The effect of bi-terminal PEGylation of an integrin α<inf>v</inf>β<inf>6</inf>-targeted <sup>18</sup>F peptide on pharmacokinetics and tumor uptake

Sven H. Hausner, Nadine Bauer, Lina Y. Hu, Leah M. Knight, Julie Sutcliffe

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

Radiotracers based on the peptide A20FMDV2 selectively target the cell surface receptor integrin α<inf>v</inf>β<inf>6</inf>. This integrin has been identified as a prognostic indicator correlating with the severity of disease for several challenging malignancies. In previous studies of A20FMDV2 peptides labeled with 4-<sup>18</sup>F-fluorobenzoic acid (<sup>18</sup>F-FBA), we have shown that the introduction of poly(ethylene glycol) (PEG) improves pharmacokinetics, including increased uptake in α<inf>v</inf>β<inf>6</inf>-expressing tumors. The present study evaluated the effect of site-specific C-terminal or dual (N- and C-terminal) PEGylation, yielding <sup>18</sup>F-FBA-A20FMDV2-PEG<inf>28</inf> (4) and <sup>18</sup>F-FBA-PEG<inf>28</inf>-A20FMDV2-PEG<inf>28</inf> (5), on α<inf>v</inf>β<inf>6</inf>-targeted tumor uptake and pharmacokinetics. The results are compared with <sup>18</sup>F-FBA-labeled A20FMDV2 radiotracers (1-3) bearing either no PEG or different PEG units at the N terminus. Methods: The radiotracers were prepared and radiolabeled on solid phase. Using 3 cell lines, DX3puroβ6 (α<inf>v</inf>β<inf>6</inf>+), DX3puro (α<inf>v</inf>β<inf>6</inf>-), and BxPC-3 (α<inf>v</inf>β<inf>6</inf>+), we evaluated the radiotracers in vitro (serum stability; cell binding and internalization) and in vivo in mouse models bearing paired DX3puroβ6-DX3puro and, for 5, BxPC-3 xenografts. Results: The size and location of the PEG units significantly affected α<inf>v</inf>β<inf>6</inf>targeting and pharmacokinetics. Although the C-terminally PEGylated 4 showed some improvements over the un-PEGylated <sup>18</sup>F-FBA-A20FMDV2 (1), it was the bi-terminally PEGylated 5 that displayed the more favorable combination of high α<inf>v</inf>β<inf>6</inf>affinity, selectivity, and pharmacokinetic profile. In vitro, 5 bound to α<inf>v</inf>β<inf>6</inf>-expressing DX3puroβ6 and BxPC-3 cells with 60.5% ± 3.3% and 48.8% ± 8.3%, respectively, with a significant fraction of internalization (37.2% ± 4.0% and 37.6% ± 4.1% of total radioactivity, respectively). By comparison, in the DX3puro control 5 showed only 3.0% ± 0.5% binding and 0.9% ± 0.2% internalization. In vivo, 5 maintained high, α<inf>v</inf>β<inf>6</inf>-directed binding in the paired DX3puroβ6-DX3puro model (1 h: DX3puroβ6, 2.3 ± 0.2 percentage injected dose per gram [%ID/g]; DX3puroβ6/DX3puro ratio, 6.5:1; 4 h: 10.7:1). In the pancreatic BxPC-3 model, uptake was 4.7 ± 0.9%ID/g (1 h) despite small tumor sizes (20-80 mg). Conclusion: The bi-PEGylated radiotracer 5 showed a greatly improved pharmacokinetic profile, beyond what was predicted from individual N- or C-terminal PEGylation. It appears that the 2 PEG units acted synergistically to result in an improved metabolic profile including high α<inf>v</inf>β<inf>6</inf>+ tumor uptake and retention.

Original languageEnglish (US)
Pages (from-to)784-790
Number of pages7
JournalJournal of Nuclear Medicine
Volume56
Issue number5
DOIs
StatePublished - May 1 2015

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Integrins
Pharmacokinetics
Peptides
Neoplasms
Metabolome
Ethylene Glycol
Cell Surface Receptors
Heterografts
Radioactivity
4-fluorobenzoic acid
Cell Line
Serum
In Vitro Techniques

Keywords

  • Integrin α<inf>v</inf>β<inf>6</inf>
  • Metabolism
  • PEGylation
  • Peptide
  • Positron emission tomography

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

Cite this

The effect of bi-terminal PEGylation of an integrin α<inf>v</inf>β<inf>6</inf>-targeted <sup>18</sup>F peptide on pharmacokinetics and tumor uptake. / Hausner, Sven H.; Bauer, Nadine; Hu, Lina Y.; Knight, Leah M.; Sutcliffe, Julie.

In: Journal of Nuclear Medicine, Vol. 56, No. 5, 01.05.2015, p. 784-790.

