Nanoprobe Points to Outcome Following Tumor Treatment

Liposomal probe with iodine enhanced rat tumors on imaging; uptake linked to treatment outcome

THURSDAY, Feb. 5 (HealthDay News) -- A method of assessing vascular permeability in tumors in rats using a nanoprobe helped predict the effect of later treatment with liposomal doxorubicin, according to research published in the February issue of Radiology.

Efstathios Karathanasis, Ph.D., of the Georgia Institute of Technology/Emory University in Atlanta, and colleagues analyzed data from rats that had been injected with mammary adenocarcinoma cells. On the sixth day after tumor inoculation, animals were injected with a 100-nanometer-scale liposomal probe containing iodine, then were imaged with a digital mammography system over three days. After the final imaging, animals were injected with liposomal doxorubicin.

The tumors collected enough of the probe to provide sufficient signal for detection, without producing a detectable signal from the blood, the investigators found. The tumors demonstrated different vasculature leakiness, and over the period of imaging some tumors showed faster and more pronounced enhancement than others. The doxorubicin slowed tumor progress in treated animals compared to untreated controls, the researchers report. Higher probe uptake in tumors -- suggesting leakier vasculature -- was associated with slower tumor growth rate, the report indicates.

"Our study demonstrates a contrast agent with the potential of helping to predict the therapeutic outcome of a clinically used nanoparticle-based chemotherapeutic agent," the authors write. "In our study, although planar x-ray imaging enabled prognosis by employing a clinically relevant breast cancer imaging modality, mammography, we hypothesize that such a strategy would also be possible with tomographic methods (e.g., computed tomography), yielding further insights."

Two of the study co-authors founded a company to which a contrast formulation similar to the one used in this study has been licensed.

Abstract
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