Researchers in Netherlands have shown the potential to pre-target the treatment of cancer cells, by bringing personalized medicine one step closer from the laboratory to patients.
Pretargeting combines new molecular imaging techniques with targeted therapy, and offers a more individualized treatment for cancer patients.
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In traditional radioimmunoimaging (RAII), radioisotopes are linked directly to antibodies and are delivered together to tumor targets.
However, this approach has limited sensitivity and selectivity.
"This study demonstrates the advantages of pretargeting-an alternative strategy that uses a 'two-step' approach to the delivery of radioisotopes-when applied to the imaging of tumors using a combination of radioisotope and antibody or RAII," said Otto Boerman, lead researcher of the study.
Boerman claimed that in this process, a bispecific monoclonal antibody (bsMAb), with one arm that recognizes a tumor-associated antigen and another arm that recognizes a peptide carrying an imaging agent, is given as a first injection.
When the non-tumor-bound bsMAb has substantially cleared non-target tissues and has reached a maximum level in the tumor, the bsMAb-recognizable imaging agent is given.
The latter agent either targets the bsMAb localized at the tumor or is rapidly removed in the urine.
Because the delivery of imaging isotopes is rapid and is separated from the long antibody delivery process, radioisotope uptake in the tumor is significantly higher than in the blood, making pretargeting RAII an attractive alternative to traditional RAII.
"Pretargeting has applications beyond molecular imaging. As has been demonstrated in this study, pretargeting with bsMAb can also be employed to improve the selective delivery of therapeutic isotopes, as well as cytotoxic drugs, to cancers. In fact, the major attribute of pretargeting is that the same bsMAb can be used for diagnostic imaging and therapy," said Boerman.
In the study, high specific uptake was obtained in human colon cancer cells transplanted in mice, resulting in very high tumor-to-blood and tumor-to-kidney ratios of radioisotope uptake.
The study was presented at the SNM 55th Annual Meeting.