January 17, 2006
Antibody and Magnetic Nanoparticles Provide Double Targeting to Liver Cancer Cells
Cancer researchers have long sought to harness the tumor-targeting ability of monoclonal antibodies with the cell-killing property of radioisotopes, particularly iodine-131 ( 131I). But clinical results with numerous 131I-antibody formulations have failed to live up to expectations, in large part because the therapy is not specific enough for tumors. In attempt to remedy that problem, a group led by Jin Chen, Ph.D., and Changsheng Xie, Ph.D., both at Huazhong University of Science & Technology in Wuhan, China, has added magnetic nanoparticles to the 131I-antibody preparation, and the preliminary results suggest that this approach could be promising for treating human liver cancer.
Writing in the journal Cancer Letters, the investigators describe how they coupled dextran-coated magnetic nanoparticles to an 131I-labeled monoclonal antibody that binds to vascular endothelial growth factor (VEGF), a protein found on the surface of the blood vessels that surround most solid tumors. The idea here was that a focused magnetic field could be used as an initial targeting vector that would concentrate radioactively labeled antibody in the vicinity of a tumor. Once there, the antibody would provide a second level of targeting to the blood vessels surrounding the tumor. Radiation would then kill the neighboring malignant cells.
Results in mice with implanted human liver tumors found that a focused magnetic field did indeed concentrate the nanoparticle-antibody formulation as desired, with very little of the formulation accumulating in healthy tissue. In a second experiment, animals in which the nanoparticle-antibody formulation was injected into tumors experienced a marked shrinkage of the tumors, with little toxicity as measured by white blood cell production and weight loss. This work is detailed in a paper titled, “Using anti-VEGF McAb and magnetic nanoparticles as double-targeting vector for the radioimmunotherapy of liver cancer.” An abstract is available through PubMed.