Boron delivery to a murine lung carcinoma using folate receptor-targeted liposomes

Anticancer Res. May-Jun 2002;22(3):1629-33.


Background: Folate receptor (FR) is amplified in a variety of human tumors. Folate-derived liposomes have been shown to selectively deliver entrapped agents into tumor cells via receptor-mediated endocytosis. In this preliminary study, the biodistribution of FR-targeted liposomes were evaluated as a potential delivery agent for Na3 (B20H17NH3) for boron neutron capture therapy (BNCT) of FR(+) tumors.

Materials and methods: Na3 (B20H17NH3) was incorporated into liposomes by passive entrapment, following which they were administered intravenously into BALB/c mice bearing subcutaneous implants of FR(+) M109 murine lung carcinoma. Tumor and normal tissue boron content was measured by direct current plasma atomic emission spectroscopy.

Results: Mice that received FR-targeted and non-targeted control liposomes showed indistinguishable levels of tumor boron uptake (up to 85 microg/g tumor), which reached a maximum at the 24 hour time-point, while the tumor-to-blood (T/B) ratio continued to rise until the 72 hour time-point.

Conclusion: High-level boron delivery is possible using liposomes as a delivery agent. FR targeting does not significantly enhance overall tumor localization but may improve boron delivery at the cellular and subcellular levels, which warrant further investigation.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Boron / administration & dosage
  • Boron / pharmacokinetics
  • Boron Compounds / administration & dosage*
  • Boron Compounds / pharmacokinetics
  • Boron Neutron Capture Therapy / methods*
  • Carrier Proteins / metabolism*
  • Female
  • Folate Receptors, GPI-Anchored
  • Liposomes / administration & dosage
  • Liposomes / metabolism
  • Lung Neoplasms / metabolism*
  • Lung Neoplasms / therapy
  • Mice
  • Mice, Inbred BALB C
  • Receptors, Cell Surface*
  • Tissue Distribution
  • Tumor Cells, Cultured


  • Boron Compounds
  • Carrier Proteins
  • Folate Receptors, GPI-Anchored
  • Liposomes
  • Receptors, Cell Surface
  • Boron