ImmunoPET imaging of B-cell lymphoma using 124I-anti-CD20 scFv dimers (diabodies)

Tove Olafsen, Shannon J. Sirk, David J. Betting, Vania E. Kenanova, Karl B. Bauer, Waldemar Ladno, Andrew A. Raubitschek, John M. Timmerman, Anna M. Wu

Research output: Contribution to journalArticlepeer-review


Rapid clearing engineered antibody fragments for immunoPET promise high sensitivity at early time points. Here, tumor targeting of anti-CD20 diabodies (scFv dimers) for detection of low-grade B-cell lymphomas were evaluated. In addition, the effect of linker length on oligomerization of the diabody was investigated. Four rituximab scFv variants in the VL-VH orientation with different linker lengths between the V domains (scFv-1, scFv-3, scFv-5, scFv-8), plus the scFv-5 with a C-terminal cysteine (Cys-Db) for site-specific modification were generated. The scFv-8 and Cys-Db were radioiodinated with 124I for PET imaging, and biodistribution of 131I-Cys-Db was carried out at 2, 4 10 and 20 h. The five anti-CD20 scFv variants were expressed as fully functional dimers. Shortening the linker to three or one residue did not produce higher order of multimers. Both 124I-labeled scFv-8 and Cys-Db exhibited similar tumor targeting at 8 h post injection, with significantly higher uptakes than in control tumors (P < 0.05). At 20 h, less than 1 ID/g of 131I-labeled Cys-Db was present in tumors and tissues. Specific tumor targeting and high contrast images were achieved with the anti-CD20 diabodies. These agents extend the repertoire of reagents that can potentially be used to improve detection of low-grade lymphomas.

Original languageEnglish (US)
Pages (from-to)243-249
Number of pages7
JournalProtein Engineering, Design and Selection
Issue number4
StatePublished - Apr 2010
Externally publishedYes


  • CD20
  • PET
  • lymphoma model
  • scFv

ASJC Scopus subject areas

  • Medicine(all)


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