Targeting breast carcinoma with radioiodinated anti-HER2 Nanobody.

Published

Journal Article

INTRODUCTION: With a molecular weight an order of magnitude lower than antibodies but possessing comparable affinities, Nanobodies (Nbs) are attractive as targeting agents for cancer diagnosis and therapy. An anti-HER2 Nb could be utilized to determine HER2 status in breast cancer patients prior to trastuzumab treatment. This provided motivation for the generation of HER2-specific 5F7GGC Nb, its radioiodination and evaluation for targeting HER2 expressing tumors. METHODS: 5F7GGC Nb was radioiodinated with ¹²⁵I using Iodogen and with ¹³¹I using the residualizing agent N(ɛ)-(3-[¹³¹I]iodobenzoyl)-Lys⁵-N(α)-maleimido-Gly¹-GEEEK ([¹³¹I]IB-Mal-D-GEEEK) used previously successfully with intact antibodies. Paired-label internalization assays using BT474M1 cells and tissue distribution experiments in athymic mice bearing BT474M1 xenografts were performed to compare the two labeled Nb preparations. RESULTS: The radiochemical yields for Iodogen and [¹³¹I]IB-Mal-D-GEEEK labeling were 83.6±5.0% (n=10) and 59.6±9.4% (n=15), respectively. The immunoreactivity of labeled proteins was preserved as confirmed by in vitro and in vivo binding to tumor cells. Biodistribution studies showed that Nb radiolabeled using [¹³¹I]IB-Mal-D-GEEEK, compared with the directly labeled Nb, had a higher tumor uptake (4.65±0.61% ID/g vs. 2.92±0.24% ID/g at 8h), faster blood clearance, lower accumulation in non-target organs except kidneys, and as a result, higher concomitant tumor-to-blood and tumor-to-tissue ratios. CONCLUSIONS: Taken together, these results demonstrate that 5F7GGC anti-HER2 Nb labeled with residualizing [¹³¹I]IB-Mal-D-GEEEK had better tumor targeting properties compared to the directly labeled Nb suggesting the potential utility of this Nb conjugate for SPECT (¹²⁹I) and PET imaging (¹²⁴I) of patients with HER2-expressing tumors.

Full Text

Duke Authors

Cited Authors

  • Pruszynski, M; Koumarianou, E; Vaidyanathan, G; Revets, H; Devoogdt, N; Lahoutte, T; Zalutsky, MR

Published Date

  • January 2013

Published In

Volume / Issue

  • 40 / 1

Start / End Page

  • 52 - 59

PubMed ID

  • 23159171

Pubmed Central ID

  • 23159171

Electronic International Standard Serial Number (EISSN)

  • 1872-9614

Digital Object Identifier (DOI)

  • 10.1016/j.nucmedbio.2012.08.008

Language

  • eng

Conference Location

  • United States