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Differentiation between temporary and real non-clearability of biotinylated IgG antibody by avidin in mice.

Dou S, Virostko J, Rusckowski M, Greiner DL, Powers AC, Liu G - Front Pharmacol (2014)

Bottom Line: By comparing the effects of natural clearance at a longer post-injection time and avidin clearance, we demonstrated that avidin clearance is much more effective.By directly attaching avidin to a biotinylated antibody prior to injection, we found that the biotinylated antibody in blood, once bound to the clearing agent, can be removed from the circulation immediately and completely, while the real non-clearable antibody without biotin stays.In conclusion, the use of antibody pretargeting as a tool in this study has improved understanding of the incomplete clearance by avidin and can aid in overcoming this obstacle.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, University of Massachusetts Medical School Worcester, MA, USA.

ABSTRACT
Although an increasing number of antibody conjugates are being used in the clinic, there remain many unmet needs in antibody targeting. Normal tissue background is one of the key issues that limits the therapeutic efficacy and the detection sensitivity. Background reduction coupled with dose increase may provide the required target accumulation of the label or toxin at an acceptable normal tissue background. However, the knowledge about the in vivo interaction between antibody and a clearing agent is currently inadequate for designing a rational clearance regimen or system. The current investigation focuses on the clearability of antibody for background reduction, an important topic to antibody targeting in general. The investigation employs pretargeting as a research tool and avidin as a model clearing agent. By comparing the effects of natural clearance at a longer post-injection time and avidin clearance, we demonstrated that avidin clearance is much more effective. By directly attaching avidin to a biotinylated antibody prior to injection, we found that the biotinylated antibody in blood, once bound to the clearing agent, can be removed from the circulation immediately and completely, while the real non-clearable antibody without biotin stays. The study of multiple avidin injections confirmed that the presence of clearable biotinylated antibodies after an avidin injection is due to their temporary inaccessibility and subsequent return from tissue compartments. The collective clearance efficiency of 91% by three avidin injections indicates a continuous IV infusion would be recommended to remove all of the biotinylated IgG molecules. In conclusion, the use of antibody pretargeting as a tool in this study has improved understanding of the incomplete clearance by avidin and can aid in overcoming this obstacle.

No MeSH data available.


Pharmacokinetics of both avidin-bound and radiolabeled biotin-CC49-MORF vs. radiolabeled biotin-CC49-MORF (no avidin). Shown are pharmacokinetics for (A) Blood, (B) Liver, (C) whole body retention, and (D) kidney. It mimics how a biotinylated antibody molecule behaves once bound to avidin in blood.
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Figure 2: Pharmacokinetics of both avidin-bound and radiolabeled biotin-CC49-MORF vs. radiolabeled biotin-CC49-MORF (no avidin). Shown are pharmacokinetics for (A) Blood, (B) Liver, (C) whole body retention, and (D) kidney. It mimics how a biotinylated antibody molecule behaves once bound to avidin in blood.

Mentions: As shown in Figure 2A, the blood concentration of the radiolabeled biotin-CC49-MORF not treated with avidin is much higher than that for the avidin-treated. The percentages cleared from circulation (1-the ratio of blood levels with/without avidin) are 65 ± 3%, 84 ± 1%, 89 ± 1%, and 88 ± 1% for 2, 30 min, 1.5, and 2 h, respectively. At 0.5 h, the clearance of the avidin-treated antibody is almost complete, although additional slight improvement is observed until 1.5 h. Thus, about 88% of the avidin-treated biotin-CC49-MORF is clearable. The approximate 12% of avidin that is non-clearable (that cannot be cleared by avidin) is likely due to the lack of a biotin group.


Differentiation between temporary and real non-clearability of biotinylated IgG antibody by avidin in mice.

Dou S, Virostko J, Rusckowski M, Greiner DL, Powers AC, Liu G - Front Pharmacol (2014)

Pharmacokinetics of both avidin-bound and radiolabeled biotin-CC49-MORF vs. radiolabeled biotin-CC49-MORF (no avidin). Shown are pharmacokinetics for (A) Blood, (B) Liver, (C) whole body retention, and (D) kidney. It mimics how a biotinylated antibody molecule behaves once bound to avidin in blood.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4109569&req=5

Figure 2: Pharmacokinetics of both avidin-bound and radiolabeled biotin-CC49-MORF vs. radiolabeled biotin-CC49-MORF (no avidin). Shown are pharmacokinetics for (A) Blood, (B) Liver, (C) whole body retention, and (D) kidney. It mimics how a biotinylated antibody molecule behaves once bound to avidin in blood.
Mentions: As shown in Figure 2A, the blood concentration of the radiolabeled biotin-CC49-MORF not treated with avidin is much higher than that for the avidin-treated. The percentages cleared from circulation (1-the ratio of blood levels with/without avidin) are 65 ± 3%, 84 ± 1%, 89 ± 1%, and 88 ± 1% for 2, 30 min, 1.5, and 2 h, respectively. At 0.5 h, the clearance of the avidin-treated antibody is almost complete, although additional slight improvement is observed until 1.5 h. Thus, about 88% of the avidin-treated biotin-CC49-MORF is clearable. The approximate 12% of avidin that is non-clearable (that cannot be cleared by avidin) is likely due to the lack of a biotin group.

Bottom Line: By comparing the effects of natural clearance at a longer post-injection time and avidin clearance, we demonstrated that avidin clearance is much more effective.By directly attaching avidin to a biotinylated antibody prior to injection, we found that the biotinylated antibody in blood, once bound to the clearing agent, can be removed from the circulation immediately and completely, while the real non-clearable antibody without biotin stays.In conclusion, the use of antibody pretargeting as a tool in this study has improved understanding of the incomplete clearance by avidin and can aid in overcoming this obstacle.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology, University of Massachusetts Medical School Worcester, MA, USA.

ABSTRACT
Although an increasing number of antibody conjugates are being used in the clinic, there remain many unmet needs in antibody targeting. Normal tissue background is one of the key issues that limits the therapeutic efficacy and the detection sensitivity. Background reduction coupled with dose increase may provide the required target accumulation of the label or toxin at an acceptable normal tissue background. However, the knowledge about the in vivo interaction between antibody and a clearing agent is currently inadequate for designing a rational clearance regimen or system. The current investigation focuses on the clearability of antibody for background reduction, an important topic to antibody targeting in general. The investigation employs pretargeting as a research tool and avidin as a model clearing agent. By comparing the effects of natural clearance at a longer post-injection time and avidin clearance, we demonstrated that avidin clearance is much more effective. By directly attaching avidin to a biotinylated antibody prior to injection, we found that the biotinylated antibody in blood, once bound to the clearing agent, can be removed from the circulation immediately and completely, while the real non-clearable antibody without biotin stays. The study of multiple avidin injections confirmed that the presence of clearable biotinylated antibodies after an avidin injection is due to their temporary inaccessibility and subsequent return from tissue compartments. The collective clearance efficiency of 91% by three avidin injections indicates a continuous IV infusion would be recommended to remove all of the biotinylated IgG molecules. In conclusion, the use of antibody pretargeting as a tool in this study has improved understanding of the incomplete clearance by avidin and can aid in overcoming this obstacle.

No MeSH data available.