of hCD45+/CD34+ progenitor cells in the BM of recipent mice. (D) Percentage of hCD45+/CD34+/CD38- stem cells in the BM of recipient mice. Bars represent the mean±SD and values for individual mice are shown. Significant differences (P<0.05) are indicated by an asterisk.
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f0005: Effect of treatment of NOD/SCID mice engrafted with AML specimen 090295 with radioimmunoconjugates (17–18 MBq; 20–27 μg) on leukemic cells in the bone marrow (BM). (A) Percentage of human hCD45+/CD123+ cells in the BM of primary engrafted mice at 8 weeks. Data shown for untreated mice was taken from reference 12. (B) Percentage of hCD45+ cells in the BM of secondary recipient mice engrafted with donor cells from primary AML-engrafted mice treated with radioimmunoconjugates. (C) Percentage of hCD45+/CD34+ progenitor cells in the BM of recipent mice. (D) Percentage of hCD45+/CD34+/CD38- stem cells in the BM of recipient mice. Bars represent the mean±SD and values for individual mice are shown. Significant differences (P<0.05) are indicated by an asterisk.

Mentions: Specimen 090295 almost completely repopulated the NOD/SCID mouse BM after 8-weeks reaching hCD45+/CD123+ engraftment levels of 84.7%±3.5% [12]. This efficiently and reproducibly-engrafting AML specimen serves as a robust initial challenge to provide insight on the efficacy of a LSC-targeted Auger electron RIT approach. A single dose of radioactivity (16–19 MBq; 20–27 μg) administered per mouse of 111In-NLS-CSL360 was potent after only 72 h. 111In-NLS-CSL360 treatment resulted in a 1.8-fold reduction in the engraftment of hCD45+/CD123+ cells in the BM compared to mice injected with 111In-NLS-chIgG1 (47.2%±7.7% vs. 82.6%±1.8%, respectively; P<0.0001; Fig. 1A). This result is encouraging as a rapid molecular response to treatment in AML patients is a favorable characteristic associated with good outcome [13]. These results were supported by biodistribution studies which showed 3-fold greater uptake of 111In-NLS-CSL360 than 111In-NLS-chIgG1 in the femurs which included the BM [8.8±3.2 vs. 3.0±0.3 percent injected dose/g (%ID/g); P=0.004] and 2-fold greater spleen uptake (24.1±3.2 vs. 13.8±2.3%ID/g; P=0.004) [12]. These are known sites of engraftment of AML in the NOD/SCID mouse. To test the effect on the repopulation capacity of LSCs, transplantations in secondary NOD/SCID mice were conducted. 111In-NLS-CSL360 could reduce the leukemic hCD45+ engraftment by a factor of 4.3 after 8 weeks compared to mice treated with 111In-NLS-chIgG1 (Fig. 1B; P=0.04). The proportion of hCD45+/CD34+ progenitor cells in the BM was significantly decreased by 12-fold (Fig. 1C; P=0.03). A 3.3-fold lower proportion of cells occurred in the hCD45+/CD34+/CD38− cell fraction in the BM of 111In-NLS-CSL360 treated mice compared to 111In-NLS-chIgG1 treated mice (Fig. 1D). Under these conditions, the NOD/SCID mouse assay was useful to monitor a rapid (72 h) treatment response to 111In-NLS-CSL360 and secondary transplantations demonstrated impairment of LSCs. We next determined if non-irradiated and non-engrafted NOD/SCID mice could tolerate similar doses of 111In-NLS-CSL360 (17–19 MBq; 21–24 μg) to evaluate long-term AML disease. All mice exhibited decreased body weight and had to be sacrificed by day 21. Engraftment of AML into NOD/SCID mice has been instrumental in understanding leukemia biology but these mice have a defect in DNA repair that makes them very sensitive to radiation [14] and we demonstrate how this limitation of the NOD/SCID assay poses a challenge to assess RIT approaches.


A radiolabeled antibody targeting CD123(+) leukemia stem cells - initial radioimmunotherapy studies in NOD/SCID mice engrafted with primary human AML.

Leyton JV, Gao C, Williams B, Keating A, Minden M, Reilly RM - Leuk Res Rep (2015)

Effect of treatment of NOD/SCID mice engrafted with AML specimen 090295 with radioimmunoconjugates (17–18 MBq; 20–27 μg) on leukemic cells in the bone marrow (BM). (A) Percentage of human hCD45+/CD123+ cells in the BM of primary engrafted mice at 8 weeks. Data shown for untreated mice was taken from reference 12. (B) Percentage of hCD45+ cells in the BM of secondary recipient mice engrafted with donor cells from primary AML-engrafted mice treated with radioimmunoconjugates. (C) Percentage of hCD45+/CD34+ progenitor cells in the BM of recipent mice. (D) Percentage of hCD45+/CD34+/CD38- stem cells in the BM of recipient mice. Bars represent the mean±SD and values for individual mice are shown. Significant differences (P<0.05) are indicated by an asterisk.
© Copyright Policy - CC BY-NC-ND
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4588397&req=5

