Oncotarget

Research Papers:

A comparison of 64Cu-labeled bi-terminally PEGylated A20FMDV2 peptides targeting integrin ανβ6

Truc T. Huynh, Sreeja Sreekumar, Cedric Mpoy and Buck E. Rogers _

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Abstract

Truc T. Huynh1,2, Sreeja Sreekumar1, Cedric Mpoy1 and Buck E. Rogers1

1 Department of Radiation Oncology, Washington University School of Medicine, St. Louis, MO, USA

2 Department of Chemistry, Washington University, St. Louis, MO, USA

Correspondence to:

Buck E. Rogers, email: b.rogers@wustl.edu

Keywords: integrin ανβ6; PEGylation; Copper-64; DOTA; PCTA

Abbreviations: DOTA: (S-2-(4-isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane-tetraacetic acid); PCTA: (3,6,9,15-tetraazabicyclo[9.3.1]pentadeca-1(15),11,13-triene-4-S-(4-isothiocyanatobenzyl)-3,6,9-triacetic acid); MFU: mean fluorescence unit

Received: November 23, 2021     Accepted: February 07, 2022     Published: February 16, 2022

Copyright: © 2022 Huynh et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

ABSTRACT

Expression of epithelial-specific integrin ανβ6 is up-regulated in various aggressive cancers and serves as a prognostic marker. Integrin-targeted PET imaging probes have been successfully developed and tested in the clinic. Radiotracers based on the peptide A20FMDV2 derived from foot-and-mouth disease virus represent specific and selective PET ligands for imaging ανβ6-positive cancers. The present study aims to describe the radiolabeling, in vitro and in vivo evaluation of a bi-terminally PEGylated A20FMDV2 conjugated with DOTA or PCTA for 64Cu radiolabeling. Stability studies showed radiolabeled complexes remained stable up to 24 h in PBS and human serum. In vitro cell assays in CaSki cervical cancer cells and BxPC-3 pancreatic cancer cells confirmed that the peptides displayed high affinity for αvβ6 with Kd values of ~50 nM. Biodistribution studies revealed that [64Cu] Cu-PCTA-(PEG28)2-A20FMDV2 exhibited higher tumor uptake (1.63 ± 0.53 %ID/g in CaSki and 3.86 ± 0.58 %ID/g in BxPC-3 at 1 h) when compared to [64Cu]Cu-DOTA-(PEG28)2-A20FMDV2 (0.95 ± 0.29 %ID/g in CaSki and 2.12 ± 0.83 %ID/g in BxPC-3 at 1 h) . However, higher tumor uptake was accompanied by increased radioactive uptake in normal organs. Therefore, both peptides are appropriate for imaging ανβ6-positive lesions although further optimization is needed to improve tumor-to-normal-tissue ratios.


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