Research output: Contribution to journalArticle

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title = "The effect of bi-terminal PEGylation of an integrin αvβ6-targeted 18F peptide on pharmacokinetics and tumor uptake",
abstract = "Radiotracers based on the peptide A20FMDV2 selectively target the cell surface receptor integrin αvβ6. This integrin has been identified as a prognostic indicator correlating with the severity of disease for several challenging malignancies. In previous studies of A20FMDV2 peptides labeled with 4-18F-fluorobenzoic acid (18F-FBA), we have shown that the introduction of poly(ethylene glycol) (PEG) improves pharmacokinetics, including increased uptake in αvβ6-expressing tumors. The present study evaluated the effect of site-specific C-terminal or dual (N- and C-terminal) PEGylation, yielding 18F-FBA-A20FMDV2-PEG28 (4) and 18F-FBA-PEG28-A20FMDV2-PEG28 (5), on αvβ6-targeted tumor uptake and pharmacokinetics. The results are compared with 18F-FBA-labeled A20FMDV2 radiotracers (1-3) bearing either no PEG or different PEG units at the N terminus. Methods: The radiotracers were prepared and radiolabeled on solid phase. Using 3 cell lines, DX3puroβ6 (αvβ6+), DX3puro (αvβ6-), and BxPC-3 (αvβ6+), we evaluated the radiotracers in vitro (serum stability; cell binding and internalization) and in vivo in mouse models bearing paired DX3puroβ6-DX3puro and, for 5, BxPC-3 xenografts. Results: The size and location of the PEG units significantly affected αvβ6targeting and pharmacokinetics. Although the C-terminally PEGylated 4 showed some improvements over the un-PEGylated 18F-FBA-A20FMDV2 (1), it was the bi-terminally PEGylated 5 that displayed the more favorable combination of high αvβ6affinity, selectivity, and pharmacokinetic profile. In vitro, 5 bound to αvβ6-expressing DX3puroβ6 and BxPC-3 cells with 60.5{\%} ± 3.3{\%} and 48.8{\%} ± 8.3{\%}, respectively, with a significant fraction of internalization (37.2{\%} ± 4.0{\%} and 37.6{\%} ± 4.1{\%} of total radioactivity, respectively). By comparison, in the DX3puro control 5 showed only 3.0{\%} ± 0.5{\%} binding and 0.9{\%} ± 0.2{\%} internalization. In vivo, 5 maintained high, αvβ6-directed binding in the paired DX3puroβ6-DX3puro model (1 h: DX3puroβ6, 2.3 ± 0.2 percentage injected dose per gram [{\%}ID/g]; DX3puroβ6/DX3puro ratio, 6.5:1; 4 h: 10.7:1). In the pancreatic BxPC-3 model, uptake was 4.7 ± 0.9{\%}ID/g (1 h) despite small tumor sizes (20-80 mg). Conclusion: The bi-PEGylated radiotracer 5 showed a greatly improved pharmacokinetic profile, beyond what was predicted from individual N- or C-terminal PEGylation. It appears that the 2 PEG units acted synergistically to result in an improved metabolic profile including high αvβ6+ tumor uptake and retention.",
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author = "Hausner, {Sven H.} and Nadine Bauer and Hu, {Lina Y.} and Knight, {Leah M.} and Julie Sutcliffe",
year = "2015",
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TY - JOUR

T1 - The effect of bi-terminal PEGylation of an integrin αvβ6-targeted 18F peptide on pharmacokinetics and tumor uptake

AU - Hausner, Sven H.

AU - Bauer, Nadine

AU - Hu, Lina Y.

AU - Knight, Leah M.