f0005: Effect of treatment of NOD/SCID mice engrafted with AML specimen 090295 with radioimmunoconjugates (17–18 MBq; 20–27 μg) on leukemic cells in the bone marrow (BM). (A) Percentage of human hCD45+/CD123+ cells in the BM of primary engrafted mice at 8 weeks. Data shown for untreated mice was taken from reference 12. (B) Percentage of hCD45+ cells in the BM of secondary recipient mice engrafted with donor cells from primary AML-engrafted mice treated with radioimmunoconjugates. (C) Percentage of hCD45+/CD34+ progenitor cells in the BM of recipent mice. (D) Percentage of hCD45+/CD34+/CD38- stem cells in the BM of recipient mice. Bars represent the mean±SD and values for individual mice are shown. Significant differences (P<0.05) are indicated by an asterisk.
Mentions: Specimen 090295 almost completely repopulated the NOD/SCID mouse BM after 8-weeks reaching hCD45+/CD123+ engraftment levels of 84.7%±3.5% [12]. This efficiently and reproducibly-engrafting AML specimen serves as a robust initial challenge to provide insight on the efficacy of a LSC-targeted Auger electron RIT approach. A single dose of radioactivity (16–19 MBq; 20–27 μg) administered per mouse of 111In-NLS-CSL360 was potent after only 72 h. 111In-NLS-CSL360 treatment resulted in a 1.8-fold reduction in the engraftment of hCD45+/CD123+ cells in the BM compared to mice injected with 111In-NLS-chIgG1 (47.2%±7.7% vs. 82.6%±1.8%, respectively; P<0.0001; Fig. 1A). This result is encouraging as a rapid molecular response to treatment in AML patients is a favorable characteristic associated with good outcome [13]. These results were supported by biodistribution studies which showed 3-fold greater uptake of 111In-NLS-CSL360 than 111In-NLS-chIgG1 in the femurs which included the BM [8.8±3.2 vs. 3.0±0.3 percent injected dose/g (%ID/g); P=0.004] and 2-fold greater spleen uptake (24.1±3.2 vs. 13.8±2.3%ID/g; P=0.004) [12]. These are known sites of engraftment of AML in the NOD/SCID mouse. To test the effect on the repopulation capacity of LSCs, transplantations in secondary NOD/SCID mice were conducted. 111In-NLS-CSL360 could reduce the leukemic hCD45+ engraftment by a factor of 4.3 after 8 weeks compared to mice treated with 111In-NLS-chIgG1 (Fig. 1B; P=0.04). The proportion of hCD45+/CD34+ progenitor cells in the BM was significantly decreased by 12-fold (Fig. 1C; P=0.03). A 3.3-fold lower proportion of cells occurred in the hCD45+/CD34+/CD38− cell fraction in the BM of 111In-NLS-CSL360 treated mice compared to 111In-NLS-chIgG1 treated mice (Fig. 1D). Under these conditions, the NOD/SCID mouse assay was useful to monitor a rapid (72 h) treatment response to 111In-NLS-CSL360 and secondary transplantations demonstrated impairment of LSCs. We next determined if non-irradiated and non-engrafted NOD/SCID mice could tolerate similar doses of 111In-NLS-CSL360 (17–19 MBq; 21–24 μg) to evaluate long-term AML disease. All mice exhibited decreased body weight and had to be sacrificed by day 21. Engraftment of AML into NOD/SCID mice has been instrumental in understanding leukemia biology but these mice have a defect in DNA repair that makes them very sensitive to radiation [14] and we demonstrate how this limitation of the NOD/SCID assay poses a challenge to assess RIT approaches.

Bottom Line: Radioimmunotherapy (RIT) with anti-CD123 monoclonal antibody CSL360 modified with nuclear translocation sequence (NLS) peptides and labeled with the Auger electron-emitter, (111)In ((111)In-NLS-CSL360) was studied in the prevalent NOD/SCID mouse AML engraftment assay.Significant decreases in CD123(+) leukemic cells and impairment of leukemic stem cell self-renewal were achieved with high doses of RIT.At low non-toxic treatment doses, (111)In-NLS-CSL360 demonstrated a trend towards improved survival associated with decreased spleen/body weight ratio, an indicator of leukemia burden, and almost complete eradication of leukemia from the bone marrow in some mice.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON, Canada.

ABSTRACT
Radioimmunotherapy (RIT) with anti-CD123 monoclonal antibody CSL360 modified with nuclear translocation sequence (NLS) peptides and labeled with the Auger electron-emitter, (111)In ((111)In-NLS-CSL360) was studied in the prevalent NOD/SCID mouse AML engraftment assay. Significant decreases in CD123(+) leukemic cells and impairment of leukemic stem cell self-renewal were achieved with high doses of RIT. However, NOD/SCID mice were very radiosensitive to these doses. At low non-toxic treatment doses, (111)In-NLS-CSL360 demonstrated a trend towards improved survival associated with decreased spleen/body weight ratio, an indicator of leukemia burden, and almost complete eradication of leukemia from the bone marrow in some mice.

No MeSH data available.


Related in: MedlinePlus