Chemical modification to reduce renal uptake of disulfide-bonded variable region fragment of anti-Tac monoclonal antibody labeled with 99mTc

In S. Kim, Tae M. Yoo, Hisataka Kobayashi, Meyoung Kon Kim, Nhat Le, Q. C. Wang, Ira Pastan, Jorge A. Carrasquillo, Chang H. Paik

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)

Abstract

The anti-Tac disulfide-bonded variable region fragment (dsFv) is a genetically engineered, 25 kDa, murine monoclonal antibody fragment that recognizes the α subunit of the interleukin-2 receptor (IL-2Rα). The dsFv radiolabeled with the tetrafluorophenyl ester (TFP) of [99mTc]mercaptoacetyltriglycine ([99mTc]MAG3-TFP) showed rapid tumor uptake and fast blood clearance in mice, resulting in high tumor-to-nontumor background ratios. However, its high renal uptake was a problem. In this study, we tested the effect of lowering the isoelectric point (pI) of dsFv to <9.3 on renal and tumor uptake. To lower the pI, dsFv was acylated simultaneously with both [99mTc]MAG3-TFP and TFP-glycolate. The acylation of dsFv decreased its pI and its immunoreactivity inversely proportional to the molar ratio of TFP-glycolate to dsFv, whereas the conjugation of [99mTc]MAG3-TFP alone did not. When biodistribution studies were performed in nude mice, the effect of the lowered pI was reflected primarily in decreased kidney uptake and whole-body retention, with its highest effect seen at the earliest time point (15 min) after injection. In tumor-bearing nude mice, glycolated [99mTc]MAG3-dsFv with a pI range of 4.9 to 6.5 accumulated selectively into IL-2 receptor-positive SP2/Tac tumor similar to that of the control [125I]dsFv labeled by the Iodo-Gen method, whereas its renal uptake was 25% of [125I]dsFv at 15 min. At 90 min, the ratios of tumor to receptor-negative SP2/0 tumor, liver, kidney, stomach, and blood had peaked at 10.9, 8.5, 0.3, 5.0, and 6.2, respectively, for the glycolated [99mTc]MAG3-dsFv. The corresponding ratios for [125I]dsFv were 3.7, 5.0, 0.1, 1.5, and 2.1, respectively.

Original languageEnglish
Pages (from-to)447-453
Number of pages7
JournalBioconjugate Chemistry
Volume10
Issue number3
DOIs
Publication statusPublished - 1999 May
Externally publishedYes

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Biomedical Engineering
  • Pharmacology
  • Pharmaceutical Science
  • Organic Chemistry

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