Biodistribution Study of Intravenously Injected Cetuximab-IRDye700DX in Cynomolgus Macaques

Mol Imaging Biol. 2016 Apr;18(2):232-42. doi: 10.1007/s11307-015-0892-y.


Purpose: The use of receptor-targeted antibodies conjugated to photosensitizers is actively being explored to enhance treatment efficacy. To facilitate clinical testing, we evaluated cetuximab conjugated to IRDye700DX (IR700) in cynomolgus macaques.

Procedures: Total IR700 and intact cetuximab-IR700 were measured in 51 tissues at 2 and 14 days after intravenous injection of 40 and 80 mg/kg cetuximab-IR700, respectively, and compared with an unlabeled cetuximab-dosed control group (two each per sex per time point per group).

Results: The IR700 retrieved from all tissues at 2 and 14 days after dosing was estimated at 34.9 ± 1.8 and 2.53 ± 0.67% of the total dose, respectively. The tissues with the highest levels of intact cetuximab-IR700 at 2 days after dosing were the blood, lung, and skin. Formalin-fixed paraffin-embedded tissue sections at 2 days after dosing showed the highest IR700 signals in the axillary lymph node, mammary gland, and gall bladder.

Conclusions: Both IR700 and intact cetuximab-IR700 biodistributions were consistent with known epidermal growth factor receptor (EGFR) expression, and changes between 2 and 14 days were consistent with rapid metabolism and excretion of the cetuximab-IR700.

Keywords: Biodistribution; Cetuximab; IRDye700DX; Macaques; Photoimmunotherapy.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cetuximab / administration & dosage*
  • Cetuximab / metabolism*
  • Coloring Agents / metabolism*
  • Female
  • Fluorescence
  • Injections, Intravenous
  • Macaca fascicularis
  • Male
  • Molecular Imaging / methods*
  • Tissue Distribution


  • Coloring Agents
  • Cetuximab