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Further characterization of the epidermal growth factor receptor ligand 11C-PD153035.

BACKGROUND
(11)C-4-N-(3-bromoanilino)-6,7-dimethoxyquinazoline ((11)C-PD153035) has been reported as a tracer for imaging human tumors that overexpress epidermal growth factor receptor (EGFR). However it is still unclear whether (11)C-PD153035 uptake correlates with EGFR expression levels. The objective of this study was to investigate the relationship between (11)C-PD153035 accumulation and EGFR expression levels.


METHODS
Synthesis of (11)C-PD153035 was performed in the Tracerlab FXc system. Accumulation of (11)C-PD153035 by MDA-MB-468, A549 and MDA-MB-231 cells was measured in vitro. There were six tumor-bearing mice in each group. (11)C-PD153035 uptake in tumors was determined by positron emission tomography/computed tomography (PET/CT). Tumor/normal muscle tissue (T/NT) analysis in PET images was applied to quantify the PET data. Sixty minutes after PET/CT scanning, the nude mice were sacrificed and the tumors were excised. The (11)C-PD153035 accumulation in different tumors was determined by a gamma counter.


RESULTS
Close correlation existed between the uptake and the level of EGFR expression both in vitro and ex vivo (r(2) = 0.72, P < 0.001; r(2) = 0.63, P = 0.003). When the static T/NT analysis method was applied to analyze the PET data, the observed correlation was again excellent (r(2) = 0.70, P = 0.001).


CONCLUSIONS
The uptake of PET tracer (11)C-PD153035 closely correlates with the EGFR expression levels in tumor cells. (11)C-PD153035 has the potential to yield useful information for both cancer diagnosis and therapy.