A combination of new molecular imaging techniques and targeted therapy could help give cancer patients a more individualized treatment for their cancer and avoid discomfort associated with prevailing treatment methods.
In traditional radioimmunoimaging (RAII), radioisotopes are linked directly to antibodies and are delivered together to tumour targets.
In the targeted therapy a bispecific monoclonal antibody (bsMAb), with one arm that recognizes a tumour-associated antigen and another arm that recognizes a peptide carrying an imaging agent, is given as a first injection
"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 tumours using a combination of radioisotope and antibody or RAII," said Otto Boerman, professor in the department of nuclear medicine, Radboud University Nijmegen Medical Center, Nijmegen, Netherlands, and lead researcher of this study.
During the study, high specific uptake was obtained in human colon cancer cells transplanted in mice, resulting in very high tumour-to-blood and tumour-to-kidney ratios of radioisotope uptake.
Additionally, PET/CT imaging of mice pretargeted with the bispecific antibody 16 hours earlier revealed excellent high-contrast images of CEA-expressing tumours within one hour after injection.
The major attribute of pretargeting is that the same bsMAb can be used for diagnostic imaging and therapy," said Boerman.
"When the imaging component of a pretargeting agent is used in concert with the therapeutic component, it permits the selection of a patient population that over-expresses a particular antigen, thus increasing these pre-screened patients' probability of responding to the therapeutic."
"The prescreening of patients afforded by pretargeting prior to therapy represents a potential major advancement in the management of neoplastic diseases," Boerman added.
The study was presented at SNM's 55th Annual Meeting.