AU - Sutcliffe, Julie

PY - 2015/5/1

Y1 - 2015/5/1

N2 - Radiotracers based on the peptide A20FMDV2 selectively target the cell surface receptor integrin αvβ6. This integrin has been identified as a prognostic indicator correlating with the severity of disease for several challenging malignancies. In previous studies of A20FMDV2 peptides labeled with 4-18F-fluorobenzoic acid (18F-FBA), we have shown that the introduction of poly(ethylene glycol) (PEG) improves pharmacokinetics, including increased uptake in αvβ6-expressing tumors. The present study evaluated the effect of site-specific C-terminal or dual (N- and C-terminal) PEGylation, yielding 18F-FBA-A20FMDV2-PEG28 (4) and 18F-FBA-PEG28-A20FMDV2-PEG28 (5), on αvβ6-targeted tumor uptake and pharmacokinetics. The results are compared with 18F-FBA-labeled A20FMDV2 radiotracers (1-3) bearing either no PEG or different PEG units at the N terminus. Methods: The radiotracers were prepared and radiolabeled on solid phase. Using 3 cell lines, DX3puroβ6 (αvβ6+), DX3puro (αvβ6-), and BxPC-3 (αvβ6+), we evaluated the radiotracers in vitro (serum stability; cell binding and internalization) and in vivo in mouse models bearing paired DX3puroβ6-DX3puro and, for 5, BxPC-3 xenografts. Results: The size and location of the PEG units significantly affected αvβ6targeting and pharmacokinetics. Although the C-terminally PEGylated 4 showed some improvements over the un-PEGylated 18F-FBA-A20FMDV2 (1), it was the bi-terminally PEGylated 5 that displayed the more favorable combination of high αvβ6affinity, selectivity, and pharmacokinetic profile. In vitro, 5 bound to αvβ6-expressing DX3puroβ6 and BxPC-3 cells with 60.5% ± 3.3% and 48.8% ± 8.3%, respectively, with a significant fraction of internalization (37.2% ± 4.0% and 37.6% ± 4.1% of total radioactivity, respectively). By comparison, in the DX3puro control 5 showed only 3.0% ± 0.5% binding and 0.9% ± 0.2% internalization. In vivo, 5 maintained high, αvβ6-directed binding in the paired DX3puroβ6-DX3puro model (1 h: DX3puroβ6, 2.3 ± 0.2 percentage injected dose per gram [%ID/g]; DX3puroβ6/DX3puro ratio, 6.5:1; 4 h: 10.7:1). In the pancreatic BxPC-3 model, uptake was 4.7 ± 0.9%ID/g (1 h) despite small tumor sizes (20-80 mg). Conclusion: The bi-PEGylated radiotracer 5 showed a greatly improved pharmacokinetic profile, beyond what was predicted from individual N- or C-terminal PEGylation. It appears that the 2 PEG units acted synergistically to result in an improved metabolic profile including high αvβ6+ tumor uptake and retention.

AB - Radiotracers based on the peptide A20FMDV2 selectively target the cell surface receptor integrin αvβ6. This integrin has been identified as a prognostic indicator correlating with the severity of disease for several challenging malignancies. In previous studies of A20FMDV2 peptides labeled with 4-18F-fluorobenzoic acid (18F-FBA), we have shown that the introduction of poly(ethylene glycol) (PEG) improves pharmacokinetics, including increased uptake in αvβ6-expressing tumors. The present study evaluated the effect of site-specific C-terminal or dual (N- and C-terminal) PEGylation, yielding 18F-FBA-A20FMDV2-PEG28 (4) and 18F-FBA-PEG28-A20FMDV2-PEG28 (5), on αvβ6-targeted tumor uptake and pharmacokinetics. The results are compared with 18F-FBA-labeled A20FMDV2 radiotracers (1-3) bearing either no PEG or different PEG units at the N terminus. Methods: The radiotracers were prepared and radiolabeled on solid phase. Using 3 cell lines, DX3puroβ6 (αvβ6+), DX3puro (αvβ6-), and BxPC-3 (αvβ6+), we evaluated the radiotracers in vitro (serum stability; cell binding and internalization) and in vivo in mouse models bearing paired DX3puroβ6-DX3puro and, for 5, BxPC-3 xenografts. Results: The size and location of the PEG units significantly affected αvβ6targeting and pharmacokinetics. Although the C-terminally PEGylated 4 showed some improvements over the un-PEGylated 18F-FBA-A20FMDV2 (1), it was the bi-terminally PEGylated 5 that displayed the more favorable combination of high αvβ6affinity, selectivity, and pharmacokinetic profile. In vitro, 5 bound to αvβ6-expressing DX3puroβ6 and BxPC-3 cells with 60.5% ± 3.3% and 48.8% ± 8.3%, respectively, with a significant fraction of internalization (37.2% ± 4.0% and 37.6% ± 4.1% of total radioactivity, respectively). By comparison, in the DX3puro control 5 showed only 3.0% ± 0.5% binding and 0.9% ± 0.2% internalization. In vivo, 5 maintained high, αvβ6-directed binding in the paired DX3puroβ6-DX3puro model (1 h: DX3puroβ6, 2.3 ± 0.2 percentage injected dose per gram [%ID/g]; DX3puroβ6/DX3puro ratio, 6.5:1; 4 h: 10.7:1). In the pancreatic BxPC-3 model, uptake was 4.7 ± 0.9%ID/g (1 h) despite small tumor sizes (20-80 mg). Conclusion: The bi-PEGylated radiotracer 5 showed a greatly improved pharmacokinetic profile, beyond what was predicted from individual N- or C-terminal PEGylation. It appears that the 2 PEG units acted synergistically to result in an improved metabolic profile including high αvβ6+ tumor uptake and retention.

KW - Integrin α<inf>v</inf>β<inf>6</inf>

KW - Metabolism

KW - PEGylation

KW - Peptide

KW - Positron emission tomography

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